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Merge pull request #11 from amw-zero/decrement-x

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DEX instruction
This commit is contained in:
Andrew Keeton 2014-10-19 20:45:43 -04:00
commit 6d7388c779
1 changed files with 54 additions and 0 deletions
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54
src/machine.rs
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@ -90,6 +90,10 @@ impl Machine {
self.add_with_carry(val);
},
(instruction::DEX, instruction::UseImplied) => {
self.dec_x();
}
(instruction::LDA, instruction::UseImmediate(val)) => {
log!(log::DEBUG, "load A immediate: {}", val);
self.load_accumulator(val as i8);
@ -199,6 +203,11 @@ impl Machine {
log!(log::DEBUG, "accumulator: {}", self.registers.accumulator);
}
pub fn dec_x(&mut self) {
let val = self.registers.index_x;
self.load_x_register(val - 1);
}
}
impl std::fmt::Show for Machine {
@ -281,3 +290,48 @@ fn add_with_carry_test() {
assert_eq!(machine.registers.status.contains(PS_NEGATIVE), true);
assert_eq!(machine.registers.status.contains(PS_OVERFLOW), true);
}
#[test]
fn dec_x_test() {
let mut machine = Machine::new();
machine.dec_x();
assert_eq!(machine.registers.index_x, -1);
assert_eq!(machine.registers.status.contains(PS_CARRY), false);
assert_eq!(machine.registers.status.contains(PS_ZERO), false);
assert_eq!(machine.registers.status.contains(PS_NEGATIVE), true);
assert_eq!(machine.registers.status.contains(PS_OVERFLOW), false);
machine.dec_x();
assert_eq!(machine.registers.index_x, -2);
assert_eq!(machine.registers.status.contains(PS_CARRY), false);
assert_eq!(machine.registers.status.contains(PS_ZERO), false);
assert_eq!(machine.registers.status.contains(PS_NEGATIVE), true);
assert_eq!(machine.registers.status.contains(PS_OVERFLOW), false);
machine.load_x_register(5);
machine.dec_x();
assert_eq!(machine.registers.index_x, 4);
assert_eq!(machine.registers.status.contains(PS_CARRY), false);
assert_eq!(machine.registers.status.contains(PS_ZERO), false);
assert_eq!(machine.registers.status.contains(PS_NEGATIVE), false);
assert_eq!(machine.registers.status.contains(PS_OVERFLOW), false);
machine.dec_x();
machine.dec_x();
machine.dec_x();
machine.dec_x();
assert_eq!(machine.registers.index_x, 0);
assert_eq!(machine.registers.status.contains(PS_CARRY), false);
assert_eq!(machine.registers.status.contains(PS_ZERO), true);
assert_eq!(machine.registers.status.contains(PS_NEGATIVE), false);
assert_eq!(machine.registers.status.contains(PS_OVERFLOW), false);
machine.dec_x();
assert_eq!(machine.registers.index_x, -1);
assert_eq!(machine.registers.status.contains(PS_CARRY), false);
assert_eq!(machine.registers.status.contains(PS_ZERO), false);
assert_eq!(machine.registers.status.contains(PS_NEGATIVE), true);
assert_eq!(machine.registers.status.contains(PS_OVERFLOW), false);
}