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set carry flag if carry_in && value == "$ff" (#44)

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omarandlorraine 2022-06-07 10:03:51 +01:00 committed by GitHub
parent e2fd2469e3
commit ef9a49ac8b
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1 changed files with 7 additions and 1 deletions
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8
src/cpu.rs
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@ -552,7 +552,7 @@ impl CPU {
a_after
};
let did_carry = (result as u8) < (a_before as u8);
let did_carry = (result as u8) < (a_before as u8) || (c_before == 1 && value == -1);
let did_overflow = (a_before < 0 && value < 0 && a_after >= 0)
|| (a_before > 0 && value > 0 && a_after <= 0);
@ -914,6 +914,12 @@ mod tests {
assert_eq!(cpu.registers.status.contains(Status::PS_ZERO), false);
assert_eq!(cpu.registers.status.contains(Status::PS_NEGATIVE), true);
assert_eq!(cpu.registers.status.contains(Status::PS_OVERFLOW), true);
let mut cpu = CPU::new();
cpu.registers.status.or(Status::PS_CARRY);
cpu.add_with_carry(-1);
assert_eq!(cpu.registers.accumulator, 0);
assert_eq!(cpu.registers.status.contains(Status::PS_CARRY), true);
}
#[test]