Function Adam7_deinterlace

depends/lodepng/lodepng.cpp:4239–4277

in: Adam7 interlaced image, with no padding bits between scanlines, but between reduced images so that each reduced image starts at a byte. out: the same pixels, but re-ordered so that they're now a non-interlaced image with size w*h bpp: bits per pixel out has the following size in bits: w * h * bpp. in is possibly bigger due to padding bits between reduced images. out must be big enough AND mus

NOTE: comments about padding bits are only relevant if bpp < 8
*/
static void Adam7_deinterlace(unsigned char* out, const unsigned char* in, unsigned w, unsigned h, unsigned bpp) {
  unsigned passw[7], passh[7];
  size_t filter_passstart[8], padded_passstart[8], passstart[8];
  unsigned i;

  Adam7_getpassvalues(passw, passh, filter_passstart, padded_passstart, passstart, w, h, bpp);

  if(bpp >= 8) {
    for(i = 0; i != 7; ++i) {
      unsigned x, y, b;
      size_t bytewidth = bpp / 8u;
      for(y = 0; y < passh[i]; ++y)
      for(x = 0; x < passw[i]; ++x) {
        size_t pixelinstart = passstart[i] + (y * passw[i] + x) * bytewidth;
        size_t pixeloutstart = ((ADAM7_IY[i] + (size_t)y * ADAM7_DY[i]) * (size_t)w
                             + ADAM7_IX[i] + (size_t)x * ADAM7_DX[i]) * bytewidth;
        for(b = 0; b < bytewidth; ++b) {
          out[pixeloutstart + b] = in[pixelinstart + b];
        }
      }
    }
  } else /*bpp < 8: Adam7 with pixels < 8 bit is a bit trickier: with bit pointers*/ {
    for(i = 0; i != 7; ++i) {
      unsigned x, y, b;
      unsigned ilinebits = bpp * passw[i];
      unsigned olinebits = bpp * w;
      size_t obp, ibp; /*bit pointers (for out and in buffer)*/
      for(y = 0; y < passh[i]; ++y)
      for(x = 0; x < passw[i]; ++x) {
        ibp = (8 * passstart[i]) + (y * ilinebits + x * bpp);
        obp = (ADAM7_IY[i] + (size_t)y * ADAM7_DY[i]) * olinebits + (ADAM7_IX[i] + (size_t)x * ADAM7_DX[i]) * bpp;
        for(b = 0; b < bpp; ++b) {
          unsigned char bit = readBitFromReversedStream(&ibp, in);
          setBitOfReversedStream(&obp, out, bit);
        }
      }
    }
  }
}

static void removePaddingBits(unsigned char* out, const unsigned char* in,
                              size_t olinebits, size_t ilinebits, unsigned h) {