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Merge pull request #24 from amw-zero/ark-bcc

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Implement BCC instruction
This commit is contained in:
Andrew Keeton 2014-11-06 19:35:50 -05:00
commit 8c0e4949a9
1 changed files with 26 additions and 0 deletions
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26
src/machine.rs
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@ -110,6 +110,13 @@ impl Machine {
&mut self.registers.status);
}
(instruction::BCC, instruction::UseRelative(rel)) => {
let addr = self.registers.program_counter
+ AddressDiff(rel as i32);
self.branch_if_carry_clear(addr);
}
(instruction::BIT, instruction::UseAddress(addr)) => {
let a: u8 = self.registers.accumulator as u8;
let m: u8 = self.memory.get_byte(addr);
@ -541,6 +548,12 @@ impl Machine {
self.registers.program_counter = addr;
}
fn branch_if_carry_clear(&mut self, addr: Address) {
if !self.registers.status.contains(PS_CARRY) {
self.registers.program_counter = addr;
}
}
fn branch_if_minus(&mut self, addr: Address) {
if self.registers.status.contains(PS_NEGATIVE) {
self.registers.program_counter = addr;
@ -860,6 +873,19 @@ fn jump_test() {
assert_eq!(machine.registers.program_counter, addr);
}
#[test]
fn branch_if_carry_clear_test() {
let mut machine = Machine::new();
machine.execute_instruction((instruction::SEC, instruction::UseImplied));
machine.branch_if_carry_clear(Address(0xABCD));
assert_eq!(machine.registers.program_counter, Address(0));
machine.execute_instruction((instruction::CLC, instruction::UseImplied));
machine.branch_if_carry_clear(Address(0xABCD));
assert_eq!(machine.registers.program_counter, Address(0xABCD));
}
#[test]
fn branch_if_minus_test() {
{