math.unsigned: add uint128 tests (#13213)

vlib/math/unsigned/uint128.v

@@ -307,7 +307,7 @@ pub fn (u Uint128) lsh(n u32) Uint128 {
 	return s
 }
 
-// lsh returns u >> n
+// rsh returns u >> n
 pub fn (u Uint128) rsh(n u32) Uint128 {
 	mut s := Uint128{}
 	if n > 64 {
@@ -460,3 +460,7 @@ pub fn (u Uint128) - (v Uint128) Uint128 {
 pub fn (u Uint128) * (v Uint128) Uint128 {
 	return u.mul(v)
 }
+
+pub fn (u Uint128) < (v Uint128) bool {
+	return u.cmp(v) == -1
+}

vlib/math/unsigned/uint128_test.v

@@ -0,0 +1,99 @@
+import math.unsigned
+
+fn test_str() {
+	x := unsigned.uint128_from_dec_str('170141183460469231713240559642174554112') or { panic('') }
+	assert x.str() == '170141183460469231713240559642174554112'
+	y := unsigned.uint128_from_64(42)
+	assert y.str() == '42'
+}
+
+fn test_ops() {
+	x := unsigned.uint128_from_64(18446744073709551615)
+	y := unsigned.uint128_from_64(18446744073709551615)
+	z := unsigned.uint128_from_dec_str('340282366920938463426481119284349108225') or {
+		assert false
+		panic('')
+	}
+	assert (x * y).str() == '340282366920938463426481119284349108225'
+	assert (x + y).str() == '36893488147419103230'
+	assert (z / unsigned.uint128_from_64(2)).str() == '170141183460469231713240559642174554112'
+	assert (unsigned.uint128_from_dec_str('170141183460469231713240559642174554112') or {
+		panic('')
+	} - unsigned.uint128_from_64(2)).str() == '170141183460469231713240559642174554110'
+
+	assert x == y
+	assert unsigned.uint128_from_dec_str('340282366920938463426481119284349108225') or {
+		assert false
+		panic('')
+	} > y
+}
+
+struct LeadingZeros {
+	l     unsigned.Uint128
+	r     unsigned.Uint128
+	zeros int
+}
+
+fn new(x u64, y u64) unsigned.Uint128 {
+	return unsigned.Uint128{x, y}
+}
+
+fn test_leading_zeros() {
+	tcs := [
+		LeadingZeros{
+			l: new(0x00, 0xf000000000000000)
+			r: new(0x00, 0x8000000000000000)
+			zeros: 1
+		},
+		LeadingZeros{
+			l: new(0x00, 0xf000000000000000)
+			r: new(0x00, 0xc000000000000000)
+			zeros: 2
+		},
+		LeadingZeros{
+			l: new(0x00, 0xf000000000000000)
+			r: new(0x00, 0xe000000000000000)
+			zeros: 3
+		},
+		LeadingZeros{
+			l: new(0x00, 0xffff000000000000)
+			r: new(0x00, 0xff00000000000000)
+			zeros: 8
+		},
+		LeadingZeros{
+			l: new(0x00, 0x000000000000ffff)
+			r: new(0x00, 0x000000000000ff00)
+			zeros: 56
+		},
+		LeadingZeros{
+			l: new(0xf000000000000000, 0x01)
+			r: new(0x4000000000000000, 0x00)
+			zeros: 63
+		},
+		LeadingZeros{
+			l: new(0xf000000000000000, 0x00)
+			r: new(0x4000000000000000, 0x00)
+			zeros: 64
+		},
+		LeadingZeros{
+			l: new(0xf000000000000000, 0x00)
+			r: new(0x8000000000000000, 0x00)
+			zeros: 65
+		},
+		LeadingZeros{
+			l: new(0x00, 0x00)
+			r: new(0x00, 0x00)
+			zeros: 128
+		},
+		LeadingZeros{
+			l: new(0x01, 0x00)
+			r: new(0x00, 0x00)
+			zeros: 127
+		},
+	]
+
+	for tc in tcs {
+		zeros := tc.l.xor(tc.r).leading_zeros()
+		assert zeros == tc.zeros
+	}
+}