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lz4frame.c  view on Meta::CPAN

{
    LZ4F_cctx_t* const cctxPtr = (LZ4F_cctx_t*)LZ4F_compressionContext;

    if (cctxPtr != NULL) {  /* support free on NULL */
       FREEMEM(cctxPtr->lz4CtxPtr);  /* works because LZ4_streamHC_t and LZ4_stream_t are simple POD types */
       FREEMEM(cctxPtr->tmpBuff);
       FREEMEM(LZ4F_compressionContext);
    }

    return LZ4F_OK_NoError;
}


/*! LZ4F_compressBegin_usingCDict() :
 *  init streaming compression and writes frame header into dstBuffer.
 *  dstBuffer must be >= LZ4F_HEADER_SIZE_MAX bytes.
 * @return : number of bytes written into dstBuffer for the header
 *           or an error code (can be tested using LZ4F_isError())
 */
size_t LZ4F_compressBegin_usingCDict(LZ4F_cctx* cctxPtr,
                          void* dstBuffer, size_t dstCapacity,
                          const LZ4F_CDict* cdict,
                          const LZ4F_preferences_t* preferencesPtr)
{
    LZ4F_preferences_t prefNull;
    BYTE* const dstStart = (BYTE*)dstBuffer;
    BYTE* dstPtr = dstStart;
    BYTE* headerStart;

    if (dstCapacity < maxFHSize) return err0r(LZ4F_ERROR_dstMaxSize_tooSmall);
    memset(&prefNull, 0, sizeof(prefNull));
    if (preferencesPtr == NULL) preferencesPtr = &prefNull;
    cctxPtr->prefs = *preferencesPtr;

    /* Ctx Management */
    {   U32 const ctxTypeID = (cctxPtr->prefs.compressionLevel < LZ4HC_CLEVEL_MIN) ? 1 : 2;  /* 0:nothing ; 1:LZ4 table ; 2:HC tables */
        if (cctxPtr->lz4CtxLevel < ctxTypeID) {
            FREEMEM(cctxPtr->lz4CtxPtr);
            if (cctxPtr->prefs.compressionLevel < LZ4HC_CLEVEL_MIN)
                cctxPtr->lz4CtxPtr = (void*)LZ4_createStream();
            else
                cctxPtr->lz4CtxPtr = (void*)LZ4_createStreamHC();
            if (cctxPtr->lz4CtxPtr == NULL) return err0r(LZ4F_ERROR_allocation_failed);
            cctxPtr->lz4CtxLevel = ctxTypeID;
    }   }

    /* Buffer Management */
    if (cctxPtr->prefs.frameInfo.blockSizeID == 0)
        cctxPtr->prefs.frameInfo.blockSizeID = LZ4F_BLOCKSIZEID_DEFAULT;
    cctxPtr->maxBlockSize = LZ4F_getBlockSize(cctxPtr->prefs.frameInfo.blockSizeID);

    {   size_t const requiredBuffSize = preferencesPtr->autoFlush ?
                (cctxPtr->prefs.frameInfo.blockMode == LZ4F_blockLinked) * 64 KB :  /* only needs windows size */
                cctxPtr->maxBlockSize + ((cctxPtr->prefs.frameInfo.blockMode == LZ4F_blockLinked) * 128 KB);

        if (cctxPtr->maxBufferSize < requiredBuffSize) {
            cctxPtr->maxBufferSize = 0;
            FREEMEM(cctxPtr->tmpBuff);
            cctxPtr->tmpBuff = (BYTE*)ALLOCATOR(requiredBuffSize);
            if (cctxPtr->tmpBuff == NULL) return err0r(LZ4F_ERROR_allocation_failed);
            cctxPtr->maxBufferSize = requiredBuffSize;
    }   }
    cctxPtr->tmpIn = cctxPtr->tmpBuff;
    cctxPtr->tmpInSize = 0;
    XXH32_reset(&(cctxPtr->xxh), 0);

    /* context init */
    cctxPtr->cdict = cdict;
    if (cctxPtr->prefs.frameInfo.blockMode == LZ4F_blockLinked) {
        /* frame init only for blockLinked : blockIndependent will be init at each block */
        if (cdict) {
            if (cctxPtr->prefs.compressionLevel < LZ4HC_CLEVEL_MIN) {
                memcpy(cctxPtr->lz4CtxPtr, cdict->fastCtx, sizeof(*cdict->fastCtx));
            } else {
                memcpy(cctxPtr->lz4CtxPtr, cdict->HCCtx, sizeof(*cdict->HCCtx));
                LZ4_setCompressionLevel((LZ4_streamHC_t*)cctxPtr->lz4CtxPtr, cctxPtr->prefs.compressionLevel);
            }
        } else {
            if (cctxPtr->prefs.compressionLevel < LZ4HC_CLEVEL_MIN)
                LZ4_resetStream((LZ4_stream_t*)(cctxPtr->lz4CtxPtr));
            else
                LZ4_resetStreamHC((LZ4_streamHC_t*)(cctxPtr->lz4CtxPtr), cctxPtr->prefs.compressionLevel);
        }
    }

    /* Magic Number */
    LZ4F_writeLE32(dstPtr, LZ4F_MAGICNUMBER);
    dstPtr += 4;
    headerStart = dstPtr;

    /* FLG Byte */
    *dstPtr++ = (BYTE)(((1 & _2BITS) << 6)    /* Version('01') */
        + ((cctxPtr->prefs.frameInfo.blockMode & _1BIT ) << 5)
        + ((cctxPtr->prefs.frameInfo.blockChecksumFlag & _1BIT ) << 4)
        + ((cctxPtr->prefs.frameInfo.contentSize > 0) << 3)
        + ((cctxPtr->prefs.frameInfo.contentChecksumFlag & _1BIT ) << 2)
        +  (cctxPtr->prefs.frameInfo.dictID > 0) );
    /* BD Byte */
    *dstPtr++ = (BYTE)((cctxPtr->prefs.frameInfo.blockSizeID & _3BITS) << 4);
    /* Optional Frame content size field */
    if (cctxPtr->prefs.frameInfo.contentSize) {
        LZ4F_writeLE64(dstPtr, cctxPtr->prefs.frameInfo.contentSize);
        dstPtr += 8;
        cctxPtr->totalInSize = 0;
    }
    /* Optional dictionary ID field */
    if (cctxPtr->prefs.frameInfo.dictID) {
        LZ4F_writeLE32(dstPtr, cctxPtr->prefs.frameInfo.dictID);
        dstPtr += 4;
    }
    /* Header CRC Byte */
    *dstPtr = LZ4F_headerChecksum(headerStart, dstPtr - headerStart);
    dstPtr++;

    cctxPtr->cStage = 1;   /* header written, now request input data block */
    return (dstPtr - dstStart);
}


/*! LZ4F_compressBegin() :
 *  init streaming compression and writes frame header into dstBuffer.