feat(rust): port divsufsort

Move the dictionary builder's suffix-array construction from
lib/dictBuilder/divsufsort.c to rust/src/divsufsort.rs, the first
dictBuilder module to migrate.  It rides on the dict-builder cargo
feature dimension introduced by the previous commit.

divsufsort() is a self-contained algorithm (two-stage sort of type-B*
substrings via sssort, rank refinement via trsort, then induced sorting
of the full array), so its context-free signature allows a direct symbol
takeover: the Rust #[no_mangle] export provides the existing `divsufsort`
symbol and the C file becomes a declaration-only shim that just keeps the
header's prototypes in the build.  Only divsufsort() moved; divbwt() has
no callers anywhere in zstd, so it is now declaration-only, keeping the
Rust export surface minimal.  The unused openMP parameter is retained for
signature compatibility (zstd never defines LIBBSC_OPENMP).

The port is a mechanical translation of the exact configuration zstd
compiles: ALPHABET_SIZE=256, SS_INSERTIONSORT_THRESHOLD=8,
SS_BLOCKSIZE=1024, SS_MISORT_STACKSIZE=16, SS_SMERGE_STACKSIZE=32,
TR_STACKSIZE=64.  Every C `int*` cursor into the SA buffer becomes an
`isize` index into a single `&mut [i32]` slice, preserving the pointer
arithmetic (including transient one-before-the-range cursors and the
bitwise-complement rank marking) while staying bounds-checked; all value
arithmetic keeps C int semantics.  The C -1/-2 error results are
preserved, with Vec::try_reserve_exact standing in for the bucket-array
malloc failure path.  Behavior is bit-identical by construction and by
measurement (see test plan); runtime on an 11 MB training buffer is
within ~5% of the C build end-to-end.

Users see no behavioral change: dictionaries trained through
ZDICT_trainFromBuffer_legacy() are byte-identical to the C build.  The
only external difference is that the never-called `divbwt` symbol is no
longer defined in the library.

Test plan:
- cd rust && cargo fmt --check && cargo clippy --all-targets
  -- -D warnings && cargo test --all-targets && cargo build --release
  (125 tests pass; new unit tests cover empty/one/two-byte inputs,
  all-equal bytes, an exact hand-computed "abracadabra" SA, and
  fixed-seed LCG buffers at 256-, 4-, and 2-symbol alphabets verified
  against a naive reference sort plus permutation/sorted invariants)
- Feature matrix: cargo build --release --no-default-features
  --features compression,decompression (and decompression-only,
  compression-only, compression,dict-builder); `divsufsort` is exported
  only when dict-builder is enabled
- make -C tests fuzzer && ./tests/fuzzer -i1 --no-big-tests (includes
  ZDICT training tests): pass
- make -C tests test-rust-lib-smoke: pass
- make -C tests test-invalidDictionaries: pass
- make -C programs zstd zstd-dictBuilder zstd-small zstd-compress
  zstd-decompress: build; compress/decompress round-trip verified
- Byte-identity vs pristine C build (commit 959e4852): a harness calling
  ZDICT_trainFromBuffer_legacy() (the only zstd path reaching
  divsufsort) and divsufsort() directly, linked against both libzstd.a
  builds, produces byte-identical dictionaries (80,288 B and full
  112,640 B capacity) and byte-identical suffix arrays on a 1 MB source
  set and an 11 MB binary/repetitive set; a differential driver over 148
  random and structured buffers (sizes 3..6000, alphabets 1..256,
  Fibonacci word, sawtooth, 6 KB near-constant) shows zero mismatches.
  The CLI --train path could not be exercised because the Rust CLI
  frontend rejects --train in both the pristine and ported builds (a
  pre-existing migration gap unrelated to this change).

build/cmake/lib/CMakeLists.txt

@@ -142,6 +142,7 @@ endif()
 set(_zstd_rust_features)
 set(_zstd_rust_compression 0)
 set(_zstd_rust_decompression 0)
+set(_zstd_rust_dictbuilder 0)
 if(ZSTD_BUILD_COMPRESSION)
     list(APPEND _zstd_rust_features compression)
     set(_zstd_rust_compression 1)
@@ -150,6 +151,10 @@ if(ZSTD_BUILD_DECOMPRESSION)
     list(APPEND _zstd_rust_features decompression)
     set(_zstd_rust_decompression 1)
 endif()
+if(ZSTD_BUILD_DICTBUILDER)
+    list(APPEND _zstd_rust_features dict-builder)
+    set(_zstd_rust_dictbuilder 1)
+endif()
 
 set(_zstd_rust_huf_mode default)
 if(_zstd_huf_force_x1)
@@ -190,7 +195,7 @@ if(_zstd_rust_features)
 endif()
 
 set(_zstd_rust_build_config
-    "c${_zstd_rust_compression}-d${_zstd_rust_decompression}-${_zstd_rust_huf_mode}")
+    "c${_zstd_rust_compression}-d${_zstd_rust_decompression}-b${_zstd_rust_dictbuilder}-${_zstd_rust_huf_mode}")
 set(ZSTD_RUST_MANIFEST "${ZSTD_SOURCE_DIR}/rust/Cargo.toml")
 set(ZSTD_RUST_TARGET_DIR
     "${CMAKE_CURRENT_BINARY_DIR}/rust-target/${_zstd_rust_build_config}")

build/meson/lib/meson.build

@@ -73,7 +73,9 @@ if rust_huf_force_x1 and rust_huf_force_x2
   error('HUF_FORCE_DECOMPRESS_X1 and HUF_FORCE_DECOMPRESS_X2 are mutually exclusive')
 endif
 
-rust_features = ['compression', 'decompression']
+# Meson always compiles the dictBuilder sources above, so the Rust archive
+# must always carry the matching dict-builder module set.
+rust_features = ['compression', 'decompression', 'dict-builder']
 rust_huf_mode = 'default'
 rust_huf_c_args = []
 if rust_huf_force_x1
@@ -96,7 +98,7 @@ if rust_target == ''
   endif
 endif
 
-rust_build_config = 'c1-d1-' + rust_huf_mode
+rust_build_config = 'c1-d1-b1-' + rust_huf_mode
 rust_target_dir = join_paths(meson.current_build_dir(), 'rust-target', rust_build_config)
 is_msvc = cc_id == compiler_msvc or cc_id == 'clang-cl'
 rust_staticlib_name = is_msvc ? 'zstd_rs.lib' : 'libzstd_rs.a'

lib/Makefile

@@ -84,16 +84,20 @@ endif
 ifneq ($(ZSTD_LIB_DECOMPRESSION),0)
 RUST_CARGO_FEATURES += decompression
 endif
+ifneq ($(ZSTD_LIB_DICTBUILDER),0)
+RUST_CARGO_FEATURES += dict-builder
+endif
 
+RUST_MODULE_CONFIG := c$(ZSTD_LIB_COMPRESSION)-d$(ZSTD_LIB_DECOMPRESSION)-b$(ZSTD_LIB_DICTBUILDER)
 RUST_HUF_FEATURE :=
-RUST_BUILD_CONFIG := c$(ZSTD_LIB_COMPRESSION)-d$(ZSTD_LIB_DECOMPRESSION)-default
+RUST_BUILD_CONFIG := $(RUST_MODULE_CONFIG)-default
 ifneq ($(RUST_HUF_FORCE_X1),0)
 RUST_HUF_FEATURE := huf-force-decompress-x1
-RUST_BUILD_CONFIG := c$(ZSTD_LIB_COMPRESSION)-d$(ZSTD_LIB_DECOMPRESSION)-huf-force-decompress-x1
+RUST_BUILD_CONFIG := $(RUST_MODULE_CONFIG)-huf-force-decompress-x1
 endif
 ifneq ($(RUST_HUF_FORCE_X2),0)
 RUST_HUF_FEATURE := huf-force-decompress-x2
-RUST_BUILD_CONFIG := c$(ZSTD_LIB_COMPRESSION)-d$(ZSTD_LIB_DECOMPRESSION)-huf-force-decompress-x2
+RUST_BUILD_CONFIG := $(RUST_MODULE_CONFIG)-huf-force-decompress-x2
 endif
 ifneq ($(RUST_HUF_FEATURE),)
 ifneq ($(ZSTD_LIB_DECOMPRESSION),0)

lib/compress/zstd_compress.c

@@ -88,67 +88,6 @@ size_t ZSTD_rust_params_estimateCDictSizeFromCParams(
         size_t dictSize, ZSTD_compressionParameters cParams,
         int dictLoadMethod, const ZSTD_rustCDictSizing* sizing);
 
-/* Sequence statistics and seqStore entropy compression live in Rust
- * (rust/src/zstd_compress_stats.rs), which also exports ZSTD_seqToCodes()
- * under its original name.  The shims below extract the sequence store, the
- * entropy-table leaves, and the only two ZSTD_CCtx_params fields these paths
- * read (the strategy and the literals-compression switch), so the private
- * parameter structure layout never crosses the language boundary.  The
- * shared leaf layouts are pinned by the compile-time asserts that follow. */
-size_t ZSTD_rust_entropyCompressSeqStore_internal(
-        void* dst, size_t dstCapacity,
-        const void* literals, size_t litSize,
-        const SeqStore_t* seqStorePtr,
-        const ZSTD_entropyCTables_t* prevEntropy,
-        ZSTD_entropyCTables_t* nextEntropy,
-        int strategy, int disableLiteralCompression,
-        void* entropyWorkspace, size_t entropyWkspSize,
-        int bmi2);
-size_t ZSTD_rust_entropyCompressSeqStore(
-        const SeqStore_t* seqStorePtr,
-        const ZSTD_entropyCTables_t* prevEntropy,
-        ZSTD_entropyCTables_t* nextEntropy,
-        int strategy, int disableLiteralCompression,
-        void* dst, size_t dstCapacity,
-        size_t srcSize,
-        void* entropyWorkspace, size_t entropyWkspSize,
-        int bmi2);
-size_t ZSTD_rust_buildBlockEntropyStats(
-        const SeqStore_t* seqStorePtr,
-        const ZSTD_entropyCTables_t* prevEntropy,
-        ZSTD_entropyCTables_t* nextEntropy,
-        int strategy, int disableLiteralCompression,
-        ZSTD_entropyCTablesMetadata_t* entropyMetadata,
-        void* workspace, size_t wkspSize);
-size_t ZSTD_rust_copyBlockSequences(
-        SeqCollector* seqCollector, const SeqStore_t* seqStore,
-        const U32 prevRepcodes[ZSTD_REP_NUM]);
-
-typedef char ZSTD_rust_stats_seqdef_layout[(sizeof(SeqDef) == 8) ? 1 : -1];
-typedef char ZSTD_rust_stats_seqstore_long_length_pos[
-        (offsetof(SeqStore_t, longLengthPos) == 9 * sizeof(size_t) + 4) ? 1 : -1];
-typedef char ZSTD_rust_stats_seqstore_layout[
-        (sizeof(SeqStore_t) == 9 * sizeof(size_t) + 8) ? 1 : -1];
-typedef char ZSTD_rust_stats_huf_layout[
-        (sizeof(ZSTD_hufCTables_t) == 258 * sizeof(size_t)) ? 1 : -1];
-typedef char ZSTD_rust_stats_fse_layout[(sizeof(ZSTD_fseCTables_t) == 3552) ? 1 : -1];
-typedef char ZSTD_rust_stats_entropy_fse_offset[
-        (offsetof(ZSTD_entropyCTables_t, fse) == sizeof(ZSTD_hufCTables_t)) ? 1 : -1];
-typedef char ZSTD_rust_stats_huf_metadata_buffer[
-        (offsetof(ZSTD_hufCTablesMetadata_t, hufDesBuffer) == 4
-         && ZSTD_MAX_HUF_HEADER_SIZE == 128) ? 1 : -1];
-typedef char ZSTD_rust_stats_fse_metadata_buffer[
-        (offsetof(ZSTD_fseCTablesMetadata_t, fseTablesBuffer) == 12
-         && ZSTD_MAX_FSE_HEADERS_SIZE == 133) ? 1 : -1];
-typedef char ZSTD_rust_stats_entropy_metadata_layout[
-        (offsetof(ZSTD_entropyCTablesMetadata_t, fseMetadata)
-                == sizeof(ZSTD_hufCTablesMetadata_t)) ? 1 : -1];
-typedef char ZSTD_rust_stats_sequence_layout[(sizeof(ZSTD_Sequence) == 16) ? 1 : -1];
-typedef char ZSTD_rust_stats_seqcollector_layout[
-        (offsetof(SeqCollector, seqStart) == sizeof(size_t)
-         && offsetof(SeqCollector, seqIndex) == 2 * sizeof(size_t)
-         && sizeof(SeqCollector) == 4 * sizeof(size_t)) ? 1 : -1];
-
 #if ZSTD_ADDRESS_SANITIZER && !defined (ZSTD_ASAN_DONT_POISON_WORKSPACE)
 #  define ZSTD_RUST_ASAN_REDZONE_SIZE ((size_t)ZSTD_CWKSP_ASAN_REDZONE_SIZE)
 #else
@@ -2622,7 +2561,33 @@ static void ZSTD_reduceIndex (ZSTD_MatchState_t* ms, ZSTD_CCtx_params const* par
 
 /* See doc/zstd_compression_format.md for detailed format description */
 
-/* ZSTD_seqToCodes() lives in rust/src/zstd_compress_stats.rs. */
+int ZSTD_seqToCodes(const SeqStore_t* seqStorePtr)
+{
+    const SeqDef* const sequences = seqStorePtr->sequencesStart;
+    BYTE* const llCodeTable = seqStorePtr->llCode;
+    BYTE* const ofCodeTable = seqStorePtr->ofCode;
+    BYTE* const mlCodeTable = seqStorePtr->mlCode;
+    U32 const nbSeq = (U32)(seqStorePtr->sequences - seqStorePtr->sequencesStart);
+    U32 u;
+    int longOffsets = 0;
+    assert(nbSeq <= seqStorePtr->maxNbSeq);
+    for (u=0; u<nbSeq; u++) {
+        U32 const llv = sequences[u].litLength;
+        U32 const ofCode = ZSTD_highbit32(sequences[u].offBase);
+        U32 const mlv = sequences[u].mlBase;
+        llCodeTable[u] = (BYTE)ZSTD_LLcode(llv);
+        ofCodeTable[u] = (BYTE)ofCode;
+        mlCodeTable[u] = (BYTE)ZSTD_MLcode(mlv);
+        assert(!(MEM_64bits() && ofCode >= STREAM_ACCUMULATOR_MIN));
+        if (MEM_32bits() && ofCode >= STREAM_ACCUMULATOR_MIN)
+            longOffsets = 1;
+    }
+    if (seqStorePtr->longLengthType==ZSTD_llt_literalLength)
+        llCodeTable[seqStorePtr->longLengthPos] = MaxLL;
+    if (seqStorePtr->longLengthType==ZSTD_llt_matchLength)
+        mlCodeTable[seqStorePtr->longLengthPos] = MaxML;
+    return longOffsets;
+}
 
 /* ZSTD_useTargetCBlockSize():
  * Returns if target compressed block size param is being used.
@@ -2646,11 +2611,150 @@ static int ZSTD_blockSplitterEnabled(ZSTD_CCtx_params* cctxParams)
     return (cctxParams->postBlockSplitter == ZSTD_ps_enable);
 }
 
-/* ZSTD_buildSequencesStatistics() and the ZSTD_entropyCompressSeqStore*()
+/* Type returned by ZSTD_buildSequencesStatistics containing finalized symbol encoding types
- * implementations live in rust/src/zstd_compress_stats.rs.  The wrappers
+ * and size of the sequences statistics
- * below keep the original signatures and extract the only two
+ */
- * ZSTD_CCtx_params fields those paths read. */
+typedef struct {
+    U32 LLtype;
+    U32 Offtype;
+    U32 MLtype;
+    size_t size;
+    size_t lastCountSize; /* Accounts for bug in 1.3.4. More detail in ZSTD_entropyCompressSeqStore_internal() */
+    int longOffsets;
+} ZSTD_symbolEncodingTypeStats_t;
 
+/* ZSTD_buildSequencesStatistics():
+ * Returns a ZSTD_symbolEncodingTypeStats_t, or a zstd error code in the `size` field.
+ * Modifies `nextEntropy` to have the appropriate values as a side effect.
+ * nbSeq must be greater than 0.
+ *
+ * entropyWkspSize must be of size at least ENTROPY_WORKSPACE_SIZE - (MaxSeq + 1)*sizeof(U32)
+ */
+static ZSTD_symbolEncodingTypeStats_t
+ZSTD_buildSequencesStatistics(
+                const SeqStore_t* seqStorePtr, size_t nbSeq,
+                const ZSTD_fseCTables_t* prevEntropy, ZSTD_fseCTables_t* nextEntropy,
+                      BYTE* dst, const BYTE* const dstEnd,
+                      ZSTD_strategy strategy, unsigned* countWorkspace,
+                      void* entropyWorkspace, size_t entropyWkspSize)
+{
+    BYTE* const ostart = dst;
+    const BYTE* const oend = dstEnd;
+    BYTE* op = ostart;
+    FSE_CTable* CTable_LitLength = nextEntropy->litlengthCTable;
+    FSE_CTable* CTable_OffsetBits = nextEntropy->offcodeCTable;
+    FSE_CTable* CTable_MatchLength = nextEntropy->matchlengthCTable;
+    const BYTE* const ofCodeTable = seqStorePtr->ofCode;
+    const BYTE* const llCodeTable = seqStorePtr->llCode;
+    const BYTE* const mlCodeTable = seqStorePtr->mlCode;
+    ZSTD_symbolEncodingTypeStats_t stats;
+
+    stats.lastCountSize = 0;
+    /* convert length/distances into codes */
+    stats.longOffsets = ZSTD_seqToCodes(seqStorePtr);
+    assert(op <= oend);
+    assert(nbSeq != 0); /* ZSTD_selectEncodingType() divides by nbSeq */
+    /* build CTable for Literal Lengths */
+    {   unsigned max = MaxLL;
+        size_t const mostFrequent = HIST_countFast_wksp(countWorkspace, &max, llCodeTable, nbSeq, entropyWorkspace, entropyWkspSize);   /* can't fail */
+        DEBUGLOG(5, "Building LL table");
+        nextEntropy->litlength_repeatMode = prevEntropy->litlength_repeatMode;
+        stats.LLtype = ZSTD_selectEncodingType(&nextEntropy->litlength_repeatMode,
+                                        countWorkspace, max, mostFrequent, nbSeq,
+                                        LLFSELog, prevEntropy->litlengthCTable,
+                                        LL_defaultNorm, LL_defaultNormLog,
+                                        ZSTD_defaultAllowed, strategy);
+        assert(set_basic < set_compressed && set_rle < set_compressed);
+        assert(!(stats.LLtype < set_compressed && nextEntropy->litlength_repeatMode != FSE_repeat_none)); /* We don't copy tables */
+        {   size_t const countSize = ZSTD_buildCTable(
+                op, (size_t)(oend - op),
+                CTable_LitLength, LLFSELog, (SymbolEncodingType_e)stats.LLtype,
+                countWorkspace, max, llCodeTable, nbSeq,
+                LL_defaultNorm, LL_defaultNormLog, MaxLL,
+                prevEntropy->litlengthCTable,
+                sizeof(prevEntropy->litlengthCTable),
+                entropyWorkspace, entropyWkspSize);
+            if (ZSTD_isError(countSize)) {
+                DEBUGLOG(3, "ZSTD_buildCTable for LitLens failed");
+                stats.size = countSize;
+                return stats;
+            }
+            if (stats.LLtype == set_compressed)
+                stats.lastCountSize = countSize;
+            op += countSize;
+            assert(op <= oend);
+    }   }
+    /* build CTable for Offsets */
+    {   unsigned max = MaxOff;
+        size_t const mostFrequent = HIST_countFast_wksp(
+            countWorkspace, &max, ofCodeTable, nbSeq, entropyWorkspace, entropyWkspSize);  /* can't fail */
+        /* We can only use the basic table if max <= DefaultMaxOff, otherwise the offsets are too large */
+        ZSTD_DefaultPolicy_e const defaultPolicy = (max <= DefaultMaxOff) ? ZSTD_defaultAllowed : ZSTD_defaultDisallowed;
+        DEBUGLOG(5, "Building OF table");
+        nextEntropy->offcode_repeatMode = prevEntropy->offcode_repeatMode;
+        stats.Offtype = ZSTD_selectEncodingType(&nextEntropy->offcode_repeatMode,
+                                        countWorkspace, max, mostFrequent, nbSeq,
+                                        OffFSELog, prevEntropy->offcodeCTable,
+                                        OF_defaultNorm, OF_defaultNormLog,
+                                        defaultPolicy, strategy);
+        assert(!(stats.Offtype < set_compressed && nextEntropy->offcode_repeatMode != FSE_repeat_none)); /* We don't copy tables */
+        {   size_t const countSize = ZSTD_buildCTable(
+                op, (size_t)(oend - op),
+                CTable_OffsetBits, OffFSELog, (SymbolEncodingType_e)stats.Offtype,
+                countWorkspace, max, ofCodeTable, nbSeq,
+                OF_defaultNorm, OF_defaultNormLog, DefaultMaxOff,
+                prevEntropy->offcodeCTable,
+                sizeof(prevEntropy->offcodeCTable),
+                entropyWorkspace, entropyWkspSize);
+            if (ZSTD_isError(countSize)) {
+                DEBUGLOG(3, "ZSTD_buildCTable for Offsets failed");
+                stats.size = countSize;
+                return stats;
+            }
+            if (stats.Offtype == set_compressed)
+                stats.lastCountSize = countSize;
+            op += countSize;
+            assert(op <= oend);
+    }   }
+    /* build CTable for MatchLengths */
+    {   unsigned max = MaxML;
+        size_t const mostFrequent = HIST_countFast_wksp(
+            countWorkspace, &max, mlCodeTable, nbSeq, entropyWorkspace, entropyWkspSize);   /* can't fail */
+        DEBUGLOG(5, "Building ML table (remaining space : %i)", (int)(oend-op));
+        nextEntropy->matchlength_repeatMode = prevEntropy->matchlength_repeatMode;
+        stats.MLtype = ZSTD_selectEncodingType(&nextEntropy->matchlength_repeatMode,
+                                        countWorkspace, max, mostFrequent, nbSeq,
+                                        MLFSELog, prevEntropy->matchlengthCTable,
+                                        ML_defaultNorm, ML_defaultNormLog,
+                                        ZSTD_defaultAllowed, strategy);
+        assert(!(stats.MLtype < set_compressed && nextEntropy->matchlength_repeatMode != FSE_repeat_none)); /* We don't copy tables */
+        {   size_t const countSize = ZSTD_buildCTable(
+                op, (size_t)(oend - op),
+                CTable_MatchLength, MLFSELog, (SymbolEncodingType_e)stats.MLtype,
+                countWorkspace, max, mlCodeTable, nbSeq,
+                ML_defaultNorm, ML_defaultNormLog, MaxML,
+                prevEntropy->matchlengthCTable,
+                sizeof(prevEntropy->matchlengthCTable),
+                entropyWorkspace, entropyWkspSize);
+            if (ZSTD_isError(countSize)) {
+                DEBUGLOG(3, "ZSTD_buildCTable for MatchLengths failed");
+                stats.size = countSize;
+                return stats;
+            }
+            if (stats.MLtype == set_compressed)
+                stats.lastCountSize = countSize;
+            op += countSize;
+            assert(op <= oend);
+    }   }
+    stats.size = (size_t)(op-ostart);
+    return stats;
+}
+
+/* ZSTD_entropyCompressSeqStore_internal():
+ * compresses both literals and sequences
+ * Returns compressed size of block, or a zstd error.
+ */
+#define SUSPECT_UNCOMPRESSIBLE_LITERAL_RATIO 20
 MEM_STATIC size_t
 ZSTD_entropyCompressSeqStore_internal(
                               void* dst, size_t dstCapacity,
@@ -2662,13 +2766,150 @@ ZSTD_entropyCompressSeqStore_internal(
                               void* entropyWorkspace, size_t entropyWkspSize,
                         const int bmi2)
 {
-    return ZSTD_rust_entropyCompressSeqStore_internal(
+    ZSTD_strategy const strategy = cctxParams->cParams.strategy;
-                dst, dstCapacity,
+    unsigned* count = (unsigned*)entropyWorkspace;
-                literals, litSize,
+    FSE_CTable* CTable_LitLength = nextEntropy->fse.litlengthCTable;
-                seqStorePtr, prevEntropy, nextEntropy,
+    FSE_CTable* CTable_OffsetBits = nextEntropy->fse.offcodeCTable;
-                (int)cctxParams->cParams.strategy,
+    FSE_CTable* CTable_MatchLength = nextEntropy->fse.matchlengthCTable;
-                ZSTD_literalsCompressionIsDisabled(cctxParams),
+    const SeqDef* const sequences = seqStorePtr->sequencesStart;
-                entropyWorkspace, entropyWkspSize, bmi2);
+    const size_t nbSeq = (size_t)(seqStorePtr->sequences - seqStorePtr->sequencesStart);
+    const BYTE* const ofCodeTable = seqStorePtr->ofCode;
+    const BYTE* const llCodeTable = seqStorePtr->llCode;
+    const BYTE* const mlCodeTable = seqStorePtr->mlCode;
+    BYTE* const ostart = (BYTE*)dst;
+    BYTE* const oend = ostart + dstCapacity;
+    BYTE* op = ostart;
+    size_t lastCountSize;
+    int longOffsets = 0;
+
+    entropyWorkspace = count + (MaxSeq + 1);
+    entropyWkspSize -= (MaxSeq + 1) * sizeof(*count);
+
+    DEBUGLOG(5, "ZSTD_entropyCompressSeqStore_internal (nbSeq=%zu, dstCapacity=%zu)", nbSeq, dstCapacity);
+    ZSTD_STATIC_ASSERT(HUF_WORKSPACE_SIZE >= (1<<MAX(MLFSELog,LLFSELog)));
+    assert(entropyWkspSize >= HUF_WORKSPACE_SIZE);
+
+    /* Compress literals */
+    {   size_t const numSequences = (size_t)(seqStorePtr->sequences - seqStorePtr->sequencesStart);
+        /* Base suspicion of uncompressibility on ratio of literals to sequences */
+        int const suspectUncompressible = (numSequences == 0) || (litSize / numSequences >= SUSPECT_UNCOMPRESSIBLE_LITERAL_RATIO);
+
+        size_t const cSize = ZSTD_compressLiterals(
+                                    op, dstCapacity,
+                                    literals, litSize,
+                                    entropyWorkspace, entropyWkspSize,
+                                    &prevEntropy->huf, &nextEntropy->huf,
+                                    cctxParams->cParams.strategy,
+                                    ZSTD_literalsCompressionIsDisabled(cctxParams),
+                                    suspectUncompressible, bmi2);
+        FORWARD_IF_ERROR(cSize, "ZSTD_compressLiterals failed");
+        assert(cSize <= dstCapacity);
+        op += cSize;
+    }
+
+    /* Sequences Header */
+    RETURN_ERROR_IF((oend-op) < 3 /*max nbSeq Size*/ + 1 /*seqHead*/,
+                    dstSize_tooSmall, "Can't fit seq hdr in output buf!");
+    if (nbSeq < 128) {
+        *op++ = (BYTE)nbSeq;
+    } else if (nbSeq < LONGNBSEQ) {
+        op[0] = (BYTE)((nbSeq>>8) + 0x80);
+        op[1] = (BYTE)nbSeq;
+        op+=2;
+    } else {
+        op[0]=0xFF;
+        MEM_writeLE16(op+1, (U16)(nbSeq - LONGNBSEQ));
+        op+=3;
+    }
+    assert(op <= oend);
+    if (nbSeq==0) {
+        /* Copy the old tables over as if we repeated them */
+        ZSTD_memcpy(&nextEntropy->fse, &prevEntropy->fse, sizeof(prevEntropy->fse));
+        return (size_t)(op - ostart);
+    }
+    {   BYTE* const seqHead = op++;
+        /* build stats for sequences */
+        const ZSTD_symbolEncodingTypeStats_t stats =
+                ZSTD_buildSequencesStatistics(seqStorePtr, nbSeq,
+                                             &prevEntropy->fse, &nextEntropy->fse,
+                                              op, oend,
+                                              strategy, count,
+                                              entropyWorkspace, entropyWkspSize);
+        FORWARD_IF_ERROR(stats.size, "ZSTD_buildSequencesStatistics failed!");
+        *seqHead = (BYTE)((stats.LLtype<<6) + (stats.Offtype<<4) + (stats.MLtype<<2));
+        lastCountSize = stats.lastCountSize;
+        op += stats.size;
+        longOffsets = stats.longOffsets;
+    }
+
+    {   size_t const bitstreamSize = ZSTD_encodeSequences(
+                                        op, (size_t)(oend - op),
+                                        CTable_MatchLength, mlCodeTable,
+                                        CTable_OffsetBits, ofCodeTable,
+                                        CTable_LitLength, llCodeTable,
+                                        sequences, nbSeq,
+                                        longOffsets, bmi2);
+        FORWARD_IF_ERROR(bitstreamSize, "ZSTD_encodeSequences failed");
+        op += bitstreamSize;
+        assert(op <= oend);
+        /* zstd versions <= 1.3.4 mistakenly report corruption when
+         * FSE_readNCount() receives a buffer < 4 bytes.
+         * Fixed by https://github.com/facebook/zstd/pull/1146.
+         * This can happen when the last set_compressed table present is 2
+         * bytes and the bitstream is only one byte.
+         * In this exceedingly rare case, we will simply emit an uncompressed
+         * block, since it isn't worth optimizing.
+         */
+        if (lastCountSize && (lastCountSize + bitstreamSize) < 4) {
+            /* lastCountSize >= 2 && bitstreamSize > 0 ==> lastCountSize == 3 */
+            assert(lastCountSize + bitstreamSize == 3);
+            DEBUGLOG(5, "Avoiding bug in zstd decoder in versions <= 1.3.4 by "
+                        "emitting an uncompressed block.");
+            return 0;
+        }
+    }
+
+    DEBUGLOG(5, "compressed block size : %u", (unsigned)(op - ostart));
+    return (size_t)(op - ostart);
+}
+
+static size_t
+ZSTD_entropyCompressSeqStore_wExtLitBuffer(
+                          void* dst, size_t dstCapacity,
+                    const void* literals, size_t litSize,
+                          size_t blockSize,
+                    const SeqStore_t* seqStorePtr,
+                    const ZSTD_entropyCTables_t* prevEntropy,
+                          ZSTD_entropyCTables_t* nextEntropy,
+                    const ZSTD_CCtx_params* cctxParams,
+                          void* entropyWorkspace, size_t entropyWkspSize,
+                          int bmi2)
+{
+    size_t const cSize = ZSTD_entropyCompressSeqStore_internal(
+                            dst, dstCapacity,
+                            literals, litSize,
+                            seqStorePtr, prevEntropy, nextEntropy, cctxParams,
+                            entropyWorkspace, entropyWkspSize, bmi2);
+    if (cSize == 0) return 0;
+    /* When srcSize <= dstCapacity, there is enough space to write a raw uncompressed block.
+     * Since we ran out of space, block must be not compressible, so fall back to raw uncompressed block.
+     */
+    if ((cSize == ERROR(dstSize_tooSmall)) & (blockSize <= dstCapacity)) {
+        DEBUGLOG(4, "not enough dstCapacity (%zu) for ZSTD_entropyCompressSeqStore_internal()=> do not compress block", dstCapacity);
+        return 0;  /* block not compressed */
+    }
+    FORWARD_IF_ERROR(cSize, "ZSTD_entropyCompressSeqStore_internal failed");
+
+    /* Check compressibility */
+    {   size_t const maxCSize = blockSize - ZSTD_minGain(blockSize, cctxParams->cParams.strategy);
+        if (cSize >= maxCSize) return 0;  /* block not compressed */
+    }
+    DEBUGLOG(5, "ZSTD_entropyCompressSeqStore() cSize: %zu", cSize);
+    /* libzstd decoder before  > v1.5.4 is not compatible with compressed blocks of size ZSTD_BLOCKSIZE_MAX exactly.
+     * This restriction is indirectly already fulfilled by respecting ZSTD_minGain() condition above.
+     */
+    assert(cSize < ZSTD_BLOCKSIZE_MAX);
+    return cSize;
 }
 
 static size_t
@@ -2682,12 +2923,13 @@ ZSTD_entropyCompressSeqStore(
                           void* entropyWorkspace, size_t entropyWkspSize,
                           int bmi2)
 {
-    return ZSTD_rust_entropyCompressSeqStore(
+    return ZSTD_entropyCompressSeqStore_wExtLitBuffer(
-                seqStorePtr, prevEntropy, nextEntropy,
-                (int)cctxParams->cParams.strategy,
-                ZSTD_literalsCompressionIsDisabled(cctxParams),
                 dst, dstCapacity,
+                seqStorePtr->litStart, (size_t)(seqStorePtr->lit - seqStorePtr->litStart),
                 srcSize,
+                seqStorePtr,
+                prevEntropy, nextEntropy,
+                cctxParams,
                 entropyWorkspace, entropyWkspSize,
                 bmi2);
 }
@@ -3057,8 +3299,87 @@ static size_t ZSTD_buildSeqStore(ZSTD_CCtx* zc, const void* src, size_t srcSize)
 
 static size_t ZSTD_copyBlockSequences(SeqCollector* seqCollector, const SeqStore_t* seqStore, const U32 prevRepcodes[ZSTD_REP_NUM])
 {
-    /* The implementation lives in rust/src/zstd_compress_stats.rs. */
+    const SeqDef* inSeqs = seqStore->sequencesStart;
-    return ZSTD_rust_copyBlockSequences(seqCollector, seqStore, prevRepcodes);
+    const size_t nbInSequences = (size_t)(seqStore->sequences - inSeqs);
+    const size_t nbInLiterals = (size_t)(seqStore->lit - seqStore->litStart);
+
+    ZSTD_Sequence* outSeqs = seqCollector->seqIndex == 0 ? seqCollector->seqStart : seqCollector->seqStart + seqCollector->seqIndex;
+    const size_t nbOutSequences = nbInSequences + 1;
+    size_t nbOutLiterals = 0;
+    Repcodes_t repcodes;
+    size_t i;
+
+    /* Bounds check that we have enough space for every input sequence
+     * and the block delimiter
+     */
+    assert(seqCollector->seqIndex <= seqCollector->maxSequences);
+    RETURN_ERROR_IF(
+        nbOutSequences > (size_t)(seqCollector->maxSequences - seqCollector->seqIndex),
+        dstSize_tooSmall,
+        "Not enough space to copy sequences");
+
+    ZSTD_memcpy(&repcodes, prevRepcodes, sizeof(repcodes));
+    for (i = 0; i < nbInSequences; ++i) {
+        U32 rawOffset;
+        outSeqs[i].litLength = inSeqs[i].litLength;
+        outSeqs[i].matchLength = inSeqs[i].mlBase + MINMATCH;
+        outSeqs[i].rep = 0;
+
+        /* Handle the possible single length >= 64K
+         * There can only be one because we add MINMATCH to every match length,
+         * and blocks are at most 128K.
+         */
+        if (i == seqStore->longLengthPos) {
+            if (seqStore->longLengthType == ZSTD_llt_literalLength) {
+                outSeqs[i].litLength += 0x10000;
+            } else if (seqStore->longLengthType == ZSTD_llt_matchLength) {
+                outSeqs[i].matchLength += 0x10000;
+            }
+        }
+
+        /* Determine the raw offset given the offBase, which may be a repcode. */
+        if (OFFBASE_IS_REPCODE(inSeqs[i].offBase)) {
+            const U32 repcode = OFFBASE_TO_REPCODE(inSeqs[i].offBase);
+            assert(repcode > 0);
+            outSeqs[i].rep = repcode;
+            if (outSeqs[i].litLength != 0) {
+                rawOffset = repcodes.rep[repcode - 1];
+            } else {
+                if (repcode == 3) {
+                    assert(repcodes.rep[0] > 1);
+                    rawOffset = repcodes.rep[0] - 1;
+                } else {
+                    rawOffset = repcodes.rep[repcode];
+                }
+            }
+        } else {
+            rawOffset = OFFBASE_TO_OFFSET(inSeqs[i].offBase);
+        }
+        outSeqs[i].offset = rawOffset;
+
+        /* Update repcode history for the sequence */
+        ZSTD_updateRep(repcodes.rep,
+                       inSeqs[i].offBase,
+                       inSeqs[i].litLength == 0);
+
+        nbOutLiterals += outSeqs[i].litLength;
+    }
+    /* Insert last literals (if any exist) in the block as a sequence with ml == off == 0.
+     * If there are no last literals, then we'll emit (of: 0, ml: 0, ll: 0), which is a marker
+     * for the block boundary, according to the API.
+     */
+    assert(nbInLiterals >= nbOutLiterals);
+    {
+        const size_t lastLLSize = nbInLiterals - nbOutLiterals;
+        outSeqs[nbInSequences].litLength = (U32)lastLLSize;
+        outSeqs[nbInSequences].matchLength = 0;
+        outSeqs[nbInSequences].offset = 0;
+        assert(nbOutSequences == nbInSequences + 1);
+    }
+    seqCollector->seqIndex += nbOutSequences;
+    assert(seqCollector->seqIndex <= seqCollector->maxSequences);
+
+    return 0;
 }
 
 /* ZSTD_sequenceBound() lives in rust/src/zstd_compress_api.rs. */
@@ -3154,14 +3475,178 @@ writeBlockHeader(void* op, size_t cSize, size_t blockSize, U32 lastBlock)
     DEBUGLOG(5, "writeBlockHeader: cSize: %zu blockSize: %zu lastBlock: %u", cSize, blockSize, lastBlock);
 }
 
+/** ZSTD_buildBlockEntropyStats_literals() :
+ *  Builds entropy for the literals.
+ *  Stores literals block type (raw, rle, compressed, repeat) and
+ *  huffman description table to hufMetadata.
+ *  Requires ENTROPY_WORKSPACE_SIZE workspace
+ * @return : size of huffman description table, or an error code
+ */
+static size_t
+ZSTD_buildBlockEntropyStats_literals(void* const src, size_t srcSize,
+                               const ZSTD_hufCTables_t* prevHuf,
+                                     ZSTD_hufCTables_t* nextHuf,
+                                     ZSTD_hufCTablesMetadata_t* hufMetadata,
+                               const int literalsCompressionIsDisabled,
+                                     void* workspace, size_t wkspSize,
+                                     int hufFlags)
+{
+    BYTE* const wkspStart = (BYTE*)workspace;
+    BYTE* const wkspEnd = wkspStart + wkspSize;
+    BYTE* const countWkspStart = wkspStart;
+    unsigned* const countWksp = (unsigned*)workspace;
+    const size_t countWkspSize = (HUF_SYMBOLVALUE_MAX + 1) * sizeof(unsigned);
+    BYTE* const nodeWksp = countWkspStart + countWkspSize;
+    const size_t nodeWkspSize = (size_t)(wkspEnd - nodeWksp);
+    unsigned maxSymbolValue = HUF_SYMBOLVALUE_MAX;
+    unsigned huffLog = LitHufLog;
+    HUF_repeat repeat = prevHuf->repeatMode;
+    DEBUGLOG(5, "ZSTD_buildBlockEntropyStats_literals (srcSize=%zu)", srcSize);
+
+    /* Prepare nextEntropy assuming reusing the existing table */
+    ZSTD_memcpy(nextHuf, prevHuf, sizeof(*prevHuf));
+
+    if (literalsCompressionIsDisabled) {
+        DEBUGLOG(5, "set_basic - disabled");
+        hufMetadata->hType = set_basic;
+        return 0;
+    }
+
+    /* small ? don't even attempt compression (speed opt) */
+#ifndef COMPRESS_LITERALS_SIZE_MIN
+# define COMPRESS_LITERALS_SIZE_MIN 63  /* heuristic */
+#endif
+    {   size_t const minLitSize = (prevHuf->repeatMode == HUF_repeat_valid) ? 6 : COMPRESS_LITERALS_SIZE_MIN;
+        if (srcSize <= minLitSize) {
+            DEBUGLOG(5, "set_basic - too small");
+            hufMetadata->hType = set_basic;
+            return 0;
+    }   }
+
+    /* Scan input and build symbol stats */
+    {   size_t const largest =
+            HIST_count_wksp (countWksp, &maxSymbolValue,
+                            (const BYTE*)src, srcSize,
+                            workspace, wkspSize);
+        FORWARD_IF_ERROR(largest, "HIST_count_wksp failed");
+        if (largest == srcSize) {
+            /* only one literal symbol */
+            DEBUGLOG(5, "set_rle");
+            hufMetadata->hType = set_rle;
+            return 0;
+        }
+        if (largest <= (srcSize >> 7)+4) {
+            /* heuristic: likely not compressible */
+            DEBUGLOG(5, "set_basic - no gain");
+            hufMetadata->hType = set_basic;
+            return 0;
+    }   }
+
+    /* Validate the previous Huffman table */
+    if (repeat == HUF_repeat_check
+      && !HUF_validateCTable((HUF_CElt const*)prevHuf->CTable, countWksp, maxSymbolValue)) {
+        repeat = HUF_repeat_none;
+    }
+
+    /* Build Huffman Tree */
+    ZSTD_memset(nextHuf->CTable, 0, sizeof(nextHuf->CTable));
+    huffLog = HUF_optimalTableLog(huffLog, srcSize, maxSymbolValue, nodeWksp, nodeWkspSize, nextHuf->CTable, countWksp, hufFlags);
+    assert(huffLog <= LitHufLog);
+    {   size_t const maxBits = HUF_buildCTable_wksp((HUF_CElt*)nextHuf->CTable, countWksp,
+                                                    maxSymbolValue, huffLog,
+                                                    nodeWksp, nodeWkspSize);
+        FORWARD_IF_ERROR(maxBits, "HUF_buildCTable_wksp");
+        huffLog = (U32)maxBits;
+    }
+    {   /* Build and write the CTable */
+        size_t const newCSize = HUF_estimateCompressedSize(
+                (HUF_CElt*)nextHuf->CTable, countWksp, maxSymbolValue);
+        size_t const hSize = HUF_writeCTable_wksp(
+                hufMetadata->hufDesBuffer, sizeof(hufMetadata->hufDesBuffer),
+                (HUF_CElt*)nextHuf->CTable, maxSymbolValue, huffLog,
+                nodeWksp, nodeWkspSize);
+        /* Check against repeating the previous CTable */
+        if (repeat != HUF_repeat_none) {
+            size_t const oldCSize = HUF_estimateCompressedSize(
+                    (HUF_CElt const*)prevHuf->CTable, countWksp, maxSymbolValue);
+            if (oldCSize < srcSize && (oldCSize <= hSize + newCSize || hSize + 12 >= srcSize)) {
+                DEBUGLOG(5, "set_repeat - smaller");
+                ZSTD_memcpy(nextHuf, prevHuf, sizeof(*prevHuf));
+                hufMetadata->hType = set_repeat;
+                return 0;
+        }   }
+        if (newCSize + hSize >= srcSize) {
+            DEBUGLOG(5, "set_basic - no gains");
+            ZSTD_memcpy(nextHuf, prevHuf, sizeof(*prevHuf));
+            hufMetadata->hType = set_basic;
+            return 0;
+        }
+        DEBUGLOG(5, "set_compressed (hSize=%u)", (U32)hSize);
+        hufMetadata->hType = set_compressed;
+        nextHuf->repeatMode = HUF_repeat_check;
+        return hSize;
+    }
+}
+
+
+/* ZSTD_buildDummySequencesStatistics():
+ * Returns a ZSTD_symbolEncodingTypeStats_t with all encoding types as set_basic,
+ * and updates nextEntropy to the appropriate repeatMode.
+ */
+static ZSTD_symbolEncodingTypeStats_t
+ZSTD_buildDummySequencesStatistics(ZSTD_fseCTables_t* nextEntropy)
+{
+    ZSTD_symbolEncodingTypeStats_t stats = {set_basic, set_basic, set_basic, 0, 0, 0};
+    nextEntropy->litlength_repeatMode = FSE_repeat_none;
+    nextEntropy->offcode_repeatMode = FSE_repeat_none;
+    nextEntropy->matchlength_repeatMode = FSE_repeat_none;
+    return stats;
+}
+
+/** ZSTD_buildBlockEntropyStats_sequences() :
+ *  Builds entropy for the sequences.
+ *  Stores symbol compression modes and fse table to fseMetadata.
+ *  Requires ENTROPY_WORKSPACE_SIZE wksp.
+ * @return : size of fse tables or error code */
+static size_t
+ZSTD_buildBlockEntropyStats_sequences(
+                const SeqStore_t* seqStorePtr,
+                const ZSTD_fseCTables_t* prevEntropy,
+                      ZSTD_fseCTables_t* nextEntropy,
+                const ZSTD_CCtx_params* cctxParams,
+                      ZSTD_fseCTablesMetadata_t* fseMetadata,
+                      void* workspace, size_t wkspSize)
+{
+    ZSTD_strategy const strategy = cctxParams->cParams.strategy;
+    size_t const nbSeq = (size_t)(seqStorePtr->sequences - seqStorePtr->sequencesStart);
+    BYTE* const ostart = fseMetadata->fseTablesBuffer;
+    BYTE* const oend = ostart + sizeof(fseMetadata->fseTablesBuffer);
+    BYTE* op = ostart;
+    unsigned* countWorkspace = (unsigned*)workspace;
+    unsigned* entropyWorkspace = countWorkspace + (MaxSeq + 1);
+    size_t entropyWorkspaceSize = wkspSize - (MaxSeq + 1) * sizeof(*countWorkspace);
+    ZSTD_symbolEncodingTypeStats_t stats;
+
+    DEBUGLOG(5, "ZSTD_buildBlockEntropyStats_sequences (nbSeq=%zu)", nbSeq);
+    stats = nbSeq != 0 ? ZSTD_buildSequencesStatistics(seqStorePtr, nbSeq,
+                                          prevEntropy, nextEntropy, op, oend,
+                                          strategy, countWorkspace,
+                                          entropyWorkspace, entropyWorkspaceSize)
+                       : ZSTD_buildDummySequencesStatistics(nextEntropy);
+    FORWARD_IF_ERROR(stats.size, "ZSTD_buildSequencesStatistics failed!");
+    fseMetadata->llType = (SymbolEncodingType_e) stats.LLtype;
+    fseMetadata->ofType = (SymbolEncodingType_e) stats.Offtype;
+    fseMetadata->mlType = (SymbolEncodingType_e) stats.MLtype;
+    fseMetadata->lastCountSize = stats.lastCountSize;
+    return stats.size;
+}
+
+
 /** ZSTD_buildBlockEntropyStats() :
  *  Builds entropy for the block.
  *  Requires workspace size ENTROPY_WORKSPACE_SIZE
  * @return : 0 on success, or an error code
  *  Note : also employed in superblock
- *
- *  The implementation, together with its literals/sequences/dummy helpers,
- *  lives in rust/src/zstd_compress_stats.rs.
  */
 size_t ZSTD_buildBlockEntropyStats(
             const SeqStore_t* seqStorePtr,
@@ -3171,12 +3656,26 @@ size_t ZSTD_buildBlockEntropyStats(
                   ZSTD_entropyCTablesMetadata_t* entropyMetadata,
                   void* workspace, size_t wkspSize)
 {
-    return ZSTD_rust_buildBlockEntropyStats(
+    size_t const litSize = (size_t)(seqStorePtr->lit - seqStorePtr->litStart);
-                seqStorePtr, prevEntropy, nextEntropy,
+    int const huf_useOptDepth = (cctxParams->cParams.strategy >= HUF_OPTIMAL_DEPTH_THRESHOLD);
-                (int)cctxParams->cParams.strategy,
+    int const hufFlags = huf_useOptDepth ? HUF_flags_optimalDepth : 0;
-                ZSTD_literalsCompressionIsDisabled(cctxParams),
+
-                entropyMetadata,
+    entropyMetadata->hufMetadata.hufDesSize =
-                workspace, wkspSize);
+        ZSTD_buildBlockEntropyStats_literals(seqStorePtr->litStart, litSize,
+                                            &prevEntropy->huf, &nextEntropy->huf,
+                                            &entropyMetadata->hufMetadata,
+                                            ZSTD_literalsCompressionIsDisabled(cctxParams),
+                                            workspace, wkspSize, hufFlags);
+
+    FORWARD_IF_ERROR(entropyMetadata->hufMetadata.hufDesSize, "ZSTD_buildBlockEntropyStats_literals failed");
+    entropyMetadata->fseMetadata.fseTablesSize =
+        ZSTD_buildBlockEntropyStats_sequences(seqStorePtr,
+                                              &prevEntropy->fse, &nextEntropy->fse,
+                                              cctxParams,
+                                              &entropyMetadata->fseMetadata,
+                                              workspace, wkspSize);
+    FORWARD_IF_ERROR(entropyMetadata->fseMetadata.fseTablesSize, "ZSTD_buildBlockEntropyStats_sequences failed");
+    return 0;
 }
 
 /* Returns the size estimate for the literals section (header + content) of a block */

lib/compress/zstd_compress_superblock.c

@@ -29,7 +29,7 @@ size_t ZSTD_rust_compressSuperBlock(
         const SeqStore_t* seqStore,
         const ZSTD_compressedBlockState_t* prevCBlock,
         ZSTD_compressedBlockState_t* nextCBlock,
-        int strategy, int disableLiteralCompression,
+        const ZSTD_CCtx_params* cctxParams,
         void* workspace, size_t wkspSize,
         int bmi2, U32 windowLog, size_t targetCBlockSize,
         void* dst, size_t dstCapacity,
@@ -45,8 +45,7 @@ size_t ZSTD_compressSuperBlock(ZSTD_CCtx* zc,
             &zc->seqStore,
             zc->blockState.prevCBlock,
             zc->blockState.nextCBlock,
-            (int)zc->appliedParams.cParams.strategy,
+            &zc->appliedParams,
-            ZSTD_literalsCompressionIsDisabled(&zc->appliedParams),
             zc->tmpWorkspace, zc->tmpWkspSize,
             zc->bmi2, zc->appliedParams.cParams.windowLog,
             zc->appliedParams.targetCBlockSize,

lib/dictBuilder/divsufsort.c

@@ -24,1890 +24,9 @@
  * OTHER DEALINGS IN THE SOFTWARE.
  */
 
-/*- Compiler specifics -*/
+/* divsufsort() is implemented in rust/src/divsufsort.rs, which provides the
-#ifdef __clang__
+ * symbol directly.  This translation unit keeps the header's prototypes in
-#pragma clang diagnostic ignored "-Wshorten-64-to-32"
+ * the build so the dictionary builder continues to compile against the
-#endif
+ * original interface.  divbwt() has no callers in zstd and is declaration-
-
+ * only; it moves to Rust if a user ever appears. */
-#if defined(_MSC_VER)
-#  pragma warning(disable : 4244)
-#  pragma warning(disable : 4127)    /* C4127 : Condition expression is constant */
-#endif
-
-
-/*- Dependencies -*/
-#include <assert.h>
-#include <stdio.h>
-#include <stdlib.h>
-
 #include "divsufsort.h"
-
-/*- Constants -*/
-#if defined(INLINE)
-# undef INLINE
-#endif
-#if !defined(INLINE)
-# define INLINE __inline
-#endif
-#if defined(ALPHABET_SIZE) && (ALPHABET_SIZE < 1)
-# undef ALPHABET_SIZE
-#endif
-#if !defined(ALPHABET_SIZE)
-# define ALPHABET_SIZE (256)
-#endif
-#define BUCKET_A_SIZE (ALPHABET_SIZE)
-#define BUCKET_B_SIZE (ALPHABET_SIZE * ALPHABET_SIZE)
-#if defined(SS_INSERTIONSORT_THRESHOLD)
-# if SS_INSERTIONSORT_THRESHOLD < 1
-#  undef SS_INSERTIONSORT_THRESHOLD
-#  define SS_INSERTIONSORT_THRESHOLD (1)
-# endif
-#else
-# define SS_INSERTIONSORT_THRESHOLD (8)
-#endif
-#if defined(SS_BLOCKSIZE)
-# if SS_BLOCKSIZE < 0
-#  undef SS_BLOCKSIZE
-#  define SS_BLOCKSIZE (0)
-# elif 32768 <= SS_BLOCKSIZE
-#  undef SS_BLOCKSIZE
-#  define SS_BLOCKSIZE (32767)
-# endif
-#else
-# define SS_BLOCKSIZE (1024)
-#endif
-/* minstacksize = log(SS_BLOCKSIZE) / log(3) * 2 */
-#if SS_BLOCKSIZE == 0
-# define SS_MISORT_STACKSIZE (96)
-#elif SS_BLOCKSIZE <= 4096
-# define SS_MISORT_STACKSIZE (16)
-#else
-# define SS_MISORT_STACKSIZE (24)
-#endif
-#define SS_SMERGE_STACKSIZE (32)
-#define TR_INSERTIONSORT_THRESHOLD (8)
-#define TR_STACKSIZE (64)
-
-
-/*- Macros -*/
-#ifndef SWAP
-# define SWAP(_a, _b) do { t = (_a); (_a) = (_b); (_b) = t; } while(0)
-#endif /* SWAP */
-#ifndef MIN
-# define MIN(_a, _b) (((_a) < (_b)) ? (_a) : (_b))
-#endif /* MIN */
-#ifndef MAX
-# define MAX(_a, _b) (((_a) > (_b)) ? (_a) : (_b))
-#endif /* MAX */
-#define STACK_PUSH(_a, _b, _c, _d)\
-  do {\
-    assert(ssize < STACK_SIZE);\
-    stack[ssize].a = (_a), stack[ssize].b = (_b),\
-    stack[ssize].c = (_c), stack[ssize++].d = (_d);\
-  } while(0)
-#define STACK_PUSH5(_a, _b, _c, _d, _e)\
-  do {\
-    assert(ssize < STACK_SIZE);\
-    stack[ssize].a = (_a), stack[ssize].b = (_b),\
-    stack[ssize].c = (_c), stack[ssize].d = (_d), stack[ssize++].e = (_e);\
-  } while(0)
-#define STACK_POP(_a, _b, _c, _d)\
-  do {\
-    assert(0 <= ssize);\
-    if(ssize == 0) { return; }\
-    (_a) = stack[--ssize].a, (_b) = stack[ssize].b,\
-    (_c) = stack[ssize].c, (_d) = stack[ssize].d;\
-  } while(0)
-#define STACK_POP5(_a, _b, _c, _d, _e)\
-  do {\
-    assert(0 <= ssize);\
-    if(ssize == 0) { return; }\
-    (_a) = stack[--ssize].a, (_b) = stack[ssize].b,\
-    (_c) = stack[ssize].c, (_d) = stack[ssize].d, (_e) = stack[ssize].e;\
-  } while(0)
-#define BUCKET_A(_c0) bucket_A[(_c0)]
-#if ALPHABET_SIZE == 256
-#define BUCKET_B(_c0, _c1) (bucket_B[((_c1) << 8) | (_c0)])
-#define BUCKET_BSTAR(_c0, _c1) (bucket_B[((_c0) << 8) | (_c1)])
-#else
-#define BUCKET_B(_c0, _c1) (bucket_B[(_c1) * ALPHABET_SIZE + (_c0)])
-#define BUCKET_BSTAR(_c0, _c1) (bucket_B[(_c0) * ALPHABET_SIZE + (_c1)])
-#endif
-
-
-/*- Private Functions -*/
-
-static const int lg_table[256]= {
- -1,0,1,1,2,2,2,2,3,3,3,3,3,3,3,3,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,
-  5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,
-  6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
-  6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
-  7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
-  7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
-  7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
-  7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7
-};
-
-#if (SS_BLOCKSIZE == 0) || (SS_INSERTIONSORT_THRESHOLD < SS_BLOCKSIZE)
-
-static INLINE
-int
-ss_ilg(int n) {
-#if SS_BLOCKSIZE == 0
-  return (n & 0xffff0000) ?
-          ((n & 0xff000000) ?
-            24 + lg_table[(n >> 24) & 0xff] :
-            16 + lg_table[(n >> 16) & 0xff]) :
-          ((n & 0x0000ff00) ?
-             8 + lg_table[(n >>  8) & 0xff] :
-             0 + lg_table[(n >>  0) & 0xff]);
-#elif SS_BLOCKSIZE < 256
-  return lg_table[n];
-#else
-  return (n & 0xff00) ?
-          8 + lg_table[(n >> 8) & 0xff] :
-          0 + lg_table[(n >> 0) & 0xff];
-#endif
-}
-
-#endif /* (SS_BLOCKSIZE == 0) || (SS_INSERTIONSORT_THRESHOLD < SS_BLOCKSIZE) */
-
-#if SS_BLOCKSIZE != 0
-
-static const int sqq_table[256] = {
-  0,  16,  22,  27,  32,  35,  39,  42,  45,  48,  50,  53,  55,  57,  59,  61,
- 64,  65,  67,  69,  71,  73,  75,  76,  78,  80,  81,  83,  84,  86,  87,  89,
- 90,  91,  93,  94,  96,  97,  98,  99, 101, 102, 103, 104, 106, 107, 108, 109,
-110, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126,
-128, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142,
-143, 144, 144, 145, 146, 147, 148, 149, 150, 150, 151, 152, 153, 154, 155, 155,
-156, 157, 158, 159, 160, 160, 161, 162, 163, 163, 164, 165, 166, 167, 167, 168,
-169, 170, 170, 171, 172, 173, 173, 174, 175, 176, 176, 177, 178, 178, 179, 180,
-181, 181, 182, 183, 183, 184, 185, 185, 186, 187, 187, 188, 189, 189, 190, 191,
-192, 192, 193, 193, 194, 195, 195, 196, 197, 197, 198, 199, 199, 200, 201, 201,
-202, 203, 203, 204, 204, 205, 206, 206, 207, 208, 208, 209, 209, 210, 211, 211,
-212, 212, 213, 214, 214, 215, 215, 216, 217, 217, 218, 218, 219, 219, 220, 221,
-221, 222, 222, 223, 224, 224, 225, 225, 226, 226, 227, 227, 228, 229, 229, 230,
-230, 231, 231, 232, 232, 233, 234, 234, 235, 235, 236, 236, 237, 237, 238, 238,
-239, 240, 240, 241, 241, 242, 242, 243, 243, 244, 244, 245, 245, 246, 246, 247,
-247, 248, 248, 249, 249, 250, 250, 251, 251, 252, 252, 253, 253, 254, 254, 255
-};
-
-static INLINE
-int
-ss_isqrt(int x) {
-  int y, e;
-
-  if(x >= (SS_BLOCKSIZE * SS_BLOCKSIZE)) { return SS_BLOCKSIZE; }
-  e = (x & 0xffff0000) ?
-        ((x & 0xff000000) ?
-          24 + lg_table[(x >> 24) & 0xff] :
-          16 + lg_table[(x >> 16) & 0xff]) :
-        ((x & 0x0000ff00) ?
-           8 + lg_table[(x >>  8) & 0xff] :
-           0 + lg_table[(x >>  0) & 0xff]);
-
-  if(e >= 16) {
-    y = sqq_table[x >> ((e - 6) - (e & 1))] << ((e >> 1) - 7);
-    if(e >= 24) { y = (y + 1 + x / y) >> 1; }
-    y = (y + 1 + x / y) >> 1;
-  } else if(e >= 8) {
-    y = (sqq_table[x >> ((e - 6) - (e & 1))] >> (7 - (e >> 1))) + 1;
-  } else {
-    return sqq_table[x] >> 4;
-  }
-
-  return (x < (y * y)) ? y - 1 : y;
-}
-
-#endif /* SS_BLOCKSIZE != 0 */
-
-
-/*---------------------------------------------------------------------------*/
-
-/* Compares two suffixes. */
-static INLINE
-int
-ss_compare(const unsigned char *T,
-           const int *p1, const int *p2,
-           int depth) {
-  const unsigned char *U1, *U2, *U1n, *U2n;
-
-  for(U1 = T + depth + *p1,
-      U2 = T + depth + *p2,
-      U1n = T + *(p1 + 1) + 2,
-      U2n = T + *(p2 + 1) + 2;
-      (U1 < U1n) && (U2 < U2n) && (*U1 == *U2);
-      ++U1, ++U2) {
-  }
-
-  return U1 < U1n ?
-        (U2 < U2n ? *U1 - *U2 : 1) :
-        (U2 < U2n ? -1 : 0);
-}
-
-
-/*---------------------------------------------------------------------------*/
-
-#if (SS_BLOCKSIZE != 1) && (SS_INSERTIONSORT_THRESHOLD != 1)
-
-/* Insertionsort for small size groups */
-static
-void
-ss_insertionsort(const unsigned char *T, const int *PA,
-                 int *first, int *last, int depth) {
-  int *i, *j;
-  int t;
-  int r;
-
-  for(i = last - 2; first <= i; --i) {
-    for(t = *i, j = i + 1; 0 < (r = ss_compare(T, PA + t, PA + *j, depth));) {
-      do { *(j - 1) = *j; } while((++j < last) && (*j < 0));
-      if(last <= j) { break; }
-    }
-    if(r == 0) { *j = ~*j; }
-    *(j - 1) = t;
-  }
-}
-
-#endif /* (SS_BLOCKSIZE != 1) && (SS_INSERTIONSORT_THRESHOLD != 1) */
-
-
-/*---------------------------------------------------------------------------*/
-
-#if (SS_BLOCKSIZE == 0) || (SS_INSERTIONSORT_THRESHOLD < SS_BLOCKSIZE)
-
-static INLINE
-void
-ss_fixdown(const unsigned char *Td, const int *PA,
-           int *SA, int i, int size) {
-  int j, k;
-  int v;
-  int c, d, e;
-
-  for(v = SA[i], c = Td[PA[v]]; (j = 2 * i + 1) < size; SA[i] = SA[k], i = k) {
-    d = Td[PA[SA[k = j++]]];
-    if(d < (e = Td[PA[SA[j]]])) { k = j; d = e; }
-    if(d <= c) { break; }
-  }
-  SA[i] = v;
-}
-
-/* Simple top-down heapsort. */
-static
-void
-ss_heapsort(const unsigned char *Td, const int *PA, int *SA, int size) {
-  int i, m;
-  int t;
-
-  m = size;
-  if((size % 2) == 0) {
-    m--;
-    if(Td[PA[SA[m / 2]]] < Td[PA[SA[m]]]) { SWAP(SA[m], SA[m / 2]); }
-  }
-
-  for(i = m / 2 - 1; 0 <= i; --i) { ss_fixdown(Td, PA, SA, i, m); }
-  if((size % 2) == 0) { SWAP(SA[0], SA[m]); ss_fixdown(Td, PA, SA, 0, m); }
-  for(i = m - 1; 0 < i; --i) {
-    t = SA[0], SA[0] = SA[i];
-    ss_fixdown(Td, PA, SA, 0, i);
-    SA[i] = t;
-  }
-}
-
-
-/*---------------------------------------------------------------------------*/
-
-/* Returns the median of three elements. */
-static INLINE
-int *
-ss_median3(const unsigned char *Td, const int *PA,
-           int *v1, int *v2, int *v3) {
-  int *t;
-  if(Td[PA[*v1]] > Td[PA[*v2]]) { SWAP(v1, v2); }
-  if(Td[PA[*v2]] > Td[PA[*v3]]) {
-    if(Td[PA[*v1]] > Td[PA[*v3]]) { return v1; }
-    else { return v3; }
-  }
-  return v2;
-}
-
-/* Returns the median of five elements. */
-static INLINE
-int *
-ss_median5(const unsigned char *Td, const int *PA,
-           int *v1, int *v2, int *v3, int *v4, int *v5) {
-  int *t;
-  if(Td[PA[*v2]] > Td[PA[*v3]]) { SWAP(v2, v3); }
-  if(Td[PA[*v4]] > Td[PA[*v5]]) { SWAP(v4, v5); }
-  if(Td[PA[*v2]] > Td[PA[*v4]]) { SWAP(v2, v4); SWAP(v3, v5); }
-  if(Td[PA[*v1]] > Td[PA[*v3]]) { SWAP(v1, v3); }
-  if(Td[PA[*v1]] > Td[PA[*v4]]) { SWAP(v1, v4); SWAP(v3, v5); }
-  if(Td[PA[*v3]] > Td[PA[*v4]]) { return v4; }
-  return v3;
-}
-
-/* Returns the pivot element. */
-static INLINE
-int *
-ss_pivot(const unsigned char *Td, const int *PA, int *first, int *last) {
-  int *middle;
-  int t;
-
-  t = last - first;
-  middle = first + t / 2;
-
-  if(t <= 512) {
-    if(t <= 32) {
-      return ss_median3(Td, PA, first, middle, last - 1);
-    } else {
-      t >>= 2;
-      return ss_median5(Td, PA, first, first + t, middle, last - 1 - t, last - 1);
-    }
-  }
-  t >>= 3;
-  first  = ss_median3(Td, PA, first, first + t, first + (t << 1));
-  middle = ss_median3(Td, PA, middle - t, middle, middle + t);
-  last   = ss_median3(Td, PA, last - 1 - (t << 1), last - 1 - t, last - 1);
-  return ss_median3(Td, PA, first, middle, last);
-}
-
-
-/*---------------------------------------------------------------------------*/
-
-/* Binary partition for substrings. */
-static INLINE
-int *
-ss_partition(const int *PA,
-                    int *first, int *last, int depth) {
-  int *a, *b;
-  int t;
-  for(a = first - 1, b = last;;) {
-    for(; (++a < b) && ((PA[*a] + depth) >= (PA[*a + 1] + 1));) { *a = ~*a; }
-    for(; (a < --b) && ((PA[*b] + depth) <  (PA[*b + 1] + 1));) { }
-    if(b <= a) { break; }
-    t = ~*b;
-    *b = *a;
-    *a = t;
-  }
-  if(first < a) { *first = ~*first; }
-  return a;
-}
-
-/* Multikey introsort for medium size groups. */
-static
-void
-ss_mintrosort(const unsigned char *T, const int *PA,
-              int *first, int *last,
-              int depth) {
-#define STACK_SIZE SS_MISORT_STACKSIZE
-  struct { int *a, *b, c; int d; } stack[STACK_SIZE];
-  const unsigned char *Td;
-  int *a, *b, *c, *d, *e, *f;
-  int s, t;
-  int ssize;
-  int limit;
-  int v, x = 0;
-
-  for(ssize = 0, limit = ss_ilg(last - first);;) {
-
-    if((last - first) <= SS_INSERTIONSORT_THRESHOLD) {
-#if 1 < SS_INSERTIONSORT_THRESHOLD
-      if(1 < (last - first)) { ss_insertionsort(T, PA, first, last, depth); }
-#endif
-      STACK_POP(first, last, depth, limit);
-      continue;
-    }
-
-    Td = T + depth;
-    if(limit-- == 0) { ss_heapsort(Td, PA, first, last - first); }
-    if(limit < 0) {
-      for(a = first + 1, v = Td[PA[*first]]; a < last; ++a) {
-        if((x = Td[PA[*a]]) != v) {
-          if(1 < (a - first)) { break; }
-          v = x;
-          first = a;
-        }
-      }
-      if(Td[PA[*first] - 1] < v) {
-        first = ss_partition(PA, first, a, depth);
-      }
-      if((a - first) <= (last - a)) {
-        if(1 < (a - first)) {
-          STACK_PUSH(a, last, depth, -1);
-          last = a, depth += 1, limit = ss_ilg(a - first);
-        } else {
-          first = a, limit = -1;
-        }
-      } else {
-        if(1 < (last - a)) {
-          STACK_PUSH(first, a, depth + 1, ss_ilg(a - first));
-          first = a, limit = -1;
-        } else {
-          last = a, depth += 1, limit = ss_ilg(a - first);
-        }
-      }
-      continue;
-    }
-
-    /* choose pivot */
-    a = ss_pivot(Td, PA, first, last);
-    v = Td[PA[*a]];
-    SWAP(*first, *a);
-
-    /* partition */
-    for(b = first; (++b < last) && ((x = Td[PA[*b]]) == v);) { }
-    if(((a = b) < last) && (x < v)) {
-      for(; (++b < last) && ((x = Td[PA[*b]]) <= v);) {
-        if(x == v) { SWAP(*b, *a); ++a; }
-      }
-    }
-    for(c = last; (b < --c) && ((x = Td[PA[*c]]) == v);) { }
-    if((b < (d = c)) && (x > v)) {
-      for(; (b < --c) && ((x = Td[PA[*c]]) >= v);) {
-        if(x == v) { SWAP(*c, *d); --d; }
-      }
-    }
-    for(; b < c;) {
-      SWAP(*b, *c);
-      for(; (++b < c) && ((x = Td[PA[*b]]) <= v);) {
-        if(x == v) { SWAP(*b, *a); ++a; }
-      }
-      for(; (b < --c) && ((x = Td[PA[*c]]) >= v);) {
-        if(x == v) { SWAP(*c, *d); --d; }
-      }
-    }
-
-    if(a <= d) {
-      c = b - 1;
-
-      if((s = a - first) > (t = b - a)) { s = t; }
-      for(e = first, f = b - s; 0 < s; --s, ++e, ++f) { SWAP(*e, *f); }
-      if((s = d - c) > (t = last - d - 1)) { s = t; }
-      for(e = b, f = last - s; 0 < s; --s, ++e, ++f) { SWAP(*e, *f); }
-
-      a = first + (b - a), c = last - (d - c);
-      b = (v <= Td[PA[*a] - 1]) ? a : ss_partition(PA, a, c, depth);
-
-      if((a - first) <= (last - c)) {
-        if((last - c) <= (c - b)) {
-          STACK_PUSH(b, c, depth + 1, ss_ilg(c - b));
-          STACK_PUSH(c, last, depth, limit);
-          last = a;
-        } else if((a - first) <= (c - b)) {
-          STACK_PUSH(c, last, depth, limit);
-          STACK_PUSH(b, c, depth + 1, ss_ilg(c - b));
-          last = a;
-        } else {
-          STACK_PUSH(c, last, depth, limit);
-          STACK_PUSH(first, a, depth, limit);
-          first = b, last = c, depth += 1, limit = ss_ilg(c - b);
-        }
-      } else {
-        if((a - first) <= (c - b)) {
-          STACK_PUSH(b, c, depth + 1, ss_ilg(c - b));
-          STACK_PUSH(first, a, depth, limit);
-          first = c;
-        } else if((last - c) <= (c - b)) {
-          STACK_PUSH(first, a, depth, limit);
-          STACK_PUSH(b, c, depth + 1, ss_ilg(c - b));
-          first = c;
-        } else {
-          STACK_PUSH(first, a, depth, limit);
-          STACK_PUSH(c, last, depth, limit);
-          first = b, last = c, depth += 1, limit = ss_ilg(c - b);
-        }
-      }
-    } else {
-      limit += 1;
-      if(Td[PA[*first] - 1] < v) {
-        first = ss_partition(PA, first, last, depth);
-        limit = ss_ilg(last - first);
-      }
-      depth += 1;
-    }
-  }
-#undef STACK_SIZE
-}
-
-#endif /* (SS_BLOCKSIZE == 0) || (SS_INSERTIONSORT_THRESHOLD < SS_BLOCKSIZE) */
-
-
-/*---------------------------------------------------------------------------*/
-
-#if SS_BLOCKSIZE != 0
-
-static INLINE
-void
-ss_blockswap(int *a, int *b, int n) {
-  int t;
-  for(; 0 < n; --n, ++a, ++b) {
-    t = *a, *a = *b, *b = t;
-  }
-}
-
-static INLINE
-void
-ss_rotate(int *first, int *middle, int *last) {
-  int *a, *b, t;
-  int l, r;
-  l = middle - first, r = last - middle;
-  for(; (0 < l) && (0 < r);) {
-    if(l == r) { ss_blockswap(first, middle, l); break; }
-    if(l < r) {
-      a = last - 1, b = middle - 1;
-      t = *a;
-      do {
-        *a-- = *b, *b-- = *a;
-        if(b < first) {
-          *a = t;
-          last = a;
-          if((r -= l + 1) <= l) { break; }
-          a -= 1, b = middle - 1;
-          t = *a;
-        }
-      } while(1);
-    } else {
-      a = first, b = middle;
-      t = *a;
-      do {
-        *a++ = *b, *b++ = *a;
-        if(last <= b) {
-          *a = t;
-          first = a + 1;
-          if((l -= r + 1) <= r) { break; }
-          a += 1, b = middle;
-          t = *a;
-        }
-      } while(1);
-    }
-  }
-}
-
-
-/*---------------------------------------------------------------------------*/
-
-static
-void
-ss_inplacemerge(const unsigned char *T, const int *PA,
-                int *first, int *middle, int *last,
-                int depth) {
-  const int *p;
-  int *a, *b;
-  int len, half;
-  int q, r;
-  int x;
-
-  for(;;) {
-    if(*(last - 1) < 0) { x = 1; p = PA + ~*(last - 1); }
-    else                { x = 0; p = PA +  *(last - 1); }
-    for(a = first, len = middle - first, half = len >> 1, r = -1;
-        0 < len;
-        len = half, half >>= 1) {
-      b = a + half;
-      q = ss_compare(T, PA + ((0 <= *b) ? *b : ~*b), p, depth);
-      if(q < 0) {
-        a = b + 1;
-        half -= (len & 1) ^ 1;
-      } else {
-        r = q;
-      }
-    }
-    if(a < middle) {
-      if(r == 0) { *a = ~*a; }
-      ss_rotate(a, middle, last);
-      last -= middle - a;
-      middle = a;
-      if(first == middle) { break; }
-    }
-    --last;
-    if(x != 0) { while(*--last < 0) { } }
-    if(middle == last) { break; }
-  }
-}
-
-
-/*---------------------------------------------------------------------------*/
-
-/* Merge-forward with internal buffer. */
-static
-void
-ss_mergeforward(const unsigned char *T, const int *PA,
-                int *first, int *middle, int *last,
-                int *buf, int depth) {
-  int *a, *b, *c, *bufend;
-  int t;
-  int r;
-
-  bufend = buf + (middle - first) - 1;
-  ss_blockswap(buf, first, middle - first);
-
-  for(t = *(a = first), b = buf, c = middle;;) {
-    r = ss_compare(T, PA + *b, PA + *c, depth);
-    if(r < 0) {
-      do {
-        *a++ = *b;
-        if(bufend <= b) { *bufend = t; return; }
-        *b++ = *a;
-      } while(*b < 0);
-    } else if(r > 0) {
-      do {
-        *a++ = *c, *c++ = *a;
-        if(last <= c) {
-          while(b < bufend) { *a++ = *b, *b++ = *a; }
-          *a = *b, *b = t;
-          return;
-        }
-      } while(*c < 0);
-    } else {
-      *c = ~*c;
-      do {
-        *a++ = *b;
-        if(bufend <= b) { *bufend = t; return; }
-        *b++ = *a;
-      } while(*b < 0);
-
-      do {
-        *a++ = *c, *c++ = *a;
-        if(last <= c) {
-          while(b < bufend) { *a++ = *b, *b++ = *a; }
-          *a = *b, *b = t;
-          return;
-        }
-      } while(*c < 0);
-    }
-  }
-}
-
-/* Merge-backward with internal buffer. */
-static
-void
-ss_mergebackward(const unsigned char *T, const int *PA,
-                 int *first, int *middle, int *last,
-                 int *buf, int depth) {
-  const int *p1, *p2;
-  int *a, *b, *c, *bufend;
-  int t;
-  int r;
-  int x;
-
-  bufend = buf + (last - middle) - 1;
-  ss_blockswap(buf, middle, last - middle);
-
-  x = 0;
-  if(*bufend < 0)       { p1 = PA + ~*bufend; x |= 1; }
-  else                  { p1 = PA +  *bufend; }
-  if(*(middle - 1) < 0) { p2 = PA + ~*(middle - 1); x |= 2; }
-  else                  { p2 = PA +  *(middle - 1); }
-  for(t = *(a = last - 1), b = bufend, c = middle - 1;;) {
-    r = ss_compare(T, p1, p2, depth);
-    if(0 < r) {
-      if(x & 1) { do { *a-- = *b, *b-- = *a; } while(*b < 0); x ^= 1; }
-      *a-- = *b;
-      if(b <= buf) { *buf = t; break; }
-      *b-- = *a;
-      if(*b < 0) { p1 = PA + ~*b; x |= 1; }
-      else       { p1 = PA +  *b; }
-    } else if(r < 0) {
-      if(x & 2) { do { *a-- = *c, *c-- = *a; } while(*c < 0); x ^= 2; }
-      *a-- = *c, *c-- = *a;
-      if(c < first) {
-        while(buf < b) { *a-- = *b, *b-- = *a; }
-        *a = *b, *b = t;
-        break;
-      }
-      if(*c < 0) { p2 = PA + ~*c; x |= 2; }
-      else       { p2 = PA +  *c; }
-    } else {
-      if(x & 1) { do { *a-- = *b, *b-- = *a; } while(*b < 0); x ^= 1; }
-      *a-- = ~*b;
-      if(b <= buf) { *buf = t; break; }
-      *b-- = *a;
-      if(x & 2) { do { *a-- = *c, *c-- = *a; } while(*c < 0); x ^= 2; }
-      *a-- = *c, *c-- = *a;
-      if(c < first) {
-        while(buf < b) { *a-- = *b, *b-- = *a; }
-        *a = *b, *b = t;
-        break;
-      }
-      if(*b < 0) { p1 = PA + ~*b; x |= 1; }
-      else       { p1 = PA +  *b; }
-      if(*c < 0) { p2 = PA + ~*c; x |= 2; }
-      else       { p2 = PA +  *c; }
-    }
-  }
-}
-
-/* D&C based merge. */
-static
-void
-ss_swapmerge(const unsigned char *T, const int *PA,
-             int *first, int *middle, int *last,
-             int *buf, int bufsize, int depth) {
-#define STACK_SIZE SS_SMERGE_STACKSIZE
-#define GETIDX(a) ((0 <= (a)) ? (a) : (~(a)))
-#define MERGE_CHECK(a, b, c)\
-  do {\
-    if(((c) & 1) ||\
-       (((c) & 2) && (ss_compare(T, PA + GETIDX(*((a) - 1)), PA + *(a), depth) == 0))) {\
-      *(a) = ~*(a);\
-    }\
-    if(((c) & 4) && ((ss_compare(T, PA + GETIDX(*((b) - 1)), PA + *(b), depth) == 0))) {\
-      *(b) = ~*(b);\
-    }\
-  } while(0)
-  struct { int *a, *b, *c; int d; } stack[STACK_SIZE];
-  int *l, *r, *lm, *rm;
-  int m, len, half;
-  int ssize;
-  int check, next;
-
-  for(check = 0, ssize = 0;;) {
-    if((last - middle) <= bufsize) {
-      if((first < middle) && (middle < last)) {
-        ss_mergebackward(T, PA, first, middle, last, buf, depth);
-      }
-      MERGE_CHECK(first, last, check);
-      STACK_POP(first, middle, last, check);
-      continue;
-    }
-
-    if((middle - first) <= bufsize) {
-      if(first < middle) {
-        ss_mergeforward(T, PA, first, middle, last, buf, depth);
-      }
-      MERGE_CHECK(first, last, check);
-      STACK_POP(first, middle, last, check);
-      continue;
-    }
-
-    for(m = 0, len = MIN(middle - first, last - middle), half = len >> 1;
-        0 < len;
-        len = half, half >>= 1) {
-      if(ss_compare(T, PA + GETIDX(*(middle + m + half)),
-                       PA + GETIDX(*(middle - m - half - 1)), depth) < 0) {
-        m += half + 1;
-        half -= (len & 1) ^ 1;
-      }
-    }
-
-    if(0 < m) {
-      lm = middle - m, rm = middle + m;
-      ss_blockswap(lm, middle, m);
-      l = r = middle, next = 0;
-      if(rm < last) {
-        if(*rm < 0) {
-          *rm = ~*rm;
-          if(first < lm) { for(; *--l < 0;) { } next |= 4; }
-          next |= 1;
-        } else if(first < lm) {
-          for(; *r < 0; ++r) { }
-          next |= 2;
-        }
-      }
-
-      if((l - first) <= (last - r)) {
-        STACK_PUSH(r, rm, last, (next & 3) | (check & 4));
-        middle = lm, last = l, check = (check & 3) | (next & 4);
-      } else {
-        if((next & 2) && (r == middle)) { next ^= 6; }
-        STACK_PUSH(first, lm, l, (check & 3) | (next & 4));
-        first = r, middle = rm, check = (next & 3) | (check & 4);
-      }
-    } else {
-      if(ss_compare(T, PA + GETIDX(*(middle - 1)), PA + *middle, depth) == 0) {
-        *middle = ~*middle;
-      }
-      MERGE_CHECK(first, last, check);
-      STACK_POP(first, middle, last, check);
-    }
-  }
-#undef STACK_SIZE
-}
-
-#endif /* SS_BLOCKSIZE != 0 */
-
-
-/*---------------------------------------------------------------------------*/
-
-/* Substring sort */
-static
-void
-sssort(const unsigned char *T, const int *PA,
-       int *first, int *last,
-       int *buf, int bufsize,
-       int depth, int n, int lastsuffix) {
-  int *a;
-#if SS_BLOCKSIZE != 0
-  int *b, *middle, *curbuf;
-  int j, k, curbufsize, limit;
-#endif
-  int i;
-
-  if(lastsuffix != 0) { ++first; }
-
-#if SS_BLOCKSIZE == 0
-  ss_mintrosort(T, PA, first, last, depth);
-#else
-  if((bufsize < SS_BLOCKSIZE) &&
-      (bufsize < (last - first)) &&
-      (bufsize < (limit = ss_isqrt(last - first)))) {
-    if(SS_BLOCKSIZE < limit) { limit = SS_BLOCKSIZE; }
-    buf = middle = last - limit, bufsize = limit;
-  } else {
-    middle = last, limit = 0;
-  }
-  for(a = first, i = 0; SS_BLOCKSIZE < (middle - a); a += SS_BLOCKSIZE, ++i) {
-#if SS_INSERTIONSORT_THRESHOLD < SS_BLOCKSIZE
-    ss_mintrosort(T, PA, a, a + SS_BLOCKSIZE, depth);
-#elif 1 < SS_BLOCKSIZE
-    ss_insertionsort(T, PA, a, a + SS_BLOCKSIZE, depth);
-#endif
-    curbufsize = last - (a + SS_BLOCKSIZE);
-    curbuf = a + SS_BLOCKSIZE;
-    if(curbufsize <= bufsize) { curbufsize = bufsize, curbuf = buf; }
-    for(b = a, k = SS_BLOCKSIZE, j = i; j & 1; b -= k, k <<= 1, j >>= 1) {
-      ss_swapmerge(T, PA, b - k, b, b + k, curbuf, curbufsize, depth);
-    }
-  }
-#if SS_INSERTIONSORT_THRESHOLD < SS_BLOCKSIZE
-  ss_mintrosort(T, PA, a, middle, depth);
-#elif 1 < SS_BLOCKSIZE
-  ss_insertionsort(T, PA, a, middle, depth);
-#endif
-  for(k = SS_BLOCKSIZE; i != 0; k <<= 1, i >>= 1) {
-    if(i & 1) {
-      ss_swapmerge(T, PA, a - k, a, middle, buf, bufsize, depth);
-      a -= k;
-    }
-  }
-  if(limit != 0) {
-#if SS_INSERTIONSORT_THRESHOLD < SS_BLOCKSIZE
-    ss_mintrosort(T, PA, middle, last, depth);
-#elif 1 < SS_BLOCKSIZE
-    ss_insertionsort(T, PA, middle, last, depth);
-#endif
-    ss_inplacemerge(T, PA, first, middle, last, depth);
-  }
-#endif
-
-  if(lastsuffix != 0) {
-    /* Insert last type B* suffix. */
-    int PAi[2]; PAi[0] = PA[*(first - 1)], PAi[1] = n - 2;
-    for(a = first, i = *(first - 1);
-        (a < last) && ((*a < 0) || (0 < ss_compare(T, &(PAi[0]), PA + *a, depth)));
-        ++a) {
-      *(a - 1) = *a;
-    }
-    *(a - 1) = i;
-  }
-}
-
-
-/*---------------------------------------------------------------------------*/
-
-static INLINE
-int
-tr_ilg(int n) {
-  return (n & 0xffff0000) ?
-          ((n & 0xff000000) ?
-            24 + lg_table[(n >> 24) & 0xff] :
-            16 + lg_table[(n >> 16) & 0xff]) :
-          ((n & 0x0000ff00) ?
-             8 + lg_table[(n >>  8) & 0xff] :
-             0 + lg_table[(n >>  0) & 0xff]);
-}
-
-
-/*---------------------------------------------------------------------------*/
-
-/* Simple insertionsort for small size groups. */
-static
-void
-tr_insertionsort(const int *ISAd, int *first, int *last) {
-  int *a, *b;
-  int t, r;
-
-  for(a = first + 1; a < last; ++a) {
-    for(t = *a, b = a - 1; 0 > (r = ISAd[t] - ISAd[*b]);) {
-      do { *(b + 1) = *b; } while((first <= --b) && (*b < 0));
-      if(b < first) { break; }
-    }
-    if(r == 0) { *b = ~*b; }
-    *(b + 1) = t;
-  }
-}
-
-
-/*---------------------------------------------------------------------------*/
-
-static INLINE
-void
-tr_fixdown(const int *ISAd, int *SA, int i, int size) {
-  int j, k;
-  int v;
-  int c, d, e;
-
-  for(v = SA[i], c = ISAd[v]; (j = 2 * i + 1) < size; SA[i] = SA[k], i = k) {
-    d = ISAd[SA[k = j++]];
-    if(d < (e = ISAd[SA[j]])) { k = j; d = e; }
-    if(d <= c) { break; }
-  }
-  SA[i] = v;
-}
-
-/* Simple top-down heapsort. */
-static
-void
-tr_heapsort(const int *ISAd, int *SA, int size) {
-  int i, m;
-  int t;
-
-  m = size;
-  if((size % 2) == 0) {
-    m--;
-    if(ISAd[SA[m / 2]] < ISAd[SA[m]]) { SWAP(SA[m], SA[m / 2]); }
-  }
-
-  for(i = m / 2 - 1; 0 <= i; --i) { tr_fixdown(ISAd, SA, i, m); }
-  if((size % 2) == 0) { SWAP(SA[0], SA[m]); tr_fixdown(ISAd, SA, 0, m); }
-  for(i = m - 1; 0 < i; --i) {
-    t = SA[0], SA[0] = SA[i];
-    tr_fixdown(ISAd, SA, 0, i);
-    SA[i] = t;
-  }
-}
-
-
-/*---------------------------------------------------------------------------*/
-
-/* Returns the median of three elements. */
-static INLINE
-int *
-tr_median3(const int *ISAd, int *v1, int *v2, int *v3) {
-  int *t;
-  if(ISAd[*v1] > ISAd[*v2]) { SWAP(v1, v2); }
-  if(ISAd[*v2] > ISAd[*v3]) {
-    if(ISAd[*v1] > ISAd[*v3]) { return v1; }
-    else { return v3; }
-  }
-  return v2;
-}
-
-/* Returns the median of five elements. */
-static INLINE
-int *
-tr_median5(const int *ISAd,
-           int *v1, int *v2, int *v3, int *v4, int *v5) {
-  int *t;
-  if(ISAd[*v2] > ISAd[*v3]) { SWAP(v2, v3); }
-  if(ISAd[*v4] > ISAd[*v5]) { SWAP(v4, v5); }
-  if(ISAd[*v2] > ISAd[*v4]) { SWAP(v2, v4); SWAP(v3, v5); }
-  if(ISAd[*v1] > ISAd[*v3]) { SWAP(v1, v3); }
-  if(ISAd[*v1] > ISAd[*v4]) { SWAP(v1, v4); SWAP(v3, v5); }
-  if(ISAd[*v3] > ISAd[*v4]) { return v4; }
-  return v3;
-}
-
-/* Returns the pivot element. */
-static INLINE
-int *
-tr_pivot(const int *ISAd, int *first, int *last) {
-  int *middle;
-  int t;
-
-  t = last - first;
-  middle = first + t / 2;
-
-  if(t <= 512) {
-    if(t <= 32) {
-      return tr_median3(ISAd, first, middle, last - 1);
-    } else {
-      t >>= 2;
-      return tr_median5(ISAd, first, first + t, middle, last - 1 - t, last - 1);
-    }
-  }
-  t >>= 3;
-  first  = tr_median3(ISAd, first, first + t, first + (t << 1));
-  middle = tr_median3(ISAd, middle - t, middle, middle + t);
-  last   = tr_median3(ISAd, last - 1 - (t << 1), last - 1 - t, last - 1);
-  return tr_median3(ISAd, first, middle, last);
-}
-
-
-/*---------------------------------------------------------------------------*/
-
-typedef struct _trbudget_t trbudget_t;
-struct _trbudget_t {
-  int chance;
-  int remain;
-  int incval;
-  int count;
-};
-
-static INLINE
-void
-trbudget_init(trbudget_t *budget, int chance, int incval) {
-  budget->chance = chance;
-  budget->remain = budget->incval = incval;
-}
-
-static INLINE
-int
-trbudget_check(trbudget_t *budget, int size) {
-  if(size <= budget->remain) { budget->remain -= size; return 1; }
-  if(budget->chance == 0) { budget->count += size; return 0; }
-  budget->remain += budget->incval - size;
-  budget->chance -= 1;
-  return 1;
-}
-
-
-/*---------------------------------------------------------------------------*/
-
-static INLINE
-void
-tr_partition(const int *ISAd,
-             int *first, int *middle, int *last,
-             int **pa, int **pb, int v) {
-  int *a, *b, *c, *d, *e, *f;
-  int t, s;
-  int x = 0;
-
-  for(b = middle - 1; (++b < last) && ((x = ISAd[*b]) == v);) { }
-  if(((a = b) < last) && (x < v)) {
-    for(; (++b < last) && ((x = ISAd[*b]) <= v);) {
-      if(x == v) { SWAP(*b, *a); ++a; }
-    }
-  }
-  for(c = last; (b < --c) && ((x = ISAd[*c]) == v);) { }
-  if((b < (d = c)) && (x > v)) {
-    for(; (b < --c) && ((x = ISAd[*c]) >= v);) {
-      if(x == v) { SWAP(*c, *d); --d; }
-    }
-  }
-  for(; b < c;) {
-    SWAP(*b, *c);
-    for(; (++b < c) && ((x = ISAd[*b]) <= v);) {
-      if(x == v) { SWAP(*b, *a); ++a; }
-    }
-    for(; (b < --c) && ((x = ISAd[*c]) >= v);) {
-      if(x == v) { SWAP(*c, *d); --d; }
-    }
-  }
-
-  if(a <= d) {
-    c = b - 1;
-    if((s = a - first) > (t = b - a)) { s = t; }
-    for(e = first, f = b - s; 0 < s; --s, ++e, ++f) { SWAP(*e, *f); }
-    if((s = d - c) > (t = last - d - 1)) { s = t; }
-    for(e = b, f = last - s; 0 < s; --s, ++e, ++f) { SWAP(*e, *f); }
-    first += (b - a), last -= (d - c);
-  }
-  *pa = first, *pb = last;
-}
-
-static
-void
-tr_copy(int *ISA, const int *SA,
-        int *first, int *a, int *b, int *last,
-        int depth) {
-  /* sort suffixes of middle partition
-     by using sorted order of suffixes of left and right partition. */
-  int *c, *d, *e;
-  int s, v;
-
-  v = b - SA - 1;
-  for(c = first, d = a - 1; c <= d; ++c) {
-    if((0 <= (s = *c - depth)) && (ISA[s] == v)) {
-      *++d = s;
-      ISA[s] = d - SA;
-    }
-  }
-  for(c = last - 1, e = d + 1, d = b; e < d; --c) {
-    if((0 <= (s = *c - depth)) && (ISA[s] == v)) {
-      *--d = s;
-      ISA[s] = d - SA;
-    }
-  }
-}
-
-static
-void
-tr_partialcopy(int *ISA, const int *SA,
-               int *first, int *a, int *b, int *last,
-               int depth) {
-  int *c, *d, *e;
-  int s, v;
-  int rank, lastrank, newrank = -1;
-
-  v = b - SA - 1;
-  lastrank = -1;
-  for(c = first, d = a - 1; c <= d; ++c) {
-    if((0 <= (s = *c - depth)) && (ISA[s] == v)) {
-      *++d = s;
-      rank = ISA[s + depth];
-      if(lastrank != rank) { lastrank = rank; newrank = d - SA; }
-      ISA[s] = newrank;
-    }
-  }
-
-  lastrank = -1;
-  for(e = d; first <= e; --e) {
-    rank = ISA[*e];
-    if(lastrank != rank) { lastrank = rank; newrank = e - SA; }
-    if(newrank != rank) { ISA[*e] = newrank; }
-  }
-
-  lastrank = -1;
-  for(c = last - 1, e = d + 1, d = b; e < d; --c) {
-    if((0 <= (s = *c - depth)) && (ISA[s] == v)) {
-      *--d = s;
-      rank = ISA[s + depth];
-      if(lastrank != rank) { lastrank = rank; newrank = d - SA; }
-      ISA[s] = newrank;
-    }
-  }
-}
-
-static
-void
-tr_introsort(int *ISA, const int *ISAd,
-             int *SA, int *first, int *last,
-             trbudget_t *budget) {
-#define STACK_SIZE TR_STACKSIZE
-  struct { const int *a; int *b, *c; int d, e; }stack[STACK_SIZE];
-  int *a, *b, *c;
-  int t;
-  int v, x = 0;
-  int incr = ISAd - ISA;
-  int limit, next;
-  int ssize, trlink = -1;
-
-  for(ssize = 0, limit = tr_ilg(last - first);;) {
-
-    if(limit < 0) {
-      if(limit == -1) {
-        /* tandem repeat partition */
-        tr_partition(ISAd - incr, first, first, last, &a, &b, last - SA - 1);
-
-        /* update ranks */
-        if(a < last) {
-          for(c = first, v = a - SA - 1; c < a; ++c) { ISA[*c] = v; }
-        }
-        if(b < last) {
-          for(c = a, v = b - SA - 1; c < b; ++c) { ISA[*c] = v; }
-        }
-
-        /* push */
-        if(1 < (b - a)) {
-          STACK_PUSH5(NULL, a, b, 0, 0);
-          STACK_PUSH5(ISAd - incr, first, last, -2, trlink);
-          trlink = ssize - 2;
-        }
-        if((a - first) <= (last - b)) {
-          if(1 < (a - first)) {
-            STACK_PUSH5(ISAd, b, last, tr_ilg(last - b), trlink);
-            last = a, limit = tr_ilg(a - first);
-          } else if(1 < (last - b)) {
-            first = b, limit = tr_ilg(last - b);
-          } else {
-            STACK_POP5(ISAd, first, last, limit, trlink);
-          }
-        } else {
-          if(1 < (last - b)) {
-            STACK_PUSH5(ISAd, first, a, tr_ilg(a - first), trlink);
-            first = b, limit = tr_ilg(last - b);
-          } else if(1 < (a - first)) {
-            last = a, limit = tr_ilg(a - first);
-          } else {
-            STACK_POP5(ISAd, first, last, limit, trlink);
-          }
-        }
-      } else if(limit == -2) {
-        /* tandem repeat copy */
-        a = stack[--ssize].b, b = stack[ssize].c;
-        if(stack[ssize].d == 0) {
-          tr_copy(ISA, SA, first, a, b, last, ISAd - ISA);
-        } else {
-          if(0 <= trlink) { stack[trlink].d = -1; }
-          tr_partialcopy(ISA, SA, first, a, b, last, ISAd - ISA);
-        }
-        STACK_POP5(ISAd, first, last, limit, trlink);
-      } else {
-        /* sorted partition */
-        if(0 <= *first) {
-          a = first;
-          do { ISA[*a] = a - SA; } while((++a < last) && (0 <= *a));
-          first = a;
-        }
-        if(first < last) {
-          a = first; do { *a = ~*a; } while(*++a < 0);
-          next = (ISA[*a] != ISAd[*a]) ? tr_ilg(a - first + 1) : -1;
-          if(++a < last) { for(b = first, v = a - SA - 1; b < a; ++b) { ISA[*b] = v; } }
-
-          /* push */
-          if(trbudget_check(budget, a - first)) {
-            if((a - first) <= (last - a)) {
-              STACK_PUSH5(ISAd, a, last, -3, trlink);
-              ISAd += incr, last = a, limit = next;
-            } else {
-              if(1 < (last - a)) {
-                STACK_PUSH5(ISAd + incr, first, a, next, trlink);
-                first = a, limit = -3;
-              } else {
-                ISAd += incr, last = a, limit = next;
-              }
-            }
-          } else {
-            if(0 <= trlink) { stack[trlink].d = -1; }
-            if(1 < (last - a)) {
-              first = a, limit = -3;
-            } else {
-              STACK_POP5(ISAd, first, last, limit, trlink);
-            }
-          }
-        } else {
-          STACK_POP5(ISAd, first, last, limit, trlink);
-        }
-      }
-      continue;
-    }
-
-    if((last - first) <= TR_INSERTIONSORT_THRESHOLD) {
-      tr_insertionsort(ISAd, first, last);
-      limit = -3;
-      continue;
-    }
-
-    if(limit-- == 0) {
-      tr_heapsort(ISAd, first, last - first);
-      for(a = last - 1; first < a; a = b) {
-        for(x = ISAd[*a], b = a - 1; (first <= b) && (ISAd[*b] == x); --b) { *b = ~*b; }
-      }
-      limit = -3;
-      continue;
-    }
-
-    /* choose pivot */
-    a = tr_pivot(ISAd, first, last);
-    SWAP(*first, *a);
-    v = ISAd[*first];
-
-    /* partition */
-    tr_partition(ISAd, first, first + 1, last, &a, &b, v);
-    if((last - first) != (b - a)) {
-      next = (ISA[*a] != v) ? tr_ilg(b - a) : -1;
-
-      /* update ranks */
-      for(c = first, v = a - SA - 1; c < a; ++c) { ISA[*c] = v; }
-      if(b < last) { for(c = a, v = b - SA - 1; c < b; ++c) { ISA[*c] = v; } }
-
-      /* push */
-      if((1 < (b - a)) && (trbudget_check(budget, b - a))) {
-        if((a - first) <= (last - b)) {
-          if((last - b) <= (b - a)) {
-            if(1 < (a - first)) {
-              STACK_PUSH5(ISAd + incr, a, b, next, trlink);
-              STACK_PUSH5(ISAd, b, last, limit, trlink);
-              last = a;
-            } else if(1 < (last - b)) {
-              STACK_PUSH5(ISAd + incr, a, b, next, trlink);
-              first = b;
-            } else {
-              ISAd += incr, first = a, last = b, limit = next;
-            }
-          } else if((a - first) <= (b - a)) {
-            if(1 < (a - first)) {
-              STACK_PUSH5(ISAd, b, last, limit, trlink);
-              STACK_PUSH5(ISAd + incr, a, b, next, trlink);
-              last = a;
-            } else {
-              STACK_PUSH5(ISAd, b, last, limit, trlink);
-              ISAd += incr, first = a, last = b, limit = next;
-            }
-          } else {
-            STACK_PUSH5(ISAd, b, last, limit, trlink);
-            STACK_PUSH5(ISAd, first, a, limit, trlink);
-            ISAd += incr, first = a, last = b, limit = next;
-          }
-        } else {
-          if((a - first) <= (b - a)) {
-            if(1 < (last - b)) {
-              STACK_PUSH5(ISAd + incr, a, b, next, trlink);
-              STACK_PUSH5(ISAd, first, a, limit, trlink);
-              first = b;
-            } else if(1 < (a - first)) {
-              STACK_PUSH5(ISAd + incr, a, b, next, trlink);
-              last = a;
-            } else {
-              ISAd += incr, first = a, last = b, limit = next;
-            }
-          } else if((last - b) <= (b - a)) {
-            if(1 < (last - b)) {
-              STACK_PUSH5(ISAd, first, a, limit, trlink);
-              STACK_PUSH5(ISAd + incr, a, b, next, trlink);
-              first = b;
-            } else {
-              STACK_PUSH5(ISAd, first, a, limit, trlink);
-              ISAd += incr, first = a, last = b, limit = next;
-            }
-          } else {
-            STACK_PUSH5(ISAd, first, a, limit, trlink);
-            STACK_PUSH5(ISAd, b, last, limit, trlink);
-            ISAd += incr, first = a, last = b, limit = next;
-          }
-        }
-      } else {
-        if((1 < (b - a)) && (0 <= trlink)) { stack[trlink].d = -1; }
-        if((a - first) <= (last - b)) {
-          if(1 < (a - first)) {
-            STACK_PUSH5(ISAd, b, last, limit, trlink);
-            last = a;
-          } else if(1 < (last - b)) {
-            first = b;
-          } else {
-            STACK_POP5(ISAd, first, last, limit, trlink);
-          }
-        } else {
-          if(1 < (last - b)) {
-            STACK_PUSH5(ISAd, first, a, limit, trlink);
-            first = b;
-          } else if(1 < (a - first)) {
-            last = a;
-          } else {
-            STACK_POP5(ISAd, first, last, limit, trlink);
-          }
-        }
-      }
-    } else {
-      if(trbudget_check(budget, last - first)) {
-        limit = tr_ilg(last - first), ISAd += incr;
-      } else {
-        if(0 <= trlink) { stack[trlink].d = -1; }
-        STACK_POP5(ISAd, first, last, limit, trlink);
-      }
-    }
-  }
-#undef STACK_SIZE
-}
-
-
-
-/*---------------------------------------------------------------------------*/
-
-/* Tandem repeat sort */
-static
-void
-trsort(int *ISA, int *SA, int n, int depth) {
-  int *ISAd;
-  int *first, *last;
-  trbudget_t budget;
-  int t, skip, unsorted;
-
-  trbudget_init(&budget, tr_ilg(n) * 2 / 3, n);
-/*  trbudget_init(&budget, tr_ilg(n) * 3 / 4, n); */
-  for(ISAd = ISA + depth; -n < *SA; ISAd += ISAd - ISA) {
-    first = SA;
-    skip = 0;
-    unsorted = 0;
-    do {
-      if((t = *first) < 0) { first -= t; skip += t; }
-      else {
-        if(skip != 0) { *(first + skip) = skip; skip = 0; }
-        last = SA + ISA[t] + 1;
-        if(1 < (last - first)) {
-          budget.count = 0;
-          tr_introsort(ISA, ISAd, SA, first, last, &budget);
-          if(budget.count != 0) { unsorted += budget.count; }
-          else { skip = first - last; }
-        } else if((last - first) == 1) {
-          skip = -1;
-        }
-        first = last;
-      }
-    } while(first < (SA + n));
-    if(skip != 0) { *(first + skip) = skip; }
-    if(unsorted == 0) { break; }
-  }
-}
-
-
-/*---------------------------------------------------------------------------*/
-
-/* Sorts suffixes of type B*. */
-static
-int
-sort_typeBstar(const unsigned char *T, int *SA,
-               int *bucket_A, int *bucket_B,
-               int n, int openMP) {
-  int *PAb, *ISAb, *buf;
-#ifdef LIBBSC_OPENMP
-  int *curbuf;
-  int l;
-#endif
-  int i, j, k, t, m, bufsize;
-  int c0, c1;
-#ifdef LIBBSC_OPENMP
-  int d0, d1;
-#endif
-  (void)openMP;
-
-  /* Initialize bucket arrays. */
-  for(i = 0; i < BUCKET_A_SIZE; ++i) { bucket_A[i] = 0; }
-  for(i = 0; i < BUCKET_B_SIZE; ++i) { bucket_B[i] = 0; }
-
-  /* Count the number of occurrences of the first one or two characters of each
-     type A, B and B* suffix. Moreover, store the beginning position of all
-     type B* suffixes into the array SA. */
-  for(i = n - 1, m = n, c0 = T[n - 1]; 0 <= i;) {
-    /* type A suffix. */
-    do { ++BUCKET_A(c1 = c0); } while((0 <= --i) && ((c0 = T[i]) >= c1));
-    if(0 <= i) {
-      /* type B* suffix. */
-      ++BUCKET_BSTAR(c0, c1);
-      SA[--m] = i;
-      /* type B suffix. */
-      for(--i, c1 = c0; (0 <= i) && ((c0 = T[i]) <= c1); --i, c1 = c0) {
-        ++BUCKET_B(c0, c1);
-      }
-    }
-  }
-  m = n - m;
-/*
-note:
-  A type B* suffix is lexicographically smaller than a type B suffix that
-  begins with the same first two characters.
-*/
-
-  /* Calculate the index of start/end point of each bucket. */
-  for(c0 = 0, i = 0, j = 0; c0 < ALPHABET_SIZE; ++c0) {
-    t = i + BUCKET_A(c0);
-    BUCKET_A(c0) = i + j; /* start point */
-    i = t + BUCKET_B(c0, c0);
-    for(c1 = c0 + 1; c1 < ALPHABET_SIZE; ++c1) {
-      j += BUCKET_BSTAR(c0, c1);
-      BUCKET_BSTAR(c0, c1) = j; /* end point */
-      i += BUCKET_B(c0, c1);
-    }
-  }
-
-  if(0 < m) {
-    /* Sort the type B* suffixes by their first two characters. */
-    PAb = SA + n - m; ISAb = SA + m;
-    for(i = m - 2; 0 <= i; --i) {
-      t = PAb[i], c0 = T[t], c1 = T[t + 1];
-      SA[--BUCKET_BSTAR(c0, c1)] = i;
-    }
-    t = PAb[m - 1], c0 = T[t], c1 = T[t + 1];
-    SA[--BUCKET_BSTAR(c0, c1)] = m - 1;
-
-    /* Sort the type B* substrings using sssort. */
-#ifdef LIBBSC_OPENMP
-    if (openMP)
-    {
-        buf = SA + m;
-        c0 = ALPHABET_SIZE - 2, c1 = ALPHABET_SIZE - 1, j = m;
-#pragma omp parallel default(shared) private(bufsize, curbuf, k, l, d0, d1)
-        {
-          bufsize = (n - (2 * m)) / omp_get_num_threads();
-          curbuf = buf + omp_get_thread_num() * bufsize;
-          k = 0;
-          for(;;) {
-            #pragma omp critical(sssort_lock)
-            {
-              if(0 < (l = j)) {
-                d0 = c0, d1 = c1;
-                do {
-                  k = BUCKET_BSTAR(d0, d1);
-                  if(--d1 <= d0) {
-                    d1 = ALPHABET_SIZE - 1;
-                    if(--d0 < 0) { break; }
-                  }
-                } while(((l - k) <= 1) && (0 < (l = k)));
-                c0 = d0, c1 = d1, j = k;
-              }
-            }
-            if(l == 0) { break; }
-            sssort(T, PAb, SA + k, SA + l,
-                   curbuf, bufsize, 2, n, *(SA + k) == (m - 1));
-          }
-        }
-    }
-    else
-    {
-        buf = SA + m, bufsize = n - (2 * m);
-        for(c0 = ALPHABET_SIZE - 2, j = m; 0 < j; --c0) {
-          for(c1 = ALPHABET_SIZE - 1; c0 < c1; j = i, --c1) {
-            i = BUCKET_BSTAR(c0, c1);
-            if(1 < (j - i)) {
-              sssort(T, PAb, SA + i, SA + j,
-                     buf, bufsize, 2, n, *(SA + i) == (m - 1));
-            }
-          }
-        }
-    }
-#else
-    buf = SA + m, bufsize = n - (2 * m);
-    for(c0 = ALPHABET_SIZE - 2, j = m; 0 < j; --c0) {
-      for(c1 = ALPHABET_SIZE - 1; c0 < c1; j = i, --c1) {
-        i = BUCKET_BSTAR(c0, c1);
-        if(1 < (j - i)) {
-          sssort(T, PAb, SA + i, SA + j,
-                 buf, bufsize, 2, n, *(SA + i) == (m - 1));
-        }
-      }
-    }
-#endif
-
-    /* Compute ranks of type B* substrings. */
-    for(i = m - 1; 0 <= i; --i) {
-      if(0 <= SA[i]) {
-        j = i;
-        do { ISAb[SA[i]] = i; } while((0 <= --i) && (0 <= SA[i]));
-        SA[i + 1] = i - j;
-        if(i <= 0) { break; }
-      }
-      j = i;
-      do { ISAb[SA[i] = ~SA[i]] = j; } while(SA[--i] < 0);
-      ISAb[SA[i]] = j;
-    }
-
-    /* Construct the inverse suffix array of type B* suffixes using trsort. */
-    trsort(ISAb, SA, m, 1);
-
-    /* Set the sorted order of type B* suffixes. */
-    for(i = n - 1, j = m, c0 = T[n - 1]; 0 <= i;) {
-      for(--i, c1 = c0; (0 <= i) && ((c0 = T[i]) >= c1); --i, c1 = c0) { }
-      if(0 <= i) {
-        t = i;
-        for(--i, c1 = c0; (0 <= i) && ((c0 = T[i]) <= c1); --i, c1 = c0) { }
-        SA[ISAb[--j]] = ((t == 0) || (1 < (t - i))) ? t : ~t;
-      }
-    }
-
-    /* Calculate the index of start/end point of each bucket. */
-    BUCKET_B(ALPHABET_SIZE - 1, ALPHABET_SIZE - 1) = n; /* end point */
-    for(c0 = ALPHABET_SIZE - 2, k = m - 1; 0 <= c0; --c0) {
-      i = BUCKET_A(c0 + 1) - 1;
-      for(c1 = ALPHABET_SIZE - 1; c0 < c1; --c1) {
-        t = i - BUCKET_B(c0, c1);
-        BUCKET_B(c0, c1) = i; /* end point */
-
-        /* Move all type B* suffixes to the correct position. */
-        for(i = t, j = BUCKET_BSTAR(c0, c1);
-            j <= k;
-            --i, --k) { SA[i] = SA[k]; }
-      }
-      BUCKET_BSTAR(c0, c0 + 1) = i - BUCKET_B(c0, c0) + 1; /* start point */
-      BUCKET_B(c0, c0) = i; /* end point */
-    }
-  }
-
-  return m;
-}
-
-/* Constructs the suffix array by using the sorted order of type B* suffixes. */
-static
-void
-construct_SA(const unsigned char *T, int *SA,
-             int *bucket_A, int *bucket_B,
-             int n, int m) {
-  int *i, *j, *k;
-  int s;
-  int c0, c1, c2;
-
-  if(0 < m) {
-    /* Construct the sorted order of type B suffixes by using
-       the sorted order of type B* suffixes. */
-    for(c1 = ALPHABET_SIZE - 2; 0 <= c1; --c1) {
-      /* Scan the suffix array from right to left. */
-      for(i = SA + BUCKET_BSTAR(c1, c1 + 1),
-          j = SA + BUCKET_A(c1 + 1) - 1, k = NULL, c2 = -1;
-          i <= j;
-          --j) {
-        if(0 < (s = *j)) {
-          assert(T[s] == c1);
-          assert(((s + 1) < n) && (T[s] <= T[s + 1]));
-          assert(T[s - 1] <= T[s]);
-          *j = ~s;
-          c0 = T[--s];
-          if((0 < s) && (T[s - 1] > c0)) { s = ~s; }
-          if(c0 != c2) {
-            if(0 <= c2) { BUCKET_B(c2, c1) = k - SA; }
-            k = SA + BUCKET_B(c2 = c0, c1);
-          }
-          assert(k < j); assert(k != NULL);
-          *k-- = s;
-        } else {
-          assert(((s == 0) && (T[s] == c1)) || (s < 0));
-          *j = ~s;
-        }
-      }
-    }
-  }
-
-  /* Construct the suffix array by using
-     the sorted order of type B suffixes. */
-  k = SA + BUCKET_A(c2 = T[n - 1]);
-  *k++ = (T[n - 2] < c2) ? ~(n - 1) : (n - 1);
-  /* Scan the suffix array from left to right. */
-  for(i = SA, j = SA + n; i < j; ++i) {
-    if(0 < (s = *i)) {
-      assert(T[s - 1] >= T[s]);
-      c0 = T[--s];
-      if((s == 0) || (T[s - 1] < c0)) { s = ~s; }
-      if(c0 != c2) {
-        BUCKET_A(c2) = k - SA;
-        k = SA + BUCKET_A(c2 = c0);
-      }
-      assert(i < k);
-      *k++ = s;
-    } else {
-      assert(s < 0);
-      *i = ~s;
-    }
-  }
-}
-
-/* Constructs the burrows-wheeler transformed string directly
-   by using the sorted order of type B* suffixes. */
-static
-int
-construct_BWT(const unsigned char *T, int *SA,
-              int *bucket_A, int *bucket_B,
-              int n, int m) {
-  int *i, *j, *k, *orig;
-  int s;
-  int c0, c1, c2;
-
-  if(0 < m) {
-    /* Construct the sorted order of type B suffixes by using
-       the sorted order of type B* suffixes. */
-    for(c1 = ALPHABET_SIZE - 2; 0 <= c1; --c1) {
-      /* Scan the suffix array from right to left. */
-      for(i = SA + BUCKET_BSTAR(c1, c1 + 1),
-          j = SA + BUCKET_A(c1 + 1) - 1, k = NULL, c2 = -1;
-          i <= j;
-          --j) {
-        if(0 < (s = *j)) {
-          assert(T[s] == c1);
-          assert(((s + 1) < n) && (T[s] <= T[s + 1]));
-          assert(T[s - 1] <= T[s]);
-          c0 = T[--s];
-          *j = ~((int)c0);
-          if((0 < s) && (T[s - 1] > c0)) { s = ~s; }
-          if(c0 != c2) {
-            if(0 <= c2) { BUCKET_B(c2, c1) = k - SA; }
-            k = SA + BUCKET_B(c2 = c0, c1);
-          }
-          assert(k < j); assert(k != NULL);
-          *k-- = s;
-        } else if(s != 0) {
-          *j = ~s;
-#ifndef NDEBUG
-        } else {
-          assert(T[s] == c1);
-#endif
-        }
-      }
-    }
-  }
-
-  /* Construct the BWTed string by using
-     the sorted order of type B suffixes. */
-  k = SA + BUCKET_A(c2 = T[n - 1]);
-  *k++ = (T[n - 2] < c2) ? ~((int)T[n - 2]) : (n - 1);
-  /* Scan the suffix array from left to right. */
-  for(i = SA, j = SA + n, orig = SA; i < j; ++i) {
-    if(0 < (s = *i)) {
-      assert(T[s - 1] >= T[s]);
-      c0 = T[--s];
-      *i = c0;
-      if((0 < s) && (T[s - 1] < c0)) { s = ~((int)T[s - 1]); }
-      if(c0 != c2) {
-        BUCKET_A(c2) = k - SA;
-        k = SA + BUCKET_A(c2 = c0);
-      }
-      assert(i < k);
-      *k++ = s;
-    } else if(s != 0) {
-      *i = ~s;
-    } else {
-      orig = i;
-    }
-  }
-
-  return orig - SA;
-}
-
-/* Constructs the burrows-wheeler transformed string directly
-   by using the sorted order of type B* suffixes. */
-static
-int
-construct_BWT_indexes(const unsigned char *T, int *SA,
-                      int *bucket_A, int *bucket_B,
-                      int n, int m,
-                      unsigned char * num_indexes, int * indexes) {
-  int *i, *j, *k, *orig;
-  int s;
-  int c0, c1, c2;
-
-  int mod = n / 8;
-  {
-      mod |= mod >> 1;  mod |= mod >> 2;
-      mod |= mod >> 4;  mod |= mod >> 8;
-      mod |= mod >> 16; mod >>= 1;
-
-      *num_indexes = (unsigned char)((n - 1) / (mod + 1));
-  }
-
-  if(0 < m) {
-    /* Construct the sorted order of type B suffixes by using
-       the sorted order of type B* suffixes. */
-    for(c1 = ALPHABET_SIZE - 2; 0 <= c1; --c1) {
-      /* Scan the suffix array from right to left. */
-      for(i = SA + BUCKET_BSTAR(c1, c1 + 1),
-          j = SA + BUCKET_A(c1 + 1) - 1, k = NULL, c2 = -1;
-          i <= j;
-          --j) {
-        if(0 < (s = *j)) {
-          assert(T[s] == c1);
-          assert(((s + 1) < n) && (T[s] <= T[s + 1]));
-          assert(T[s - 1] <= T[s]);
-
-          if ((s & mod) == 0) indexes[s / (mod + 1) - 1] = j - SA;
-
-          c0 = T[--s];
-          *j = ~((int)c0);
-          if((0 < s) && (T[s - 1] > c0)) { s = ~s; }
-          if(c0 != c2) {
-            if(0 <= c2) { BUCKET_B(c2, c1) = k - SA; }
-            k = SA + BUCKET_B(c2 = c0, c1);
-          }
-          assert(k < j); assert(k != NULL);
-          *k-- = s;
-        } else if(s != 0) {
-          *j = ~s;
-#ifndef NDEBUG
-        } else {
-          assert(T[s] == c1);
-#endif
-        }
-      }
-    }
-  }
-
-  /* Construct the BWTed string by using
-     the sorted order of type B suffixes. */
-  k = SA + BUCKET_A(c2 = T[n - 1]);
-  if (T[n - 2] < c2) {
-    if (((n - 1) & mod) == 0) indexes[(n - 1) / (mod + 1) - 1] = k - SA;
-    *k++ = ~((int)T[n - 2]);
-  }
-  else {
-    *k++ = n - 1;
-  }
-
-  /* Scan the suffix array from left to right. */
-  for(i = SA, j = SA + n, orig = SA; i < j; ++i) {
-    if(0 < (s = *i)) {
-      assert(T[s - 1] >= T[s]);
-
-      if ((s & mod) == 0) indexes[s / (mod + 1) - 1] = i - SA;
-
-      c0 = T[--s];
-      *i = c0;
-      if(c0 != c2) {
-        BUCKET_A(c2) = k - SA;
-        k = SA + BUCKET_A(c2 = c0);
-      }
-      assert(i < k);
-      if((0 < s) && (T[s - 1] < c0)) {
-          if ((s & mod) == 0) indexes[s / (mod + 1) - 1] = k - SA;
-          *k++ = ~((int)T[s - 1]);
-      } else
-        *k++ = s;
-    } else if(s != 0) {
-      *i = ~s;
-    } else {
-      orig = i;
-    }
-  }
-
-  return orig - SA;
-}
-
-
-/*---------------------------------------------------------------------------*/
-
-/*- Function -*/
-
-int
-divsufsort(const unsigned char *T, int *SA, int n, int openMP) {
-  int *bucket_A, *bucket_B;
-  int m;
-  int err = 0;
-
-  /* Check arguments. */
-  if((T == NULL) || (SA == NULL) || (n < 0)) { return -1; }
-  else if(n == 0) { return 0; }
-  else if(n == 1) { SA[0] = 0; return 0; }
-  else if(n == 2) { m = (T[0] < T[1]); SA[m ^ 1] = 0, SA[m] = 1; return 0; }
-
-  bucket_A = (int *)malloc(BUCKET_A_SIZE * sizeof(int));
-  bucket_B = (int *)malloc(BUCKET_B_SIZE * sizeof(int));
-
-  /* Suffixsort. */
-  if((bucket_A != NULL) && (bucket_B != NULL)) {
-    m = sort_typeBstar(T, SA, bucket_A, bucket_B, n, openMP);
-    construct_SA(T, SA, bucket_A, bucket_B, n, m);
-  } else {
-    err = -2;
-  }
-
-  free(bucket_B);
-  free(bucket_A);
-
-  return err;
-}
-
-int
-divbwt(const unsigned char *T, unsigned char *U, int *A, int n, unsigned char * num_indexes, int * indexes, int openMP) {
-  int *B;
-  int *bucket_A, *bucket_B;
-  int m, pidx, i;
-
-  /* Check arguments. */
-  if((T == NULL) || (U == NULL) || (n < 0)) { return -1; }
-  else if(n <= 1) { if(n == 1) { U[0] = T[0]; } return n; }
-
-  if((B = A) == NULL) { B = (int *)malloc((size_t)(n + 1) * sizeof(int)); }
-  bucket_A = (int *)malloc(BUCKET_A_SIZE * sizeof(int));
-  bucket_B = (int *)malloc(BUCKET_B_SIZE * sizeof(int));
-
-  /* Burrows-Wheeler Transform. */
-  if((B != NULL) && (bucket_A != NULL) && (bucket_B != NULL)) {
-    m = sort_typeBstar(T, B, bucket_A, bucket_B, n, openMP);
-
-    if (num_indexes == NULL || indexes == NULL) {
-        pidx = construct_BWT(T, B, bucket_A, bucket_B, n, m);
-    } else {
-        pidx = construct_BWT_indexes(T, B, bucket_A, bucket_B, n, m, num_indexes, indexes);
-    }
-
-    /* Copy to output string. */
-    U[0] = T[n - 1];
-    for(i = 0; i < pidx; ++i) { U[i + 1] = (unsigned char)B[i]; }
-    for(i += 1; i < n; ++i) { U[i] = (unsigned char)B[i]; }
-    pidx += 1;
-  } else {
-    pidx = -2;
-  }
-
-  free(bucket_B);
-  free(bucket_A);
-  if(A == NULL) { free(B); }
-
-  return pidx;
-}

programs/Makefile

@@ -71,7 +71,7 @@ RUST_TARGET_32 ?= i686-unknown-linux-gnu
 RUST_STATICLIB_32 := $(RUST_TARGET_DIR)/$(RUST_TARGET_32)/release/libzstd_rs.a
 RUST_CARGO_FLAGS := --manifest-path $(RUST_MANIFEST) --release \
                     --target-dir $(RUST_TARGET_DIR) --no-default-features
-RUST_CARGO_FLAGS += --features compression,decompression
+RUST_CARGO_FLAGS += --features compression,decompression,dict-builder
 ifneq ($(RUST_HUF_FEATURE),)
 RUST_CARGO_FLAGS += --features $(RUST_HUF_FEATURE)
 endif
@@ -96,7 +96,7 @@ $(RUST_CLI_STATICLIB): $(RUST_CLI_SOURCES)
 $(RUST_CLI_STATICLIB_32): $(RUST_CLI_SOURCES)
 	$(CARGO) build $(RUST_CLI_CARGO_FLAGS) --target $(RUST_TARGET_32)
 
-RUST_DECOMPRESS_BUILD_CONFIG := lib-c0-d1-$(RUST_BUILD_CONFIG)
+RUST_DECOMPRESS_BUILD_CONFIG := lib-c0-d1-b0-$(RUST_BUILD_CONFIG)
 RUST_DECOMPRESS_TARGET_DIR := $(RUST_DIR)/target/$(RUST_DECOMPRESS_BUILD_CONFIG)
 RUST_DECOMPRESS_STATICLIB := $(RUST_DECOMPRESS_TARGET_DIR)/release/libzstd_rs.a
 RUST_DECOMPRESS_CARGO_FLAGS := --manifest-path $(RUST_MANIFEST) --release \
@@ -119,7 +119,7 @@ RUST_DECOMPRESS_CLI_CARGO_FLAGS := --manifest-path $(RUST_CLI_MANIFEST) --releas
 $(RUST_DECOMPRESS_CLI_STATICLIB): $(RUST_CLI_SOURCES)
 	$(CARGO) build $(RUST_DECOMPRESS_CLI_CARGO_FLAGS)
 
-RUST_COMPRESS_BUILD_CONFIG := lib-c1-d0-$(RUST_BUILD_CONFIG)
+RUST_COMPRESS_BUILD_CONFIG := lib-c1-d0-b0-$(RUST_BUILD_CONFIG)
 RUST_COMPRESS_TARGET_DIR := $(RUST_DIR)/target/$(RUST_COMPRESS_BUILD_CONFIG)
 RUST_COMPRESS_STATICLIB := $(RUST_COMPRESS_TARGET_DIR)/release/libzstd_rs.a
 RUST_COMPRESS_CARGO_FLAGS := --manifest-path $(RUST_MANIFEST) --release \
@@ -129,6 +129,17 @@ RUST_COMPRESS_CARGO_FLAGS := --manifest-path $(RUST_MANIFEST) --release \
 $(RUST_COMPRESS_STATICLIB): $(RUST_SOURCES)
 	$(CARGO) build $(RUST_COMPRESS_CARGO_FLAGS)
 
+RUST_DICTBUILDER_BUILD_CONFIG := lib-c1-d0-b1-$(RUST_BUILD_CONFIG)
+RUST_DICTBUILDER_TARGET_DIR := $(RUST_DIR)/target/$(RUST_DICTBUILDER_BUILD_CONFIG)
+RUST_DICTBUILDER_STATICLIB := $(RUST_DICTBUILDER_TARGET_DIR)/release/libzstd_rs.a
+RUST_DICTBUILDER_CARGO_FLAGS := --manifest-path $(RUST_MANIFEST) --release \
+                                 --target-dir $(RUST_DICTBUILDER_TARGET_DIR) \
+                                 --no-default-features \
+                                 --features compression,dict-builder
+
+$(RUST_DICTBUILDER_STATICLIB): $(RUST_SOURCES)
+	$(CARGO) build $(RUST_DICTBUILDER_CARGO_FLAGS)
+
 RUST_COMPRESS_CLI_BUILD_CONFIG := cli-c1-d0-$(RUST_BUILD_CONFIG)
 RUST_COMPRESS_CLI_TARGET_DIR := $(RUST_DIR)/target/$(RUST_COMPRESS_CLI_BUILD_CONFIG)
 RUST_COMPRESS_CLI_STATICLIB := $(RUST_COMPRESS_CLI_TARGET_DIR)/release/libzstd_cli_rs.a
@@ -412,7 +423,7 @@ zstd-compress: $(ZSTDLIB_COMMON_SRC) $(ZSTDLIB_COMPRESS_SRC) zstdcli.c util.c ti
 
 ## zstd-dictBuilder: executable supporting dictionary creation and compression (only)
 CLEAN += zstd-dictBuilder
-zstd-dictBuilder: $(ZSTDLIB_COMMON_SRC) $(ZSTDLIB_COMPRESS_SRC) $(ZDICT_SRC) zstdcli.c util.c timefn.c fileio.c fileio_asyncio.c dibio.c $(RUST_COMPRESS_STATICLIB) $(RUST_COMPRESS_CLI_STATICLIB)
+zstd-dictBuilder: $(ZSTDLIB_COMMON_SRC) $(ZSTDLIB_COMPRESS_SRC) $(ZDICT_SRC) zstdcli.c util.c timefn.c fileio.c fileio_asyncio.c dibio.c $(RUST_DICTBUILDER_STATICLIB) $(RUST_COMPRESS_CLI_STATICLIB)
 	$(CC) $(FLAGS) -DZSTD_NOBENCH -DZSTD_NODECOMPRESS -DZSTD_NOTRACE $^ -o $@$(EXT)
 
 RUST_DIRECT_LINK_TARGETS := zstd32 zstd-nolegacy zstd-small zstd-frugal \

rust/Cargo.toml

@@ -7,9 +7,10 @@ edition = "2021"
 crate-type = ["staticlib"]
 
 [features]
-default = ["compression", "decompression"]
+default = ["compression", "decompression", "dict-builder"]
 compression = []
 decompression = []
+dict-builder = []
 huf-force-decompress-x1 = []
 huf-force-decompress-x2 = []
 

rust/README.md

@@ -31,13 +31,6 @@ zstd ABI:
   - `zstd_presplit` chooses split points for full compression blocks.
   - `zstd_compress_literals` emits raw, RLE, and Huffman literal sections
     while preserving the compressor's Huffman-table repeat state.
-  - `zstd_compress_stats` converts stored sequences into symbol codes,
-    selects each block's symbol encoding types, compresses a seqStore's
-    literals and sequences into a compressed-block body, builds the block
-    entropy statistics shared with the superblock writer and the block
-    splitter, and exports collected sequences in the public `ZSTD_Sequence`
-    format.  Its C shims extract the sequence store, the entropy-table
-    leaves, and the two `ZSTD_CCtx_params` scalars these paths read.
   - `zstd_compress_frame` serializes frame headers, skippable frames, and the
     last empty block; it takes scalar frame parameters so the C-owned
     `ZSTD_CCtx_params` layout never crosses the language boundary.
@@ -55,6 +48,10 @@ zstd ABI:
     the dynamic-programming optimal parser itself remains in C for now.
   - `zstd_ldm` implements long-distance-match parameter selection, table
     maintenance, sequence generation, and sequence consumption.
+- Dictionary building
+  - `divsufsort` constructs the suffix array that drives the legacy `ZDICT`
+    trainer (`ZDICT_trainFromBuffer_legacy`).  The sample analysis and
+    dictionary assembly in `zdict.c`, `cover.c`, and `fastcover.c` remain C.
 - Runtime support
   - `threading` provides platform pthread wrappers required by zstd headers.
   - `pool` implements the bounded worker pool used by multithreaded compression.
@@ -73,10 +70,11 @@ zstd ABI:
     `fileio` backend still owns file opening, safe replacement, sparse writes,
     metadata, and streaming I/O.
 
-The optimal block matcher, high-level frame compression, dictionary-building,
+The optimal block matcher, high-level frame compression, dictionary-building
-legacy decoding callbacks, and the CLI file-I/O backend are still C. They must
+except suffix-array construction, legacy decoding callbacks, and the CLI
-move before the rewrite is complete. Keeping that boundary explicit prevents a
+file-I/O backend are still C. They must move before the rewrite is complete.
-passing hybrid build from being mistaken for the final all-Rust result.
+Keeping that boundary explicit prevents a passing hybrid build from being
+mistaken for the final all-Rust result.
 
 ## Compatibility boundary
 
@@ -87,8 +85,9 @@ makefile source list as a small shim so header configuration and platform
 preprocessor behavior stay available during the transition.
 
 The library, test, and program makefiles select an archive directory for the
-active C configuration: enabled compression/decompression modules, default or
+active C configuration: enabled compression/decompression/dictionary-builder
-forced HUF X1/X2, and the matching Rust target for 32-bit C binaries. The
+modules, default or forced HUF X1/X2, and the matching Rust target for 32-bit
+C binaries. The
 native static archive flattens Rust object members rather than nesting a Rust
 archive, while the native shared library retains all migrated Rust exports.
 When the HUF mode changes, the test and program paths also rebuild cached C

rust/src/divsufsort.rs

@@ -0,0 +1,2756 @@
+#![allow(clippy::missing_safety_doc)]
+#![allow(clippy::too_many_arguments)]
+
+//! Suffix-array construction for the dictionary builder.
+//!
+//! Port of `lib/dictBuilder/divsufsort.c` (libdivsufsort-lite, Copyright (c)
+//! 2003-2008 Yuta Mori, MIT license) in the exact configuration zstd compiles
+//! it with: `ALPHABET_SIZE = 256`, `SS_INSERTIONSORT_THRESHOLD = 8`,
+//! `SS_BLOCKSIZE = 1024`, and no OpenMP.  Only `divsufsort()` is exported;
+//! `divbwt()` has no callers anywhere in zstd and was not ported.
+//!
+//! The C implementation walks raw `int*` cursors through the caller's SA
+//! buffer, including transient one-before-the-range positions.  Every such
+//! cursor is translated to an `isize` index into one `&mut [i32]` slice
+//! covering the whole buffer, so all arithmetic — including the
+//! bitwise-complement rank marking and the C `int` value semantics — matches
+//! the original exactly while staying bounds-checked.
+
+use std::os::raw::c_int;
+use std::slice;
+
+const BUCKET_A_SIZE: usize = 256; /* ALPHABET_SIZE */
+const BUCKET_B_SIZE: usize = 256 * 256; /* ALPHABET_SIZE * ALPHABET_SIZE */
+const ALPHABET_SIZE: i32 = 256;
+const SS_INSERTIONSORT_THRESHOLD: isize = 8;
+const SS_BLOCKSIZE: isize = 1024;
+/* minstacksize = log(SS_BLOCKSIZE) / log(3) * 2 */
+const SS_MISORT_STACKSIZE: usize = 16;
+const SS_SMERGE_STACKSIZE: usize = 32;
+const TR_INSERTIONSORT_THRESHOLD: isize = 8;
+const TR_STACKSIZE: usize = 64;
+
+#[rustfmt::skip]
+static LG_TABLE: [i32; 256] = [
+ -1,0,1,1,2,2,2,2,3,3,3,3,3,3,3,3,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,
+  5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,
+  6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
+  6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
+  7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
+  7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
+  7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
+  7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
+];
+
+#[rustfmt::skip]
+static SQQ_TABLE: [i32; 256] = [
+  0,  16,  22,  27,  32,  35,  39,  42,  45,  48,  50,  53,  55,  57,  59,  61,
+ 64,  65,  67,  69,  71,  73,  75,  76,  78,  80,  81,  83,  84,  86,  87,  89,
+ 90,  91,  93,  94,  96,  97,  98,  99, 101, 102, 103, 104, 106, 107, 108, 109,
+110, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126,
+128, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142,
+143, 144, 144, 145, 146, 147, 148, 149, 150, 150, 151, 152, 153, 154, 155, 155,
+156, 157, 158, 159, 160, 160, 161, 162, 163, 163, 164, 165, 166, 167, 167, 168,
+169, 170, 170, 171, 172, 173, 173, 174, 175, 176, 176, 177, 178, 178, 179, 180,
+181, 181, 182, 183, 183, 184, 185, 185, 186, 187, 187, 188, 189, 189, 190, 191,
+192, 192, 193, 193, 194, 195, 195, 196, 197, 197, 198, 199, 199, 200, 201, 201,
+202, 203, 203, 204, 204, 205, 206, 206, 207, 208, 208, 209, 209, 210, 211, 211,
+212, 212, 213, 214, 214, 215, 215, 216, 217, 217, 218, 218, 219, 219, 220, 221,
+221, 222, 222, 223, 224, 224, 225, 225, 226, 226, 227, 227, 228, 229, 229, 230,
+230, 231, 231, 232, 232, 233, 234, 234, 235, 235, 236, 236, 237, 237, 238, 238,
+239, 240, 240, 241, 241, 242, 242, 243, 243, 244, 244, 245, 245, 246, 246, 247,
+247, 248, 248, 249, 249, 250, 250, 251, 251, 252, 252, 253, 253, 254, 254, 255,
+];
+
+/* `ss_ilg` in its `256 <= SS_BLOCKSIZE` configuration. */
+#[inline]
+fn ss_ilg(n: isize) -> i32 {
+    let n = n as i32;
+    if n & 0xff00 != 0 {
+        8 + LG_TABLE[((n >> 8) & 0xff) as usize]
+    } else {
+        LG_TABLE[(n & 0xff) as usize]
+    }
+}
+
+#[inline]
+fn ss_isqrt(x: isize) -> isize {
+    if x >= SS_BLOCKSIZE * SS_BLOCKSIZE {
+        return SS_BLOCKSIZE;
+    }
+    let x = x as i32;
+    let e = if (x as u32) & 0xffff_0000 != 0 {
+        if (x as u32) & 0xff00_0000 != 0 {
+            24 + LG_TABLE[((x >> 24) & 0xff) as usize]
+        } else {
+            16 + LG_TABLE[((x >> 16) & 0xff) as usize]
+        }
+    } else if x & 0xff00 != 0 {
+        8 + LG_TABLE[((x >> 8) & 0xff) as usize]
+    } else {
+        LG_TABLE[(x & 0xff) as usize]
+    };
+
+    let mut y;
+    if e >= 16 {
+        y = SQQ_TABLE[(x >> ((e - 6) - (e & 1))) as usize] << ((e >> 1) - 7);
+        if e >= 24 {
+            y = (y + 1 + x / y) >> 1;
+        }
+        y = (y + 1 + x / y) >> 1;
+    } else if e >= 8 {
+        y = (SQQ_TABLE[(x >> ((e - 6) - (e & 1))) as usize] >> (7 - (e >> 1))) + 1;
+    } else {
+        return (SQQ_TABLE[x as usize] >> 4) as isize;
+    }
+
+    (if x < y * y { y - 1 } else { y }) as isize
+}
+
+/* --------------------------------------------------------------------- */
+
+/// Compares two suffixes.  `(p10, p11)` and `(p20, p21)` are the `p[0]`/`p[1]`
+/// pairs the C routine reads through its `const int*` arguments; passing the
+/// values directly also serves `sssort()`'s local two-element `PAi` array.
+#[inline]
+fn ss_compare(t: &[u8], p10: i32, p11: i32, p20: i32, p21: i32, depth: i32) -> i32 {
+    let mut u1 = (depth + p10) as isize;
+    let mut u2 = (depth + p20) as isize;
+    let u1n = (p11 + 2) as isize;
+    let u2n = (p21 + 2) as isize;
+
+    while u1 < u1n && u2 < u2n && t[u1 as usize] == t[u2 as usize] {
+        u1 += 1;
+        u2 += 1;
+    }
+
+    if u1 < u1n {
+        if u2 < u2n {
+            t[u1 as usize] as i32 - t[u2 as usize] as i32
+        } else {
+            1
+        }
+    } else if u2 < u2n {
+        -1
+    } else {
+        0
+    }
+}
+
+/// `ss_compare(T, p1, p2, depth)` for pointers `p1`/`p2` into the SA buffer.
+#[inline]
+fn ss_compare_pa(t: &[u8], sa: &[i32], p1: isize, p2: isize, depth: i32) -> i32 {
+    ss_compare(
+        t,
+        sa[p1 as usize],
+        sa[(p1 + 1) as usize],
+        sa[p2 as usize],
+        sa[(p2 + 1) as usize],
+        depth,
+    )
+}
+
+/* --------------------------------------------------------------------- */
+
+/* Insertionsort for small size groups */
+fn ss_insertionsort(t: &[u8], sa: &mut [i32], pa: isize, first: isize, last: isize, depth: i32) {
+    let mut i = last - 2;
+    while first <= i {
+        let t0 = sa[i as usize];
+        let mut j = i + 1;
+        let mut r;
+        loop {
+            r = ss_compare_pa(t, sa, pa + t0 as isize, pa + sa[j as usize] as isize, depth);
+            if r <= 0 {
+                break;
+            }
+            loop {
+                sa[(j - 1) as usize] = sa[j as usize];
+                j += 1;
+                if !(j < last && sa[j as usize] < 0) {
+                    break;
+                }
+            }
+            if last <= j {
+                break;
+            }
+        }
+        if r == 0 {
+            sa[j as usize] = !sa[j as usize];
+        }
+        sa[(j - 1) as usize] = t0;
+        i -= 1;
+    }
+}
+
+/* --------------------------------------------------------------------- */
+
+/// `Td[PA[SA[p]]]` — the depth-`td` sorting key of the suffix stored at `p`.
+#[inline(always)]
+fn ss_key(t: &[u8], sa: &[i32], td: isize, pa: isize, p: isize) -> i32 {
+    t[(td + sa[(pa + sa[p as usize] as isize) as usize] as isize) as usize] as i32
+}
+
+/// `Td[v]` for an already-loaded SA element `v` (`Td[PA[v]]` in C).
+#[inline(always)]
+fn ss_key_of(t: &[u8], sa: &[i32], td: isize, pa: isize, v: i32) -> i32 {
+    t[(td + sa[(pa + v as isize) as usize] as isize) as usize] as i32
+}
+
+/// `Td[PA[SA[p]] - 1]` — the character preceding the depth-`td` key.
+#[inline(always)]
+fn ss_key_pred(t: &[u8], sa: &[i32], td: isize, pa: isize, p: isize) -> i32 {
+    t[(td + sa[(pa + sa[p as usize] as isize) as usize] as isize - 1) as usize] as i32
+}
+
+fn ss_fixdown(t: &[u8], td: isize, sa: &mut [i32], pa: isize, base: isize, i: isize, size: isize) {
+    let mut i = i;
+    let v = sa[(base + i) as usize];
+    let c = ss_key_of(t, sa, td, pa, v);
+    loop {
+        let mut j = 2 * i + 1;
+        if j >= size {
+            break;
+        }
+        let mut k = j;
+        j += 1;
+        let mut d = ss_key(t, sa, td, pa, base + k);
+        let e = ss_key(t, sa, td, pa, base + j);
+        if d < e {
+            k = j;
+            d = e;
+        }
+        if d <= c {
+            break;
+        }
+        sa[(base + i) as usize] = sa[(base + k) as usize];
+        i = k;
+    }
+    sa[(base + i) as usize] = v;
+}
+
+/* Simple top-down heapsort. */
+fn ss_heapsort(t: &[u8], td: isize, sa: &mut [i32], pa: isize, base: isize, size: isize) {
+    let mut m = size;
+    if size % 2 == 0 {
+        m -= 1;
+        if ss_key(t, sa, td, pa, base + m / 2) < ss_key(t, sa, td, pa, base + m) {
+            sa.swap((base + m) as usize, (base + m / 2) as usize);
+        }
+    }
+
+    let mut i = m / 2 - 1;
+    while 0 <= i {
+        ss_fixdown(t, td, sa, pa, base, i, m);
+        i -= 1;
+    }
+    if size % 2 == 0 {
+        sa.swap(base as usize, (base + m) as usize);
+        ss_fixdown(t, td, sa, pa, base, 0, m);
+    }
+    let mut i = m - 1;
+    while 0 < i {
+        let t0 = sa[base as usize];
+        sa[base as usize] = sa[(base + i) as usize];
+        ss_fixdown(t, td, sa, pa, base, 0, i);
+        sa[(base + i) as usize] = t0;
+        i -= 1;
+    }
+}
+
+/* --------------------------------------------------------------------- */
+
+/* Returns the median of three elements. */
+#[inline]
+fn ss_median3(
+    t: &[u8],
+    sa: &[i32],
+    td: isize,
+    pa: isize,
+    v1: isize,
+    v2: isize,
+    v3: isize,
+) -> isize {
+    let mut v1 = v1;
+    let mut v2 = v2;
+    if ss_key(t, sa, td, pa, v1) > ss_key(t, sa, td, pa, v2) {
+        std::mem::swap(&mut v1, &mut v2);
+    }
+    if ss_key(t, sa, td, pa, v2) > ss_key(t, sa, td, pa, v3) {
+        if ss_key(t, sa, td, pa, v1) > ss_key(t, sa, td, pa, v3) {
+            return v1;
+        }
+        return v3;
+    }
+    v2
+}
+
+/* Returns the median of five elements. */
+#[inline]
+fn ss_median5(
+    t: &[u8],
+    sa: &[i32],
+    td: isize,
+    pa: isize,
+    v1: isize,
+    v2: isize,
+    v3: isize,
+    v4: isize,
+    v5: isize,
+) -> isize {
+    let mut v1 = v1;
+    let mut v2 = v2;
+    let mut v3 = v3;
+    let mut v4 = v4;
+    let mut v5 = v5;
+    if ss_key(t, sa, td, pa, v2) > ss_key(t, sa, td, pa, v3) {
+        std::mem::swap(&mut v2, &mut v3);
+    }
+    if ss_key(t, sa, td, pa, v4) > ss_key(t, sa, td, pa, v5) {
+        std::mem::swap(&mut v4, &mut v5);
+    }
+    if ss_key(t, sa, td, pa, v2) > ss_key(t, sa, td, pa, v4) {
+        std::mem::swap(&mut v2, &mut v4);
+        std::mem::swap(&mut v3, &mut v5);
+    }
+    if ss_key(t, sa, td, pa, v1) > ss_key(t, sa, td, pa, v3) {
+        std::mem::swap(&mut v1, &mut v3);
+    }
+    if ss_key(t, sa, td, pa, v1) > ss_key(t, sa, td, pa, v4) {
+        std::mem::swap(&mut v1, &mut v4);
+        std::mem::swap(&mut v3, &mut v5);
+    }
+    if ss_key(t, sa, td, pa, v3) > ss_key(t, sa, td, pa, v4) {
+        return v4;
+    }
+    v3
+}
+
+/* Returns the pivot element. */
+#[inline]
+fn ss_pivot(t: &[u8], sa: &[i32], td: isize, pa: isize, first: isize, last: isize) -> isize {
+    let mut t0 = last - first;
+    let middle = first + t0 / 2;
+
+    if t0 <= 512 {
+        if t0 <= 32 {
+            return ss_median3(t, sa, td, pa, first, middle, last - 1);
+        }
+        t0 >>= 2;
+        return ss_median5(
+            t,
+            sa,
+            td,
+            pa,
+            first,
+            first + t0,
+            middle,
+            last - 1 - t0,
+            last - 1,
+        );
+    }
+    t0 >>= 3;
+    let first = ss_median3(t, sa, td, pa, first, first + t0, first + (t0 << 1));
+    let middle = ss_median3(t, sa, td, pa, middle - t0, middle, middle + t0);
+    let last = ss_median3(t, sa, td, pa, last - 1 - (t0 << 1), last - 1 - t0, last - 1);
+    ss_median3(t, sa, td, pa, first, middle, last)
+}
+
+/* --------------------------------------------------------------------- */
+
+/* Binary partition for substrings. */
+/* The `>= x + 1` comparison deliberately mirrors the C expression shape. */
+#[allow(clippy::int_plus_one)]
+fn ss_partition(sa: &mut [i32], pa: isize, first: isize, last: isize, depth: i32) -> isize {
+    let mut a = first - 1;
+    let mut b = last;
+    loop {
+        loop {
+            a += 1;
+            if !(a < b) {
+                break;
+            }
+            if !(sa[(pa + sa[a as usize] as isize) as usize] + depth
+                >= sa[(pa + sa[a as usize] as isize + 1) as usize] + 1)
+            {
+                break;
+            }
+            sa[a as usize] = !sa[a as usize];
+        }
+        loop {
+            b -= 1;
+            if !(a < b) {
+                break;
+            }
+            if !(sa[(pa + sa[b as usize] as isize) as usize] + depth
+                < sa[(pa + sa[b as usize] as isize + 1) as usize] + 1)
+            {
+                break;
+            }
+        }
+        if b <= a {
+            break;
+        }
+        let t0 = !sa[b as usize];
+        sa[b as usize] = sa[a as usize];
+        sa[a as usize] = t0;
+    }
+    if first < a {
+        sa[first as usize] = !sa[first as usize];
+    }
+    a
+}
+
+/* Multikey introsort for medium size groups. */
+fn ss_mintrosort(t: &[u8], sa: &mut [i32], pa: isize, first: isize, last: isize, depth: i32) {
+    let mut stack = [(0isize, 0isize, 0i32, 0i32); SS_MISORT_STACKSIZE];
+    let mut ssize = 0usize;
+    let mut first = first;
+    let mut last = last;
+    let mut depth = depth;
+    let mut limit = ss_ilg(last - first);
+    let mut x: i32 = 0;
+
+    loop {
+        if last - first <= SS_INSERTIONSORT_THRESHOLD {
+            if 1 < last - first {
+                ss_insertionsort(t, sa, pa, first, last, depth);
+            }
+            /* STACK_POP */
+            if ssize == 0 {
+                return;
+            }
+            ssize -= 1;
+            (first, last, depth, limit) = stack[ssize];
+            continue;
+        }
+
+        let td = depth as isize;
+        if limit == 0 {
+            ss_heapsort(t, td, sa, pa, first, last - first);
+        }
+        limit -= 1;
+        if limit < 0 {
+            let mut a = first + 1;
+            let mut v = ss_key(t, sa, td, pa, first);
+            while a < last {
+                x = ss_key(t, sa, td, pa, a);
+                if x != v {
+                    if 1 < a - first {
+                        break;
+                    }
+                    v = x;
+                    first = a;
+                }
+                a += 1;
+            }
+            if ss_key_pred(t, sa, td, pa, first) < v {
+                first = ss_partition(sa, pa, first, a, depth);
+            }
+            if a - first <= last - a {
+                if 1 < a - first {
+                    stack[ssize] = (a, last, depth, -1);
+                    ssize += 1;
+                    last = a;
+                    depth += 1;
+                    limit = ss_ilg(a - first);
+                } else {
+                    first = a;
+                    limit = -1;
+                }
+            } else if 1 < last - a {
+                stack[ssize] = (first, a, depth + 1, ss_ilg(a - first));
+                ssize += 1;
+                first = a;
+                limit = -1;
+            } else {
+                last = a;
+                depth += 1;
+                limit = ss_ilg(a - first);
+            }
+            continue;
+        }
+
+        /* choose pivot */
+        let mut a = ss_pivot(t, sa, td, pa, first, last);
+        let v = ss_key(t, sa, td, pa, a);
+        sa.swap(first as usize, a as usize);
+
+        /* partition */
+        let mut b = first;
+        loop {
+            b += 1;
+            if !(b < last) {
+                break;
+            }
+            x = ss_key(t, sa, td, pa, b);
+            if x != v {
+                break;
+            }
+        }
+        a = b;
+        if a < last && x < v {
+            loop {
+                b += 1;
+                if !(b < last) {
+                    break;
+                }
+                x = ss_key(t, sa, td, pa, b);
+                if !(x <= v) {
+                    break;
+                }
+                if x == v {
+                    sa.swap(b as usize, a as usize);
+                    a += 1;
+                }
+            }
+        }
+        let mut c = last;
+        loop {
+            c -= 1;
+            if !(b < c) {
+                break;
+            }
+            x = ss_key(t, sa, td, pa, c);
+            if x != v {
+                break;
+            }
+        }
+        let mut d = c;
+        if b < d && x > v {
+            loop {
+                c -= 1;
+                if !(b < c) {
+                    break;
+                }
+                x = ss_key(t, sa, td, pa, c);
+                if !(x >= v) {
+                    break;
+                }
+                if x == v {
+                    sa.swap(c as usize, d as usize);
+                    d -= 1;
+                }
+            }
+        }
+        while b < c {
+            sa.swap(b as usize, c as usize);
+            loop {
+                b += 1;
+                if !(b < c) {
+                    break;
+                }
+                x = ss_key(t, sa, td, pa, b);
+                if !(x <= v) {
+                    break;
+                }
+                if x == v {
+                    sa.swap(b as usize, a as usize);
+                    a += 1;
+                }
+            }
+            loop {
+                c -= 1;
+                if !(b < c) {
+                    break;
+                }
+                x = ss_key(t, sa, td, pa, c);
+                if !(x >= v) {
+                    break;
+                }
+                if x == v {
+                    sa.swap(c as usize, d as usize);
+                    d -= 1;
+                }
+            }
+        }
+
+        if a <= d {
+            c = b - 1;
+
+            let mut s = a - first;
+            let t0 = b - a;
+            if s > t0 {
+                s = t0;
+            }
+            let mut e = first;
+            let mut f = b - s;
+            while 0 < s {
+                sa.swap(e as usize, f as usize);
+                s -= 1;
+                e += 1;
+                f += 1;
+            }
+            let mut s = d - c;
+            let t0 = last - d - 1;
+            if s > t0 {
+                s = t0;
+            }
+            let mut e = b;
+            let mut f = last - s;
+            while 0 < s {
+                sa.swap(e as usize, f as usize);
+                s -= 1;
+                e += 1;
+                f += 1;
+            }
+
+            a = first + (b - a);
+            c = last - (d - c);
+            b = if v <= ss_key_pred(t, sa, td, pa, a) {
+                a
+            } else {
+                ss_partition(sa, pa, a, c, depth)
+            };
+
+            if a - first <= last - c {
+                if last - c <= c - b {
+                    stack[ssize] = (b, c, depth + 1, ss_ilg(c - b));
+                    ssize += 1;
+                    stack[ssize] = (c, last, depth, limit);
+                    ssize += 1;
+                    last = a;
+                } else if a - first <= c - b {
+                    stack[ssize] = (c, last, depth, limit);
+                    ssize += 1;
+                    stack[ssize] = (b, c, depth + 1, ss_ilg(c - b));
+                    ssize += 1;
+                    last = a;
+                } else {
+                    stack[ssize] = (c, last, depth, limit);
+                    ssize += 1;
+                    stack[ssize] = (first, a, depth, limit);
+                    ssize += 1;
+                    first = b;
+                    last = c;
+                    depth += 1;
+                    limit = ss_ilg(c - b);
+                }
+            } else if a - first <= c - b {
+                stack[ssize] = (b, c, depth + 1, ss_ilg(c - b));
+                ssize += 1;
+                stack[ssize] = (first, a, depth, limit);
+                ssize += 1;
+                first = c;
+            } else if last - c <= c - b {
+                stack[ssize] = (first, a, depth, limit);
+                ssize += 1;
+                stack[ssize] = (b, c, depth + 1, ss_ilg(c - b));
+                ssize += 1;
+                first = c;
+            } else {
+                stack[ssize] = (first, a, depth, limit);
+                ssize += 1;
+                stack[ssize] = (c, last, depth, limit);
+                ssize += 1;
+                first = b;
+                last = c;
+                depth += 1;
+                limit = ss_ilg(c - b);
+            }
+        } else {
+            limit += 1;
+            if ss_key_pred(t, sa, td, pa, first) < v {
+                first = ss_partition(sa, pa, first, last, depth);
+                limit = ss_ilg(last - first);
+            }
+            depth += 1;
+        }
+    }
+}
+
+/* --------------------------------------------------------------------- */
+
+#[inline]
+fn ss_blockswap(sa: &mut [i32], a: isize, b: isize, n: isize) {
+    let mut a = a;
+    let mut b = b;
+    let mut n = n;
+    while 0 < n {
+        sa.swap(a as usize, b as usize);
+        n -= 1;
+        a += 1;
+        b += 1;
+    }
+}
+
+#[inline]
+fn ss_rotate(sa: &mut [i32], first: isize, middle: isize, last: isize) {
+    let mut first = first;
+    let mut last = last;
+    let mut l = middle - first;
+    let mut r = last - middle;
+    while 0 < l && 0 < r {
+        if l == r {
+            ss_blockswap(sa, first, middle, l);
+            break;
+        }
+        if l < r {
+            let mut a = last - 1;
+            let mut b = middle - 1;
+            let mut t0 = sa[a as usize];
+            loop {
+                sa[a as usize] = sa[b as usize];
+                a -= 1;
+                sa[b as usize] = sa[a as usize];
+                b -= 1;
+                if b < first {
+                    sa[a as usize] = t0;
+                    last = a;
+                    r -= l + 1;
+                    if r <= l {
+                        break;
+                    }
+                    a -= 1;
+                    b = middle - 1;
+                    t0 = sa[a as usize];
+                }
+            }
+        } else {
+            let mut a = first;
+            let mut b = middle;
+            let mut t0 = sa[a as usize];
+            loop {
+                sa[a as usize] = sa[b as usize];
+                a += 1;
+                sa[b as usize] = sa[a as usize];
+                b += 1;
+                if last <= b {
+                    sa[a as usize] = t0;
+                    first = a + 1;
+                    l -= r + 1;
+                    if l <= r {
+                        break;
+                    }
+                    a += 1;
+                    b = middle;
+                    t0 = sa[a as usize];
+                }
+            }
+        }
+    }
+}
+
+/* --------------------------------------------------------------------- */
+
+fn ss_inplacemerge(
+    t: &[u8],
+    sa: &mut [i32],
+    pa: isize,
+    first: isize,
+    middle: isize,
+    last: isize,
+    depth: i32,
+) {
+    let mut middle = middle;
+    let mut last = last;
+    loop {
+        let x: i32;
+        let p: isize;
+        if sa[(last - 1) as usize] < 0 {
+            x = 1;
+            p = pa + (!sa[(last - 1) as usize]) as isize;
+        } else {
+            x = 0;
+            p = pa + sa[(last - 1) as usize] as isize;
+        }
+        let mut a = first;
+        let mut len = middle - first;
+        let mut half = len >> 1;
+        let mut r: i32 = -1;
+        while 0 < len {
+            let b = a + half;
+            let bv = sa[b as usize];
+            let q = ss_compare_pa(
+                t,
+                sa,
+                pa + (if 0 <= bv { bv } else { !bv }) as isize,
+                p,
+                depth,
+            );
+            if q < 0 {
+                a = b + 1;
+                half -= (len & 1) ^ 1;
+            } else {
+                r = q;
+            }
+            len = half;
+            half >>= 1;
+        }
+        if a < middle {
+            if r == 0 {
+                sa[a as usize] = !sa[a as usize];
+            }
+            ss_rotate(sa, a, middle, last);
+            last -= middle - a;
+            middle = a;
+            if first == middle {
+                break;
+            }
+        }
+        last -= 1;
+        if x != 0 {
+            loop {
+                last -= 1;
+                if !(sa[last as usize] < 0) {
+                    break;
+                }
+            }
+        }
+        if middle == last {
+            break;
+        }
+    }
+}
+
+/* --------------------------------------------------------------------- */
+
+/* Merge-forward with internal buffer. */
+fn ss_mergeforward(
+    t: &[u8],
+    sa: &mut [i32],
+    pa: isize,
+    first: isize,
+    middle: isize,
+    last: isize,
+    buf: isize,
+    depth: i32,
+) {
+    let bufend = buf + (middle - first) - 1;
+    ss_blockswap(sa, buf, first, middle - first);
+
+    let mut a = first;
+    let t0 = sa[a as usize];
+    let mut b = buf;
+    let mut c = middle;
+    loop {
+        let r = ss_compare_pa(
+            t,
+            sa,
+            pa + sa[b as usize] as isize,
+            pa + sa[c as usize] as isize,
+            depth,
+        );
+        if r < 0 {
+            loop {
+                sa[a as usize] = sa[b as usize];
+                a += 1;
+                if bufend <= b {
+                    sa[bufend as usize] = t0;
+                    return;
+                }
+                sa[b as usize] = sa[a as usize];
+                b += 1;
+                if !(sa[b as usize] < 0) {
+                    break;
+                }
+            }
+        } else if r > 0 {
+            loop {
+                sa[a as usize] = sa[c as usize];
+                a += 1;
+                sa[c as usize] = sa[a as usize];
+                c += 1;
+                if last <= c {
+                    while b < bufend {
+                        sa[a as usize] = sa[b as usize];
+                        a += 1;
+                        sa[b as usize] = sa[a as usize];
+                        b += 1;
+                    }
+                    sa[a as usize] = sa[b as usize];
+                    sa[b as usize] = t0;
+                    return;
+                }
+                if !(sa[c as usize] < 0) {
+                    break;
+                }
+            }
+        } else {
+            sa[c as usize] = !sa[c as usize];
+            loop {
+                sa[a as usize] = sa[b as usize];
+                a += 1;
+                if bufend <= b {
+                    sa[bufend as usize] = t0;
+                    return;
+                }
+                sa[b as usize] = sa[a as usize];
+                b += 1;
+                if !(sa[b as usize] < 0) {
+                    break;
+                }
+            }
+            loop {
+                sa[a as usize] = sa[c as usize];
+                a += 1;
+                sa[c as usize] = sa[a as usize];
+                c += 1;
+                if last <= c {
+                    while b < bufend {
+                        sa[a as usize] = sa[b as usize];
+                        a += 1;
+                        sa[b as usize] = sa[a as usize];
+                        b += 1;
+                    }
+                    sa[a as usize] = sa[b as usize];
+                    sa[b as usize] = t0;
+                    return;
+                }
+                if !(sa[c as usize] < 0) {
+                    break;
+                }
+            }
+        }
+    }
+}
+
+/* Merge-backward with internal buffer. */
+fn ss_mergebackward(
+    t: &[u8],
+    sa: &mut [i32],
+    pa: isize,
+    first: isize,
+    middle: isize,
+    last: isize,
+    buf: isize,
+    depth: i32,
+) {
+    let bufend = buf + (last - middle) - 1;
+    ss_blockswap(sa, buf, middle, last - middle);
+
+    let mut x = 0i32;
+    let mut p1: isize;
+    let mut p2: isize;
+    if sa[bufend as usize] < 0 {
+        p1 = pa + (!sa[bufend as usize]) as isize;
+        x |= 1;
+    } else {
+        p1 = pa + sa[bufend as usize] as isize;
+    }
+    if sa[(middle - 1) as usize] < 0 {
+        p2 = pa + (!sa[(middle - 1) as usize]) as isize;
+        x |= 2;
+    } else {
+        p2 = pa + sa[(middle - 1) as usize] as isize;
+    }
+    let mut a = last - 1;
+    let t0 = sa[a as usize];
+    let mut b = bufend;
+    let mut c = middle - 1;
+    loop {
+        let r = ss_compare_pa(t, sa, p1, p2, depth);
+        if 0 < r {
+            if x & 1 != 0 {
+                loop {
+                    sa[a as usize] = sa[b as usize];
+                    a -= 1;
+                    sa[b as usize] = sa[a as usize];
+                    b -= 1;
+                    if !(sa[b as usize] < 0) {
+                        break;
+                    }
+                }
+                x ^= 1;
+            }
+            sa[a as usize] = sa[b as usize];
+            a -= 1;
+            if b <= buf {
+                sa[buf as usize] = t0;
+                break;
+            }
+            sa[b as usize] = sa[a as usize];
+            b -= 1;
+            if sa[b as usize] < 0 {
+                p1 = pa + (!sa[b as usize]) as isize;
+                x |= 1;
+            } else {
+                p1 = pa + sa[b as usize] as isize;
+            }
+        } else if r < 0 {
+            if x & 2 != 0 {
+                loop {
+                    sa[a as usize] = sa[c as usize];
+                    a -= 1;
+                    sa[c as usize] = sa[a as usize];
+                    c -= 1;
+                    if !(sa[c as usize] < 0) {
+                        break;
+                    }
+                }
+                x ^= 2;
+            }
+            sa[a as usize] = sa[c as usize];
+            a -= 1;
+            sa[c as usize] = sa[a as usize];
+            c -= 1;
+            if c < first {
+                while buf < b {
+                    sa[a as usize] = sa[b as usize];
+                    a -= 1;
+                    sa[b as usize] = sa[a as usize];
+                    b -= 1;
+                }
+                sa[a as usize] = sa[b as usize];
+                sa[b as usize] = t0;
+                break;
+            }
+            if sa[c as usize] < 0 {
+                p2 = pa + (!sa[c as usize]) as isize;
+                x |= 2;
+            } else {
+                p2 = pa + sa[c as usize] as isize;
+            }
+        } else {
+            if x & 1 != 0 {
+                loop {
+                    sa[a as usize] = sa[b as usize];
+                    a -= 1;
+                    sa[b as usize] = sa[a as usize];
+                    b -= 1;
+                    if !(sa[b as usize] < 0) {
+                        break;
+                    }
+                }
+                x ^= 1;
+            }
+            sa[a as usize] = !sa[b as usize];
+            a -= 1;
+            if b <= buf {
+                sa[buf as usize] = t0;
+                break;
+            }
+            sa[b as usize] = sa[a as usize];
+            b -= 1;
+            if x & 2 != 0 {
+                loop {
+                    sa[a as usize] = sa[c as usize];
+                    a -= 1;
+                    sa[c as usize] = sa[a as usize];
+                    c -= 1;
+                    if !(sa[c as usize] < 0) {
+                        break;
+                    }
+                }
+                x ^= 2;
+            }
+            sa[a as usize] = sa[c as usize];
+            a -= 1;
+            sa[c as usize] = sa[a as usize];
+            c -= 1;
+            if c < first {
+                while buf < b {
+                    sa[a as usize] = sa[b as usize];
+                    a -= 1;
+                    sa[b as usize] = sa[a as usize];
+                    b -= 1;
+                }
+                sa[a as usize] = sa[b as usize];
+                sa[b as usize] = t0;
+                break;
+            }
+            if sa[b as usize] < 0 {
+                p1 = pa + (!sa[b as usize]) as isize;
+                x |= 1;
+            } else {
+                p1 = pa + sa[b as usize] as isize;
+            }
+            if sa[c as usize] < 0 {
+                p2 = pa + (!sa[c as usize]) as isize;
+                x |= 2;
+            } else {
+                p2 = pa + sa[c as usize] as isize;
+            }
+        }
+    }
+}
+
+/// `GETIDX` — undoes the "already merged" complement marking.
+#[inline(always)]
+fn getidx(a: i32) -> i32 {
+    if 0 <= a {
+        a
+    } else {
+        !a
+    }
+}
+
+/// `MERGE_CHECK` — restores or sets the complement marks after a merge.
+#[inline]
+fn ss_merge_check(t: &[u8], sa: &mut [i32], pa: isize, a: isize, b: isize, c: i32, depth: i32) {
+    if (c & 1) != 0
+        || ((c & 2) != 0
+            && ss_compare_pa(
+                t,
+                sa,
+                pa + getidx(sa[(a - 1) as usize]) as isize,
+                pa + sa[a as usize] as isize,
+                depth,
+            ) == 0)
+    {
+        sa[a as usize] = !sa[a as usize];
+    }
+    if (c & 4) != 0
+        && ss_compare_pa(
+            t,
+            sa,
+            pa + getidx(sa[(b - 1) as usize]) as isize,
+            pa + sa[b as usize] as isize,
+            depth,
+        ) == 0
+    {
+        sa[b as usize] = !sa[b as usize];
+    }
+}
+
+/* D&C based merge. */
+fn ss_swapmerge(
+    t: &[u8],
+    sa: &mut [i32],
+    pa: isize,
+    first: isize,
+    middle: isize,
+    last: isize,
+    buf: isize,
+    bufsize: isize,
+    depth: i32,
+) {
+    let mut stack = [(0isize, 0isize, 0isize, 0i32); SS_SMERGE_STACKSIZE];
+    let mut ssize = 0usize;
+    let mut first = first;
+    let mut middle = middle;
+    let mut last = last;
+    let mut check = 0i32;
+
+    loop {
+        if last - middle <= bufsize {
+            if first < middle && middle < last {
+                ss_mergebackward(t, sa, pa, first, middle, last, buf, depth);
+            }
+            ss_merge_check(t, sa, pa, first, last, check, depth);
+            if ssize == 0 {
+                return;
+            }
+            ssize -= 1;
+            (first, middle, last, check) = stack[ssize];
+            continue;
+        }
+
+        if middle - first <= bufsize {
+            if first < middle {
+                ss_mergeforward(t, sa, pa, first, middle, last, buf, depth);
+            }
+            ss_merge_check(t, sa, pa, first, last, check, depth);
+            if ssize == 0 {
+                return;
+            }
+            ssize -= 1;
+            (first, middle, last, check) = stack[ssize];
+            continue;
+        }
+
+        let mut m: isize = 0;
+        let mut len = std::cmp::min(middle - first, last - middle);
+        let mut half = len >> 1;
+        while 0 < len {
+            if ss_compare_pa(
+                t,
+                sa,
+                pa + getidx(sa[(middle + m + half) as usize]) as isize,
+                pa + getidx(sa[(middle - m - half - 1) as usize]) as isize,
+                depth,
+            ) < 0
+            {
+                m += half + 1;
+                half -= (len & 1) ^ 1;
+            }
+            len = half;
+            half >>= 1;
+        }
+
+        if 0 < m {
+            let lm = middle - m;
+            let rm = middle + m;
+            ss_blockswap(sa, lm, middle, m);
+            let mut l = middle;
+            let mut r = middle;
+            let mut next = 0i32;
+            if rm < last {
+                if sa[rm as usize] < 0 {
+                    sa[rm as usize] = !sa[rm as usize];
+                    if first < lm {
+                        loop {
+                            l -= 1;
+                            if !(sa[l as usize] < 0) {
+                                break;
+                            }
+                        }
+                        next |= 4;
+                    }
+                    next |= 1;
+                } else if first < lm {
+                    while sa[r as usize] < 0 {
+                        r += 1;
+                    }
+                    next |= 2;
+                }
+            }
+
+            if l - first <= last - r {
+                stack[ssize] = (r, rm, last, (next & 3) | (check & 4));
+                ssize += 1;
+                middle = lm;
+                last = l;
+                check = (check & 3) | (next & 4);
+            } else {
+                if (next & 2) != 0 && r == middle {
+                    next ^= 6;
+                }
+                stack[ssize] = (first, lm, l, (check & 3) | (next & 4));
+                ssize += 1;
+                first = r;
+                middle = rm;
+                check = (next & 3) | (check & 4);
+            }
+        } else {
+            if ss_compare_pa(
+                t,
+                sa,
+                pa + getidx(sa[(middle - 1) as usize]) as isize,
+                pa + sa[middle as usize] as isize,
+                depth,
+            ) == 0
+            {
+                sa[middle as usize] = !sa[middle as usize];
+            }
+            ss_merge_check(t, sa, pa, first, last, check, depth);
+            if ssize == 0 {
+                return;
+            }
+            ssize -= 1;
+            (first, middle, last, check) = stack[ssize];
+        }
+    }
+}
+
+/* --------------------------------------------------------------------- */
+
+/* Substring sort */
+fn sssort(
+    t: &[u8],
+    sa: &mut [i32],
+    pa: isize,
+    first: isize,
+    last: isize,
+    buf: isize,
+    bufsize: isize,
+    depth: i32,
+    n: isize,
+    lastsuffix: bool,
+) {
+    let mut first = first;
+    let mut buf = buf;
+    let mut bufsize = bufsize;
+
+    if lastsuffix {
+        first += 1;
+    }
+
+    let mut limit: isize = 0;
+    let mut middle = last;
+    if bufsize < SS_BLOCKSIZE && bufsize < last - first {
+        limit = ss_isqrt(last - first);
+        if bufsize < limit {
+            if SS_BLOCKSIZE < limit {
+                limit = SS_BLOCKSIZE;
+            }
+            middle = last - limit;
+            buf = middle;
+            bufsize = limit;
+        } else {
+            limit = 0;
+        }
+    }
+    let mut a = first;
+    let mut i: isize = 0;
+    while SS_BLOCKSIZE < middle - a {
+        ss_mintrosort(t, sa, pa, a, a + SS_BLOCKSIZE, depth);
+        let mut curbufsize = last - (a + SS_BLOCKSIZE);
+        let mut curbuf = a + SS_BLOCKSIZE;
+        if curbufsize <= bufsize {
+            curbufsize = bufsize;
+            curbuf = buf;
+        }
+        let mut b = a;
+        let mut k = SS_BLOCKSIZE;
+        let mut j = i;
+        while j & 1 != 0 {
+            ss_swapmerge(t, sa, pa, b - k, b, b + k, curbuf, curbufsize, depth);
+            b -= k;
+            k <<= 1;
+            j >>= 1;
+        }
+        a += SS_BLOCKSIZE;
+        i += 1;
+    }
+    ss_mintrosort(t, sa, pa, a, middle, depth);
+    let mut k = SS_BLOCKSIZE;
+    while i != 0 {
+        if i & 1 != 0 {
+            ss_swapmerge(t, sa, pa, a - k, a, middle, buf, bufsize, depth);
+            a -= k;
+        }
+        k <<= 1;
+        i >>= 1;
+    }
+    if limit != 0 {
+        ss_mintrosort(t, sa, pa, middle, last, depth);
+        ss_inplacemerge(t, sa, pa, first, middle, last, depth);
+    }
+
+    if lastsuffix {
+        /* Insert last type B* suffix. */
+        let pai0 = sa[(pa + sa[(first - 1) as usize] as isize) as usize];
+        let pai1 = (n - 2) as i32;
+        let i0 = sa[(first - 1) as usize];
+        let mut a = first;
+        while a < last {
+            let av = sa[a as usize];
+            if !(av < 0
+                || 0 < ss_compare(
+                    t,
+                    pai0,
+                    pai1,
+                    sa[(pa + av as isize) as usize],
+                    sa[(pa + av as isize + 1) as usize],
+                    depth,
+                ))
+            {
+                break;
+            }
+            sa[(a - 1) as usize] = av;
+            a += 1;
+        }
+        sa[(a - 1) as usize] = i0;
+    }
+}
+
+/* --------------------------------------------------------------------- */
+
+#[inline]
+fn tr_ilg(n: isize) -> i32 {
+    let n = n as i32;
+    if (n as u32) & 0xffff_0000 != 0 {
+        if (n as u32) & 0xff00_0000 != 0 {
+            24 + LG_TABLE[((n >> 24) & 0xff) as usize]
+        } else {
+            16 + LG_TABLE[((n >> 16) & 0xff) as usize]
+        }
+    } else if n & 0xff00 != 0 {
+        8 + LG_TABLE[((n >> 8) & 0xff) as usize]
+    } else {
+        LG_TABLE[(n & 0xff) as usize]
+    }
+}
+
+/* --------------------------------------------------------------------- */
+
+/// `ISAd[SA[p]]` — the depth-offset rank of the suffix stored at `p`.
+#[inline(always)]
+fn tr_key(sa: &[i32], isad: isize, p: isize) -> i32 {
+    sa[(isad + sa[p as usize] as isize) as usize]
+}
+
+/* Simple insertionsort for small size groups. */
+fn tr_insertionsort(sa: &mut [i32], isad: isize, first: isize, last: isize) {
+    let mut a = first + 1;
+    while a < last {
+        let t0 = sa[a as usize];
+        let mut b = a - 1;
+        let mut r;
+        loop {
+            r = sa[(isad + t0 as isize) as usize] - tr_key(sa, isad, b);
+            if !(0 > r) {
+                break;
+            }
+            loop {
+                sa[(b + 1) as usize] = sa[b as usize];
+                b -= 1;
+                if !(first <= b && sa[b as usize] < 0) {
+                    break;
+                }
+            }
+            if b < first {
+                break;
+            }
+        }
+        if r == 0 {
+            sa[b as usize] = !sa[b as usize];
+        }
+        sa[(b + 1) as usize] = t0;
+        a += 1;
+    }
+}
+
+/* --------------------------------------------------------------------- */
+
+fn tr_fixdown(sa: &mut [i32], isad: isize, base: isize, i: isize, size: isize) {
+    let mut i = i;
+    let v = sa[(base + i) as usize];
+    let c = sa[(isad + v as isize) as usize];
+    loop {
+        let mut j = 2 * i + 1;
+        if j >= size {
+            break;
+        }
+        let mut k = j;
+        j += 1;
+        let mut d = tr_key(sa, isad, base + k);
+        let e = tr_key(sa, isad, base + j);
+        if d < e {
+            k = j;
+            d = e;
+        }
+        if d <= c {
+            break;
+        }
+        sa[(base + i) as usize] = sa[(base + k) as usize];
+        i = k;
+    }
+    sa[(base + i) as usize] = v;
+}
+
+/* Simple top-down heapsort. */
+fn tr_heapsort(sa: &mut [i32], isad: isize, base: isize, size: isize) {
+    let mut m = size;
+    if size % 2 == 0 {
+        m -= 1;
+        if tr_key(sa, isad, base + m / 2) < tr_key(sa, isad, base + m) {
+            sa.swap((base + m) as usize, (base + m / 2) as usize);
+        }
+    }
+
+    let mut i = m / 2 - 1;
+    while 0 <= i {
+        tr_fixdown(sa, isad, base, i, m);
+        i -= 1;
+    }
+    if size % 2 == 0 {
+        sa.swap(base as usize, (base + m) as usize);
+        tr_fixdown(sa, isad, base, 0, m);
+    }
+    let mut i = m - 1;
+    while 0 < i {
+        let t0 = sa[base as usize];
+        sa[base as usize] = sa[(base + i) as usize];
+        tr_fixdown(sa, isad, base, 0, i);
+        sa[(base + i) as usize] = t0;
+        i -= 1;
+    }
+}
+
+/* --------------------------------------------------------------------- */
+
+/* Returns the median of three elements. */
+#[inline]
+fn tr_median3(sa: &[i32], isad: isize, v1: isize, v2: isize, v3: isize) -> isize {
+    let mut v1 = v1;
+    let mut v2 = v2;
+    if tr_key(sa, isad, v1) > tr_key(sa, isad, v2) {
+        std::mem::swap(&mut v1, &mut v2);
+    }
+    if tr_key(sa, isad, v2) > tr_key(sa, isad, v3) {
+        if tr_key(sa, isad, v1) > tr_key(sa, isad, v3) {
+            return v1;
+        }
+        return v3;
+    }
+    v2
+}
+
+/* Returns the median of five elements. */
+#[inline]
+fn tr_median5(
+    sa: &[i32],
+    isad: isize,
+    v1: isize,
+    v2: isize,
+    v3: isize,
+    v4: isize,
+    v5: isize,
+) -> isize {
+    let mut v1 = v1;
+    let mut v2 = v2;
+    let mut v3 = v3;
+    let mut v4 = v4;
+    let mut v5 = v5;
+    if tr_key(sa, isad, v2) > tr_key(sa, isad, v3) {
+        std::mem::swap(&mut v2, &mut v3);
+    }
+    if tr_key(sa, isad, v4) > tr_key(sa, isad, v5) {
+        std::mem::swap(&mut v4, &mut v5);
+    }
+    if tr_key(sa, isad, v2) > tr_key(sa, isad, v4) {
+        std::mem::swap(&mut v2, &mut v4);
+        std::mem::swap(&mut v3, &mut v5);
+    }
+    if tr_key(sa, isad, v1) > tr_key(sa, isad, v3) {
+        std::mem::swap(&mut v1, &mut v3);
+    }
+    if tr_key(sa, isad, v1) > tr_key(sa, isad, v4) {
+        std::mem::swap(&mut v1, &mut v4);
+        std::mem::swap(&mut v3, &mut v5);
+    }
+    if tr_key(sa, isad, v3) > tr_key(sa, isad, v4) {
+        return v4;
+    }
+    v3
+}
+
+/* Returns the pivot element. */
+#[inline]
+fn tr_pivot(sa: &[i32], isad: isize, first: isize, last: isize) -> isize {
+    let mut t0 = last - first;
+    let middle = first + t0 / 2;
+
+    if t0 <= 512 {
+        if t0 <= 32 {
+            return tr_median3(sa, isad, first, middle, last - 1);
+        }
+        t0 >>= 2;
+        return tr_median5(sa, isad, first, first + t0, middle, last - 1 - t0, last - 1);
+    }
+    t0 >>= 3;
+    let first = tr_median3(sa, isad, first, first + t0, first + (t0 << 1));
+    let middle = tr_median3(sa, isad, middle - t0, middle, middle + t0);
+    let last = tr_median3(sa, isad, last - 1 - (t0 << 1), last - 1 - t0, last - 1);
+    tr_median3(sa, isad, first, middle, last)
+}
+
+/* --------------------------------------------------------------------- */
+
+struct TrBudget {
+    chance: i32,
+    remain: i32,
+    incval: i32,
+    count: i32,
+}
+
+impl TrBudget {
+    fn new(chance: i32, incval: i32) -> Self {
+        TrBudget {
+            chance,
+            remain: incval,
+            incval,
+            count: 0,
+        }
+    }
+
+    fn check(&mut self, size: isize) -> bool {
+        let size = size as i32;
+        if size <= self.remain {
+            self.remain -= size;
+            return true;
+        }
+        if self.chance == 0 {
+            self.count += size;
+            return false;
+        }
+        self.remain += self.incval - size;
+        self.chance -= 1;
+        true
+    }
+}
+
+/* --------------------------------------------------------------------- */
+
+fn tr_partition(
+    sa: &mut [i32],
+    isad: isize,
+    first: isize,
+    middle: isize,
+    last: isize,
+    v: i32,
+) -> (isize, isize) {
+    let mut first = first;
+    let mut last = last;
+    let mut x: i32 = 0;
+
+    let mut b = middle - 1;
+    loop {
+        b += 1;
+        if !(b < last) {
+            break;
+        }
+        x = tr_key(sa, isad, b);
+        if x != v {
+            break;
+        }
+    }
+    let mut a = b;
+    if a < last && x < v {
+        loop {
+            b += 1;
+            if !(b < last) {
+                break;
+            }
+            x = tr_key(sa, isad, b);
+            if !(x <= v) {
+                break;
+            }
+            if x == v {
+                sa.swap(b as usize, a as usize);
+                a += 1;
+            }
+        }
+    }
+    let mut c = last;
+    loop {
+        c -= 1;
+        if !(b < c) {
+            break;
+        }
+        x = tr_key(sa, isad, c);
+        if x != v {
+            break;
+        }
+    }
+    let mut d = c;
+    if b < d && x > v {
+        loop {
+            c -= 1;
+            if !(b < c) {
+                break;
+            }
+            x = tr_key(sa, isad, c);
+            if !(x >= v) {
+                break;
+            }
+            if x == v {
+                sa.swap(c as usize, d as usize);
+                d -= 1;
+            }
+        }
+    }
+    while b < c {
+        sa.swap(b as usize, c as usize);
+        loop {
+            b += 1;
+            if !(b < c) {
+                break;
+            }
+            x = tr_key(sa, isad, b);
+            if !(x <= v) {
+                break;
+            }
+            if x == v {
+                sa.swap(b as usize, a as usize);
+                a += 1;
+            }
+        }
+        loop {
+            c -= 1;
+            if !(b < c) {
+                break;
+            }
+            x = tr_key(sa, isad, c);
+            if !(x >= v) {
+                break;
+            }
+            if x == v {
+                sa.swap(c as usize, d as usize);
+                d -= 1;
+            }
+        }
+    }
+
+    if a <= d {
+        c = b - 1;
+        let mut s = a - first;
+        let t0 = b - a;
+        if s > t0 {
+            s = t0;
+        }
+        let mut e = first;
+        let mut f = b - s;
+        while 0 < s {
+            sa.swap(e as usize, f as usize);
+            s -= 1;
+            e += 1;
+            f += 1;
+        }
+        let mut s = d - c;
+        let t0 = last - d - 1;
+        if s > t0 {
+            s = t0;
+        }
+        let mut e = b;
+        let mut f = last - s;
+        while 0 < s {
+            sa.swap(e as usize, f as usize);
+            s -= 1;
+            e += 1;
+            f += 1;
+        }
+        first += b - a;
+        last -= d - c;
+    }
+    (first, last)
+}
+
+/* sort suffixes of middle partition by using sorted order of suffixes of
+ * left and right partition. */
+fn tr_copy(
+    sa: &mut [i32],
+    isa: isize,
+    first: isize,
+    a: isize,
+    b: isize,
+    last: isize,
+    depth: isize,
+) {
+    /* All cursor arithmetic is relative to the slice start, which is the C
+     * routine's `SA` pointer, so `x - SA` becomes plain `x`. */
+    let v = (b - 1) as i32;
+
+    let mut c = first;
+    let mut d = a - 1;
+    while c <= d {
+        let s = sa[c as usize] - depth as i32;
+        if 0 <= s && sa[(isa + s as isize) as usize] == v {
+            d += 1;
+            sa[d as usize] = s;
+            sa[(isa + s as isize) as usize] = d as i32;
+        }
+        c += 1;
+    }
+    let mut c = last - 1;
+    let e = d + 1;
+    let mut d = b;
+    while e < d {
+        let s = sa[c as usize] - depth as i32;
+        if 0 <= s && sa[(isa + s as isize) as usize] == v {
+            d -= 1;
+            sa[d as usize] = s;
+            sa[(isa + s as isize) as usize] = d as i32;
+        }
+        c -= 1;
+    }
+}
+
+fn tr_partialcopy(
+    sa: &mut [i32],
+    isa: isize,
+    first: isize,
+    a: isize,
+    b: isize,
+    last: isize,
+    depth: isize,
+) {
+    let v = (b - 1) as i32;
+    let mut newrank: i32 = -1;
+
+    let mut lastrank: i32 = -1;
+    let mut c = first;
+    let mut d = a - 1;
+    while c <= d {
+        let s = sa[c as usize] - depth as i32;
+        if 0 <= s && sa[(isa + s as isize) as usize] == v {
+            d += 1;
+            sa[d as usize] = s;
+            let rank = sa[(isa + s as isize + depth) as usize];
+            if lastrank != rank {
+                lastrank = rank;
+                newrank = d as i32;
+            }
+            sa[(isa + s as isize) as usize] = newrank;
+        }
+        c += 1;
+    }
+
+    let mut lastrank: i32 = -1;
+    let mut e = d;
+    while first <= e {
+        let rank = sa[(isa + sa[e as usize] as isize) as usize];
+        if lastrank != rank {
+            lastrank = rank;
+            newrank = e as i32;
+        }
+        if newrank != rank {
+            sa[(isa + sa[e as usize] as isize) as usize] = newrank;
+        }
+        e -= 1;
+    }
+
+    let mut lastrank: i32 = -1;
+    let mut c = last - 1;
+    let e = d + 1;
+    let mut d = b;
+    while e < d {
+        let s = sa[c as usize] - depth as i32;
+        if 0 <= s && sa[(isa + s as isize) as usize] == v {
+            d -= 1;
+            sa[d as usize] = s;
+            let rank = sa[(isa + s as isize + depth) as usize];
+            if lastrank != rank {
+                lastrank = rank;
+                newrank = d as i32;
+            }
+            sa[(isa + s as isize) as usize] = newrank;
+        }
+        c -= 1;
+    }
+}
+
+fn tr_introsort(
+    sa: &mut [i32],
+    isa: isize,
+    isad: isize,
+    first: isize,
+    last: isize,
+    budget: &mut TrBudget,
+) {
+    /* Stack frames are (ISAd, first, last, limit, trlink); the tandem-repeat
+     * copy frame stores its `(a, b)` pair in the pointer fields with a zero
+     * placeholder where C pushes a NULL ISAd. */
+    let mut stack = [(0isize, 0isize, 0isize, 0i32, 0i32); TR_STACKSIZE];
+    let mut ssize = 0usize;
+    let mut trlink: i32 = -1;
+    let mut isad = isad;
+    let mut first = first;
+    let mut last = last;
+    let incr = isad - isa;
+    let mut limit = tr_ilg(last - first);
+
+    loop {
+        if limit < 0 {
+            if limit == -1 {
+                /* tandem repeat partition */
+                let (a, b) = tr_partition(sa, isad - incr, first, first, last, (last - 1) as i32);
+
+                /* update ranks */
+                if a < last {
+                    let v = (a - 1) as i32;
+                    let mut c = first;
+                    while c < a {
+                        sa[(isa + sa[c as usize] as isize) as usize] = v;
+                        c += 1;
+                    }
+                }
+                if b < last {
+                    let v = (b - 1) as i32;
+                    let mut c = a;
+                    while c < b {
+                        sa[(isa + sa[c as usize] as isize) as usize] = v;
+                        c += 1;
+                    }
+                }
+
+                /* push */
+                if 1 < b - a {
+                    stack[ssize] = (0, a, b, 0, 0);
+                    ssize += 1;
+                    stack[ssize] = (isad - incr, first, last, -2, trlink);
+                    ssize += 1;
+                    trlink = ssize as i32 - 2;
+                }
+                if a - first <= last - b {
+                    if 1 < a - first {
+                        stack[ssize] = (isad, b, last, tr_ilg(last - b), trlink);
+                        ssize += 1;
+                        last = a;
+                        limit = tr_ilg(a - first);
+                    } else if 1 < last - b {
+                        first = b;
+                        limit = tr_ilg(last - b);
+                    } else {
+                        if ssize == 0 {
+                            return;
+                        }
+                        ssize -= 1;
+                        (isad, first, last, limit, trlink) = stack[ssize];
+                    }
+                } else if 1 < last - b {
+                    stack[ssize] = (isad, first, a, tr_ilg(a - first), trlink);
+                    ssize += 1;
+                    first = b;
+                    limit = tr_ilg(last - b);
+                } else if 1 < a - first {
+                    last = a;
+                    limit = tr_ilg(a - first);
+                } else {
+                    if ssize == 0 {
+                        return;
+                    }
+                    ssize -= 1;
+                    (isad, first, last, limit, trlink) = stack[ssize];
+                }
+            } else if limit == -2 {
+                /* tandem repeat copy */
+                ssize -= 1;
+                let a = stack[ssize].1;
+                let b = stack[ssize].2;
+                if stack[ssize].3 == 0 {
+                    tr_copy(sa, isa, first, a, b, last, isad - isa);
+                } else {
+                    if 0 <= trlink {
+                        stack[trlink as usize].3 = -1;
+                    }
+                    tr_partialcopy(sa, isa, first, a, b, last, isad - isa);
+                }
+                if ssize == 0 {
+                    return;
+                }
+                ssize -= 1;
+                (isad, first, last, limit, trlink) = stack[ssize];
+            } else {
+                /* sorted partition */
+                if 0 <= sa[first as usize] {
+                    let mut a = first;
+                    loop {
+                        sa[(isa + sa[a as usize] as isize) as usize] = a as i32;
+                        a += 1;
+                        if !(a < last && 0 <= sa[a as usize]) {
+                            break;
+                        }
+                    }
+                    first = a;
+                }
+                if first < last {
+                    let mut a = first;
+                    loop {
+                        sa[a as usize] = !sa[a as usize];
+                        a += 1;
+                        if !(sa[a as usize] < 0) {
+                            break;
+                        }
+                    }
+                    let next =
+                        if sa[(isa + sa[a as usize] as isize) as usize] != tr_key(sa, isad, a) {
+                            tr_ilg(a - first + 1)
+                        } else {
+                            -1
+                        };
+                    a += 1;
+                    if a < last {
+                        let v = (a - 1) as i32;
+                        let mut b = first;
+                        while b < a {
+                            sa[(isa + sa[b as usize] as isize) as usize] = v;
+                            b += 1;
+                        }
+                    }
+
+                    /* push */
+                    if budget.check(a - first) {
+                        if a - first <= last - a {
+                            stack[ssize] = (isad, a, last, -3, trlink);
+                            ssize += 1;
+                            isad += incr;
+                            last = a;
+                            limit = next;
+                        } else if 1 < last - a {
+                            stack[ssize] = (isad + incr, first, a, next, trlink);
+                            ssize += 1;
+                            first = a;
+                            limit = -3;
+                        } else {
+                            isad += incr;
+                            last = a;
+                            limit = next;
+                        }
+                    } else {
+                        if 0 <= trlink {
+                            stack[trlink as usize].3 = -1;
+                        }
+                        if 1 < last - a {
+                            first = a;
+                            limit = -3;
+                        } else {
+                            if ssize == 0 {
+                                return;
+                            }
+                            ssize -= 1;
+                            (isad, first, last, limit, trlink) = stack[ssize];
+                        }
+                    }
+                } else {
+                    if ssize == 0 {
+                        return;
+                    }
+                    ssize -= 1;
+                    (isad, first, last, limit, trlink) = stack[ssize];
+                }
+            }
+            continue;
+        }
+
+        if last - first <= TR_INSERTIONSORT_THRESHOLD {
+            tr_insertionsort(sa, isad, first, last);
+            limit = -3;
+            continue;
+        }
+
+        /* C decrements `limit` here (`limit-- == 0`); the decrement is
+         * observable only on the not-taken path because the taken path
+         * overwrites `limit` with -3. */
+        if limit == 0 {
+            tr_heapsort(sa, isad, first, last - first);
+            let mut a = last - 1;
+            while first < a {
+                let x = tr_key(sa, isad, a);
+                let mut b = a - 1;
+                while first <= b && tr_key(sa, isad, b) == x {
+                    sa[b as usize] = !sa[b as usize];
+                    b -= 1;
+                }
+                a = b;
+            }
+            limit = -3;
+            continue;
+        }
+        limit -= 1;
+
+        /* choose pivot */
+        let a = tr_pivot(sa, isad, first, last);
+        sa.swap(first as usize, a as usize);
+        let v = tr_key(sa, isad, first);
+
+        /* partition */
+        let (a, b) = tr_partition(sa, isad, first, first + 1, last, v);
+        if last - first != b - a {
+            let next = if sa[(isa + sa[a as usize] as isize) as usize] != v {
+                tr_ilg(b - a)
+            } else {
+                -1
+            };
+
+            /* update ranks */
+            {
+                let vv = (a - 1) as i32;
+                let mut c = first;
+                while c < a {
+                    sa[(isa + sa[c as usize] as isize) as usize] = vv;
+                    c += 1;
+                }
+            }
+            if b < last {
+                let vv = (b - 1) as i32;
+                let mut c = a;
+                while c < b {
+                    sa[(isa + sa[c as usize] as isize) as usize] = vv;
+                    c += 1;
+                }
+            }
+
+            /* push */
+            if 1 < b - a && budget.check(b - a) {
+                if a - first <= last - b {
+                    if last - b <= b - a {
+                        if 1 < a - first {
+                            stack[ssize] = (isad + incr, a, b, next, trlink);
+                            ssize += 1;
+                            stack[ssize] = (isad, b, last, limit, trlink);
+                            ssize += 1;
+                            last = a;
+                        } else if 1 < last - b {
+                            stack[ssize] = (isad + incr, a, b, next, trlink);
+                            ssize += 1;
+                            first = b;
+                        } else {
+                            isad += incr;
+                            first = a;
+                            last = b;
+                            limit = next;
+                        }
+                    } else if a - first <= b - a {
+                        if 1 < a - first {
+                            stack[ssize] = (isad, b, last, limit, trlink);
+                            ssize += 1;
+                            stack[ssize] = (isad + incr, a, b, next, trlink);
+                            ssize += 1;
+                            last = a;
+                        } else {
+                            stack[ssize] = (isad, b, last, limit, trlink);
+                            ssize += 1;
+                            isad += incr;
+                            first = a;
+                            last = b;
+                            limit = next;
+                        }
+                    } else {
+                        stack[ssize] = (isad, b, last, limit, trlink);
+                        ssize += 1;
+                        stack[ssize] = (isad, first, a, limit, trlink);
+                        ssize += 1;
+                        isad += incr;
+                        first = a;
+                        last = b;
+                        limit = next;
+                    }
+                } else if a - first <= b - a {
+                    if 1 < last - b {
+                        stack[ssize] = (isad + incr, a, b, next, trlink);
+                        ssize += 1;
+                        stack[ssize] = (isad, first, a, limit, trlink);
+                        ssize += 1;
+                        first = b;
+                    } else if 1 < a - first {
+                        stack[ssize] = (isad + incr, a, b, next, trlink);
+                        ssize += 1;
+                        last = a;
+                    } else {
+                        isad += incr;
+                        first = a;
+                        last = b;
+                        limit = next;
+                    }
+                } else if last - b <= b - a {
+                    if 1 < last - b {
+                        stack[ssize] = (isad, first, a, limit, trlink);
+                        ssize += 1;
+                        stack[ssize] = (isad + incr, a, b, next, trlink);
+                        ssize += 1;
+                        first = b;
+                    } else {
+                        stack[ssize] = (isad, first, a, limit, trlink);
+                        ssize += 1;
+                        isad += incr;
+                        first = a;
+                        last = b;
+                        limit = next;
+                    }
+                } else {
+                    stack[ssize] = (isad, first, a, limit, trlink);
+                    ssize += 1;
+                    stack[ssize] = (isad, b, last, limit, trlink);
+                    ssize += 1;
+                    isad += incr;
+                    first = a;
+                    last = b;
+                    limit = next;
+                }
+            } else {
+                if 1 < b - a && 0 <= trlink {
+                    stack[trlink as usize].3 = -1;
+                }
+                if a - first <= last - b {
+                    if 1 < a - first {
+                        stack[ssize] = (isad, b, last, limit, trlink);
+                        ssize += 1;
+                        last = a;
+                    } else if 1 < last - b {
+                        first = b;
+                    } else {
+                        if ssize == 0 {
+                            return;
+                        }
+                        ssize -= 1;
+                        (isad, first, last, limit, trlink) = stack[ssize];
+                    }
+                } else if 1 < last - b {
+                    stack[ssize] = (isad, first, a, limit, trlink);
+                    ssize += 1;
+                    first = b;
+                } else if 1 < a - first {
+                    last = a;
+                } else {
+                    if ssize == 0 {
+                        return;
+                    }
+                    ssize -= 1;
+                    (isad, first, last, limit, trlink) = stack[ssize];
+                }
+            }
+        } else if budget.check(last - first) {
+            limit = tr_ilg(last - first);
+            isad += incr;
+        } else {
+            if 0 <= trlink {
+                stack[trlink as usize].3 = -1;
+            }
+            if ssize == 0 {
+                return;
+            }
+            ssize -= 1;
+            (isad, first, last, limit, trlink) = stack[ssize];
+        }
+    }
+}
+
+/* --------------------------------------------------------------------- */
+
+/* Tandem repeat sort */
+fn trsort(sa: &mut [i32], isa: isize, n: isize, depth: isize) {
+    let mut budget = TrBudget::new(tr_ilg(n) * 2 / 3, n as i32);
+    /* trbudget_init(&budget, tr_ilg(n) * 3 / 4, n); */
+    let mut isad = isa + depth;
+    while -(n as i32) < sa[0] {
+        let mut first: isize = 0;
+        let mut skip: isize = 0;
+        let mut unsorted: i32 = 0;
+        loop {
+            let t0 = sa[first as usize];
+            if t0 < 0 {
+                first -= t0 as isize;
+                skip += t0 as isize;
+            } else {
+                if skip != 0 {
+                    sa[(first + skip) as usize] = skip as i32;
+                    skip = 0;
+                }
+                let last = sa[(isa + t0 as isize) as usize] as isize + 1;
+                if 1 < last - first {
+                    budget.count = 0;
+                    tr_introsort(sa, isa, isad, first, last, &mut budget);
+                    if budget.count != 0 {
+                        unsorted += budget.count;
+                    } else {
+                        skip = first - last;
+                    }
+                } else if last - first == 1 {
+                    skip = -1;
+                }
+                first = last;
+            }
+            if !(first < n) {
+                break;
+            }
+        }
+        if skip != 0 {
+            sa[(first + skip) as usize] = skip as i32;
+        }
+        if unsorted == 0 {
+            break;
+        }
+        isad += isad - isa;
+    }
+}
+
+/* --------------------------------------------------------------------- */
+
+/// `BUCKET_B(c0, c1)` for the 256-symbol alphabet.
+#[inline(always)]
+fn bb(c0: i32, c1: i32) -> usize {
+    (((c1 as u32) << 8) | c0 as u32) as usize
+}
+
+/// `BUCKET_BSTAR(c0, c1)` for the 256-symbol alphabet.
+#[inline(always)]
+fn bstar(c0: i32, c1: i32) -> usize {
+    (((c0 as u32) << 8) | c1 as u32) as usize
+}
+
+/* Sorts suffixes of type B*. */
+fn sort_type_bstar(
+    t: &[u8],
+    sa: &mut [i32],
+    bucket_a: &mut [i32],
+    bucket_b: &mut [i32],
+    n: isize,
+) -> isize {
+    /* Initialize bucket arrays. */
+    for slot in bucket_a.iter_mut() {
+        *slot = 0;
+    }
+    for slot in bucket_b.iter_mut() {
+        *slot = 0;
+    }
+
+    /* Count the number of occurrences of the first one or two characters of
+    each type A, B and B* suffix. Moreover, store the beginning position of
+    all type B* suffixes into the array SA. */
+    let mut i = n - 1;
+    let mut m = n;
+    let mut c0 = t[(n - 1) as usize] as i32;
+    let mut c1;
+    while 0 <= i {
+        /* type A suffix. */
+        loop {
+            c1 = c0;
+            bucket_a[c1 as usize] += 1;
+            i -= 1;
+            if 0 <= i {
+                c0 = t[i as usize] as i32;
+                if c0 >= c1 {
+                    continue;
+                }
+            }
+            break;
+        }
+        if 0 <= i {
+            /* type B* suffix. */
+            bucket_b[bstar(c0, c1)] += 1;
+            m -= 1;
+            sa[m as usize] = i as i32;
+            /* type B suffix. */
+            i -= 1;
+            c1 = c0;
+            while 0 <= i {
+                c0 = t[i as usize] as i32;
+                if !(c0 <= c1) {
+                    break;
+                }
+                bucket_b[bb(c0, c1)] += 1;
+                i -= 1;
+                c1 = c0;
+            }
+        }
+    }
+    let m = n - m;
+    /*
+    note:
+      A type B* suffix is lexicographically smaller than a type B suffix that
+      begins with the same first two characters.
+    */
+
+    /* Calculate the index of start/end point of each bucket. */
+    {
+        let mut i: i32 = 0;
+        let mut j: i32 = 0;
+        for c0 in 0..ALPHABET_SIZE {
+            let t0 = i + bucket_a[c0 as usize];
+            bucket_a[c0 as usize] = i + j; /* start point */
+            i = t0 + bucket_b[bb(c0, c0)];
+            for c1 in (c0 + 1)..ALPHABET_SIZE {
+                j += bucket_b[bstar(c0, c1)];
+                bucket_b[bstar(c0, c1)] = j; /* end point */
+                i += bucket_b[bb(c0, c1)];
+            }
+        }
+    }
+
+    if 0 < m {
+        /* Sort the type B* suffixes by their first two characters. */
+        let pab = n - m;
+        let isab = m;
+        let mut i = m - 2;
+        while 0 <= i {
+            let t0 = sa[(pab + i) as usize];
+            let c0 = t[t0 as usize] as i32;
+            let c1 = t[(t0 + 1) as usize] as i32;
+            bucket_b[bstar(c0, c1)] -= 1;
+            sa[bucket_b[bstar(c0, c1)] as usize] = i as i32;
+            i -= 1;
+        }
+        {
+            let t0 = sa[(pab + m - 1) as usize];
+            let c0 = t[t0 as usize] as i32;
+            let c1 = t[(t0 + 1) as usize] as i32;
+            bucket_b[bstar(c0, c1)] -= 1;
+            sa[bucket_b[bstar(c0, c1)] as usize] = (m - 1) as i32;
+        }
+
+        /* Sort the type B* substrings using sssort. */
+        let buf = m;
+        let bufsize = n - 2 * m;
+        let mut c0 = ALPHABET_SIZE - 2;
+        let mut j = m;
+        while 0 < j {
+            let mut c1 = ALPHABET_SIZE - 1;
+            while c0 < c1 {
+                let i = bucket_b[bstar(c0, c1)] as isize;
+                if 1 < j - i {
+                    sssort(
+                        t,
+                        sa,
+                        pab,
+                        i,
+                        j,
+                        buf,
+                        bufsize,
+                        2,
+                        n,
+                        sa[i as usize] == (m - 1) as i32,
+                    );
+                }
+                j = i;
+                c1 -= 1;
+            }
+            c0 -= 1;
+        }
+
+        /* Compute ranks of type B* substrings. */
+        let mut i = m - 1;
+        while 0 <= i {
+            if 0 <= sa[i as usize] {
+                let j = i;
+                loop {
+                    sa[(isab + sa[i as usize] as isize) as usize] = i as i32;
+                    i -= 1;
+                    if !(0 <= i && 0 <= sa[i as usize]) {
+                        break;
+                    }
+                }
+                sa[(i + 1) as usize] = (i - j) as i32;
+                if i <= 0 {
+                    break;
+                }
+            }
+            let j = i;
+            loop {
+                sa[i as usize] = !sa[i as usize];
+                sa[(isab + sa[i as usize] as isize) as usize] = j as i32;
+                i -= 1;
+                if !(sa[i as usize] < 0) {
+                    break;
+                }
+            }
+            sa[(isab + sa[i as usize] as isize) as usize] = j as i32;
+            i -= 1;
+        }
+
+        /* Construct the inverse suffix array of type B* suffixes using
+        trsort. */
+        trsort(sa, isab, m, 1);
+
+        /* Set the sorted order of type B* suffixes. */
+        let mut i = n - 1;
+        let mut j = m;
+        let mut c0 = t[(n - 1) as usize] as i32;
+        while 0 <= i {
+            i -= 1;
+            let mut c1 = c0;
+            while 0 <= i {
+                c0 = t[i as usize] as i32;
+                if !(c0 >= c1) {
+                    break;
+                }
+                i -= 1;
+                c1 = c0;
+            }
+            if 0 <= i {
+                let t0 = i;
+                i -= 1;
+                c1 = c0;
+                while 0 <= i {
+                    c0 = t[i as usize] as i32;
+                    if !(c0 <= c1) {
+                        break;
+                    }
+                    i -= 1;
+                    c1 = c0;
+                }
+                j -= 1;
+                sa[sa[(isab + j) as usize] as usize] = if t0 == 0 || 1 < t0 - i {
+                    t0 as i32
+                } else {
+                    !(t0 as i32)
+                };
+            }
+        }
+
+        /* Calculate the index of start/end point of each bucket. */
+        bucket_b[bb(ALPHABET_SIZE - 1, ALPHABET_SIZE - 1)] = n as i32; /* end point */
+        let mut k = m - 1;
+        let mut c0 = ALPHABET_SIZE - 2;
+        while 0 <= c0 {
+            let mut i = bucket_a[(c0 + 1) as usize] as isize - 1;
+            let mut c1 = ALPHABET_SIZE - 1;
+            while c0 < c1 {
+                let t0 = i - bucket_b[bb(c0, c1)] as isize;
+                bucket_b[bb(c0, c1)] = i as i32; /* end point */
+
+                /* Move all type B* suffixes to the correct position. */
+                i = t0;
+                let j = bucket_b[bstar(c0, c1)] as isize;
+                while j <= k {
+                    sa[i as usize] = sa[k as usize];
+                    i -= 1;
+                    k -= 1;
+                }
+                c1 -= 1;
+            }
+            bucket_b[bstar(c0, c0 + 1)] = (i - bucket_b[bb(c0, c0)] as isize + 1) as i32; /* start point */
+            bucket_b[bb(c0, c0)] = i as i32; /* end point */
+            c0 -= 1;
+        }
+    }
+
+    m
+}
+
+/* Constructs the suffix array by using the sorted order of type B*
+ * suffixes. */
+fn construct_sa(
+    t: &[u8],
+    sa: &mut [i32],
+    bucket_a: &mut [i32],
+    bucket_b: &mut [i32],
+    n: isize,
+    m: isize,
+) {
+    if 0 < m {
+        /* Construct the sorted order of type B suffixes by using
+        the sorted order of type B* suffixes. */
+        let mut c1 = ALPHABET_SIZE - 2;
+        while 0 <= c1 {
+            /* Scan the suffix array from right to left. */
+            let i = bucket_b[bstar(c1, c1 + 1)] as isize;
+            let mut j = bucket_a[(c1 + 1) as usize] as isize - 1;
+            let mut k: isize = 0;
+            let mut c2: i32 = -1;
+            while i <= j {
+                let mut s = sa[j as usize];
+                if 0 < s {
+                    debug_assert_eq!(t[s as usize] as i32, c1);
+                    debug_assert!((s as isize + 1) < n && t[s as usize] <= t[(s + 1) as usize]);
+                    debug_assert!(t[(s - 1) as usize] <= t[s as usize]);
+                    sa[j as usize] = !s;
+                    s -= 1;
+                    let c0 = t[s as usize] as i32;
+                    if 0 < s && (t[(s - 1) as usize] as i32) > c0 {
+                        s = !s;
+                    }
+                    if c0 != c2 {
+                        if 0 <= c2 {
+                            bucket_b[bb(c2, c1)] = k as i32;
+                        }
+                        c2 = c0;
+                        k = bucket_b[bb(c2, c1)] as isize;
+                    }
+                    debug_assert!(k < j);
+                    sa[k as usize] = s;
+                    k -= 1;
+                } else {
+                    debug_assert!((s == 0 && t[s as usize] as i32 == c1) || s < 0);
+                    sa[j as usize] = !s;
+                }
+                j -= 1;
+            }
+            c1 -= 1;
+        }
+    }
+
+    /* Construct the suffix array by using the sorted order of type B
+    suffixes. */
+    let mut c2 = t[(n - 1) as usize] as i32;
+    let mut k = bucket_a[c2 as usize] as isize;
+    sa[k as usize] = if (t[(n - 2) as usize] as i32) < c2 {
+        !((n - 1) as i32)
+    } else {
+        (n - 1) as i32
+    };
+    k += 1;
+    /* Scan the suffix array from left to right. */
+    let mut i: isize = 0;
+    let j = n;
+    while i < j {
+        let mut s = sa[i as usize];
+        if 0 < s {
+            debug_assert!(t[(s - 1) as usize] >= t[s as usize]);
+            s -= 1;
+            let c0 = t[s as usize] as i32;
+            if s == 0 || (t[(s - 1) as usize] as i32) < c0 {
+                s = !s;
+            }
+            if c0 != c2 {
+                bucket_a[c2 as usize] = k as i32;
+                c2 = c0;
+                k = bucket_a[c2 as usize] as isize;
+            }
+            debug_assert!(i < k);
+            sa[k as usize] = s;
+            k += 1;
+        } else {
+            debug_assert!(s < 0);
+            sa[i as usize] = !s;
+        }
+        i += 1;
+    }
+}
+
+/* --------------------------------------------------------------------- */
+
+/// Rust implementation of the `divsufsort()` entry point used by
+/// `ZDICT_trainFromBuffer_legacy()`.
+///
+/// Integration removes the C function body, so this direct export provides
+/// the existing library symbol without a wrapper.  The `open_mp` parameter is
+/// accepted for signature compatibility only: zstd never defines
+/// `LIBBSC_OPENMP`, so the C implementation ignored it as well.
+///
+/// Returns 0 on success, -1 for invalid arguments, and -2 when the bucket
+/// work arrays cannot be allocated, exactly like the C routine.
+#[no_mangle]
+pub unsafe extern "C" fn divsufsort(
+    t: *const u8,
+    sa: *mut c_int,
+    n: c_int,
+    open_mp: c_int,
+) -> c_int {
+    let _ = open_mp;
+
+    /* Check arguments. */
+    if t.is_null() || sa.is_null() || n < 0 {
+        return -1;
+    }
+    if n == 0 {
+        return 0;
+    }
+
+    let text = unsafe { slice::from_raw_parts(t, n as usize) };
+    let suffix = unsafe { slice::from_raw_parts_mut(sa, n as usize) };
+    if n == 1 {
+        suffix[0] = 0;
+        return 0;
+    }
+    if n == 2 {
+        let m = usize::from(text[0] < text[1]);
+        suffix[m ^ 1] = 0;
+        suffix[m] = 1;
+        return 0;
+    }
+
+    let mut bucket_a: Vec<i32> = Vec::new();
+    let mut bucket_b: Vec<i32> = Vec::new();
+    if bucket_a.try_reserve_exact(BUCKET_A_SIZE).is_err()
+        || bucket_b.try_reserve_exact(BUCKET_B_SIZE).is_err()
+    {
+        /* Match the C implementation's -2 result when malloc fails. */
+        return -2;
+    }
+    bucket_a.resize(BUCKET_A_SIZE, 0);
+    bucket_b.resize(BUCKET_B_SIZE, 0);
+
+    /* Suffixsort. */
+    let m = sort_type_bstar(text, suffix, &mut bucket_a, &mut bucket_b, n as isize);
+    construct_sa(text, suffix, &mut bucket_a, &mut bucket_b, n as isize, m);
+    0
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use std::ptr;
+
+    fn build_sa(text: &[u8]) -> Vec<i32> {
+        let mut sa = vec![0i32; text.len()];
+        let result = unsafe { divsufsort(text.as_ptr(), sa.as_mut_ptr(), text.len() as c_int, 0) };
+        assert_eq!(result, 0);
+        sa
+    }
+
+    /// Trivial O(n^2 log n) reference: sort the suffix start positions by the
+    /// suffixes themselves.
+    fn reference_sa(text: &[u8]) -> Vec<i32> {
+        let mut sa: Vec<i32> = (0..text.len() as i32).collect();
+        sa.sort_by(|&a, &b| text[a as usize..].cmp(&text[b as usize..]));
+        sa
+    }
+
+    /// Suffix-array invariants: a permutation of `0..n` whose suffixes are in
+    /// strictly increasing lexicographic order.
+    fn assert_valid_sa(text: &[u8], sa: &[i32]) {
+        assert_eq!(sa.len(), text.len());
+        let mut seen = vec![false; text.len()];
+        for &p in sa {
+            let p = usize::try_from(p).expect("suffix index must be non-negative");
+            assert!(p < text.len(), "suffix index {p} out of range");
+            assert!(!seen[p], "duplicate suffix index {p}");
+            seen[p] = true;
+        }
+        for pair in sa.windows(2) {
+            assert!(
+                text[pair[0] as usize..] < text[pair[1] as usize..],
+                "suffixes {} and {} are not in sorted order",
+                pair[0],
+                pair[1]
+            );
+        }
+    }
+
+    /// Fixed-seed numerical-recipes LCG, used to generate reproducible
+    /// pseudo-random sample buffers.
+    fn lcg_bytes(len: usize, seed: u32, alphabet: u32) -> Vec<u8> {
+        let mut state = seed;
+        (0..len)
+            .map(|_| {
+                state = state.wrapping_mul(1_664_525).wrapping_add(1_013_904_223);
+                ((state >> 24) % alphabet) as u8
+            })
+            .collect()
+    }
+
+    #[test]
+    fn rejects_invalid_arguments() {
+        let text = [0u8; 1];
+        let mut sa = [0i32; 1];
+        assert_eq!(
+            unsafe { divsufsort(ptr::null(), sa.as_mut_ptr(), 1, 0) },
+            -1
+        );
+        assert_eq!(
+            unsafe { divsufsort(text.as_ptr(), ptr::null_mut(), 1, 0) },
+            -1
+        );
+        assert_eq!(
+            unsafe { divsufsort(text.as_ptr(), sa.as_mut_ptr(), -1, 0) },
+            -1
+        );
+    }
+
+    #[test]
+    fn sorts_trivial_inputs() {
+        /* empty */
+        let text = [0u8; 1];
+        let mut sa = [i32::MIN; 1];
+        assert_eq!(
+            unsafe { divsufsort(text.as_ptr(), sa.as_mut_ptr(), 0, 0) },
+            0
+        );
+        assert_eq!(sa[0], i32::MIN, "n == 0 must not touch the output");
+
+        /* single byte */
+        assert_eq!(build_sa(b"z"), [0]);
+
+        /* two bytes: ascending, descending, and equal */
+        assert_eq!(build_sa(b"ab"), [0, 1]);
+        assert_eq!(build_sa(b"ba"), [1, 0]);
+        assert_eq!(build_sa(b"aa"), [1, 0]);
+    }
+
+    #[test]
+    fn sorts_all_equal_bytes() {
+        let text = vec![b'q'; 10_000];
+        let sa = build_sa(&text);
+        /* For a constant text the shortest suffix sorts first. */
+        let expected: Vec<i32> = (0..text.len() as i32).rev().collect();
+        assert_eq!(sa, expected);
+    }
+
+    #[test]
+    fn sorts_abracadabra_exactly() {
+        /* Hand-computed: a(10) abra(7) abracadabra(0) acadabra(3) adabra(5)
+         * bra(8) bracadabra(1) cadabra(4) dabra(6) ra(9) racadabra(2). */
+        assert_eq!(build_sa(b"abracadabra"), [10, 7, 0, 3, 5, 8, 1, 4, 6, 9, 2]);
+    }
+
+    #[test]
+    fn matches_reference_on_periodic_text() {
+        /* Tandem repeats exercise trsort's repeat partitioning. */
+        let text: Vec<u8> = b"ab".iter().copied().cycle().take(4096).collect();
+        let sa = build_sa(&text);
+        assert_valid_sa(&text, &sa);
+        assert_eq!(sa, reference_sa(&text));
+    }
+
+    #[test]
+    fn matches_reference_on_random_bytes() {
+        let text = lcg_bytes(8192, 0x0BAD_5EED, 256);
+        let sa = build_sa(&text);
+        assert_valid_sa(&text, &sa);
+        assert_eq!(sa, reference_sa(&text));
+    }
+
+    #[test]
+    fn matches_reference_on_low_alphabet_text() {
+        /* A four-symbol alphabet produces the large first-two-character
+         * buckets that reach sssort's block merging and the deeper trsort
+         * paths. */
+        let text = lcg_bytes(16_384, 0xDEAD_BEEF, 4);
+        let sa = build_sa(&text);
+        assert_valid_sa(&text, &sa);
+        assert_eq!(sa, reference_sa(&text));
+    }
+}

rust/src/lib.rs

@@ -5,6 +5,8 @@ pub mod bitstream;
 pub mod common;
 pub mod cpu;
 pub mod debug;
+#[cfg(feature = "dict-builder")]
+pub mod divsufsort;
 pub mod entropy_common;
 pub mod errors;
 #[cfg(feature = "compression")]
@@ -32,8 +34,6 @@ pub mod zstd_compress_params;
 #[cfg(feature = "compression")]
 pub mod zstd_compress_sequences;
 #[cfg(feature = "compression")]
-pub mod zstd_compress_stats;
-#[cfg(feature = "compression")]
 pub mod zstd_compress_superblock;
 #[cfg(feature = "decompression")]
 pub mod zstd_ddict;

rust/src/zstd_cli.rs

@@ -210,6 +210,7 @@ struct Cli {
     mmap_dict: i32,
     progress: i32,
     workers: Option<i32>,
+    single_thread: bool,
     block_size: Option<usize>,
     mem_limit: Option<u32>,
     ldm: bool,
@@ -254,6 +255,7 @@ impl Cli {
             mmap_dict: ZSTD_PS_AUTO,
             progress: FIO_PS_AUTO,
             workers: None,
+            single_thread: false,
             block_size: None,
             mem_limit: None,
             ldm: false,
@@ -332,8 +334,11 @@ unsafe fn default_worker_count() -> i32 {
 }
 
 #[cfg(feature = "compression")]
-unsafe fn resolved_worker_count(workers: Option<i32>) -> i32 {
+unsafe fn resolved_worker_count(workers: Option<i32>, single_thread: bool) -> i32 {
     match workers {
+        /* --single-thread pins zero workers; a bare zero (-T0 or the zstdmt
+         * program name) auto-detects the core count as in the C CLI. */
+        Some(0) if single_thread => 0,
         Some(0) => unsafe { UTIL_countPhysicalCores() }.max(1),
         Some(workers) => workers,
         None => unsafe { default_worker_count() },
@@ -385,7 +390,7 @@ fn usage(advanced: bool) {
         let _ = writeln!(out, "\nImplemented advanced compression controls:");
         let _ = writeln!(
             out,
-            "  --fast[=#], --ultra, --long[=#], --threads=#, --block-size=#"
+            "  --fast[=#], --ultra, --long[=#], --threads=#, --single-thread, --block-size=#"
         );
         let _ = writeln!(
             out,
@@ -638,6 +643,7 @@ fn parse_long_option(
                 | "--no-row-match-finder"
                 | "--row-match-finder"
                 | "--rsyncable"
+                | "--single-thread"
                 | "--compress-literals"
                 | "--no-compress-literals"
                 | "--exclude-compressed"
@@ -809,6 +815,14 @@ fn parse_long_option(
             cli.workers = Some(parse_worker_count(&value)?);
             Ok(None)
         }
+        "--single-thread" => {
+            /* As in the C CLI: zero workers plus a latch that suppresses the
+             * automatic core-count resolution, so fileio runs its
+             * single-thread streaming mode (slightly different from -T1). */
+            cli.workers = Some(0);
+            cli.single_thread = true;
+            Ok(None)
+        }
         "--memlimit" | "--memory" | "--memlimit-decompress" => {
             let value = next_value(attached, args, index, name)?;
             cli.mem_limit = Some(parse_u32(&value, "memory limit")?);
@@ -854,7 +868,6 @@ fn parse_long_option(
         | "--trace"
         | "--format"
         | "--priority"
-        | "--single-thread"
         | "--auto-threads"
         | "--fake-stdin-is-console"
         | "--fake-stdout-is-console"
@@ -1012,7 +1025,7 @@ unsafe fn apply_preferences(cli: &Cli, prefs: *mut FIO_prefs_t, ctx: *mut FIO_ct
                 }),
         );
         #[cfg(feature = "compression")]
-        FIO_setNbWorkers(prefs, resolved_worker_count(cli.workers));
+        FIO_setNbWorkers(prefs, resolved_worker_count(cli.workers, cli.single_thread));
         FIO_setLdmFlag(prefs, u32::from(cli.ldm));
         FIO_setAdaptiveMode(prefs, i32::from(cli.adapt));
         FIO_setRsyncable(prefs, i32::from(cli.rsyncable));
@@ -1502,6 +1515,36 @@ mod tests {
         let cli = parse(&["zstdmt", "input"]);
 
         assert_eq!(cli.workers, Some(0));
+        assert!(!cli.single_thread);
+    }
+
+    #[test]
+    fn single_thread_pins_zero_workers() {
+        let cli = parse(&["zstd", "--single-thread", "input"]);
+
+        assert_eq!(cli.workers, Some(0));
+        assert!(cli.single_thread);
+    }
+
+    #[test]
+    fn a_later_thread_count_overrides_single_thread_workers() {
+        /* Mirrors the C CLI: -T after --single-thread wins the worker count,
+         * while the single-thread latch stays set. */
+        let cli = parse(&["zstd", "--single-thread", "-T2", "input"]);
+
+        assert_eq!(cli.workers, Some(2));
+        assert!(cli.single_thread);
+    }
+
+    #[test]
+    fn single_thread_rejects_attached_values() {
+        let error = parse_args(vec![
+            OsString::from("zstd"),
+            OsString::from("--single-thread=1"),
+        ])
+        .expect_err("an attached value must not activate --single-thread");
+
+        assert!(error.contains("does not take an argument"));
     }
 
     #[test]

rust/src/zstd_compress_literals.rs

@@ -65,7 +65,7 @@ unsafe fn copy_bytes(dst: *mut u8, src: *const u8, size: usize) {
 }
 
 #[inline]
-pub(crate) unsafe fn copy_huf_tables(dst: *mut ZSTD_hufCTables_t, src: *const ZSTD_hufCTables_t) {
+unsafe fn copy_huf_tables(dst: *mut ZSTD_hufCTables_t, src: *const ZSTD_hufCTables_t) {
     // Copy as bytes, not as a Rust struct: C's memcpy preserves the four tail
     // padding bytes that this layout has on 64-bit targets.  Some C callers
     // copy or compare the complete entropy state, so leaving those bytes from
@@ -192,10 +192,8 @@ fn min_literals_to_compress(strategy: c_int, huf_repeat: c_int) -> usize {
     }
 }
 
-/// C's `ZSTD_minGain()`: minimum compression gain required to emit a
-/// compressed block or compressed literals section.
 #[inline]
-pub(crate) fn min_gain(src_size: usize, strategy: c_int) -> usize {
+fn min_gain(src_size: usize, strategy: c_int) -> usize {
     let min_log = if strategy >= ZSTD_BTULTRA {
         strategy.saturating_sub(1) as u32
     } else {

rust/src/zstd_compress_stats.rs

@@ -1,1549 +0,0 @@
-#![allow(non_camel_case_types)]
-#![allow(non_snake_case)]
-
-//! Sequence statistics and seqStore entropy compression.
-//!
-//! This module translates the block entropy-statistics layer of
-//! `zstd_compress.c`: `ZSTD_seqToCodes()`, `ZSTD_buildSequencesStatistics()`,
-//! `ZSTD_entropyCompressSeqStore*()`, `ZSTD_buildBlockEntropyStats*()`, and
-//! `ZSTD_copyBlockSequences()`.  The `ZSTD_CCtx` and `ZSTD_CCtx_params`
-//! layouts stay private to C: the C shims extract the sequence store, the
-//! entropy-table leaves, and the two parameter scalars these paths read
-//! (the compression strategy and the literals-compression switch).  Block
-//! dispatch, block splitting, and the block-size estimation heuristics also
-//! remain in C for a later slice.
-
-use crate::bits::ZSTD_highbit32;
-use crate::common::{
-    DEFAULT_MAX_OFF, LL_DEFAULT_NORM, LL_DEFAULT_NORM_LOG, LL_FSE_LOG, LONGNBSEQ, MAX_LL, MAX_ML,
-    MAX_OFF, MAX_SEQ, MINMATCH, ML_DEFAULT_NORM, ML_DEFAULT_NORM_LOG, ML_FSE_LOG, OFF_FSE_LOG,
-    OF_DEFAULT_NORM, OF_DEFAULT_NORM_LOG, ZSTD_MAX_FSE_HEADERS_SIZE, ZSTD_MAX_HUF_HEADER_SIZE,
-    ZSTD_REP_NUM,
-};
-use crate::errors::{ERR_isError, ZstdErrorCode, ERROR};
-use crate::hist::{HIST_countFast_wksp, HIST_count_wksp};
-use crate::huf_compress::{
-    HUF_buildCTable_wksp, HUF_estimateCompressedSize, HUF_optimalTableLog, HUF_validateCTable,
-    HUF_writeCTable_wksp,
-};
-use crate::mem::{MEM_32bits, MEM_writeLE16};
-use crate::zstd_compress_literals::{
-    copy_huf_tables, min_gain, ZSTD_compressLiterals, ZSTD_hufCTables_t,
-};
-use crate::zstd_compress_sequences::{
-    SeqDef, ZSTD_buildCTable, ZSTD_encodeSequences, ZSTD_selectEncodingType,
-};
-use std::ffi::c_void;
-use std::mem::{size_of, size_of_val};
-use std::os::raw::{c_int, c_uint};
-use std::ptr;
-
-const SET_BASIC: c_int = 0;
-const SET_RLE: c_int = 1;
-const SET_COMPRESSED: c_int = 2;
-const SET_REPEAT: c_int = 3;
-
-const FSE_REPEAT_NONE: c_int = 0;
-
-const HUF_REPEAT_NONE: c_int = 0;
-const HUF_REPEAT_CHECK: c_int = 1;
-const HUF_REPEAT_VALID: c_int = 2;
-
-const HUF_FLAGS_OPTIMAL_DEPTH: c_int = 1 << 1;
-const HUF_OPTIMAL_DEPTH_THRESHOLD: c_int = 8; /* ZSTD_btultra */
-
-const ZSTD_DEFAULT_DISALLOWED: c_int = 0;
-const ZSTD_DEFAULT_ALLOWED: c_int = 1;
-
-const HUF_SYMBOLVALUE_MAX: c_uint = 255;
-const LIT_HUF_LOG: c_uint = 11;
-const COMPRESS_LITERALS_SIZE_MIN: usize = 63;
-const SUSPECT_UNCOMPRESSIBLE_LITERAL_RATIO: usize = 20;
-
-const STREAM_ACCUMULATOR_MIN_32: u32 = 25;
-const STREAM_ACCUMULATOR_MIN_64: u32 = 57;
-
-const LL_DELTA_CODE: u32 = 19;
-const ML_DELTA_CODE: u32 = 36;
-
-pub(crate) const ZSTD_LLT_LITERAL_LENGTH: c_int = 1;
-pub(crate) const ZSTD_LLT_MATCH_LENGTH: c_int = 2;
-
-/// `FSE_CTABLE_SIZE_U32(OffFSELog, MaxOff)` from the C headers.
-pub const OFF_CTABLE_SIZE: usize = 1 + (1 << (OFF_FSE_LOG - 1)) + ((MAX_OFF + 1) * 2);
-/// `FSE_CTABLE_SIZE_U32(MLFSELog, MaxML)` from the C headers.
-pub const ML_CTABLE_SIZE: usize = 1 + (1 << (ML_FSE_LOG - 1)) + ((MAX_ML + 1) * 2);
-/// `FSE_CTABLE_SIZE_U32(LLFSELog, MaxLL)` from the C headers.
-pub const LL_CTABLE_SIZE: usize = 1 + (1 << (LL_FSE_LOG - 1)) + ((MAX_LL + 1) * 2);
-
-/// ABI-compatible `SeqStore_t` leaf layout from `zstd_compress_internal.h`.
-///
-/// The C context itself remains opaque; its shims pass the `seqStore` member
-/// directly, so this small, stable hot-path structure is the only sequence
-/// storage representation crossing into Rust.
-#[repr(C)]
-pub struct SeqStore_t {
-    pub sequencesStart: *mut SeqDef,
-    pub sequences: *mut SeqDef,
-    pub litStart: *mut u8,
-    pub lit: *mut u8,
-    pub llCode: *mut u8,
-    pub mlCode: *mut u8,
-    pub ofCode: *mut u8,
-    pub maxNbSeq: usize,
-    pub maxNbLit: usize,
-    pub longLengthType: c_int,
-    pub longLengthPos: u32,
-}
-
-/// C's `ZSTD_fseCTables_t`.  The table element type is `FSE_CTable`, an
-/// `unsigned`, and the table lengths are the header macros expanded above.
-#[repr(C)]
-pub struct ZSTD_fseCTables_t {
-    pub offcodeCTable: [u32; OFF_CTABLE_SIZE],
-    pub matchlengthCTable: [u32; ML_CTABLE_SIZE],
-    pub litlengthCTable: [u32; LL_CTABLE_SIZE],
-    pub offcode_repeatMode: c_int,
-    pub matchlength_repeatMode: c_int,
-    pub litlength_repeatMode: c_int,
-}
-
-/// C's `ZSTD_entropyCTables_t`.
-#[repr(C)]
-pub struct ZSTD_entropyCTables_t {
-    pub huf: ZSTD_hufCTables_t,
-    pub fse: ZSTD_fseCTables_t,
-}
-
-/// C's `ZSTD_compressedBlockState_t`.
-#[repr(C)]
-pub struct ZSTD_compressedBlockState_t {
-    pub entropy: ZSTD_entropyCTables_t,
-    pub rep: [u32; ZSTD_REP_NUM],
-}
-
-/// C's `ZSTD_hufCTablesMetadata_t`.
-#[repr(C)]
-pub struct ZSTD_hufCTablesMetadata_t {
-    pub hType: c_int,
-    pub hufDesBuffer: [u8; ZSTD_MAX_HUF_HEADER_SIZE],
-    pub hufDesSize: usize,
-}
-
-/// C's `ZSTD_fseCTablesMetadata_t`.
-#[repr(C)]
-pub struct ZSTD_fseCTablesMetadata_t {
-    pub llType: c_int,
-    pub ofType: c_int,
-    pub mlType: c_int,
-    pub fseTablesBuffer: [u8; ZSTD_MAX_FSE_HEADERS_SIZE],
-    pub fseTablesSize: usize,
-    pub lastCountSize: usize,
-}
-
-/// C's `ZSTD_entropyCTablesMetadata_t`.
-#[repr(C)]
-pub struct ZSTD_entropyCTablesMetadata_t {
-    pub hufMetadata: ZSTD_hufCTablesMetadata_t,
-    pub fseMetadata: ZSTD_fseCTablesMetadata_t,
-}
-
-/// Public `ZSTD_Sequence` from `zstd.h`.
-#[repr(C)]
-#[derive(Clone, Copy)]
-pub struct ZSTD_Sequence {
-    pub offset: u32,
-    pub litLength: u32,
-    pub matchLength: u32,
-    pub rep: u32,
-}
-
-/// C's `SeqCollector` leaf from `zstd_compress_internal.h`.
-#[repr(C)]
-pub struct SeqCollector {
-    pub collectSequences: c_int,
-    pub seqStart: *mut ZSTD_Sequence,
-    pub seqIndex: usize,
-    pub maxSequences: usize,
-}
-
-/// Result of `build_sequences_statistics()`; mirrors C's
-/// `ZSTD_symbolEncodingTypeStats_t`, which no longer crosses the boundary.
-pub(crate) struct SymbolEncodingTypeStats {
-    pub ll_type: u32,
-    pub off_type: u32,
-    pub ml_type: u32,
-    pub size: usize,
-    /// Accounts for a bug in zstd 1.3.4; see
-    /// `entropy_compress_seq_store_internal()`.
-    pub last_count_size: usize,
-    pub long_offsets: c_int,
-}
-
-/// C's `ZSTD_updateRep()` repeat-offset history update.
-#[inline]
-pub(crate) fn update_rep(reps: &mut [u32; 3], off_base: u32, literal_length_is_zero: bool) {
-    if off_base > 3 {
-        reps[2] = reps[1];
-        reps[1] = reps[0];
-        reps[0] = off_base - 3;
-        return;
-    }
-    let rep_code = off_base - 1 + u32::from(literal_length_is_zero);
-    if rep_code == 0 {
-        return;
-    }
-    let current_offset = if rep_code == 3 {
-        reps[0].wrapping_sub(1)
-    } else {
-        reps[rep_code as usize]
-    };
-    reps[2] = if rep_code >= 2 { reps[1] } else { reps[2] };
-    reps[1] = reps[0];
-    reps[0] = current_offset;
-}
-
-#[inline]
-fn ll_code(lit_length: u32) -> u32 {
-    const LL_CODE: [u8; 64] = [
-        0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 16, 17, 17, 18, 18, 19, 19, 20,
-        20, 20, 20, 21, 21, 21, 21, 22, 22, 22, 22, 22, 22, 22, 22, 23, 23, 23, 23, 23, 23, 23, 23,
-        24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24,
-    ];
-    if lit_length > 63 {
-        ZSTD_highbit32(lit_length) + LL_DELTA_CODE
-    } else {
-        LL_CODE[lit_length as usize] as u32
-    }
-}
-
-#[inline]
-fn ml_code(ml_base: u32) -> u32 {
-    const ML_CODE: [u8; 128] = [
-        0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24,
-        25, 26, 27, 28, 29, 30, 31, 32, 32, 33, 33, 34, 34, 35, 35, 36, 36, 36, 36, 37, 37, 37, 37,
-        38, 38, 38, 38, 38, 38, 38, 38, 39, 39, 39, 39, 39, 39, 39, 39, 40, 40, 40, 40, 40, 40, 40,
-        40, 40, 40, 40, 40, 40, 40, 40, 40, 41, 41, 41, 41, 41, 41, 41, 41, 41, 41, 41, 41, 41, 41,
-        41, 41, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42,
-        42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42,
-    ];
-    if ml_base > 127 {
-        ZSTD_highbit32(ml_base) + ML_DELTA_CODE
-    } else {
-        ML_CODE[ml_base as usize] as u32
-    }
-}
-
-#[inline]
-unsafe fn copy_fse_tables(dst: *mut ZSTD_fseCTables_t, src: *const ZSTD_fseCTables_t) {
-    unsafe {
-        ptr::copy_nonoverlapping(
-            src.cast::<u8>(),
-            dst.cast::<u8>(),
-            size_of::<ZSTD_fseCTables_t>(),
-        )
-    };
-}
-
-/// Converts the stored lengths and distances into symbol codes.
-///
-/// Retains its original exported name: the C dictionary builder and the
-/// decodecorpus test tool link against it directly.
-#[no_mangle]
-pub unsafe extern "C" fn ZSTD_seqToCodes(seq_store: *const SeqStore_t) -> c_int {
-    let store = unsafe { &*seq_store };
-    let sequences = store.sequencesStart;
-    let nb_seq = unsafe { store.sequences.offset_from(sequences) } as usize;
-    let mut long_offsets = 0;
-    debug_assert!(nb_seq <= store.maxNbSeq);
-
-    for index in 0..nb_seq {
-        let sequence = unsafe { sequences.add(index).read() };
-        let of_code = ZSTD_highbit32(sequence.offBase);
-        unsafe {
-            *store.llCode.add(index) = ll_code(sequence.litLength as u32) as u8;
-            *store.ofCode.add(index) = of_code as u8;
-            *store.mlCode.add(index) = ml_code(sequence.mlBase as u32) as u8;
-        }
-        debug_assert!(MEM_32bits() || of_code < STREAM_ACCUMULATOR_MIN_64);
-        if MEM_32bits() && of_code >= STREAM_ACCUMULATOR_MIN_32 {
-            long_offsets = 1;
-        }
-    }
-    if store.longLengthType == ZSTD_LLT_LITERAL_LENGTH {
-        unsafe { *store.llCode.add(store.longLengthPos as usize) = MAX_LL as u8 };
-    }
-    if store.longLengthType == ZSTD_LLT_MATCH_LENGTH {
-        unsafe { *store.mlCode.add(store.longLengthPos as usize) = MAX_ML as u8 };
-    }
-    long_offsets
-}
-
-/// C's `ZSTD_buildSequencesStatistics()`.
-///
-/// Returns the statistics with a zstd error code in the `size` field on
-/// failure, and updates `next_entropy` as a side effect.  `nb_seq` must be
-/// greater than zero, and the entropy workspace must hold at least
-/// `ENTROPY_WORKSPACE_SIZE - (MaxSeq + 1) * sizeof(U32)` bytes.
-#[allow(clippy::too_many_arguments)]
-pub(crate) unsafe fn build_sequences_statistics(
-    seq_store: *const SeqStore_t,
-    nb_seq: usize,
-    prev_entropy: *const ZSTD_fseCTables_t,
-    next_entropy: *mut ZSTD_fseCTables_t,
-    dst: *mut u8,
-    dst_capacity: usize,
-    strategy: c_int,
-    count_workspace: *mut c_uint,
-    entropy_workspace: *mut c_void,
-    entropy_wksp_size: usize,
-) -> SymbolEncodingTypeStats {
-    let store = unsafe { &*seq_store };
-    let mut stats = SymbolEncodingTypeStats {
-        ll_type: 0,
-        off_type: 0,
-        ml_type: 0,
-        size: 0,
-        last_count_size: 0,
-        long_offsets: 0,
-    };
-    let mut written = 0usize;
-
-    /* convert length/distances into codes */
-    stats.long_offsets = unsafe { ZSTD_seqToCodes(seq_store) };
-    debug_assert!(nb_seq != 0); /* ZSTD_selectEncodingType() divides by nb_seq */
-
-    /* build CTable for Literal Lengths */
-    {
-        let mut max = MAX_LL as c_uint;
-        let most_frequent = unsafe {
-            HIST_countFast_wksp(
-                count_workspace,
-                &mut max,
-                store.llCode.cast::<c_void>(),
-                nb_seq,
-                entropy_workspace,
-                entropy_wksp_size,
-            )
-        }; /* can't fail */
-        unsafe { (*next_entropy).litlength_repeatMode = (*prev_entropy).litlength_repeatMode };
-        stats.ll_type = unsafe {
-            ZSTD_selectEncodingType(
-                ptr::addr_of_mut!((*next_entropy).litlength_repeatMode),
-                count_workspace,
-                max,
-                most_frequent,
-                nb_seq,
-                LL_FSE_LOG as c_uint,
-                ptr::addr_of!((*prev_entropy).litlengthCTable).cast::<u32>(),
-                LL_DEFAULT_NORM.as_ptr(),
-                LL_DEFAULT_NORM_LOG,
-                ZSTD_DEFAULT_ALLOWED,
-                strategy,
-            )
-        } as u32;
-        let count_size = unsafe {
-            ZSTD_buildCTable(
-                dst.add(written).cast::<c_void>(),
-                dst_capacity - written,
-                ptr::addr_of_mut!((*next_entropy).litlengthCTable).cast::<u32>(),
-                LL_FSE_LOG as u32,
-                stats.ll_type as c_int,
-                count_workspace,
-                max,
-                store.llCode,
-                nb_seq,
-                LL_DEFAULT_NORM.as_ptr(),
-                LL_DEFAULT_NORM_LOG,
-                MAX_LL as u32,
-                ptr::addr_of!((*prev_entropy).litlengthCTable).cast::<u32>(),
-                size_of::<[u32; LL_CTABLE_SIZE]>(),
-                entropy_workspace,
-                entropy_wksp_size,
-            )
-        };
-        if ERR_isError(count_size) {
-            stats.size = count_size;
-            return stats;
-        }
-        if stats.ll_type == SET_COMPRESSED as u32 {
-            stats.last_count_size = count_size;
-        }
-        written += count_size;
-    }
-    /* build CTable for Offsets */
-    {
-        let mut max = MAX_OFF as c_uint;
-        let most_frequent = unsafe {
-            HIST_countFast_wksp(
-                count_workspace,
-                &mut max,
-                store.ofCode.cast::<c_void>(),
-                nb_seq,
-                entropy_workspace,
-                entropy_wksp_size,
-            )
-        }; /* can't fail */
-        /* We can only use the basic table if max <= DefaultMaxOff, otherwise the offsets are too large */
-        let default_policy = if max <= DEFAULT_MAX_OFF as c_uint {
-            ZSTD_DEFAULT_ALLOWED
-        } else {
-            ZSTD_DEFAULT_DISALLOWED
-        };
-        unsafe { (*next_entropy).offcode_repeatMode = (*prev_entropy).offcode_repeatMode };
-        stats.off_type = unsafe {
-            ZSTD_selectEncodingType(
-                ptr::addr_of_mut!((*next_entropy).offcode_repeatMode),
-                count_workspace,
-                max,
-                most_frequent,
-                nb_seq,
-                OFF_FSE_LOG as c_uint,
-                ptr::addr_of!((*prev_entropy).offcodeCTable).cast::<u32>(),
-                OF_DEFAULT_NORM.as_ptr(),
-                OF_DEFAULT_NORM_LOG,
-                default_policy,
-                strategy,
-            )
-        } as u32;
-        let count_size = unsafe {
-            ZSTD_buildCTable(
-                dst.add(written).cast::<c_void>(),
-                dst_capacity - written,
-                ptr::addr_of_mut!((*next_entropy).offcodeCTable).cast::<u32>(),
-                OFF_FSE_LOG as u32,
-                stats.off_type as c_int,
-                count_workspace,
-                max,
-                store.ofCode,
-                nb_seq,
-                OF_DEFAULT_NORM.as_ptr(),
-                OF_DEFAULT_NORM_LOG,
-                DEFAULT_MAX_OFF as u32,
-                ptr::addr_of!((*prev_entropy).offcodeCTable).cast::<u32>(),
-                size_of::<[u32; OFF_CTABLE_SIZE]>(),
-                entropy_workspace,
-                entropy_wksp_size,
-            )
-        };
-        if ERR_isError(count_size) {
-            stats.size = count_size;
-            return stats;
-        }
-        if stats.off_type == SET_COMPRESSED as u32 {
-            stats.last_count_size = count_size;
-        }
-        written += count_size;
-    }
-    /* build CTable for MatchLengths */
-    {
-        let mut max = MAX_ML as c_uint;
-        let most_frequent = unsafe {
-            HIST_countFast_wksp(
-                count_workspace,
-                &mut max,
-                store.mlCode.cast::<c_void>(),
-                nb_seq,
-                entropy_workspace,
-                entropy_wksp_size,
-            )
-        }; /* can't fail */
-        unsafe { (*next_entropy).matchlength_repeatMode = (*prev_entropy).matchlength_repeatMode };
-        stats.ml_type = unsafe {
-            ZSTD_selectEncodingType(
-                ptr::addr_of_mut!((*next_entropy).matchlength_repeatMode),
-                count_workspace,
-                max,
-                most_frequent,
-                nb_seq,
-                ML_FSE_LOG as c_uint,
-                ptr::addr_of!((*prev_entropy).matchlengthCTable).cast::<u32>(),
-                ML_DEFAULT_NORM.as_ptr(),
-                ML_DEFAULT_NORM_LOG,
-                ZSTD_DEFAULT_ALLOWED,
-                strategy,
-            )
-        } as u32;
-        let count_size = unsafe {
-            ZSTD_buildCTable(
-                dst.add(written).cast::<c_void>(),
-                dst_capacity - written,
-                ptr::addr_of_mut!((*next_entropy).matchlengthCTable).cast::<u32>(),
-                ML_FSE_LOG as u32,
-                stats.ml_type as c_int,
-                count_workspace,
-                max,
-                store.mlCode,
-                nb_seq,
-                ML_DEFAULT_NORM.as_ptr(),
-                ML_DEFAULT_NORM_LOG,
-                MAX_ML as u32,
-                ptr::addr_of!((*prev_entropy).matchlengthCTable).cast::<u32>(),
-                size_of::<[u32; ML_CTABLE_SIZE]>(),
-                entropy_workspace,
-                entropy_wksp_size,
-            )
-        };
-        if ERR_isError(count_size) {
-            stats.size = count_size;
-            return stats;
-        }
-        if stats.ml_type == SET_COMPRESSED as u32 {
-            stats.last_count_size = count_size;
-        }
-        written += count_size;
-    }
-    stats.size = written;
-    stats
-}
-
-/// C's `ZSTD_entropyCompressSeqStore_internal()`: compresses literals and
-/// sequences into one compressed-block body.
-#[allow(clippy::too_many_arguments)]
-unsafe fn entropy_compress_seq_store_internal(
-    dst: *mut c_void,
-    dst_capacity: usize,
-    literals: *const c_void,
-    lit_size: usize,
-    seq_store: *const SeqStore_t,
-    prev_entropy: *const ZSTD_entropyCTables_t,
-    next_entropy: *mut ZSTD_entropyCTables_t,
-    strategy: c_int,
-    disable_literal_compression: c_int,
-    entropy_workspace: *mut c_void,
-    entropy_wksp_size: usize,
-    bmi2: c_int,
-) -> usize {
-    let count = entropy_workspace.cast::<c_uint>();
-    let entropy_workspace = unsafe { count.add(MAX_SEQ + 1) }.cast::<c_void>();
-    let entropy_wksp_size = entropy_wksp_size.wrapping_sub((MAX_SEQ + 1) * size_of::<c_uint>());
-    let store = unsafe { &*seq_store };
-    let sequences = store.sequencesStart;
-    let nb_seq = unsafe { store.sequences.offset_from(sequences) } as usize;
-    let ostart = dst.cast::<u8>();
-    let mut written = 0usize;
-    let last_count_size;
-    let long_offsets;
-
-    /* Compress literals */
-    {
-        /* Base suspicion of uncompressibility on ratio of literals to sequences */
-        let suspect_uncompressible =
-            c_int::from(nb_seq == 0 || lit_size / nb_seq >= SUSPECT_UNCOMPRESSIBLE_LITERAL_RATIO);
-        let c_size = unsafe {
-            ZSTD_compressLiterals(
-                dst,
-                dst_capacity,
-                literals,
-                lit_size,
-                entropy_workspace,
-                entropy_wksp_size,
-                ptr::addr_of!((*prev_entropy).huf),
-                ptr::addr_of_mut!((*next_entropy).huf),
-                strategy,
-                disable_literal_compression,
-                suspect_uncompressible,
-                bmi2,
-            )
-        };
-        if ERR_isError(c_size) {
-            return c_size;
-        }
-        debug_assert!(c_size <= dst_capacity);
-        written += c_size;
-    }
-
-    /* Sequences Header */
-    if (dst_capacity as isize).wrapping_sub(written as isize) < 3 /* max nbSeq Size */ + 1
-    /* seqHead */
-    {
-        return ERROR(ZstdErrorCode::DstSizeTooSmall);
-    }
-    unsafe {
-        if nb_seq < 128 {
-            *ostart.add(written) = nb_seq as u8;
-            written += 1;
-        } else if nb_seq < LONGNBSEQ as usize {
-            *ostart.add(written) = ((nb_seq >> 8) + 0x80) as u8;
-            *ostart.add(written + 1) = nb_seq as u8;
-            written += 2;
-        } else {
-            *ostart.add(written) = 0xFF;
-            MEM_writeLE16(
-                ostart.add(written + 1).cast::<c_void>(),
-                (nb_seq - LONGNBSEQ as usize) as u16,
-            );
-            written += 3;
-        }
-    }
-    if nb_seq == 0 {
-        /* Copy the old tables over as if we repeated them */
-        unsafe {
-            copy_fse_tables(
-                ptr::addr_of_mut!((*next_entropy).fse),
-                ptr::addr_of!((*prev_entropy).fse),
-            )
-        };
-        return written;
-    }
-    {
-        let seq_head = written;
-        written += 1;
-        /* build stats for sequences */
-        let stats = unsafe {
-            build_sequences_statistics(
-                seq_store,
-                nb_seq,
-                ptr::addr_of!((*prev_entropy).fse),
-                ptr::addr_of_mut!((*next_entropy).fse),
-                ostart.add(written),
-                dst_capacity - written,
-                strategy,
-                count,
-                entropy_workspace,
-                entropy_wksp_size,
-            )
-        };
-        if ERR_isError(stats.size) {
-            return stats.size;
-        }
-        unsafe {
-            *ostart.add(seq_head) =
-                ((stats.ll_type << 6) + (stats.off_type << 4) + (stats.ml_type << 2)) as u8;
-        }
-        last_count_size = stats.last_count_size;
-        written += stats.size;
-        long_offsets = stats.long_offsets;
-    }
-
-    {
-        let bitstream_size = unsafe {
-            ZSTD_encodeSequences(
-                ostart.add(written).cast::<c_void>(),
-                dst_capacity - written,
-                ptr::addr_of!((*next_entropy).fse.matchlengthCTable).cast::<u32>(),
-                store.mlCode,
-                ptr::addr_of!((*next_entropy).fse.offcodeCTable).cast::<u32>(),
-                store.ofCode,
-                ptr::addr_of!((*next_entropy).fse.litlengthCTable).cast::<u32>(),
-                store.llCode,
-                sequences,
-                nb_seq,
-                long_offsets,
-                bmi2,
-            )
-        };
-        if ERR_isError(bitstream_size) {
-            return bitstream_size;
-        }
-        written += bitstream_size;
-        /* zstd versions <= 1.3.4 mistakenly report corruption when
-         * FSE_readNCount() receives a buffer < 4 bytes.
-         * Fixed by https://github.com/facebook/zstd/pull/1146.
-         * This can happen when the last set_compressed table present is 2
-         * bytes and the bitstream is only one byte.
-         * In this exceedingly rare case, we will simply emit an uncompressed
-         * block, since it isn't worth optimizing.
-         */
-        if last_count_size != 0 && last_count_size + bitstream_size < 4 {
-            /* last_count_size >= 2 && bitstream_size > 0 ==> last_count_size == 3 */
-            debug_assert!(last_count_size + bitstream_size == 3);
-            return 0;
-        }
-    }
-
-    written
-}
-
-/// C's `ZSTD_entropyCompressSeqStore_wExtLitBuffer()`: adds the
-/// incompressibility fallbacks around the internal entropy pass.
-#[allow(clippy::too_many_arguments)]
-unsafe fn entropy_compress_seq_store_w_ext_lit_buffer(
-    dst: *mut c_void,
-    dst_capacity: usize,
-    literals: *const c_void,
-    lit_size: usize,
-    block_size: usize,
-    seq_store: *const SeqStore_t,
-    prev_entropy: *const ZSTD_entropyCTables_t,
-    next_entropy: *mut ZSTD_entropyCTables_t,
-    strategy: c_int,
-    disable_literal_compression: c_int,
-    entropy_workspace: *mut c_void,
-    entropy_wksp_size: usize,
-    bmi2: c_int,
-) -> usize {
-    let c_size = unsafe {
-        entropy_compress_seq_store_internal(
-            dst,
-            dst_capacity,
-            literals,
-            lit_size,
-            seq_store,
-            prev_entropy,
-            next_entropy,
-            strategy,
-            disable_literal_compression,
-            entropy_workspace,
-            entropy_wksp_size,
-            bmi2,
-        )
-    };
-    if c_size == 0 {
-        return 0;
-    }
-    /* When srcSize <= dstCapacity, there is enough space to write a raw uncompressed block.
-     * Since we ran out of space, block must be not compressible, so fall back to raw uncompressed block.
-     */
-    if c_size == ERROR(ZstdErrorCode::DstSizeTooSmall) && block_size <= dst_capacity {
-        return 0; /* block not compressed */
-    }
-    if ERR_isError(c_size) {
-        return c_size;
-    }
-
-    /* Check compressibility */
-    let max_c_size = block_size.wrapping_sub(min_gain(block_size, strategy));
-    if c_size >= max_c_size {
-        return 0; /* block not compressed */
-    }
-    c_size
-}
-
-/// C ABI wrapper for the external-literal-buffer entropy pass; the C shim
-/// keeps the `ZSTD_entropyCompressSeqStore_internal()` name and extracts the
-/// two `ZSTD_CCtx_params` scalars.
-#[allow(clippy::too_many_arguments)]
-#[no_mangle]
-pub unsafe extern "C" fn ZSTD_rust_entropyCompressSeqStore_internal(
-    dst: *mut c_void,
-    dst_capacity: usize,
-    literals: *const c_void,
-    lit_size: usize,
-    seq_store: *const SeqStore_t,
-    prev_entropy: *const ZSTD_entropyCTables_t,
-    next_entropy: *mut ZSTD_entropyCTables_t,
-    strategy: c_int,
-    disable_literal_compression: c_int,
-    entropy_workspace: *mut c_void,
-    entropy_wksp_size: usize,
-    bmi2: c_int,
-) -> usize {
-    unsafe {
-        entropy_compress_seq_store_internal(
-            dst,
-            dst_capacity,
-            literals,
-            lit_size,
-            seq_store,
-            prev_entropy,
-            next_entropy,
-            strategy,
-            disable_literal_compression,
-            entropy_workspace,
-            entropy_wksp_size,
-            bmi2,
-        )
-    }
-}
-
-/// C ABI implementation behind the `ZSTD_entropyCompressSeqStore()` shim.
-#[allow(clippy::too_many_arguments)]
-#[no_mangle]
-pub unsafe extern "C" fn ZSTD_rust_entropyCompressSeqStore(
-    seq_store: *const SeqStore_t,
-    prev_entropy: *const ZSTD_entropyCTables_t,
-    next_entropy: *mut ZSTD_entropyCTables_t,
-    strategy: c_int,
-    disable_literal_compression: c_int,
-    dst: *mut c_void,
-    dst_capacity: usize,
-    src_size: usize,
-    entropy_workspace: *mut c_void,
-    entropy_wksp_size: usize,
-    bmi2: c_int,
-) -> usize {
-    let store = unsafe { &*seq_store };
-    let lit_size = unsafe { store.lit.offset_from(store.litStart) } as usize;
-    unsafe {
-        entropy_compress_seq_store_w_ext_lit_buffer(
-            dst,
-            dst_capacity,
-            store.litStart.cast::<c_void>(),
-            lit_size,
-            src_size,
-            seq_store,
-            prev_entropy,
-            next_entropy,
-            strategy,
-            disable_literal_compression,
-            entropy_workspace,
-            entropy_wksp_size,
-            bmi2,
-        )
-    }
-}
-
-/// C's `ZSTD_buildBlockEntropyStats_literals()`.
-///
-/// Stores the literals block type and Huffman description table into
-/// `huf_metadata` and returns the description size, or an error code.
-#[allow(clippy::too_many_arguments)]
-unsafe fn build_block_entropy_stats_literals(
-    src: *const c_void,
-    src_size: usize,
-    prev_huf: *const ZSTD_hufCTables_t,
-    next_huf: *mut ZSTD_hufCTables_t,
-    huf_metadata: *mut ZSTD_hufCTablesMetadata_t,
-    literals_compression_is_disabled: c_int,
-    workspace: *mut c_void,
-    wksp_size: usize,
-    huf_flags: c_int,
-) -> usize {
-    let count_wksp = workspace.cast::<c_uint>();
-    let count_wksp_size = (HUF_SYMBOLVALUE_MAX as usize + 1) * size_of::<c_uint>();
-    let node_wksp = unsafe { workspace.cast::<u8>().add(count_wksp_size) }.cast::<c_void>();
-    let node_wksp_size = wksp_size.wrapping_sub(count_wksp_size);
-    let mut max_symbol_value = HUF_SYMBOLVALUE_MAX;
-    let mut huff_log = LIT_HUF_LOG;
-    let mut repeat = unsafe { (*prev_huf).repeatMode };
-
-    /* Prepare nextEntropy assuming reusing the existing table */
-    unsafe { copy_huf_tables(next_huf, prev_huf) };
-
-    if literals_compression_is_disabled != 0 {
-        unsafe { (*huf_metadata).hType = SET_BASIC };
-        return 0;
-    }
-
-    /* small ? don't even attempt compression (speed opt) */
-    {
-        let min_lit_size = if repeat == HUF_REPEAT_VALID {
-            6
-        } else {
-            COMPRESS_LITERALS_SIZE_MIN
-        };
-        if src_size <= min_lit_size {
-            unsafe { (*huf_metadata).hType = SET_BASIC };
-            return 0;
-        }
-    }
-
-    /* Scan input and build symbol stats */
-    {
-        let largest = unsafe {
-            HIST_count_wksp(
-                count_wksp,
-                &mut max_symbol_value,
-                src,
-                src_size,
-                workspace,
-                wksp_size,
-            )
-        };
-        if ERR_isError(largest) {
-            return largest;
-        }
-        if largest == src_size {
-            /* only one literal symbol */
-            unsafe { (*huf_metadata).hType = SET_RLE };
-            return 0;
-        }
-        if largest <= (src_size >> 7) + 4 {
-            /* heuristic: likely not compressible */
-            unsafe { (*huf_metadata).hType = SET_BASIC };
-            return 0;
-        }
-    }
-
-    /* Validate the previous Huffman table */
-    if repeat == HUF_REPEAT_CHECK
-        && unsafe {
-            HUF_validateCTable(
-                ptr::addr_of!((*prev_huf).CTable).cast::<usize>(),
-                count_wksp,
-                max_symbol_value,
-            )
-        } == 0
-    {
-        repeat = HUF_REPEAT_NONE;
-    }
-
-    /* Build Huffman Tree */
-    unsafe {
-        ptr::write_bytes(
-            ptr::addr_of_mut!((*next_huf).CTable).cast::<u8>(),
-            0,
-            size_of_val(&(*next_huf).CTable),
-        );
-    }
-    huff_log = unsafe {
-        HUF_optimalTableLog(
-            huff_log,
-            src_size,
-            max_symbol_value,
-            node_wksp,
-            node_wksp_size,
-            ptr::addr_of_mut!((*next_huf).CTable).cast::<usize>(),
-            count_wksp,
-            huf_flags,
-        )
-    };
-    debug_assert!(huff_log <= LIT_HUF_LOG);
-    {
-        let max_bits = unsafe {
-            HUF_buildCTable_wksp(
-                ptr::addr_of_mut!((*next_huf).CTable).cast::<usize>(),
-                count_wksp,
-                max_symbol_value,
-                huff_log,
-                node_wksp,
-                node_wksp_size,
-            )
-        };
-        if ERR_isError(max_bits) {
-            return max_bits;
-        }
-        huff_log = max_bits as c_uint;
-    }
-    {
-        /* Build and write the CTable */
-        let new_c_size = unsafe {
-            HUF_estimateCompressedSize(
-                ptr::addr_of!((*next_huf).CTable).cast::<usize>(),
-                count_wksp,
-                max_symbol_value,
-            )
-        };
-        let h_size = unsafe {
-            HUF_writeCTable_wksp(
-                ptr::addr_of_mut!((*huf_metadata).hufDesBuffer).cast::<c_void>(),
-                size_of::<[u8; ZSTD_MAX_HUF_HEADER_SIZE]>(),
-                ptr::addr_of!((*next_huf).CTable).cast::<usize>(),
-                max_symbol_value,
-                huff_log,
-                node_wksp,
-                node_wksp_size,
-            )
-        };
-        /* Check against repeating the previous CTable */
-        if repeat != HUF_REPEAT_NONE {
-            let old_c_size = unsafe {
-                HUF_estimateCompressedSize(
-                    ptr::addr_of!((*prev_huf).CTable).cast::<usize>(),
-                    count_wksp,
-                    max_symbol_value,
-                )
-            };
-            if old_c_size < src_size
-                && (old_c_size <= h_size.wrapping_add(new_c_size)
-                    || h_size.wrapping_add(12) >= src_size)
-            {
-                unsafe {
-                    copy_huf_tables(next_huf, prev_huf);
-                    (*huf_metadata).hType = SET_REPEAT;
-                }
-                return 0;
-            }
-        }
-        if new_c_size.wrapping_add(h_size) >= src_size {
-            unsafe {
-                copy_huf_tables(next_huf, prev_huf);
-                (*huf_metadata).hType = SET_BASIC;
-            }
-            return 0;
-        }
-        unsafe {
-            (*huf_metadata).hType = SET_COMPRESSED;
-            (*next_huf).repeatMode = HUF_REPEAT_CHECK;
-        }
-        h_size
-    }
-}
-
-/// C's `ZSTD_buildDummySequencesStatistics()`: marks every encoding type as
-/// basic and resets the FSE repeat modes.
-unsafe fn build_dummy_sequences_statistics(
-    next_entropy: *mut ZSTD_fseCTables_t,
-) -> SymbolEncodingTypeStats {
-    unsafe {
-        (*next_entropy).litlength_repeatMode = FSE_REPEAT_NONE;
-        (*next_entropy).offcode_repeatMode = FSE_REPEAT_NONE;
-        (*next_entropy).matchlength_repeatMode = FSE_REPEAT_NONE;
-    }
-    SymbolEncodingTypeStats {
-        ll_type: SET_BASIC as u32,
-        off_type: SET_BASIC as u32,
-        ml_type: SET_BASIC as u32,
-        size: 0,
-        last_count_size: 0,
-        long_offsets: 0,
-    }
-}
-
-/// C's `ZSTD_buildBlockEntropyStats_sequences()`.
-#[allow(clippy::too_many_arguments)]
-unsafe fn build_block_entropy_stats_sequences(
-    seq_store: *const SeqStore_t,
-    prev_entropy: *const ZSTD_fseCTables_t,
-    next_entropy: *mut ZSTD_fseCTables_t,
-    strategy: c_int,
-    fse_metadata: *mut ZSTD_fseCTablesMetadata_t,
-    workspace: *mut c_void,
-    wksp_size: usize,
-) -> usize {
-    let store = unsafe { &*seq_store };
-    let nb_seq = unsafe { store.sequences.offset_from(store.sequencesStart) } as usize;
-    let count_workspace = workspace.cast::<c_uint>();
-    let entropy_workspace = unsafe { count_workspace.add(MAX_SEQ + 1) }.cast::<c_void>();
-    let entropy_workspace_size = wksp_size.wrapping_sub((MAX_SEQ + 1) * size_of::<c_uint>());
-
-    let stats = if nb_seq != 0 {
-        unsafe {
-            build_sequences_statistics(
-                seq_store,
-                nb_seq,
-                prev_entropy,
-                next_entropy,
-                ptr::addr_of_mut!((*fse_metadata).fseTablesBuffer).cast::<u8>(),
-                ZSTD_MAX_FSE_HEADERS_SIZE,
-                strategy,
-                count_workspace,
-                entropy_workspace,
-                entropy_workspace_size,
-            )
-        }
-    } else {
-        unsafe { build_dummy_sequences_statistics(next_entropy) }
-    };
-    if ERR_isError(stats.size) {
-        return stats.size;
-    }
-    unsafe {
-        (*fse_metadata).llType = stats.ll_type as c_int;
-        (*fse_metadata).ofType = stats.off_type as c_int;
-        (*fse_metadata).mlType = stats.ml_type as c_int;
-        (*fse_metadata).lastCountSize = stats.last_count_size;
-    }
-    stats.size
-}
-
-/// C's `ZSTD_buildBlockEntropyStats()`: builds entropy statistics for one
-/// block.  Requires an `ENTROPY_WORKSPACE_SIZE` workspace.
-#[allow(clippy::too_many_arguments)]
-pub(crate) unsafe fn build_block_entropy_stats(
-    seq_store: *const SeqStore_t,
-    prev_entropy: *const ZSTD_entropyCTables_t,
-    next_entropy: *mut ZSTD_entropyCTables_t,
-    strategy: c_int,
-    disable_literal_compression: c_int,
-    entropy_metadata: *mut ZSTD_entropyCTablesMetadata_t,
-    workspace: *mut c_void,
-    wksp_size: usize,
-) -> usize {
-    let store = unsafe { &*seq_store };
-    let lit_size = unsafe { store.lit.offset_from(store.litStart) } as usize;
-    let huf_flags = if strategy >= HUF_OPTIMAL_DEPTH_THRESHOLD {
-        HUF_FLAGS_OPTIMAL_DEPTH
-    } else {
-        0
-    };
-
-    let huf_des_size = unsafe {
-        build_block_entropy_stats_literals(
-            store.litStart.cast::<c_void>(),
-            lit_size,
-            ptr::addr_of!((*prev_entropy).huf),
-            ptr::addr_of_mut!((*next_entropy).huf),
-            ptr::addr_of_mut!((*entropy_metadata).hufMetadata),
-            disable_literal_compression,
-            workspace,
-            wksp_size,
-            huf_flags,
-        )
-    };
-    unsafe { (*entropy_metadata).hufMetadata.hufDesSize = huf_des_size };
-    if ERR_isError(huf_des_size) {
-        return huf_des_size;
-    }
-
-    let fse_tables_size = unsafe {
-        build_block_entropy_stats_sequences(
-            seq_store,
-            ptr::addr_of!((*prev_entropy).fse),
-            ptr::addr_of_mut!((*next_entropy).fse),
-            strategy,
-            ptr::addr_of_mut!((*entropy_metadata).fseMetadata),
-            workspace,
-            wksp_size,
-        )
-    };
-    unsafe { (*entropy_metadata).fseMetadata.fseTablesSize = fse_tables_size };
-    if ERR_isError(fse_tables_size) {
-        return fse_tables_size;
-    }
-    0
-}
-
-/// C ABI wrapper behind the `ZSTD_buildBlockEntropyStats()` shim, which is
-/// still exported from C for the block splitter's size estimation.
-#[allow(clippy::too_many_arguments)]
-#[no_mangle]
-pub unsafe extern "C" fn ZSTD_rust_buildBlockEntropyStats(
-    seq_store: *const SeqStore_t,
-    prev_entropy: *const ZSTD_entropyCTables_t,
-    next_entropy: *mut ZSTD_entropyCTables_t,
-    strategy: c_int,
-    disable_literal_compression: c_int,
-    entropy_metadata: *mut ZSTD_entropyCTablesMetadata_t,
-    workspace: *mut c_void,
-    wksp_size: usize,
-) -> usize {
-    unsafe {
-        build_block_entropy_stats(
-            seq_store,
-            prev_entropy,
-            next_entropy,
-            strategy,
-            disable_literal_compression,
-            entropy_metadata,
-            workspace,
-            wksp_size,
-        )
-    }
-}
-
-/// C's `ZSTD_copyBlockSequences()`: exports a block's sequences in the public
-/// `ZSTD_Sequence` format, appending the last-literals block delimiter.
-#[no_mangle]
-pub unsafe extern "C" fn ZSTD_rust_copyBlockSequences(
-    seq_collector: *mut SeqCollector,
-    seq_store: *const SeqStore_t,
-    prev_repcodes: *const u32,
-) -> usize {
-    let collector = unsafe { &mut *seq_collector };
-    let store = unsafe { &*seq_store };
-    let in_seqs = store.sequencesStart;
-    let nb_in_sequences = unsafe { store.sequences.offset_from(in_seqs) } as usize;
-    let nb_in_literals = unsafe { store.lit.offset_from(store.litStart) } as usize;
-    let out_seqs = if collector.seqIndex == 0 {
-        collector.seqStart
-    } else {
-        unsafe { collector.seqStart.add(collector.seqIndex) }
-    };
-    let nb_out_sequences = nb_in_sequences + 1;
-    let mut nb_out_literals = 0usize;
-
-    /* Bounds check that we have enough space for every input sequence
-     * and the block delimiter
-     */
-    debug_assert!(collector.seqIndex <= collector.maxSequences);
-    if nb_out_sequences > collector.maxSequences.wrapping_sub(collector.seqIndex) {
-        return ERROR(ZstdErrorCode::DstSizeTooSmall);
-    }
-
-    let mut repcodes = [0u32; ZSTD_REP_NUM];
-    unsafe { ptr::copy_nonoverlapping(prev_repcodes, repcodes.as_mut_ptr(), ZSTD_REP_NUM) };
-    for index in 0..nb_in_sequences {
-        let in_seq = unsafe { in_seqs.add(index).read() };
-        let out = unsafe { out_seqs.add(index) };
-        let mut lit_length = in_seq.litLength as u32;
-        let mut match_length = in_seq.mlBase as u32 + MINMATCH as u32;
-        let mut rep = 0u32;
-
-        /* Handle the possible single length >= 64K
-         * There can only be one because we add MINMATCH to every match length,
-         * and blocks are at most 128K.
-         */
-        if index == store.longLengthPos as usize {
-            if store.longLengthType == ZSTD_LLT_LITERAL_LENGTH {
-                lit_length += 0x10000;
-            } else if store.longLengthType == ZSTD_LLT_MATCH_LENGTH {
-                match_length += 0x10000;
-            }
-        }
-
-        /* Determine the raw offset given the offBase, which may be a repcode. */
-        let raw_offset = if (1..=ZSTD_REP_NUM as u32).contains(&in_seq.offBase) {
-            let repcode = in_seq.offBase;
-            debug_assert!(repcode > 0);
-            rep = repcode;
-            if lit_length != 0 {
-                repcodes[repcode as usize - 1]
-            } else if repcode == 3 {
-                debug_assert!(repcodes[0] > 1);
-                repcodes[0].wrapping_sub(1)
-            } else {
-                repcodes[repcode as usize]
-            }
-        } else {
-            in_seq.offBase.wrapping_sub(ZSTD_REP_NUM as u32)
-        };
-        unsafe {
-            (*out).litLength = lit_length;
-            (*out).matchLength = match_length;
-            (*out).offset = raw_offset;
-            (*out).rep = rep;
-        }
-
-        /* Update repcode history for the sequence */
-        update_rep(&mut repcodes, in_seq.offBase, in_seq.litLength == 0);
-
-        nb_out_literals += lit_length as usize;
-    }
-    /* Insert last literals (if any exist) in the block as a sequence with ml == off == 0.
-     * If there are no last literals, then we'll emit (of: 0, ml: 0, ll: 0), which is a marker
-     * for the block boundary, according to the API.
-     */
-    debug_assert!(nb_in_literals >= nb_out_literals);
-    {
-        let last_ll_size = nb_in_literals.wrapping_sub(nb_out_literals);
-        unsafe {
-            let last = out_seqs.add(nb_in_sequences);
-            (*last).litLength = last_ll_size as u32;
-            (*last).matchLength = 0;
-            (*last).offset = 0;
-        }
-    }
-    collector.seqIndex += nb_out_sequences;
-    debug_assert!(collector.seqIndex <= collector.maxSequences);
-
-    0
-}
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-    use std::mem::{align_of, offset_of};
-
-    const HUF_CTABLE_SIZE_ST: usize = HUF_SYMBOLVALUE_MAX as usize + 2;
-    const ENTROPY_WORKSPACE_SIZE: usize = (8 << 10) + 512 + (MAX_SEQ + 2) * size_of::<u32>();
-
-    fn empty_huf_tables(repeat: c_int) -> ZSTD_hufCTables_t {
-        ZSTD_hufCTables_t {
-            CTable: [0; HUF_CTABLE_SIZE_ST],
-            repeatMode: repeat,
-        }
-    }
-
-    fn empty_fse_tables(repeat: c_int) -> ZSTD_fseCTables_t {
-        ZSTD_fseCTables_t {
-            offcodeCTable: [0; OFF_CTABLE_SIZE],
-            matchlengthCTable: [0; ML_CTABLE_SIZE],
-            litlengthCTable: [0; LL_CTABLE_SIZE],
-            offcode_repeatMode: repeat,
-            matchlength_repeatMode: repeat,
-            litlength_repeatMode: repeat,
-        }
-    }
-
-    struct TestSeqStore {
-        sequences: Vec<SeqDef>,
-        literals: Vec<u8>,
-        ll_codes: Vec<u8>,
-        ml_codes: Vec<u8>,
-        of_codes: Vec<u8>,
-    }
-
-    impl TestSeqStore {
-        fn new(sequences: Vec<SeqDef>, literals: Vec<u8>) -> Self {
-            let nb_seq = sequences.len();
-            TestSeqStore {
-                sequences,
-                literals,
-                ll_codes: vec![0; nb_seq],
-                ml_codes: vec![0; nb_seq],
-                of_codes: vec![0; nb_seq],
-            }
-        }
-
-        fn seq_store(&mut self) -> SeqStore_t {
-            let nb_seq = self.sequences.len();
-            let nb_lit = self.literals.len();
-            SeqStore_t {
-                sequencesStart: self.sequences.as_mut_ptr(),
-                sequences: unsafe { self.sequences.as_mut_ptr().add(nb_seq) },
-                litStart: self.literals.as_mut_ptr(),
-                lit: unsafe { self.literals.as_mut_ptr().add(nb_lit) },
-                llCode: self.ll_codes.as_mut_ptr(),
-                mlCode: self.ml_codes.as_mut_ptr(),
-                ofCode: self.of_codes.as_mut_ptr(),
-                maxNbSeq: nb_seq,
-                maxNbLit: nb_lit,
-                longLengthType: 0,
-                longLengthPos: 0,
-            }
-        }
-    }
-
-    #[test]
-    fn c_leaf_layouts_match_supported_abis() {
-        assert_eq!(size_of::<SeqDef>(), 8);
-        assert_eq!(align_of::<SeqDef>(), align_of::<u32>());
-        assert_eq!(offset_of!(SeqStore_t, sequencesStart), 0);
-        assert_eq!(
-            offset_of!(SeqStore_t, longLengthPos),
-            9 * size_of::<usize>() + 4
-        );
-        assert_eq!(size_of::<SeqStore_t>(), 9 * size_of::<usize>() + 8);
-        assert_eq!(size_of::<ZSTD_fseCTables_t>(), 3552);
-        assert_eq!(offset_of!(ZSTD_compressedBlockState_t, entropy), 0);
-        assert_eq!(
-            offset_of!(ZSTD_compressedBlockState_t, rep),
-            size_of::<ZSTD_entropyCTables_t>()
-        );
-        assert_eq!(size_of::<ZSTD_Sequence>(), 16);
-        assert_eq!(offset_of!(SeqCollector, seqStart), size_of::<usize>());
-        assert_eq!(offset_of!(SeqCollector, seqIndex), 2 * size_of::<usize>());
-        assert_eq!(size_of::<SeqCollector>(), 4 * size_of::<usize>());
-        if size_of::<usize>() == 8 {
-            assert_eq!(size_of::<ZSTD_hufCTablesMetadata_t>(), 144);
-            assert_eq!(size_of::<ZSTD_fseCTablesMetadata_t>(), 168);
-            assert_eq!(size_of::<ZSTD_entropyCTablesMetadata_t>(), 312);
-            assert_eq!(size_of::<ZSTD_entropyCTables_t>(), 5616);
-            assert_eq!(size_of::<ZSTD_compressedBlockState_t>(), 5632);
-        } else {
-            assert_eq!(size_of::<ZSTD_hufCTablesMetadata_t>(), 136);
-            assert_eq!(size_of::<ZSTD_fseCTablesMetadata_t>(), 156);
-            assert_eq!(size_of::<ZSTD_entropyCTablesMetadata_t>(), 292);
-            assert_eq!(size_of::<ZSTD_entropyCTables_t>(), 4584);
-            assert_eq!(size_of::<ZSTD_compressedBlockState_t>(), 4596);
-        }
-    }
-
-    #[test]
-    fn repcode_updates_match_the_c_sum_type_rules() {
-        let mut reps = [1, 4, 8];
-        update_rep(&mut reps, 10, false);
-        assert_eq!(reps, [7, 1, 4]);
-        update_rep(&mut reps, 1, true);
-        assert_eq!(reps, [1, 7, 4]);
-        update_rep(&mut reps, 2, false);
-        assert_eq!(reps, [7, 1, 4]);
-        update_rep(&mut reps, 3, false);
-        assert_eq!(reps, [4, 7, 1]);
-    }
-
-    #[test]
-    fn seq_to_codes_matches_the_reference_tables() {
-        let mut store = TestSeqStore::new(
-            vec![
-                SeqDef {
-                    offBase: 4,
-                    litLength: 0,
-                    mlBase: 0,
-                },
-                SeqDef {
-                    offBase: 1,
-                    litLength: 63,
-                    mlBase: 127,
-                },
-                SeqDef {
-                    offBase: 1 << 20,
-                    litLength: 64,
-                    mlBase: 128,
-                },
-            ],
-            vec![0; 127],
-        );
-        let seq_store = store.seq_store();
-        let long_offsets = unsafe { ZSTD_seqToCodes(&seq_store) };
-        assert_eq!(long_offsets, 0);
-        assert_eq!(store.ll_codes, [0, 24, 25]);
-        assert_eq!(store.ml_codes, [0, 42, 43]);
-        assert_eq!(store.of_codes, [2, 0, 20]);
-    }
-
-    #[test]
-    fn rle_sequences_produce_one_byte_table_headers() {
-        // Five identical sequences select set_rle for all three symbol kinds;
-        // each table header is then exactly the one RLE symbol byte.
-        let mut store = TestSeqStore::new(
-            vec![
-                SeqDef {
-                    offBase: 8,
-                    litLength: 2,
-                    mlBase: 3,
-                };
-                5
-            ],
-            vec![b'x'; 10],
-        );
-        let seq_store = store.seq_store();
-        let prev = empty_fse_tables(FSE_REPEAT_NONE);
-        let mut next = empty_fse_tables(FSE_REPEAT_NONE);
-        let mut metadata =
-            unsafe { std::mem::MaybeUninit::<ZSTD_fseCTablesMetadata_t>::zeroed().assume_init() };
-        let mut workspace = vec![0u64; ENTROPY_WORKSPACE_SIZE / size_of::<u64>()];
-
-        let size = unsafe {
-            build_block_entropy_stats_sequences(
-                &seq_store,
-                &prev,
-                &mut next,
-                1,
-                &mut metadata,
-                workspace.as_mut_ptr().cast::<c_void>(),
-                ENTROPY_WORKSPACE_SIZE,
-            )
-        };
-        assert_eq!(size, 3);
-        assert_eq!(metadata.llType, SET_RLE);
-        assert_eq!(metadata.ofType, SET_RLE);
-        assert_eq!(metadata.mlType, SET_RLE);
-        assert_eq!(metadata.lastCountSize, 0);
-        assert_eq!(&metadata.fseTablesBuffer[..3], &[2, 3, 3]);
-        assert_eq!(next.litlength_repeatMode, FSE_REPEAT_NONE);
-        assert_eq!(next.offcode_repeatMode, FSE_REPEAT_NONE);
-        assert_eq!(next.matchlength_repeatMode, FSE_REPEAT_NONE);
-    }
-
-    #[test]
-    fn empty_seq_store_emits_raw_literals_and_repeats_tables() {
-        let mut store = TestSeqStore::new(Vec::new(), b"hello".to_vec());
-        let seq_store = store.seq_store();
-        let prev = ZSTD_entropyCTables_t {
-            huf: empty_huf_tables(HUF_REPEAT_NONE),
-            fse: empty_fse_tables(2),
-        };
-        let mut next = ZSTD_entropyCTables_t {
-            huf: empty_huf_tables(HUF_REPEAT_NONE),
-            fse: empty_fse_tables(FSE_REPEAT_NONE),
-        };
-        let mut workspace = vec![0u64; ENTROPY_WORKSPACE_SIZE / size_of::<u64>()];
-        let mut output = [0xA5u8; 32];
-
-        let size = unsafe {
-            ZSTD_rust_entropyCompressSeqStore_internal(
-                output.as_mut_ptr().cast::<c_void>(),
-                output.len(),
-                seq_store.litStart.cast::<c_void>(),
-                5,
-                &seq_store,
-                &prev,
-                &mut next,
-                1,
-                0,
-                workspace.as_mut_ptr().cast::<c_void>(),
-                ENTROPY_WORKSPACE_SIZE,
-                0,
-            )
-        };
-        // Raw literals header (5 << 3), five literal bytes, nbSeq == 0.
-        assert_eq!(size, 7);
-        assert_eq!(&output[..7], &[0x28, b'h', b'e', b'l', b'l', b'o', 0x00]);
-        // With no sequences, the previous FSE tables are copied unchanged.
-        assert_eq!(next.fse.offcode_repeatMode, 2);
-        assert_eq!(next.fse.matchlength_repeatMode, 2);
-        assert_eq!(next.fse.litlength_repeatMode, 2);
-    }
-
-    #[test]
-    fn literal_stats_pick_rle_and_compressed_types() {
-        let mut workspace = vec![0u64; ENTROPY_WORKSPACE_SIZE / size_of::<u64>()];
-        let prev = empty_huf_tables(HUF_REPEAT_NONE);
-        let mut next = empty_huf_tables(HUF_REPEAT_NONE);
-        let mut metadata =
-            unsafe { std::mem::MaybeUninit::<ZSTD_hufCTablesMetadata_t>::zeroed().assume_init() };
-
-        let rle = [7u8; 128];
-        let size = unsafe {
-            build_block_entropy_stats_literals(
-                rle.as_ptr().cast::<c_void>(),
-                rle.len(),
-                &prev,
-                &mut next,
-                &mut metadata,
-                0,
-                workspace.as_mut_ptr().cast::<c_void>(),
-                ENTROPY_WORKSPACE_SIZE,
-                0,
-            )
-        };
-        assert_eq!(size, 0);
-        assert_eq!(metadata.hType, SET_RLE);
-
-        let mut compressible = [0u8; 1024];
-        for (index, byte) in compressible.iter_mut().enumerate() {
-            *byte = (index % 4) as u8;
-        }
-        let size = unsafe {
-            build_block_entropy_stats_literals(
-                compressible.as_ptr().cast::<c_void>(),
-                compressible.len(),
-                &prev,
-                &mut next,
-                &mut metadata,
-                0,
-                workspace.as_mut_ptr().cast::<c_void>(),
-                ENTROPY_WORKSPACE_SIZE,
-                0,
-            )
-        };
-        assert!(!ERR_isError(size));
-        assert!(size > 0);
-        assert_eq!(metadata.hType, SET_COMPRESSED);
-        assert_eq!(metadata.hufDesSize, 0); // caller stores the returned size
-        assert_eq!(next.repeatMode, HUF_REPEAT_CHECK);
-    }
-
-    #[test]
-    fn copied_sequences_resolve_repcodes_and_append_the_delimiter() {
-        let mut store = TestSeqStore::new(
-            vec![
-                SeqDef {
-                    offBase: 3 + 100, // raw offset 100
-                    litLength: 4,
-                    mlBase: 5,
-                },
-                SeqDef {
-                    offBase: 1, // repcode 1 with literals: rep[0] == 100
-                    litLength: 2,
-                    mlBase: 7,
-                },
-                SeqDef {
-                    offBase: 3, // repcode 3 without literals: rep[0] - 1 == 99
-                    litLength: 0,
-                    mlBase: 9,
-                },
-            ],
-            vec![0; 10],
-        );
-        let seq_store = store.seq_store();
-        let mut out = [ZSTD_Sequence {
-            offset: 0xAA,
-            litLength: 0xAA,
-            matchLength: 0xAA,
-            rep: 0xAA,
-        }; 8];
-        let mut collector = SeqCollector {
-            collectSequences: 1,
-            seqStart: out.as_mut_ptr(),
-            seqIndex: 1,
-            maxSequences: 8,
-        };
-        let reps = [1u32, 4, 8];
-
-        let result =
-            unsafe { ZSTD_rust_copyBlockSequences(&mut collector, &seq_store, reps.as_ptr()) };
-        assert_eq!(result, 0);
-        assert_eq!(collector.seqIndex, 5);
-        let expect = [
-            (100, 4, 5 + 3, 0),
-            (100, 2, 7 + 3, 1),
-            (99, 0, 9 + 3, 3),
-            (0, 10 - 6, 0, 0xAA), // delimiter: last literals; rep untouched
-        ];
-        for (index, &(offset, lit, matched, rep)) in expect.iter().enumerate() {
-            assert_eq!(out[1 + index].offset, offset, "offset {index}");
-            assert_eq!(out[1 + index].litLength, lit, "litLength {index}");
-            assert_eq!(out[1 + index].matchLength, matched, "matchLength {index}");
-            assert_eq!(out[1 + index].rep, rep, "rep {index}");
-        }
-
-        collector.maxSequences = 5;
-        let result =
-            unsafe { ZSTD_rust_copyBlockSequences(&mut collector, &seq_store, reps.as_ptr()) };
-        assert_eq!(result, ERROR(ZstdErrorCode::DstSizeTooSmall));
-    }
-}

rust/src/zstd_compress_superblock.rs

@@ -6,13 +6,13 @@
 //! This is the Rust implementation of `zstd_compress_superblock.c`.  Its C
 //! entry-point shim only extracts fields from the opaque `ZSTD_CCtx`; all
 //! sequence partitioning, literal and sequence section writing, entropy
-//! fallback, and repcode repair remain here.  The C-shaped leaf layouts are
+//! fallback, and repcode repair remain here.  The leaf layouts below are
-//! shared with `zstd_compress_stats`, which also owns the block entropy
+//! intentionally kept C-shaped and checked for both supported pointer widths.
-//! statistics this module consumes.
 
 use crate::common::{
     LL_BITS, LL_DEFAULT_NORM, LL_DEFAULT_NORM_LOG, MAX_LL, MAX_ML, MAX_OFF, MINMATCH, ML_BITS,
     ML_DEFAULT_NORM, ML_DEFAULT_NORM_LOG, OF_DEFAULT_NORM, OF_DEFAULT_NORM_LOG,
+    ZSTD_MAX_FSE_HEADERS_SIZE, ZSTD_MAX_HUF_HEADER_SIZE,
 };
 use crate::errors::{ERR_isError, ZstdErrorCode, ERROR};
 use crate::hist::{HIST_countFast_wksp, HIST_count_wksp};
@@ -23,17 +23,9 @@ use crate::mem::{MEM_32bits, MEM_writeLE16, MEM_writeLE24, MEM_writeLE32};
 use crate::zstd_compress_literals::{
     ZSTD_compressRleLiteralsBlock, ZSTD_hufCTables_t, ZSTD_noCompressLiterals,
 };
-use crate::zstd_compress_sequences::{
-    SeqDef, ZSTD_crossEntropyCost, ZSTD_encodeSequences, ZSTD_fseBitCost,
-};
-use crate::zstd_compress_stats::{
-    build_block_entropy_stats, update_rep, SeqStore_t, ZSTD_compressedBlockState_t,
-    ZSTD_entropyCTablesMetadata_t, ZSTD_entropyCTables_t, ZSTD_fseCTablesMetadata_t,
-    ZSTD_fseCTables_t, ZSTD_hufCTablesMetadata_t,
-};
 use std::ffi::c_void;
 use std::mem::MaybeUninit;
-use std::os::raw::c_int;
+use std::os::raw::{c_int, c_short, c_uint};
 use std::ptr;
 
 const SET_BASIC: c_int = 0;
@@ -50,6 +42,121 @@ const LONG_NB_SEQ: usize = 0x7f00;
 const DEFAULT_MAX_OFF: u32 = 28;
 const BYTE_SCALE: usize = 256;
 
+const OFF_CTABLE_SIZE: usize = 1 + (1 << 7) + ((MAX_OFF + 1) * 2);
+const ML_CTABLE_SIZE: usize = 1 + (1 << 8) + ((MAX_ML + 1) * 2);
+const LL_CTABLE_SIZE: usize = 1 + (1 << 8) + ((MAX_LL + 1) * 2);
+
+/// ABI-compatible `SeqDef` from `zstd_compress_internal.h`.
+#[repr(C)]
+#[derive(Clone, Copy, Debug, Default)]
+struct SeqDef {
+    offBase: u32,
+    litLength: u16,
+    mlBase: u16,
+}
+
+/// ABI-compatible `SeqStore_t` leaf layout.
+///
+/// The C context itself remains opaque.  The C shim passes its `seqStore`
+/// member directly, so this small, stable hot-path structure is the only
+/// sequence storage representation crossing into Rust.
+#[repr(C)]
+struct SeqStore_t {
+    sequencesStart: *mut SeqDef,
+    sequences: *mut SeqDef,
+    litStart: *mut u8,
+    lit: *mut u8,
+    llCode: *mut u8,
+    mlCode: *mut u8,
+    ofCode: *mut u8,
+    maxNbSeq: usize,
+    maxNbLit: usize,
+    longLengthType: c_int,
+    longLengthPos: u32,
+}
+
+/// C's `ZSTD_fseCTables_t`.  The table element type is `FSE_CTable`, an
+/// `unsigned`, and the table lengths are the header macros expanded above.
+#[repr(C)]
+struct ZSTD_fseCTables_t {
+    offcodeCTable: [u32; OFF_CTABLE_SIZE],
+    matchlengthCTable: [u32; ML_CTABLE_SIZE],
+    litlengthCTable: [u32; LL_CTABLE_SIZE],
+    offcode_repeatMode: c_int,
+    matchlength_repeatMode: c_int,
+    litlength_repeatMode: c_int,
+}
+
+#[repr(C)]
+struct ZSTD_entropyCTables_t {
+    huf: ZSTD_hufCTables_t,
+    fse: ZSTD_fseCTables_t,
+}
+
+#[repr(C)]
+struct ZSTD_compressedBlockState_t {
+    entropy: ZSTD_entropyCTables_t,
+    rep: [u32; 3],
+}
+
+#[repr(C)]
+struct ZSTD_hufCTablesMetadata_t {
+    hType: c_int,
+    hufDesBuffer: [u8; ZSTD_MAX_HUF_HEADER_SIZE],
+    hufDesSize: usize,
+}
+
+#[repr(C)]
+struct ZSTD_fseCTablesMetadata_t {
+    llType: c_int,
+    ofType: c_int,
+    mlType: c_int,
+    fseTablesBuffer: [u8; ZSTD_MAX_FSE_HEADERS_SIZE],
+    fseTablesSize: usize,
+    lastCountSize: usize,
+}
+
+#[repr(C)]
+struct ZSTD_entropyCTablesMetadata_t {
+    hufMetadata: ZSTD_hufCTablesMetadata_t,
+    fseMetadata: ZSTD_fseCTablesMetadata_t,
+}
+
+unsafe extern "C" {
+    fn ZSTD_buildBlockEntropyStats(
+        seq_store: *const SeqStore_t,
+        prev_entropy: *const ZSTD_entropyCTables_t,
+        next_entropy: *mut ZSTD_entropyCTables_t,
+        cctx_params: *const c_void,
+        entropy_metadata: *mut ZSTD_entropyCTablesMetadata_t,
+        workspace: *mut c_void,
+        wksp_size: usize,
+    ) -> usize;
+
+    fn ZSTD_encodeSequences(
+        dst: *mut c_void,
+        dst_capacity: usize,
+        ctable_match_length: *const u32,
+        ml_code_table: *const u8,
+        ctable_offset_bits: *const u32,
+        of_code_table: *const u8,
+        ctable_lit_length: *const u32,
+        ll_code_table: *const u8,
+        sequences: *const SeqDef,
+        nb_seq: usize,
+        long_offsets: c_int,
+        bmi2: c_int,
+    ) -> usize;
+
+    fn ZSTD_fseBitCost(ctable: *const u32, count: *const u32, max: c_uint) -> usize;
+    fn ZSTD_crossEntropyCost(
+        norm: *const c_short,
+        accuracy_log: c_uint,
+        count: *const c_uint,
+        max: c_uint,
+    ) -> usize;
+}
+
 #[inline]
 fn remaining_capacity(capacity: usize, written: usize) -> Result<usize, usize> {
     capacity
@@ -731,6 +838,28 @@ unsafe fn size_block_sequences(
     nb_seq
 }
 
+#[inline]
+fn update_rep(reps: &mut [u32; 3], off_base: u32, literal_length_is_zero: bool) {
+    if off_base > 3 {
+        reps[2] = reps[1];
+        reps[1] = reps[0];
+        reps[0] = off_base - 3;
+        return;
+    }
+    let rep_code = off_base - 1 + u32::from(literal_length_is_zero);
+    if rep_code == 0 {
+        return;
+    }
+    let current_offset = if rep_code == 3 {
+        reps[0].wrapping_sub(1)
+    } else {
+        reps[rep_code as usize]
+    };
+    reps[2] = if rep_code >= 2 { reps[1] } else { reps[2] };
+    reps[1] = reps[0];
+    reps[0] = current_offset;
+}
+
 #[allow(clippy::too_many_arguments, clippy::manual_checked_ops)]
 unsafe fn compress_subblock_multi(
     seq_store: *const SeqStore_t,
@@ -969,18 +1098,16 @@ unsafe fn compress_subblock_multi(
 
 /// C ABI implementation called by the declaration-only C superblock shim.
 ///
-/// `ZSTD_CCtx_params` deliberately remains opaque: the C shim extracts the
+/// `cctx_params` deliberately remains opaque: only its two required scalar
-/// two scalar fields this path reads (the strategy and the
+/// fields are read by the shim, while the existing C entropy builder receives
-/// literals-compression switch) and the crate-internal entropy statistics
+/// the original pointer unchanged.
-/// builder receives them directly.
 #[allow(clippy::too_many_arguments)]
 #[no_mangle]
 pub unsafe extern "C" fn ZSTD_rust_compressSuperBlock(
     seq_store: *const c_void,
     prev_cblock: *const c_void,
     next_cblock: *mut c_void,
-    strategy: c_int,
+    cctx_params: *const c_void,
-    disable_literal_compression: c_int,
     workspace: *mut c_void,
     wksp_size: usize,
     bmi2: c_int,
@@ -995,17 +1122,16 @@ pub unsafe extern "C" fn ZSTD_rust_compressSuperBlock(
     let seq_store = seq_store.cast::<SeqStore_t>();
     let prev_cblock = prev_cblock.cast::<ZSTD_compressedBlockState_t>();
     let next_cblock = next_cblock.cast::<ZSTD_compressedBlockState_t>();
-    // The statistics builder only writes the used prefixes of the two
+    // C only writes the used prefixes of its two metadata byte buffers. Start
-    // metadata byte buffers. Start with initialized storage so treating the
+    // with initialized storage so treating the completed C struct as a Rust
-    // completed struct as a Rust value never exposes uninitialized elements.
+    // value never exposes uninitialized array elements.
     let mut entropy_metadata = MaybeUninit::<ZSTD_entropyCTablesMetadata_t>::zeroed();
     let entropy_result = unsafe {
-        build_block_entropy_stats(
+        ZSTD_buildBlockEntropyStats(
             seq_store,
             ptr::addr_of!((*prev_cblock).entropy),
             ptr::addr_of_mut!((*next_cblock).entropy),
-            strategy,
+            cctx_params,
-            disable_literal_compression,
             entropy_metadata.as_mut_ptr(),
             workspace,
             wksp_size,
@@ -1037,34 +1163,50 @@ pub unsafe extern "C" fn ZSTD_rust_compressSuperBlock(
 
 #[cfg(test)]
 mod tests {
-    // The shared C leaf layouts and the repcode update rules are asserted in
-    // `zstd_compress_stats`, which owns those definitions.
     use super::*;
+    use std::mem::{align_of, offset_of, size_of};
 
     #[test]
-    fn subblock_sizing_respects_the_budget() {
+    fn c_leaf_layouts_match_supported_abis() {
-        let sequences = [SeqDef {
+        assert_eq!(size_of::<SeqDef>(), 8);
-            offBase: 4,
+        assert_eq!(align_of::<SeqDef>(), align_of::<u32>());
-            litLength: 10,
+        assert_eq!(offset_of!(SeqStore_t, sequencesStart), 0);
-            mlBase: 10,
+        assert_eq!(
-        }; 8];
+            offset_of!(SeqStore_t, longLengthPos),
+            9 * size_of::<usize>() + 4
+        );
+        assert_eq!(size_of::<SeqStore_t>(), 9 * size_of::<usize>() + 8);
+        assert_eq!(size_of::<ZSTD_fseCTables_t>(), 3552);
+        assert_eq!(offset_of!(ZSTD_compressedBlockState_t, entropy), 0);
+        assert_eq!(
+            offset_of!(ZSTD_compressedBlockState_t, rep),
+            size_of::<ZSTD_entropyCTables_t>()
+        );
+        if size_of::<usize>() == 8 {
+            assert_eq!(size_of::<ZSTD_hufCTablesMetadata_t>(), 144);
+            assert_eq!(size_of::<ZSTD_fseCTablesMetadata_t>(), 168);
+            assert_eq!(size_of::<ZSTD_entropyCTablesMetadata_t>(), 312);
+            assert_eq!(size_of::<ZSTD_entropyCTables_t>(), 5616);
+            assert_eq!(size_of::<ZSTD_compressedBlockState_t>(), 5632);
+        } else {
+            assert_eq!(size_of::<ZSTD_hufCTablesMetadata_t>(), 136);
+            assert_eq!(size_of::<ZSTD_fseCTablesMetadata_t>(), 156);
+            assert_eq!(size_of::<ZSTD_entropyCTablesMetadata_t>(), 292);
+            assert_eq!(size_of::<ZSTD_entropyCTables_t>(), 4584);
+            assert_eq!(size_of::<ZSTD_compressedBlockState_t>(), 4596);
+        }
+    }
 
-        // A generous budget keeps every sequence in one sub-block.
+    #[test]
-        let all = unsafe {
+    fn repcode_updates_match_the_c_sum_type_rules() {
-            size_block_sequences(
+        let mut reps = [1, 4, 8];
-                sequences.as_ptr(),
+        update_rep(&mut reps, 10, false);
-                sequences.len(),
+        assert_eq!(reps, [7, 1, 4]);
-                usize::MAX,
+        update_rep(&mut reps, 1, true);
-                256,
+        assert_eq!(reps, [1, 7, 4]);
-                256,
+        update_rep(&mut reps, 2, false);
-                true,
+        assert_eq!(reps, [7, 1, 4]);
-            )
+        update_rep(&mut reps, 3, false);
-        };
+        assert_eq!(reps, [4, 7, 1]);
-        assert_eq!(all, sequences.len());
-
-        // The first sequence always survives, even over budget.
-        let first =
-            unsafe { size_block_sequences(sequences.as_ptr(), sequences.len(), 0, 256, 256, true) };
-        assert_eq!(first, 1);
     }
 }

tests/Makefile

@@ -79,6 +79,8 @@ RUST_TARGET_DIR := $(RUST_DIR)/target/$(RUST_BUILD_CONFIG)
 RUST_STATICLIB := $(RUST_TARGET_DIR)/release/libzstd_rs.a
 RUST_TARGET_32 ?= i686-unknown-linux-gnu
 RUST_STATICLIB_32 := $(RUST_TARGET_DIR)/$(RUST_TARGET_32)/release/libzstd_rs.a
+# Tests build every library module, so they use the crate's default feature
+# set (compression, decompression, and dict-builder) plus any forced HUF mode.
 RUST_CARGO_FLAGS := --manifest-path $(RUST_MANIFEST) --release \
                     --target-dir $(RUST_TARGET_DIR)
 ifneq ($(RUST_HUF_FEATURE),)