AuroraMiddleware/zstd
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simplified ZSTD_decodeSequence()

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This commit is contained in:
Yann Collet 2016-07-06 02:25:44 +02:00
parent e0ce5b094b
commit fe07eaa972
1 changed files with 13 additions and 17 deletions
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30
lib/decompress/zstd_decompress.c
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@ -688,16 +688,16 @@ static seq_t ZSTD_decodeSequence(seqState_t* seqState)
0x2000, 0x4000, 0x8000, 0x10000 };
static const U32 ML_base[MaxML+1] = {
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, 34, 36, 38, 40, 44, 48, 56, 64, 80, 96, 0x80, 0x100, 0x200, 0x400, 0x800,
0x1000, 0x2000, 0x4000, 0x8000, 0x10000 };
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, 33, 34,
35, 37, 39, 41, 43, 47, 51, 59, 67, 83, 99, 0x83, 0x103, 0x203, 0x403, 0x803,
0x1003, 0x2003, 0x4003, 0x8003, 0x10003 };
static const U32 OF_base[MaxOff+1] = {
0, 1, 3, 7, 0xF, 0x1F, 0x3F, 0x7F,
0xFF, 0x1FF, 0x3FF, 0x7FF, 0xFFF, 0x1FFF, 0x3FFF, 0x7FFF,
0xFFFF, 0x1FFFF, 0x3FFFF, 0x7FFFF, 0xFFFFF, 0x1FFFFF, 0x3FFFFF, 0x7FFFFF,
0xFFFFFF, 0x1FFFFFF, 0x3FFFFFF, /*fake*/ 1, 1 };
0, 1, 1, 5, 0xD, 0x1D, 0x3D, 0x7D,
0xFD, 0x1FD, 0x3FD, 0x7FD, 0xFFD, 0x1FFD, 0x3FFD, 0x7FFD,
0xFFFD, 0x1FFFD, 0x3FFFD, 0x7FFFD, 0xFFFFD, 0x1FFFFD, 0x3FFFFD, 0x7FFFFD,
0xFFFFFD, 0x1FFFFFD, 0x3FFFFFD, /*fake*/ 1, 1 };
/* sequence */
{ size_t offset;
@ -708,22 +708,18 @@ static seq_t ZSTD_decodeSequence(seqState_t* seqState)
if (MEM_32bits()) BIT_reloadDStream(&(seqState->DStream));
}
if (offset < ZSTD_REP_NUM) {
if (llCode == 0 && offset <= 1) offset = 1-offset;
if (ofCode <= 1) {
if ((llCode == 0) & (offset <= 1)) offset = 1-offset;
if (offset != 0) {
if (offset) {
size_t const temp = seqState->prevOffset[offset];
if (offset != 1) {
seqState->prevOffset[2] = seqState->prevOffset[1];
}
if (offset != 1) seqState->prevOffset[2] = seqState->prevOffset[1];
seqState->prevOffset[1] = seqState->prevOffset[0];
seqState->prevOffset[0] = offset = temp;
} else {
offset = seqState->prevOffset[0];
}
} else {
offset -= ZSTD_REP_MOVE;
seqState->prevOffset[2] = seqState->prevOffset[1];
seqState->prevOffset[1] = seqState->prevOffset[0];
seqState->prevOffset[0] = offset;
@ -731,7 +727,7 @@ static seq_t ZSTD_decodeSequence(seqState_t* seqState)
seq.offset = offset;
}
seq.matchLength = ML_base[mlCode] + MINMATCH + ((mlCode>31) ? BIT_readBits(&(seqState->DStream), mlBits) : 0); /* <= 16 bits */
seq.matchLength = ML_base[mlCode] + ((mlCode>31) ? BIT_readBits(&(seqState->DStream), mlBits) : 0); /* <= 16 bits */
if (MEM_32bits() && (mlBits+llBits>24)) BIT_reloadDStream(&(seqState->DStream));
seq.litLength = LL_base[llCode] + ((llCode>15) ? BIT_readBits(&(seqState->DStream), llBits) : 0); /* <= 16 bits */