public static float4 subadd(float4 a, float4 b) { if (Sse3.IsSse3Supported) { v128 temp = Sse3.addsub_ps(*(v128 *)&a, *(v128 *)&b); return(*(float4 *)&temp); } else { return(a - math.select(b, -b, new bool4(false, true, false, true))); } }