lib/legacy/zstd_v01.c

644 static size_t FSE_initDStream(FSE_DStream_t* bitD, const void* srcBuffer, size_t srcSize)
651         bitD->start = (const char*)srcBuffer;
652         bitD->ptr   = (const char*)srcBuffer + srcSize - sizeof(size_t);
653         bitD->bitContainer = FSE_readLEST(bitD->ptr);
656         bitD->bitsConsumed = 8 - FSE_highbit32(contain32);
661         bitD->start = (const char*)srcBuffer;
662         bitD->ptr   = bitD->start;
663         bitD->bitContainer = *(const BYTE*)(bitD->start);
666             case 7: bitD->bitContainer += (size_t)(((const BYTE*)(bitD->start))[6]) << (sizeof(size_t)*8 - 16);
668             case 6: bitD->bitContainer += (size_t)(((const BYTE*)(bitD->start))[5]) << (sizeof(size_t)*8 - 24);
670             case 5: bitD->bitContainer += (size_t)(((const BYTE*)(bitD->start))[4]) << (sizeof(size_t)*8 - 32);
672             case 4: bitD->bitContainer += (size_t)(((const BYTE*)(bitD->start))[3]) << 24;
674             case 3: bitD->bitContainer += (size_t)(((const BYTE*)(bitD->start))[2]) << 16;
676             case 2: bitD->bitContainer += (size_t)(((const BYTE*)(bitD->start))[1]) <<  8;
682         bitD->bitsConsumed = 8 - FSE_highbit32(contain32);
683         bitD->bitsConsumed += (U32)(sizeof(size_t) - srcSize)*8;
697 static size_t FSE_lookBits(FSE_DStream_t* bitD, U32 nbBits)
699     const U32 bitMask = sizeof(bitD->bitContainer)*8 - 1;
700     return ((bitD->bitContainer << (bitD->bitsConsumed & bitMask)) >> 1) >> ((bitMask-nbBits) & bitMask);
703 static size_t FSE_lookBitsFast(FSE_DStream_t* bitD, U32 nbBits)   /* only if nbBits >= 1 !! */
705     const U32 bitMask = sizeof(bitD->bitContainer)*8 - 1;
706     return (bitD->bitContainer << (bitD->bitsConsumed & bitMask)) >> (((bitMask+1)-nbBits) & bitMask);
709 static void FSE_skipBits(FSE_DStream_t* bitD, U32 nbBits)
711     bitD->bitsConsumed += nbBits;
722 static size_t FSE_readBits(FSE_DStream_t* bitD, U32 nbBits)
724     size_t value = FSE_lookBits(bitD, nbBits);
725     FSE_skipBits(bitD, nbBits);
729 static size_t FSE_readBitsFast(FSE_DStream_t* bitD, U32 nbBits)   /* only if nbBits >= 1 !! */
731     size_t value = FSE_lookBitsFast(bitD, nbBits);
732     FSE_skipBits(bitD, nbBits);
736 static unsigned FSE_reloadDStream(FSE_DStream_t* bitD)
738     if (bitD->bitsConsumed > (sizeof(bitD->bitContainer)*8))  /* should never happen */
741     if (bitD->ptr >= bitD->start + sizeof(bitD->bitContainer))
743         bitD->ptr -= bitD->bitsConsumed >> 3;
744         bitD->bitsConsumed &= 7;
745         bitD->bitContainer = FSE_readLEST(bitD->ptr);
748     if (bitD->ptr == bitD->start)
750         if (bitD->bitsConsumed < sizeof(bitD->bitContainer)*8) return FSE_DStream_endOfBuffer;
754         U32 nbBytes = bitD->bitsConsumed >> 3;
756         if (bitD->ptr - nbBytes < bitD->start)
758             nbBytes = (U32)(bitD->ptr - bitD->start);  /* ptr > start */
761         bitD->ptr -= nbBytes;
762         bitD->bitsConsumed -= nbBytes*8;
763         bitD->bitContainer = FSE_readLEST(bitD->ptr);   /* reminder : srcSize > sizeof(bitD) */
769 static void FSE_initDState(FSE_DState_t* DStatePtr, FSE_DStream_t* bitD, const FSE_DTable* dt)
773     DStatePtr->state = FSE_readBits(bitD, DTableH->tableLog);
774     FSE_reloadDStream(bitD);
778 static BYTE FSE_decodeSymbol(FSE_DState_t* DStatePtr, FSE_DStream_t* bitD)
783     size_t lowBits = FSE_readBits(bitD, nbBits);
789 static BYTE FSE_decodeSymbolFast(FSE_DState_t* DStatePtr, FSE_DStream_t* bitD)
794     size_t lowBits = FSE_readBitsFast(bitD, nbBits);
801    Tells if bitD has reached end of bitStream or not */
803 static unsigned FSE_endOfDStream(const FSE_DStream_t* bitD)
805     return ((bitD->ptr == bitD->start) && (bitD->bitsConsumed == sizeof(bitD->bitContainer)*8));
824     FSE_DStream_t bitD;
830     errorCode = FSE_initDStream(&bitD, cSrc, cSrcSize);   /* replaced last arg by maxCompressed Size */
833     FSE_initDState(&state1, &bitD, dt);
834     FSE_initDState(&state2, &bitD, dt);
836 #define FSE_GETSYMBOL(statePtr) fast ? FSE_decodeSymbolFast(statePtr, &bitD) : FSE_decodeSymbol(statePtr, &bitD)
839     for ( ; (FSE_reloadDStream(&bitD)==FSE_DStream_unfinished) && (op<olimit) ; op+=4)
843         if (FSE_MAX_TABLELOG*2+7 > sizeof(bitD.bitContainer)*8)    /* This test must be static */
844             FSE_reloadDStream(&bitD);
848         if (FSE_MAX_TABLELOG*4+7 > sizeof(bitD.bitContainer)*8)    /* This test must be static */
849             { if (FSE_reloadDStream(&bitD) > FSE_DStream_unfinished) { op+=2; break; } }
853         if (FSE_MAX_TABLELOG*2+7 > sizeof(bitD.bitContainer)*8)    /* This test must be static */
854             FSE_reloadDStream(&bitD);
860     /* note : FSE_reloadDStream(&bitD) >= FSE_DStream_partiallyFilled; Ends at exactly FSE_DStream_completed */
863         if ( (FSE_reloadDStream(&bitD)>FSE_DStream_completed) || (op==omax) || (FSE_endOfDStream(&bitD) && (fast || FSE_endOfDState(&state1))) )
868         if ( (FSE_reloadDStream(&bitD)>FSE_DStream_completed) || (op==omax) || (FSE_endOfDStream(&bitD) && (fast || FSE_endOfDState(&state2))) )
875     if (FSE_endOfDStream(&bitD) && FSE_endOfDState(&state1) && FSE_endOfDState(&state2))