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basic flag setting and add some testcases

This commit is contained in:
45Tatami 2024-04-13 21:13:35 +02:00
parent d6bec3fa88
commit 0638bcf635
1 changed files with 111 additions and 51 deletions
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162
src/emu.rs
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@ -21,30 +21,7 @@ pub struct GameBoy {
bp_manager: BreakPointManager,
}
fn add(a: u8, b: u8) -> u8 {
if std::u8::MAX - b < a {
((a as u16 + b as u16) - std::u8::MAX as u16) as u8 - 1
} else {
a + b
}
}
fn sub(a: u8, b: u8) -> u8 {
if a < b {
std::u8::MAX - (b - a) + 1
} else {
a - b
}
}
fn add_inplace(a: &mut u8, b: u8) {
*a = add(*a, b)
}
fn sub_inplace(a: &mut u8, b: u8) {
*a = sub(*a, b)
}
#[derive(Clone, Copy, Debug)]
enum Flag {
Z, N, H ,CY
}
@ -53,12 +30,36 @@ fn flag_set(f: Flag, v: u8) -> bool {
use Flag::*;
match f {
Z => v << 0 >> 7 == 1,
N => v << 1 >> 6 == 1,
H => v << 2 >> 5 == 1,
CY => v << 3 >> 4 == 1,
N => v << 1 >> 7 == 1,
H => v << 2 >> 7 == 1,
CY => v << 3 >> 7 == 1,
}
}
fn add_noflag(a: u8, b: u8) -> u8 {
if std::u8::MAX - b < a {
((a as u16 + b as u16) - std::u8::MAX as u16) as u8 - 1
} else {
a + b
}
}
fn sub_noflag(a: u8, b: u8) -> u8 {
if a < b {
std::u8::MAX - (b - a) + 1
} else {
a - b
}
}
fn add_inplace(a: &mut u8, b: u8) {
*a = add_noflag(*a, b)
}
fn sub_inplace(a: &mut u8, b: u8) {
*a = sub_noflag(*a, b)
}
impl GameBoy {
pub fn new() -> GameBoy {
GameBoy {
@ -73,6 +74,31 @@ impl GameBoy {
}
fn add(&mut self, a: u8, b: u8) -> u8 {
let val = add_noflag(a, b);
println!("{}", val);
self.set_flag(Flag::Z, val == 0);
self.set_flag(Flag::N, false);
self.set_flag(Flag::H, false); // FIXME
self.set_flag(Flag::CY, false); // FIXME
val
}
fn sub(&mut self, a: u8, b: u8) -> u8 {
let val = sub_noflag(a, b);
self.set_flag(Flag::Z, val == 0);
self.set_flag(Flag::N, true);
self.set_flag(Flag::H, false); // FIXME
self.set_flag(Flag::CY, false); // FIXME
val
}
fn set(adr: u16, val: u8) {
// check for special registers
}
@ -80,12 +106,13 @@ impl GameBoy {
fn set_flag(&mut self, f: Flag, v: bool) {
let r = &mut self.reg[Register::F];
let v = v as u8;
//println!("setting {f:?}: {v}");
use Flag::*;
match f {
Z => *r = v << 7,
N => *r = v << 6,
H => *r = v << 5,
CY => *r = v << 4
Z => *r = (v << 7) | (*r & 0b0111_1111),
N => *r = (v << 6) | (*r & 0b1011_1111),
H => *r = (v << 5) | (*r & 0b1101_1111),
CY => *r = (v << 4) | (*r & 0b1110_1111),
}
}
@ -278,7 +305,8 @@ impl GameBoy {
BpCommand::Kill => panic!("kill from breakpoint"),
};
println!("pc:{pc:#08x}:{win:02x?} {op:?}");
let regs = &self.reg[..8];
println!("\u{1B}[1;31mpc:{pc:#08x}:{win:02x?} {op:?} {regs:?}\u{1B}[0m");
match op.inst {
Unimpl(instr) => {
@ -318,6 +346,8 @@ impl GameBoy {
println!("jr {new_pc:#06x} <- {old_pc:#06x} + {e}");
// TODO remember cycle count 3 for jump, 2 for not!!!
return;
} else {
println!("jr cond not met");
}
}
Call => {
@ -355,14 +385,14 @@ impl GameBoy {
}
Inc(dst) => {
match dst {
ValSrc::Reg(reg) => add_inplace(&mut self.reg[reg], 1),
ValSrc::Reg(reg) => self.reg[reg] = self.add(self.reg[reg], 1),
_ => todo!()
}
println!("Inc {dst:?}");
}
Dec(dst) => {
match dst {
ValSrc::Reg(reg) => sub_inplace(&mut self.reg[reg], 1),
ValSrc::Reg(reg) => self.reg[reg] = self.sub(self.reg[reg], 1),
_ => todo!()
}
println!("Dec {dst:?}");
@ -402,25 +432,55 @@ impl GameBoy {
#[cfg(test)]
mod tests {
// #[test]
// fn add_overflow() {
// use crate::emu::add;
// assert_eq!(add(1, 1), 2);
#[test]
fn add_overflow() {
let mut gb = crate::emu::GameBoy::new();
// assert_eq!(add(std::u8::MAX, 1), 0);
// assert_eq!(add(std::u8::MAX, 2), 1);
// assert_eq!(add(1, std::u8::MAX), 0);
assert_eq!(gb.add(1, 1), 2);
// assert_eq!(add(std::u8::MAX - 3, 3), std::u8::MAX);
// assert_eq!(add(3, std::u8::MAX - 3), std::u8::MAX);
// }
assert_eq!(gb.add(std::u8::MAX, 1), 0);
assert_eq!(gb.add(std::u8::MAX, 2), 1);
assert_eq!(gb.add(1, std::u8::MAX), 0);
// #[test]
// fn sub_underflow() {
// use crate::emu::sub;
// assert_eq!(sub(1, 1), 0);
// assert_eq!(sub(1, 2), std::u8::MAX);
// assert_eq!(sub(1, 3), std::u8::MAX - 1);
// }
assert_eq!(gb.add(std::u8::MAX - 3, 3), std::u8::MAX);
assert_eq!(gb.add(3, std::u8::MAX - 3), std::u8::MAX);
}
#[test]
fn sub_underflow() {
let mut gb = crate::emu::GameBoy::new();
assert_eq!(gb.sub(1, 1), 0);
assert_eq!(gb.sub(1, 2), std::u8::MAX);
assert_eq!(gb.sub(1, 3), std::u8::MAX - 1);
}
#[test]
fn flag_check() {
let mut gb = crate::emu::GameBoy::new();
use crate::emu::*;
for f in [Flag::Z, Flag::N, Flag::H, Flag::CY] {
assert!(!flag_set(f, gb.reg[Register::F]));
gb.set_flag(f, true);
assert!(flag_set(f, gb.reg[Register::F]));
gb.set_flag(f, false);
assert!(!flag_set(f, gb.reg[Register::F]));
}
}
#[test]
fn flag_set() {
use crate::emu::*;
let mut gb = GameBoy::new();
assert!(!flag_set(Flag::Z, gb.reg[Register::F]));
gb.add(std::u8::MAX - 1 , 1);
assert!(!flag_set(Flag::Z, gb.reg[Register::F]));
gb.add(std::u8::MAX, 1);
assert!(flag_set(Flag::Z, gb.reg[Register::F]));
}
}