Something

function shadowBlend(sPixel as uinteger, dPixel as uinteger, param as any ptr) as uinteger
    if sPixel = &Hffff00ff then
        return dPixel
    else
        return RGBA(dPixel shr 17 and 127, dPixel shr 9 and 127, dPixel shr 1 and 127, 255)
    end if
end function