builtin: optimize hex() (#11261)

vlib/builtin/int.v

@@ -256,13 +256,12 @@ pub fn (b bool) str() string {
 [direct_array_access; inline]
 fn u64_to_hex(nn u64, len byte) string {
 	mut n := nn
-	mut buf := [256]byte{}
+	mut buf := [17]byte{}
 	buf[len] = 0
 	mut i := 0
 	for i = len - 1; i >= 0; i-- {
 		d := byte(n & 0xF)
-		x := if d < 10 { d + `0` } else { d + 87 }
+		buf[i] = if d < 10 { d + `0` } else { d + 87 }
-		buf[i] = x
 		n = n >> 4
 	}
 	return unsafe { tos(memdup(&buf[0], len + 1), len) }
@@ -272,13 +271,12 @@ fn u64_to_hex(nn u64, len byte) string {
 [direct_array_access; inline]
 fn u64_to_hex_no_leading_zeros(nn u64, len byte) string {
 	mut n := nn
-	mut buf := [256]byte{}
+	mut buf := [17]byte{}
 	buf[len] = 0
 	mut i := 0
 	for i = len - 1; i >= 0; i-- {
 		d := byte(n & 0xF)
-		x := if d < 10 { d + `0` } else { d + 87 }
+		buf[i] = if d < 10 { d + `0` } else { d + 87 }
-		buf[i] = x
 		n = n >> 4
 		if n == 0 {
 			break
@@ -306,7 +304,11 @@ pub fn (nn byte) hex() string {
 // Example: assert i8(10).hex() == '0a'
 // Example: assert i8(15).hex() == '0f'
 pub fn (nn i8) hex() string {
-	return byte(nn).hex()
+	if nn == 0 {
+		return '00'
+	}
+	return u64_to_hex(u64(nn), 2)
+	//return byte(nn).hex()
 }
 
 // hex returns the value of the `u16` as a hexadecimal `string`.

vlib/builtin/int_test.v

@@ -23,8 +23,6 @@ fn test_str_methods() {
 	assert int(-2147483648).str() == '-2147483648'
 	assert i64(1).str() == '1'
 	assert i64(-1).str() == '-1'
-	// assert byte(1).str() == '1'
-	// assert byte(-1).str() == '255'
 	assert u16(1).str() == '1'
 	assert u16(-1).str() == '65535'
 	assert u32(1).str() == '1'
@@ -33,6 +31,8 @@ fn test_str_methods() {
 	assert u64(-1).str() == '18446744073709551615'
 	assert voidptr(-1).str() == 'ffffffffffffffff'
 	assert voidptr(1).str() == '1'
+	assert (&byte(-1)).str() == 'ffffffffffffffff'
+	assert (&byte(1)).str() == '1'
 	assert byteptr(-1).str() == 'ffffffffffffffff'
 	assert byteptr(1).str() == '1'
 }
@@ -105,6 +105,18 @@ fn test_hex() {
 	assert b.hex() == '4d2'
 	b1 := -1
 	assert b1.hex() == 'ffffffff'
+	// unsigned tests
+	assert u8(12).hex() == '0c'
+	assert u8(255).hex() == 'ff'
+	assert u16(65535).hex() == 'ffff'
+	assert u32(-1).hex() == 'ffffffff'
+	assert u64(-1).hex() == 'ffffffffffffffff'
+	// signed tests
+	assert i8(-1).hex() == 'ff'
+	assert i8(12).hex() == '0c'
+	assert i16(32767).hex() == '7fff'
+	assert int(2147483647).hex() == '7fffffff'
+	assert i64(9223372036854775807).hex() == '7fffffffffffffff'
 }
 
 fn test_bin() {
@@ -168,7 +180,6 @@ fn test_num_separator() {
 	// f32 or f64
 	assert 312_2.55 == 3122.55
 	assert 312_2.55 == 3122.55
-
 }
 
 fn test_int_decl() {