ddidderr/zstd-rs
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code simplification (but reduce decompression speed ...)

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This commit is contained in:
Yann Collet
2016-03-21 13:24:16 +01:00
parent 5c71491a46
commit b0aec17a90
5 changed files with 113 additions and 128 deletions
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lib/zstd_decompress.c
+52 -28
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@@ -531,6 +531,34 @@ FORCE_INLINE size_t ZSTD_buildSeqTable(FSE_DTable* DTable, U32 type, U32 rawBits
}
FORCE_INLINE size_t ZSTD_buildSeqTableLL(FSE_DTable* DTable, U32 type, U32 max, U32 maxLog,
const void* src, size_t srcSize)
{
switch(type)
{
case FSE_ENCODING_RLE :
if (!srcSize) return ERROR(srcSize_wrong);
if ( (*(const BYTE*)src) > max) return ERROR(corruption_detected);
FSE_buildDTable_rle(DTable, *(const BYTE*)src); /* if *src > max, data is corrupted */
return 1;
case FSE_ENCODING_RAW :
FSE_buildDTable(DTable, LL_defaultNorm, max, LL_defaultNormLog);
return 0;
case FSE_ENCODING_STATIC:
return 0;
default : /* impossible */
case FSE_ENCODING_DYNAMIC :
{ U32 tableLog;
S16 norm[MaxSeq+1];
size_t const headerSize = FSE_readNCount(norm, &max, &tableLog, src, srcSize);
if (FSE_isError(headerSize)) return ERROR(corruption_detected);
if (tableLog > maxLog) return ERROR(corruption_detected);
FSE_buildDTable(DTable, norm, max, tableLog);
return headerSize;
} }
}
size_t ZSTD_decodeSeqHeaders(int* nbSeq, const BYTE** dumpsPtr, size_t* dumpsLengthPtr,
FSE_DTable* DTableLL, FSE_DTable* DTableML, FSE_DTable* DTableOffb,
const void* src, size_t srcSize)
@@ -576,7 +604,7 @@ size_t ZSTD_decodeSeqHeaders(int* nbSeq, const BYTE** dumpsPtr, size_t* dumpsLen
if (ip > iend-3) return ERROR(srcSize_wrong); /* min : all 3 are "raw", hence no header, but at least xxLog bits per type */
/* Build DTables */
{ size_t const bhSize = ZSTD_buildSeqTable(DTableLL, LLtype, LLbits, LLFSELog, ip, iend-ip);
{ size_t const bhSize = ZSTD_buildSeqTableLL(DTableLL, LLtype, 35, LLFSELog, ip, iend-ip);
if (ZSTD_isError(bhSize)) return ERROR(corruption_detected);
ip += bhSize;
}
@@ -612,21 +640,13 @@ typedef struct {
static void ZSTD_decodeSequence(seq_t* seq, seqState_t* seqState, const U32 mls)
{
const BYTE* dumps = seqState->dumps;
const BYTE* const de = seqState->dumpsEnd;
size_t litLength, offset;
/* Literal length */
litLength = FSE_peakSymbol(&(seqState->stateLL));
if (litLength == MaxLL) {
const U32 add = *dumps++;
if (add < 255) litLength += add;
else {
litLength = MEM_readLE32(dumps) & 0xFFFFFF; /* no risk : dumps is always followed by seq tables > 1 byte */
if (litLength&1) litLength>>=1, dumps += 3;
else litLength = (U16)(litLength)>>1, dumps += 2;
}
if (dumps >= de) dumps = de-1; /* late correction, to avoid read overflow (data is now corrupted anyway) */
U32 const litCode = FSE_peakSymbol(&(seqState->stateLL));
{ static const U32 LL_base[MaxLL+1] = {
0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15,
16, 18, 20, 22, 24, 28, 32, 40, 48, 64, 0x80, 0x100, 0x200, 0x400, 0x800, 0x1000,
0x2000, 0x4000, 0x8000, 0x10000 };
seq->litLength = LL_base[litCode] + BIT_readBits(&(seqState->DStream), LL_bits[litCode]);
}
/* Offset */
@@ -637,11 +657,12 @@ static void ZSTD_decodeSequence(seq_t* seq, seqState_t* seqState, const U32 mls)
0x800000, 0x1000000, 0x2000000, 0x4000000, /*fake*/ 1, 1, 1, 1 };
U32 const offsetCode = FSE_peakSymbol(&(seqState->stateOffb)); /* <= maxOff, by table construction */
U32 const nbBits = offsetCode ? offsetCode-1 : 0;
offset = offsetPrefix[offsetCode] + BIT_readBits(&(seqState->DStream), nbBits);
size_t const offset = offsetCode ? offsetPrefix[offsetCode] + BIT_readBits(&(seqState->DStream), nbBits) :
litCode ? seq->offset : seqState->prevOffset;
if (offsetCode | !litCode) seqState->prevOffset = seq->offset; /* cmove */
seq->offset = offset;
if (MEM_32bits()) BIT_reloadDStream(&(seqState->DStream));
if (offsetCode==0) offset = litLength ? seq->offset : seqState->prevOffset;
if (offsetCode | !litLength) seqState->prevOffset = seq->offset; /* cmove */
FSE_decodeSymbol(&(seqState->stateOffb), &(seqState->DStream)); /* update */
FSE_decodeSymbol(&(seqState->stateOffb), &(seqState->DStream)); /* update */
}
/* Literal length update */
@@ -650,7 +671,9 @@ static void ZSTD_decodeSequence(seq_t* seq, seqState_t* seqState, const U32 mls)
/* MatchLength */
{ size_t matchLength = FSE_decodeSymbol(&(seqState->stateML), &(seqState->DStream));
const BYTE* dumps = seqState->dumps;
if (matchLength == MaxML) {
const BYTE* const de = seqState->dumpsEnd;
const U32 add = *dumps++;
if (add < 255) matchLength += add;
else {
@@ -662,13 +685,9 @@ static void ZSTD_decodeSequence(seq_t* seq, seqState_t* seqState, const U32 mls)
}
matchLength += mls;
seq->matchLength = matchLength;
seqState->dumps = dumps;
}
/* save result */
seq->litLength = litLength;
seq->offset = offset;
seqState->dumps = dumps;
#if 0 /* debug */
{
static U64 totalDecoded = 0;
@@ -799,13 +818,18 @@ static size_t ZSTD_decompressSequences(
FSE_initDState(&(seqState.stateOffb), &(seqState.DStream), DTableOffb);
FSE_initDState(&(seqState.stateML), &(seqState.DStream), DTableML);
for ( ; (BIT_reloadDStream(&(seqState.DStream)) <= BIT_DStream_completed) && nbSeq ; ) {
for ( ; (BIT_reloadDStream(&(seqState.DStream)) <= BIT_DStream_completed) && nbSeq ; nbSeq--) {
size_t oneSeqSize;
nbSeq--;
ZSTD_decodeSequence(&sequence, &seqState, mls);
#if 0 /* for debug */
{ U32 pos = (U32)(op-base);
if ((pos > 198618400) && (pos < 198618500))
printf("pos %6u : %3u literals & match %3u bytes at distance %6u \n",
pos, (U32)sequence.litLength, (U32)sequence.matchLength, (U32)sequence.offset);
}
#endif
oneSeqSize = ZSTD_execSequence(op, oend, sequence, &litPtr, litLimit_8, base, vBase, dictEnd);
if (ZSTD_isError(oneSeqSize))
return oneSeqSize;
if (ZSTD_isError(oneSeqSize)) return oneSeqSize;
op += oneSeqSize;
}