update

mathx/int.go

@@ -3,18 +3,32 @@ package mathx
 import (
 	"github.com/charlienet/go-mixed/expr"
 	"golang.org/x/exp/constraints"
+	"unsafe"
 )
 
-// MaxInt returns the larger one of v1 and v2.
+// Max returns the larger one of v1 and v2.
 func Max[T constraints.Ordered](v1, v2 T) T {
 	return expr.Ternary(v1 > v2, v1, v2)
 }
 
-// MinInt returns the smaller one of v1 and v2.
+// Min returns the smaller one of v1 and v2.
 func Min[T constraints.Ordered](v1, v2 T) T {
 	return expr.Ternary(v1 < v2, v1, v2)
 }
 
+func Abs1[T constraints.Signed](n T) T {
+	shift := 63
+	switch unsafe.Sizeof(n) {
+	case 1:
+		shift = 7
+	case 4:
+		shift = 31
+	}
+
+	y := n >> shift
+	return T((n ^ y) - y)
+}
+
 func Abs(n int64) int64 {
 	y := n >> 63
 	return (n ^ y) - y

mathx/int_test.go

@@ -0,0 +1,27 @@
+package mathx_test
+
+import (
+	"github.com/charlienet/go-mixed/mathx"
+	"github.com/stretchr/testify/assert"
+	"testing"
+)
+
+func TestMin(t *testing.T) {
+	assert.Equal(t, 1, mathx.Min(1, 3))
+	assert.Equal(t, 2, mathx.Min(66, 2))
+}
+
+func TestMax(t *testing.T) {
+	assert.Equal(t, 3, mathx.Max(1, 3))
+	assert.Equal(t, 66, mathx.Max(66, 2))
+}
+
+func TestAbs(t *testing.T) {
+	assert.Equal(t, 23, mathx.Abs1(23))
+	assert.Equal(t, 23, mathx.Abs1(-23))
+	assert.Equal(t, 0, mathx.Abs1(0))
+
+	var u int8 = -127
+	var exp int8 = 127
+	assert.Equal(t, exp, mathx.Abs1(u))
+}