float LibRaw::find_green(int bps, int bite, int off0, int off1)
{
  UINT64 bitbuf = 0;
  int vbits, col, i, c;
  ushort img[2][2064];
  double sum[] = {0, 0};
  if (width > 2064)
    return 0.f; // too wide

  FORC(2)
  {
    fseek(ifp, c ? off1 : off0, SEEK_SET);
    for (vbits = col = 0; col < width; col++)
    {
      for (vbits -= bps; vbits < 0; vbits += bite)
      {
        bitbuf <<= bite;
        for (i = 0; i < bite; i += 8)
          bitbuf |= (unsigned)(fgetc(ifp) << i);
      }
      img[c][col] = bitbuf << (64 - bps - vbits) >> (64 - bps);
    }
  }
  FORC(width - 1)
  {
    sum[c & 1] += ABS(img[0][c] - img[1][c + 1]);
    sum[~c & 1] += ABS(img[1][c] - img[0][c + 1]);
  }
  if (sum[0] >= 1.0 && sum[1] >= 1.0)
    return 100 * log(sum[0] / sum[1]);
  else
    return 0.f;
}
Unknown