C

Decompress Large Binary File in Blocks

See more Compression Examples

Decompresses a large binary file in blocks. C

#include <C_CkFileAccess.h>
#include <C_CkCompression.h>
#include <C_CkByteData.h>

void ChilkatSample(void)
    {
    BOOL success;
    HCkFileAccess facSrc;
    HCkFileAccess facDest;
    int blockSize;
    int numBlocks;
    HCkCompression compress;
    HCkByteData decompressedBytes;
    HCkByteData compressedBytes;
    int i;

    success = FALSE;

    //  This example requires the Chilkat API to have been previously unlocked.
    //  See Global Unlock Sample for sample code.

    facSrc = CkFileAccess_Create();
    facDest = CkFileAccess_Create();

    //  Open a previously compressed file for decompressing.
    //  See Compress Large File in Blocks

    success = CkFileAccess_OpenForRead(facSrc,"c:/temp/qa_output/compressedBmp.dat");
    if (success == FALSE) {
        printf("%s\n",CkFileAccess_lastErrorText(facSrc));
        CkFileAccess_Dispose(facSrc);
        CkFileAccess_Dispose(facDest);
        return;
    }

    //  If we compress in 32K chunks, find out how many blocks there will be.
    blockSize = 32768;
    numBlocks = CkFileAccess_GetNumBlocks(facSrc,blockSize);

    //  Open an output file for the decompressed data.
    success = CkFileAccess_OpenForWrite(facDest,"c:/temp/qa_output/decompressed.bmp");
    if (success == FALSE) {
        printf("%s\n",CkFileAccess_lastErrorText(facDest));
        CkFileAccess_Dispose(facSrc);
        CkFileAccess_Dispose(facDest);
        return;
    }

    compress = CkCompression_Create();
    CkCompression_putAlgorithm(compress,"deflate");

    decompressedBytes = CkByteData_Create();
    compressedBytes = CkByteData_Create();

    //  Assuming numBlocks > 1
    CkCompression_putFirstChunk(compress,TRUE);
    CkCompression_putLastChunk(compress,FALSE);

    i = 0;
    while (i < numBlocks) {
        success = CkFileAccess_ReadBlock(facSrc,i,blockSize,compressedBytes);

        success = CkCompression_DecompressBytes(compress,compressedBytes,decompressedBytes);
        CkFileAccess_FileWrite(facDest,decompressedBytes);

        i = i + 1;

        CkCompression_putFirstChunk(compress,FALSE);
        if (i == (numBlocks - 1)) {
            CkCompression_putLastChunk(compress,TRUE);
        }

    }

    CkFileAccess_FileClose(facSrc);
    CkFileAccess_FileClose(facDest);

    printf("Finished decompressing file.\n");


    CkFileAccess_Dispose(facSrc);
    CkFileAccess_Dispose(facDest);
    CkCompression_Dispose(compress);
    CkByteData_Dispose(decompressedBytes);
    CkByteData_Dispose(compressedBytes);

    }