diff --git a/lib/bitstream.h b/lib/bitstream.h index af9151ad..f2ed51bc 100644 --- a/lib/bitstream.h +++ b/lib/bitstream.h @@ -285,6 +285,17 @@ MEM_STATIC size_t BIT_initDStream(BIT_DStream_t* bitD, const void* srcBuffer, si return srcSize; } +MEM_STATIC size_t BIT_getUpperBits(size_t bitD, U32 const start) +{ + return bitD >> start; +} + +MEM_STATIC size_t BIT_getNBits(size_t bitD, U32 const nbBits, U32 const start) +{ + static const unsigned mask[] = { 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 }; /* up to 26 bits */ + return (bitD >> start) & mask[nbBits]; +} + MEM_STATIC size_t BIT_consumeFirstBits(size_t* bitDPtr, U32 const nbBits) { static const unsigned mask[] = { 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 }; /* up to 26 bits */ diff --git a/lib/zstd_decompress.c b/lib/zstd_decompress.c index 1de3da1e..3abd6bbc 100644 --- a/lib/zstd_decompress.c +++ b/lib/zstd_decompress.c @@ -635,7 +635,7 @@ static void ZSTD_decodeSequence(seq_t* seq, seqState_t* seqState, const U32 mls) U32 const mlBits = ML_bits[mlCode]; U32 const ofBits = ofCode ? ofCode-1 : 0; - size_t allBits = BIT_readBits(&(seqState->DStream), llBits+mlBits+ofBits); + size_t const allBits = BIT_readBits(&(seqState->DStream), llBits+mlBits+ofBits); static const U32 LL_base[MaxLL+1] = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, @@ -655,9 +655,9 @@ static void ZSTD_decodeSequence(seq_t* seq, seqState_t* seqState, const U32 mls) 0x800000, 0x1000000, 0x2000000, 0x4000000, /*fake*/ 1, 1, 1, 1 }; /* sequence */ - seq->litLength = LL_base[llCode] + BIT_consumeFirstBits(&allBits, llBits); - seq->matchLength = ML_base[mlCode] + BIT_consumeFirstBits(&allBits, mlBits) + mls; - { size_t const offset = ofCode ? OF_base[ofCode] + BIT_consumeFirstBits(&allBits, ofBits) : + seq->litLength = LL_base[llCode] + BIT_getNBits(allBits, llBits, 0); + seq->matchLength = ML_base[mlCode] + BIT_getNBits(allBits, mlBits, llBits) + mls; + { size_t const offset = ofCode ? OF_base[ofCode] + BIT_getUpperBits(allBits, llBits+mlBits) : llCode ? seq->offset : seqState->prevOffset; if (ofCode | !llCode) seqState->prevOffset = seq->offset; /* cmove */ seq->offset = offset;