83 lines
2.9 KiB
Rust
83 lines
2.9 KiB
Rust
use crate::structs::{get_register_pair, set_register, set_register_pair};
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use crate::{get_register, EmulatorState, Register};
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/// Sets the condition code flags according to `result`. `flags` parameter
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/// indicates which flags will be set, 0b1111 will set all (Z, S, C, P)
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/// while 0b1000 will only set Z.
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fn set_cc(state: &mut EmulatorState, result: u16, flags: u8) {
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if flags & 0b1000 > 0 {
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state.cc.z = (result & 0xff) == 0;
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}
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if flags & 0b0100 > 0 {
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state.cc.s = (result & 0x80) > 0;
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}
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if flags & 0b0010 > 0 {
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state.cc.c = result > 0xff;
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}
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if flags & 0b0001 > 0 {
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state.cc.p = (result & 0xff).count_ones() % 2 == 0;
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}
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}
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/// Add values of `register` and `A`
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pub fn add(register: Register, state: &mut EmulatorState) {
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let result = get_register(register, state) as u16 + state.a as u16;
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set_cc(state, result, 0b1111);
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state.a = (result & 0xff) as u8;
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}
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/// Add values of input byte and `A`
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pub fn adi(byte: u8, state: &mut EmulatorState) {
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let result = state.a as u16 + byte as u16;
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set_cc(state, result, 0b1111);
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state.a = result as u8;
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}
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/// Add values of `register` and `A` and add +1 if carry bit is set
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pub fn adc(register: Register, state: &mut EmulatorState) {
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let result = get_register(register, state) as u16 + state.a as u16 + u16::from(state.cc.c);
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set_cc(state, result, 0b1111);
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state.a = (result & 0xff) as u8;
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}
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/// Add values of input byte and `A` and add +1 if carry bit is set
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pub fn aci(byte: u8, state: &mut EmulatorState) {
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let result = state.a as u16 + byte as u16 + u16::from(state.cc.c);
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set_cc(state, result, 0b1111);
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state.a = result as u8;
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}
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/// Double precision add - Add B&C, D&E or H&L to H&L
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pub fn dad(register: Register, state: &mut EmulatorState) {
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let num = get_register_pair(register, state);
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let (result, overflow) = num.overflowing_add(u16::from_le_bytes([state.l, state.h]));
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state.cc.c = overflow;
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set_register_pair(register, result, state);
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}
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/// Increase register
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pub fn inr(register: Register, state: &mut EmulatorState) {
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let (result, _) = get_register(register, state).overflowing_add(1);
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set_cc(state, result as u16, 0b1101);
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set_register(register, result, state);
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}
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/// Decrease register
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pub fn dcr(register: Register, state: &mut EmulatorState) {
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let (result, _) = get_register(register, state).overflowing_sub(1);
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set_cc(state, result as u16, 0b1101);
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set_register(register, result, state);
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}
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/// Increase register pair
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pub fn inx(register: Register, state: &mut EmulatorState) {
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let (result, _) = get_register_pair(register, state).overflowing_add(1);
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set_register_pair(register, result, state);
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}
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/// Decrease register pair
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pub fn dcx(register: Register, state: &mut EmulatorState) {
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let (result, _) = get_register_pair(register, state).overflowing_sub(1);
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set_register_pair(register, result, state);
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}
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