contrib/python-zstandard/zstd/common/bitstream.h

30821:7005c03f7387

    if (srcSize >=  sizeof(bitD->bitContainer)) {  /* normal case */
        bitD->start = (const char*)srcBuffer;
        bitD->ptr   = (const char*)srcBuffer + srcSize - sizeof(bitD->bitContainer);
        bitD->bitContainer = MEM_readLEST(bitD->ptr);
        { BYTE const lastByte = ((const BYTE*)srcBuffer)[srcSize-1];
          bitD->bitsConsumed = lastByte ? 8 - BIT_highbit32(lastByte) : 0;
          if (lastByte == 0) return ERROR(GENERIC); /* endMark not present */ }
    } else {
        bitD->start = (const char*)srcBuffer;
        bitD->ptr   = bitD->start;
        bitD->bitContainer = *(const BYTE*)(bitD->start);

    return bitContainer >> start;
}

MEM_STATIC size_t BIT_getMiddleBits(size_t bitContainer, U32 const start, U32 const nbBits)
{
#if defined(__BMI__) && defined(__GNUC__)   /* experimental */
#  if defined(__x86_64__)
    if (sizeof(bitContainer)==8)
        return _bextr_u64(bitContainer, start, nbBits);
    else
#  endif

    BIT_skipBits(bitD, nbBits);
    return value;
}

/*! BIT_reloadDStream() :
*   Refill `BIT_DStream_t` from src buffer previously defined (see BIT_initDStream() ).
*   This function is safe, it guarantees it will not read beyond src buffer.
*   @return : status of `BIT_DStream_t` internal register.
              if status == unfinished, internal register is filled with >= (sizeof(bitD->bitContainer)*8 - 7) bits */
MEM_STATIC BIT_DStream_status BIT_reloadDStream(BIT_DStream_t* bitD)
{
	if (bitD->bitsConsumed > (sizeof(bitD->bitContainer)*8))  /* should not happen => corruption detected */
		return BIT_DStream_overflow;

30822:b54a2984cdd4

    if (srcSize >=  sizeof(bitD->bitContainer)) {  /* normal case */
        bitD->start = (const char*)srcBuffer;
        bitD->ptr   = (const char*)srcBuffer + srcSize - sizeof(bitD->bitContainer);
        bitD->bitContainer = MEM_readLEST(bitD->ptr);
        { BYTE const lastByte = ((const BYTE*)srcBuffer)[srcSize-1];
          bitD->bitsConsumed = lastByte ? 8 - BIT_highbit32(lastByte) : 0;  /* ensures bitsConsumed is always set */
          if (lastByte == 0) return ERROR(GENERIC); /* endMark not present */ }
    } else {
        bitD->start = (const char*)srcBuffer;
        bitD->ptr   = bitD->start;
        bitD->bitContainer = *(const BYTE*)(bitD->start);

    return bitContainer >> start;
}

MEM_STATIC size_t BIT_getMiddleBits(size_t bitContainer, U32 const start, U32 const nbBits)
{
#if defined(__BMI__) && defined(__GNUC__) && __GNUC__*1000+__GNUC_MINOR__ >= 4008  /* experimental */
#  if defined(__x86_64__)
    if (sizeof(bitContainer)==8)
        return _bextr_u64(bitContainer, start, nbBits);
    else
#  endif

    BIT_skipBits(bitD, nbBits);
    return value;
}

/*! BIT_reloadDStream() :
*   Refill `bitD` from buffer previously set in BIT_initDStream() .
*   This function is safe, it guarantees it will not read beyond src buffer.
*   @return : status of `BIT_DStream_t` internal register.
              if status == BIT_DStream_unfinished, internal register is filled with >= (sizeof(bitD->bitContainer)*8 - 7) bits */
MEM_STATIC BIT_DStream_status BIT_reloadDStream(BIT_DStream_t* bitD)
{
	if (bitD->bitsConsumed > (sizeof(bitD->bitContainer)*8))  /* should not happen => corruption detected */
		return BIT_DStream_overflow;