/* alpha blend routine */
unsigned int AlphaBlend(const unsigned int bg, const unsigned int src)
{
   unsigned int a = src >> 24;    /* alpha */
 
   /* If source pixel is transparent, just return the background */
   if (0 == a) 
      return bg;
 
   /* alpha blending the source and background colors */
   unsigned int rb = (((src & 0x00ff00ff) * a) +  
      ((bg & 0x00ff00ff) * (0xff - a))) & 0xff00ff00;
   unsigned int    g  = (((src & 0x0000ff00) * a) + 
      ((bg & 0x0000ff00) * (0xff - a))) & 0x00ff0000;
 
    return (src & 0xff000000) | ((rb | g) >> 8);
}