paoda
/
gb
1
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

feat(cpu): implement DAA instruction

This commit is contained in:
Rekai Nyangadzayi Musuka 2021-04-04 01:03:44 -05:00
parent 25e44f3e49
commit cb1bcdb859
1 changed files with 28 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

29
src/instruction.rs
View File

@ -542,7 +542,34 @@ impl Instruction {
cpu.set_register(Register::A, rot_a);
Cycle::new(4)
}
Instruction::DAA => todo!("Implement DAA Instruction"),
Instruction::DAA => {
// source: https://ehaskins.com/2018-01-30%20Z80%20DAA/
// TODO: Maybe i16 isn't the right choice here?
let mut correction: i16 = 0;
let mut value = cpu.register(Register::A) as i16;
let mut flags = *cpu.flags();
if flags.h() || (!flags.n() && (value & 0xF) > 9) {
correction |= 0x06;
}
if flags.c() || (!flags.n() && value > 0x99) {
correction |= 0x60;
flags.set_c(true);
}
value += if flags.n() { -correction } else { correction };
let result = value as u8;
flags.set_z(result == 0);
flags.set_h(false);
cpu.set_flags(flags);
cpu.set_register(Register::A, value as u8);
Cycle::new(4)
}
Instruction::CPL => {
// Compliment A register (inverse)
let mut flags: Flags = *cpu.flags();