nibbles :3

src/util.rs

@@ -2,9 +2,7 @@ use crate::processor::Direction;
 use std::mem::transmute;
 
 pub(crate) fn as_signed(unsigned: u8) -> i8 {
-    unsafe {
+    unsafe { transmute(unsigned) }
-        transmute(unsigned)
-    }
 }
 
 pub(crate) fn get_bit(byte: u8, flag: u8) -> bool {
@@ -50,3 +48,28 @@ pub(crate) fn get_rotation_carry(direction: &Direction) -> u8 {
         Direction::Right => 0b10000000,
     }
 }
+
+pub trait Nibbles {
+    fn get_low_nibble(&self) -> u8;
+    fn get_high_nibble(&self) -> u8;
+    fn set_low_nibble(&mut self, val: u8);
+    fn set_high_nibble(&mut self, val: u8);
+}
+
+impl Nibbles for u8 {
+    fn get_low_nibble(&self) -> u8 {
+        *self & 0x0F
+    }
+
+    fn get_high_nibble(&self) -> u8 {
+        (*self >> 4) & 0x0F
+    }
+
+    fn set_low_nibble(&mut self, val: u8) {
+        *self = (*self & 0xF0) | (val & 0x0F);
+    }
+
+    fn set_high_nibble(&mut self, val: u8) {
+        *self = (*self & 0x0F) | (val << 4);
+    }
+}