Function CompressZip

SampleFramework12/v1.00/TinyEXR.cpp:6868–6927

}

void CompressZip(unsigned char *dst, unsigned long long &compressedSize,
                 const unsigned char *src, unsigned long srcSize) {

  std::vector<unsigned char> tmpBuf(srcSize);

  //
  // Apply EXR-specific? postprocess. Grabbed from OpenEXR's
  // ImfZipCompressor.cpp
  //

  //
  // Reorder the pixel data.
  //

  {
    char *t1 = (char *)&tmpBuf.at(0);
    char *t2 = (char *)&tmpBuf.at(0) + (srcSize + 1) / 2;
    const char *stop = (const char *)src + srcSize;

    while (true) {
      if ((const char *)src < stop)
        *(t1++) = *(src++);
      else
        break;

      if ((const char *)src < stop)
        *(t2++) = *(src++);
      else
        break;
    }
  }

  //
  // Predictor.
  //

  {
    unsigned char *t = &tmpBuf.at(0) + 1;
    unsigned char *stop = &tmpBuf.at(0) + srcSize;
    int p = t[-1];

    while (t < stop) {
      int d = int(t[0]) - p + (128 + 256);
      p = t[0];
      t[0] = d;
      ++t;
    }
  }

  //
  // Compress the data using miniz
  //

  miniz::mz_ulong outSize = miniz::mz_compressBound(srcSize);
  int ret = miniz::mz_compress(dst, &outSize,
                               (const unsigned char *)&tmpBuf.at(0), srcSize);
  assert(ret == miniz::MZ_OK);