zstd/common/bitstream.h

96 MEM_STATIC size_t   BIT_initDStream(BIT_DStream_t* bitD, const void* srcBuffer, size_t srcSize);
97 MEM_STATIC size_t   BIT_readBits(BIT_DStream_t* bitD, unsigned nbBits);
98 MEM_STATIC BIT_DStream_status BIT_reloadDStream(BIT_DStream_t* bitD);
99 MEM_STATIC unsigned BIT_endOfDStream(const BIT_DStream_t* bitD);
122 MEM_STATIC size_t BIT_readBitsFast(BIT_DStream_t* bitD, unsigned nbBits);
258 MEM_STATIC size_t BIT_initDStream(BIT_DStream_t* bitD, const void* srcBuffer, size_t srcSize)  in BIT_initDStream()  argument
260     if (srcSize < 1) { ZSTD_memset(bitD, 0, sizeof(*bitD)); return ERROR(srcSize_wrong); }  in BIT_initDStream()
262     bitD->start = (const char*)srcBuffer;  in BIT_initDStream()
263     bitD->limitPtr = bitD->start + sizeof(bitD->bitContainer);  in BIT_initDStream()
265     if (srcSize >=  sizeof(bitD->bitContainer)) {  /* normal case */  in BIT_initDStream()
266         bitD->ptr   = (const char*)srcBuffer + srcSize - sizeof(bitD->bitContainer);  in BIT_initDStream()
267         bitD->bitContainer = MEM_readLEST(bitD->ptr);  in BIT_initDStream()
269 …bitD->bitsConsumed = lastByte ? 8 - BIT_highbit32(lastByte) : 0;  /* ensures bitsConsumed is alway…  in BIT_initDStream()
272         bitD->ptr   = bitD->start;  in BIT_initDStream()
273         bitD->bitContainer = *(const BYTE*)(bitD->start);  in BIT_initDStream()
276 …case 7: bitD->bitContainer += (size_t)(((const BYTE*)(srcBuffer))[6]) << (sizeof(bitD->bitContaine…  in BIT_initDStream()
279 …case 6: bitD->bitContainer += (size_t)(((const BYTE*)(srcBuffer))[5]) << (sizeof(bitD->bitContaine…  in BIT_initDStream()
282 …case 5: bitD->bitContainer += (size_t)(((const BYTE*)(srcBuffer))[4]) << (sizeof(bitD->bitContaine…  in BIT_initDStream()
285         case 4: bitD->bitContainer += (size_t)(((const BYTE*)(srcBuffer))[3]) << 24;  in BIT_initDStream()
288         case 3: bitD->bitContainer += (size_t)(((const BYTE*)(srcBuffer))[2]) << 16;  in BIT_initDStream()
291         case 2: bitD->bitContainer += (size_t)(((const BYTE*)(srcBuffer))[1]) <<  8;  in BIT_initDStream()
297             bitD->bitsConsumed = lastByte ? 8 - BIT_highbit32(lastByte) : 0;  in BIT_initDStream()
300         bitD->bitsConsumed += (U32)(sizeof(bitD->bitContainer) - srcSize)*8;  in BIT_initDStream()
340 MEM_STATIC  FORCE_INLINE_ATTR size_t BIT_lookBits(const BIT_DStream_t*  bitD, U32 nbBits)  in BIT_lookBits()  argument
346 …return BIT_getMiddleBits(bitD->bitContainer, (sizeof(bitD->bitContainer)*8) - bitD->bitsConsumed -…  in BIT_lookBits()
349     U32 const regMask = sizeof(bitD->bitContainer)*8 - 1;  in BIT_lookBits()
350 …return ((bitD->bitContainer << (bitD->bitsConsumed & regMask)) >> 1) >> ((regMask-nbBits) & regMas…  in BIT_lookBits()
356 MEM_STATIC size_t BIT_lookBitsFast(const BIT_DStream_t* bitD, U32 nbBits)  in BIT_lookBitsFast()  argument
358     U32 const regMask = sizeof(bitD->bitContainer)*8 - 1;  in BIT_lookBitsFast()
360 … return (bitD->bitContainer << (bitD->bitsConsumed & regMask)) >> (((regMask+1)-nbBits) & regMask);  in BIT_lookBitsFast()
363 MEM_STATIC FORCE_INLINE_ATTR void BIT_skipBits(BIT_DStream_t* bitD, U32 nbBits)  in BIT_skipBits()  argument
365     bitD->bitsConsumed += nbBits;  in BIT_skipBits()
372 MEM_STATIC FORCE_INLINE_ATTR size_t BIT_readBits(BIT_DStream_t* bitD, unsigned nbBits)  in BIT_readBits()  argument
374     size_t const value = BIT_lookBits(bitD, nbBits);  in BIT_readBits()
375     BIT_skipBits(bitD, nbBits);  in BIT_readBits()
381 MEM_STATIC size_t BIT_readBitsFast(BIT_DStream_t* bitD, unsigned nbBits)  in BIT_readBitsFast()  argument
383     size_t const value = BIT_lookBitsFast(bitD, nbBits);  in BIT_readBitsFast()
385     BIT_skipBits(bitD, nbBits);  in BIT_readBitsFast()
395 MEM_STATIC BIT_DStream_status BIT_reloadDStreamFast(BIT_DStream_t* bitD)  in BIT_reloadDStreamFast()  argument
397     if (UNLIKELY(bitD->ptr < bitD->limitPtr))  in BIT_reloadDStreamFast()
399     assert(bitD->bitsConsumed <= sizeof(bitD->bitContainer)*8);  in BIT_reloadDStreamFast()
400     bitD->ptr -= bitD->bitsConsumed >> 3;  in BIT_reloadDStreamFast()
401     bitD->bitsConsumed &= 7;  in BIT_reloadDStreamFast()
402     bitD->bitContainer = MEM_readLEST(bitD->ptr);  in BIT_reloadDStreamFast()
411 MEM_STATIC BIT_DStream_status BIT_reloadDStream(BIT_DStream_t* bitD)  in BIT_reloadDStream()  argument
413 …if (bitD->bitsConsumed > (sizeof(bitD->bitContainer)*8))  /* overflow detected, like end of stream…  in BIT_reloadDStream()
416     if (bitD->ptr >= bitD->limitPtr) {  in BIT_reloadDStream()
417         return BIT_reloadDStreamFast(bitD);  in BIT_reloadDStream()
419     if (bitD->ptr == bitD->start) {  in BIT_reloadDStream()
420         if (bitD->bitsConsumed < sizeof(bitD->bitContainer)*8) return BIT_DStream_endOfBuffer;  in BIT_reloadDStream()
424     {   U32 nbBytes = bitD->bitsConsumed >> 3;  in BIT_reloadDStream()
426         if (bitD->ptr - nbBytes < bitD->start) {  in BIT_reloadDStream()
427             nbBytes = (U32)(bitD->ptr - bitD->start);  /* ptr > start */  in BIT_reloadDStream()
430         bitD->ptr -= nbBytes;  in BIT_reloadDStream()
431         bitD->bitsConsumed -= nbBytes*8;  in BIT_reloadDStream()
432 …bitD->bitContainer = MEM_readLEST(bitD->ptr);   /* reminder : srcSize > sizeof(bitD->bitContainer)…  in BIT_reloadDStream()