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/*
Copyright 2021-2023 Gabriel Jensen.
This file is part of Luma.
Luma is free software: you can redistribute it
and/or modify it under the terms of the GNU
Affero General Public License as published by
the Free Software Foundation, either version 3
of the License, or (at your option) any later
version.
Luma is distributed in the hope that it will be
useful, but WITHOUT ANY WARRANTY; without even
the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Affero General Public License for more details.
You should have received a copy of the GNU
Affero General Public License along with Luma.
If not, see <https://www.gnu.org/licenses/>.
*/
use crate::log;
use crate::cpu::{Cpu, take_state_mut};
use crate::shifter::Shifter;
impl Cpu {
pub(super) fn isa_cmp(&mut self, rn: u8, shifter: Shifter) {
log!("cmp r{rn}, {shifter}");
take_state_mut!(state, self);
let rn_value = state.read_register(rn);
let (subtrahend, _) = state.shifter_value(shifter);
let (temporary, c) = rn_value.overflowing_sub(subtrahend);
let (_, v) = (rn_value as i32).overflowing_sub_unsigned(subtrahend);
let mut cpsr = state.read_cpsr() & 0b00001111111111111111111111111111;
cpsr |= (v as u32) << 0x1C;
cpsr |= (!c as u32) << 0x1D;
cpsr |= ((temporary == 0x0) as u32) << 0x1E;
cpsr |= temporary & 0b10000000000000000000000000000000;
state.write_cpsr(cpsr);
}
}
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