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Add BMI implementation. Untested

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This commit is contained in:
Andrew Keeton 2014-10-13 19:39:17 -04:00
parent 6941a29352
commit 71d15f9d08
1 changed files with 37 additions and 3 deletions
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40
src/machine.rs
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@ -48,7 +48,7 @@ impl Machine {
memory: Memory::new()
}
}
pub fn reset(&mut self) {
*self = Machine::new();
}
@ -90,6 +90,12 @@ impl Machine {
self.add_with_carry(val);
},
(instruction::BMI, instruction::UseRelative(rel)) => {
let addr = self.registers.program_counter + rel;
log!(log::DEBUG, "branch if minus relative. address: {}", addr);
self.branch_if_minus(addr);
},
(instruction::LDA, instruction::UseImmediate(val)) => {
log!(log::DEBUG, "load A immediate: {}", val);
self.load_accumulator(val as i8);
@ -199,6 +205,12 @@ impl Machine {
log!(log::DEBUG, "accumulator: {}", self.registers.accumulator);
}
pub fn branch_if_minus(&mut self, addr: Address) {
if (self.registers.status.contains(PS_NEGATIVE)) {
self.registers.program_counter = addr;
}
}
}
impl std::fmt::Show for Machine {
@ -210,7 +222,6 @@ impl std::fmt::Show for Machine {
#[test]
fn add_with_carry_test() {
let mut machine = Machine::new();
machine.add_with_carry(1);
@ -233,7 +244,7 @@ fn add_with_carry_test() {
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);
let mut machine = Machine::new();
machine.add_with_carry(127);
@ -281,3 +292,26 @@ 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 branch_if_minus_test() {
{
let mut machine = Machine::new();
let registers_before = machine.registers;
machine.branch_if_minus(Address(0xABCD));
assert_eq!(machine.registers, registers_before);
assert_eq!(machine.registers.program_counter, Address(0));
}
{
let mut machine = Machine::new();
machine.registers.status.set_with_mask(PS_NEGATIVE, PS_NEGATIVE);
let registers_before = machine.registers;
machine.branch_if_minus(Address(0xABCD));
assert_eq!(machine.registers, registers_before);
assert_eq!(machine.registers.program_counter, Address(0xABCD));
}
}