Unicode C

Decompress Large Binary File in Blocks

See more Compression Examples

Decompresses a large binary file in blocks. Unicode C

#include <C_CkFileAccessW.h>
#include <C_CkCompressionW.h>
#include <C_CkByteData.h>

void ChilkatSample(void)
    {
    BOOL success;
    HCkFileAccessW facSrc;
    HCkFileAccessW facDest;
    int blockSize;
    int numBlocks;
    HCkCompressionW 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 = CkFileAccessW_Create();
    facDest = CkFileAccessW_Create();

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

    success = CkFileAccessW_OpenForRead(facSrc,L"c:/temp/qa_output/compressedBmp.dat");
    if (success == FALSE) {
        wprintf(L"%s\n",CkFileAccessW_lastErrorText(facSrc));
        CkFileAccessW_Dispose(facSrc);
        CkFileAccessW_Dispose(facDest);
        return;
    }

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

    //  Open an output file for the decompressed data.
    success = CkFileAccessW_OpenForWrite(facDest,L"c:/temp/qa_output/decompressed.bmp");
    if (success == FALSE) {
        wprintf(L"%s\n",CkFileAccessW_lastErrorText(facDest));
        CkFileAccessW_Dispose(facSrc);
        CkFileAccessW_Dispose(facDest);
        return;
    }

    compress = CkCompressionW_Create();
    CkCompressionW_putAlgorithm(compress,L"deflate");

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

    //  Assuming numBlocks > 1
    CkCompressionW_putFirstChunk(compress,TRUE);
    CkCompressionW_putLastChunk(compress,FALSE);

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

        success = CkCompressionW_DecompressBytes(compress,compressedBytes,decompressedBytes);
        CkFileAccessW_FileWrite(facDest,decompressedBytes);

        i = i + 1;

        CkCompressionW_putFirstChunk(compress,FALSE);
        if (i == (numBlocks - 1)) {
            CkCompressionW_putLastChunk(compress,TRUE);
        }

    }

    CkFileAccessW_FileClose(facSrc);
    CkFileAccessW_FileClose(facDest);

    wprintf(L"Finished decompressing file.\n");


    CkFileAccessW_Dispose(facSrc);
    CkFileAccessW_Dispose(facDest);
    CkCompressionW_Dispose(compress);
    CkByteData_Dispose(decompressedBytes);
    CkByteData_Dispose(compressedBytes);

    }