in half2 a;
in half4 b;
void main() {
    sk_FragColor.x = half(packHalf2x16(a));
    sk_FragColor.x = half(packUnorm2x16(a));
    sk_FragColor.x = half(packSnorm2x16(a));
    sk_FragColor.x = half(packUnorm4x8(b));
    sk_FragColor.x = half(packSnorm4x8(b));
}