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do increments in the same way

This commit is contained in:
Sam M W 2022-10-21 06:45:40 +01:00
parent e4aebb9dfe
commit f821dce70f
1 changed files with 23 additions and 9 deletions
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32
src/cpu.rs
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@ -231,19 +231,16 @@ impl CPU {
}
(Instruction::INC, OpInput::UseAddress(addr)) => {
let m = self.memory.get_byte(addr);
let m = m + 1;
self.memory.set_byte(addr, m);
let i = m as i8;
CPU::set_flags_from_i8(&mut self.registers.status, i);
CPU::increment(
self.memory.get_byte_mut_ref(addr),
&mut self.registers.status,
);
}
(Instruction::INX, OpInput::UseImplied) => {
let x = self.registers.index_x + 1;
self.load_x_register(x);
CPU::increment(&mut self.registers.index_x, &mut self.registers.status);
}
(Instruction::INY, OpInput::UseImplied) => {
let y = self.registers.index_y + 1;
self.load_y_register(y);
CPU::increment(&mut self.registers.index_x, &mut self.registers.status);
}
(Instruction::JMP, OpInput::UseAddress(addr)) => self.jump(addr),
@ -675,6 +672,23 @@ impl CPU {
self.load_accumulator(result);
}
fn increment(val: &mut u8, flags: &mut Status) {
let value_new = val.wrapping_add(1);
*val = value_new;
let is_negative = (value_new as i8) < 0;
let is_zero = value_new == 0;
flags.set_with_mask(
Status::PS_NEGATIVE | Status::PS_ZERO,
Status::new(StatusArgs {
negative: is_negative,
zero: is_zero,
..StatusArgs::none()
}),
);
}
fn decrement(val: &mut u8, flags: &mut Status) {
let value_new = val.wrapping_sub(1);
*val = value_new;