static inline unsigned char *PopHexPixel(const char *const *hex_digits,
  const size_t pixel,unsigned char *pixels)
{
  register const char
    *hex;

  hex=hex_digits[pixel];
  *pixels++=(unsigned char) (*hex++);
  *pixels++=(unsigned char) (*hex);
  return(pixels);
}

The product performs an iteration or loop without sufficiently limiting the number of times that the loop is executed.