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

chore: Document instruction execution implementations

This commit is contained in:
Rekai Nyangadzayi Musuka 2020-09-07 20:57:31 -05:00
parent f193132c5e
commit a9510bed54
1 changed files with 9 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
src/instruction.rs
View File

@ -522,6 +522,7 @@ impl Instruction {
cycles
}
MATHTarget::ImmediateByte(n) => {
// ADC A, n | Add immediate byte plus the carry flag to A
let mut flags: Flags = cpu.register(Register::Flag).into();
let value = n + (flags.c as u8);
let sum = Self::add_u8s(cpu.register(Register::A), value, &mut flags);
@ -565,6 +566,7 @@ impl Instruction {
cycles
}
MATHTarget::ImmediateByte(n) => {
// SUB n | Subtract the immediate byte from register A, then store in A
let mut flags: Flags = cpu.register(Register::Flag).into();
let diff = Self::sub_u8s(cpu.register(Register::A), n, &mut flags);
@ -609,6 +611,8 @@ impl Instruction {
cycles
}
MATHTarget::ImmediateByte(n) => {
// SBC A, n | Subtract the value from immediate byte from A, add the carry flag and then store in A
// FIXME: The Fixme aboe applies to this variant as well
let mut flags: Flags = cpu.register(Register::Flag).into();
let value = n + (flags.c as u8);
let diff = Self::sub_u8s(cpu.register(Register::A), value, &mut flags);
@ -657,6 +661,7 @@ impl Instruction {
cycles
}
MATHTarget::ImmediateByte(n) => {
// AND n | Bitwise AND immediate byte and register A, sotre in register A
let mut flags: Flags = cpu.register(Register::Flag).into();
let result = cpu.register(Register::A) & n;
@ -709,6 +714,7 @@ impl Instruction {
cycles
}
MATHTarget::ImmediateByte(n) => {
// XOR n | Bitwise XOR immediate byte and register A, store in register A
let mut flags: Flags = cpu.register(Register::Flag).into();
let result = cpu.register(Register::A) ^ n;
@ -761,6 +767,7 @@ impl Instruction {
cycles
}
MATHTarget::ImmediateByte(n) => {
// OR n | Bitwise OR on immediate byte n and register A, store in register A
let mut flags: Flags = cpu.register(Register::Flag).into();
let result = cpu.register(Register::A) | n;
@ -806,6 +813,7 @@ impl Instruction {
cycles
}
MATHTarget::ImmediateByte(n) => {
// CP n | Same behaviour as SUB, except the result is not stored,
let mut flags: Flags = cpu.register(Register::Flag).into();
let _ = Self::sub_u8s(cpu.register(Register::A), n, &mut flags);
@ -1050,6 +1058,7 @@ impl Instruction {
cpu.set_register_pair(RegisterPair::SP, sp_value);
Cycles(16)
}
_ => unimplemented!(),
}
}