builtin: fix int to hex

vlib/builtin/int.v

@@ -235,8 +235,66 @@ pub fn (n int) hex1() string {
 }
 */
 
-pub fn (nn int) hex() string {
-	mut n := u32(nn)
+pub fn (nn byte) hex() string {
+	if nn == 0 {
+		return '0'
+	}
+
+	mut n := nn
+	max := 2
+	mut buf := malloc(max + 1)
+
+	mut index := max
+	buf[index--] = `\0`
+	for n > 0 {
+		d := n & 0xF
+		n = n >> 4
+		buf[index--] = if d < 10 { d + `0` } else { d + 87 }
+	}
+	//buf[index--] = `x`
+	//buf[index]   = `0`
+	index++
+
+	return tos(buf + index, (max - index))
+}
+
+pub fn (nn i8) hex() string {
+	return byte(nn).hex()
+}
+
+pub fn (nn u16) hex() string {
+	if nn == 0 {
+		return '0'
+	}
+	
+	mut n := nn
+	max := 5
+	mut buf := malloc(max + 1)
+
+	mut index := max
+	buf[index--] = `\0`
+	for n > 0 {
+		d := n & 0xF
+		n = n >> 4
+		buf[index--] = if d < 10 { d + `0` } else { d + 87 }
+	}
+	//buf[index--] = `x`
+	//buf[index]   = `0`
+	index++
+
+	return tos(buf + index, (max - index))
+}
+
+pub fn (nn i16) hex() string {
+	return u16(nn).hex()
+}
+
+pub fn (nn u32) hex() string {
+	if nn == 0 {
+		return '0'
+	}
+
+	mut n := nn
 	max := 10
 	mut buf := malloc(max + 1)
 
@@ -254,7 +312,15 @@ pub fn (nn int) hex() string {
 	return tos(buf + index, (max - index))
 }
 
+pub fn (nn int) hex() string {
+	return u32(nn).hex()
+}
+
 pub fn (nn u64) hex() string {
+	if nn == 0 {
+		return '0'
+	}
+	
 	mut n := nn
 	max := 18
 	mut buf := malloc(max + 1)
@@ -276,8 +342,7 @@ pub fn (nn u64) hex() string {
 }
 
 pub fn (nn i64) hex() string {
-	mut n := u64(nn)
-	return n.hex()
+	return u64(nn).hex()
 }
 
 // ----- utilities functions -----

vlib/builtin/int_test.v

@@ -157,3 +157,51 @@ fn test_int_decl() {
 	assert typeof(x7) == 'u64'
 }
 
+fn test_int_to_hex() {
+	// array hex
+	st := [byte(`V`),`L`,`A`,`N`,`G`]
+	assert st.hex() == "564c414e47"
+	assert st.hex().len == 10
+
+	st1 := [byte(0x41)].repeat(100)
+	assert st1.hex() == "41".repeat(100)
+
+	//--- int to hex tests
+	c0 := 12
+
+	// 8Bit
+	assert byte(0).hex()   == "0"
+	assert byte(c0).hex()  == "c"
+	assert i8(c0).hex()    == "c"
+	assert byte(127).hex() == "7f"
+	assert i8(127).hex()   == "7f"
+	assert byte(255).hex() == "ff"
+	assert byte(-1).hex()  == "ff"
+
+	// 16bit
+	assert u16(0).hex()      == "0"
+	assert i16(c0).hex()     == "c"
+	assert u16(c0).hex()     == "c"
+	assert i16(32767).hex()  == "7fff"
+	assert u16(32767).hex()  == "7fff"
+	assert i16(-1).hex()     == "ffff"
+	assert u16(65535).hex()  == "ffff"
+
+	// 32bit
+	assert u32(0).hex()           == "0"
+	assert c0.hex()               == "c"
+	assert u32(c0).hex()          == "c"
+	assert 2147483647.hex()       == "7fffffff"
+	assert u32(2147483647).hex()  == "7fffffff"
+	assert (-1).hex()             == "ffffffff"
+	assert u32(4294967295).hex()  == "ffffffff"
+
+	// 64 bit
+	assert u64(0).hex()                      == "0"
+	assert i64(c0).hex()                     == "c"
+	assert u64(c0).hex()                     == "c"
+	assert i64(9223372036854775807).hex()    == "7fffffffffffffff"
+	assert u64(9223372036854775807).hex()    == "7fffffffffffffff"
+	assert i64(-1).hex()                     == "ffffffffffffffff"
+	assert u64(18446744073709551615).hex()   == "ffffffffffffffff"
+}