Basic high res gfx

src/word.rs

@@ -0,0 +1,61 @@
+// 128k, the amount of memory in a standard Vulcan machine
+pub const MEM_SIZE: u32 = 128 * 1024;
+
+#[derive(Debug, Copy, Clone, Eq, PartialEq, Ord, PartialOrd)]
+pub struct Word(u32);
+
+impl From<u32> for Word {
+    fn from(a: u32) -> Self { Self(a & 0xffffff) }
+}
+
+impl From<Word> for u32 {
+    fn from(word: Word) -> Self { word.0 }
+}
+
+impl std::ops::Add<i32> for Word {
+    type Output = Word;
+    fn add(self, rhs: i32) -> Self::Output {
+        Word::from((self.0 as i32).overflowing_add(rhs).0 as u32)
+    }
+}
+
+impl std::ops::Sub<i32> for Word {
+    type Output = Word;
+    fn sub(self, rhs: i32) -> Self::Output { self + -rhs }
+}
+
+impl std::ops::Sub<Word> for Word {
+    type Output = Word;
+    fn sub(self, rhs: Word) -> Self::Output { Word(self.0 - rhs.0) }
+}
+
+impl std::ops::SubAssign<i32> for Word {
+    fn sub_assign(&mut self, rhs: i32) { *self = *self - rhs; }
+}
+
+impl std::ops::AddAssign<i32> for Word {
+    fn add_assign(&mut self, rhs: i32) { *self = *self + rhs; }
+}
+
+#[test]
+fn test_address_truncation() {
+    let a: Word = 0x11223344.into();
+    assert_eq!(a, 0x00223344.into());
+}
+
+#[test]
+fn test_address_overflows() {
+    let a = Word::from(0xfffffa);
+    assert_eq!(a + 10, Word(4));
+
+    let b = Word::from(3);
+    assert_eq!(b - 10, Word(0xfffff9));
+
+    let mut c = Word::from(5);
+    c += 3;
+    assert_eq!(c, Word(8));
+
+    let mut d = Word::from(5);
+    d -= 3;
+    assert_eq!(d, Word(2));
+}