unsigned lodepng_crc32(const unsigned char* buf, size_t len)
{
  unsigned c = 0xffffffffL;
  size_t n;

  for(n = 0; n < len; n++)
  {
    c = lodepng_crc32_table[(c ^ buf[n]) & 0xff] ^ (c >> 8);
  }
  return c ^ 0xffffffffL;
}
unsigned lodepng_crc32(const unsigned char* buf, size_t len)
{
  unsigned c = 0xffffffffL;
  size_t n;

  for(n = 0; n < len; n++)
  {
    c = lodepng_crc32_table[(c ^ buf[n]) & 0xff] ^ (c >> 8);
  }
  return c ^ 0xffffffffL;
}