ddidderr/zstd-rs
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disable 2-passes strategy

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This commit is contained in:
Yann Collet
2018-05-22 15:06:36 -07:00
parent 5cbef6e094
commit a8ddf1d370
2 changed files with 12 additions and 5 deletions
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lib/compress/zstd_ldm.c
+1 -3
View File
@@ -642,8 +642,6 @@ size_t ZSTD_ldm_blockCompress(rawSeqStore_t* rawSeqStore,
ZSTD_ldm_limitTableUpdate(ms, ip); ZSTD_ldm_limitTableUpdate(ms, ip);
ZSTD_ldm_fillFastTables(ms, cParams, ip); ZSTD_ldm_fillFastTables(ms, cParams, ip);
/* Compress the last literals */ /* Compress the last literals */
{ size_t const lastLiterals = blockCompressor(ms, seqStore, rep, cParams, return blockCompressor(ms, seqStore, rep, cParams,
ip, iend - ip); ip, iend - ip);
return lastLiterals;
}
} }
lib/compress/zstd_opt.c
+10 -1
View File
@@ -1012,6 +1012,7 @@ size_t ZSTD_compressBlock_btopt(
} }
/* used in 2-pass strategy */
static U32 ZSTD_upscaleStat(U32* table, U32 lastEltIndex, int bonus) static U32 ZSTD_upscaleStat(U32* table, U32 lastEltIndex, int bonus)
{ {
U32 s, sum=0; U32 s, sum=0;
@@ -1024,7 +1025,8 @@ static U32 ZSTD_upscaleStat(U32* table, U32 lastEltIndex, int bonus)
return sum; return sum;
} }
static void ZSTD_upscaleStats(optState_t* optPtr) /* used in 2-pass strategy */
MEM_STATIC void ZSTD_upscaleStats(optState_t* optPtr)
{ {
optPtr->litSum = ZSTD_upscaleStat(optPtr->litFreq, MaxLit, 0); optPtr->litSum = ZSTD_upscaleStat(optPtr->litFreq, MaxLit, 0);
optPtr->litLengthSum = ZSTD_upscaleStat(optPtr->litLengthFreq, MaxLL, 1); optPtr->litLengthSum = ZSTD_upscaleStat(optPtr->litLengthFreq, MaxLL, 1);
@@ -1037,6 +1039,12 @@ size_t ZSTD_compressBlock_btultra(
const ZSTD_compressionParameters* cParams, const void* src, size_t srcSize) const ZSTD_compressionParameters* cParams, const void* src, size_t srcSize)
{ {
DEBUGLOG(5, "ZSTD_compressBlock_btultra (srcSize=%zu)", srcSize); DEBUGLOG(5, "ZSTD_compressBlock_btultra (srcSize=%zu)", srcSize);
#if 0
/* 2-pass strategy (disabled)
* this strategy makes a first pass over first block to collect statistics
* and seed next round's statistics with it.
* The compression ratio gain is generally small (~0.5% on first block),
* the cost is 2x cpu time on first block. */
assert(srcSize <= ZSTD_BLOCKSIZE_MAX); assert(srcSize <= ZSTD_BLOCKSIZE_MAX);
if ( (ms->opt.litLengthSum==0) /* first block */ if ( (ms->opt.litLengthSum==0) /* first block */
&& (seqStore->sequences == seqStore->sequencesStart) /* no ldm */ && (seqStore->sequences == seqStore->sequencesStart) /* no ldm */
@@ -1057,6 +1065,7 @@ size_t ZSTD_compressBlock_btultra(
/* re-inforce weight of collected statistics */ /* re-inforce weight of collected statistics */
ZSTD_upscaleStats(&ms->opt); ZSTD_upscaleStats(&ms->opt);
} }
#endif
return ZSTD_compressBlock_opt_generic(ms, seqStore, rep, cParams, src, srcSize, 2 /*optLevel*/, 0 /*extDict*/); return ZSTD_compressBlock_opt_generic(ms, seqStore, rep, cParams, src, srcSize, 2 /*optLevel*/, 0 /*extDict*/);
} }