logtern.go

package operand

// CalcLogTern will calculate VPTERNLOGD/VPTERNLOGD based on a function.
// Argument order is AT&T, a being *mm3, b being *mm2, c being *mm1 and destination.
// This can be used directly in VPTERNLOGD(a, b, c, CalcLogTern(...))
func CalcLogTern(fn func(a, b, c bool) bool) U8 {
	var res U8
	for ai, av := range []bool{false, true} {
		for bi, bv := range []bool{false, true} {
			for ci, cv := range []bool{false, true} {
				if fn(av, bv, cv) {
					res |= 1 << (uint(ai) | (uint(bi) * 2) | (uint(ci) * 4))
				}
			}
		}
	}
	return res
}

logtern_test.go

package operand

import "testing"

func TestCalcLogTern(t *testing.T) {
	tests := []struct {
		name string
		args func(a, b, c bool) bool
		want U8
	}{
		{
			name: "or",
			args: func(a, b, c bool) bool {
				return a || b || c
			},
			want: 0xfe,
		},
		{
			name: "and",
			args: func(a, b, c bool) bool {
				return a && b && c
			},
			want: 0x80,
		},
		{
			name: "xor",
			args: func(a, b, c bool) bool {
				return (a != b) != c
			},
			want: 0x96,
		},
		{
			name: "onebit",
			args: func(a, b, c bool) bool {
				n := 0
				if a {
					n++
				}
				if b {
					n++
				}
				if c {
					n++
				}
				return n == 1
			},
			want: 0x16,
		},
		{
			name: "twobits",
			args: func(a, b, c bool) bool {
				n := 0
				if a {
					n++
				}
				if b {
					n++
				}
				if c {
					n++
				}
				return n == 2
			},
			want: 0x68,
		},
		{
			name: "bitselect",
			// C ? B : A.
			args: func(a, b, c bool) bool {
				if c {
					return b
				}
				return a
			},
			want: 0xca,
		},
		{
			name: "carry",
			// (A + B + C) > 1
			args: func(a, b, c bool) bool {
				n := 0
				if a {
					n++
				}
				if b {
					n++
				}
				if c {
					n++
				}
				return n > 1
			},
			want: 0xe8,
		},
		{
			name: "add",
			// (A + B + C) & 1
			args: func(a, b, c bool) bool {
				n := 0
				if a {
					n++
				}
				if b {
					n++
				}
				if c {
					n++
				}
				return n&1 == 1
			},
			want: 0x96,
		},
	}
	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			if got := CalcLogTern(tt.args); got != tt.want {
				t.Errorf("CalcLogTern() = %b, want %b", got, tt.want)
			}
		})
	}
}