alex/gb-emu
1
0
Fork 0
Code Pull requests Actions Packages Releases Activity

SO CLOSE

Browse source
This commit is contained in:
Alex Janka 2023-02-24 17:10:44 +11:00
parent d6c8be4bc5
commit 5fbc661f5c
4 changed files with 24 additions and 25 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

8
src/main.rs
View file

@ -1,4 +1,10 @@
#![feature(exclusive_range_pattern, let_chains, slice_flatten, async_closure)]
#![feature(
exclusive_range_pattern,
let_chains,
slice_flatten,
async_closure,
bigint_helper_methods
)]
mod constants;
mod processor;

14
src/processor/instructions/instructions.rs
View file

@ -32,25 +32,25 @@ impl Cpu {
}
pub(crate) fn cp(&mut self, first: u8, second: u8) {
self.sub_u8s(first, second);
self.sub_u8s(first, second, false);
}
pub(crate) fn add(&mut self, first: u8, second: u8) -> u8 {
self.add_u8s(first, second)
self.add_u8s(first, second, false)
}
pub(crate) fn adc(&mut self, first: u8, second: u8) -> u8 {
let val = second.wrapping_add(self.get_flag(Flags::Carry));
self.add_u8s(first, val)
let carry = self.is_flag(Flags::Carry);
self.clear_flag(Flags::Carry);
self.add_u8s(first, second, carry)
}
pub(crate) fn sub(&mut self, first: u8, second: u8) -> u8 {
self.sub_u8s(first, second)
self.sub_u8s(first, second, false)
}
pub(crate) fn sbc(&mut self, first: u8, second: u8) -> u8 {
let val = second.wrapping_add(self.get_flag(Flags::Carry));
self.sub_u8s(first, val)
self.sub_u8s(first, second, self.is_flag(Flags::Carry))
}
pub(crate) fn inc(&mut self, reg: Reg8) {

23
src/processor/instructions/primitives.rs
View file

@ -1,6 +1,6 @@
use crate::{
processor::{Cpu, Direction, Flags, SplitRegister},
util::{get_bit, get_rotation_carry, rotate},
util::{get_bit, get_rotation_carry, rotate, Nibbles},
};
use std::ops::{BitAnd, BitOr};
@ -82,14 +82,6 @@ impl Cpu {
rotated
}
pub(crate) fn get_flag(&mut self, flag: Flags) -> u8 {
if get_bit(self.reg.af.get_low(), flag as u8) {
0x1
} else {
0x0
}
}
pub(crate) fn is_flag(&self, flag: Flags) -> bool {
get_bit(self.reg.af.get_low(), flag as u8)
}
@ -128,14 +120,14 @@ impl Cpu {
result
}
pub(crate) fn add_u8s(&mut self, first: u8, second: u8) -> u8 {
let (result, carry) = first.overflowing_add(second);
pub(crate) fn add_u8s(&mut self, first: u8, second: u8, with_carry: bool) -> u8 {
let (result, carry) = first.carrying_add(second, with_carry);
self.clear_flag(Flags::NSubtract);
self.set_or_clear_flag(Flags::Carry, carry);
self.set_or_clear_flag(Flags::Zero, result == 0x0);
self.set_or_clear_flag(
Flags::HalfCarry,
(((first & 0xF).wrapping_add(second & 0xF)) & 0x10) == 0x10,
first.get_low_nibble() + second.get_low_nibble() + if with_carry { 1 } else { 0 } > 0xF,
);
result
}
@ -151,14 +143,15 @@ impl Cpu {
result
}
pub(crate) fn sub_u8s(&mut self, first: u8, second: u8) -> u8 {
let (result, carry) = first.overflowing_sub(second);
pub(crate) fn sub_u8s(&mut self, first: u8, second: u8, with_carry: bool) -> u8 {
let (result, carry) = first.borrowing_sub(second, with_carry);
self.set_flag(Flags::NSubtract);
self.set_or_clear_flag(Flags::Carry, carry);
self.set_or_clear_flag(Flags::Zero, result == 0x0);
self.set_or_clear_flag(
Flags::HalfCarry,
(((first & 0xF).wrapping_sub(second & 0xF)) & 0x10) == 0x10,
first.get_low_nibble() - (second.get_low_nibble() + if with_carry { 1 } else { 0 })
> 0xF,
);
result
}

4
src/processor/opcodes.rs
View file

@ -951,7 +951,7 @@ impl Cpu {
}
0xC6 => {
let byte = self.ld_immediate_byte();
let val = self.add_u8s(self.reg.get_8(Reg8::A), byte);
let val = self.add_u8s(self.reg.get_8(Reg8::A), byte, false);
self.reg.set_8(Reg8::A, val);
2
}
@ -1047,7 +1047,7 @@ impl Cpu {
}
0xD6 => {
let byte = self.ld_immediate_byte();
let val = self.sub_u8s(self.reg.get_8(Reg8::A), byte);
let val = self.sub_u8s(self.reg.get_8(Reg8::A), byte, false);
self.reg.set_8(Reg8::A, val);
2
}