unsigned int interpolate_colors(unsigned int c1, unsigned int c2, unsigned int alpha) {
    unsigned int r;
    __asm {
        pxor mm7,mm7
        movd mm0,c1
        movd mm1,c2

        mov eax,alpha
        shl eax,16
        add eax,alpha
        movd mm3,eax
        movq mm2,mm3
        punpckldq mm3,mm2

        punpcklbw mm0,mm7
        punpcklbw mm1,mm7
        psubw mm1,mm0

        pmullw mm1,mm3
        psrlw mm1,8
        paddb mm1,mm0
        packuswb mm1,mm7

        movd r,mm1
        emms;
    }
    return r;
}