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Fix addition and subtraction (#72)

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* extract decimal logic into separate function

* squash me

* I think we should be doing unsigned arithmetic here

* squash me

* remove unused function

* update the sign checks

* cargo fmt

* get tests to compile again

* get tests passing again

* squash me

* remove pointless conversion from u8 to u8

* cargo fmt

* accumulator is now u8

* add adc test from solid65

* pass the new test

---------

Co-authored-by: Sam M W <you@example.com>
This commit is contained in:
omarandlorraine 2023-06-29 11:13:49 +01:00 committed by GitHub
parent 65817524a2
commit aa1a47a76f
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GPG Key ID: 4AEE18F83AFDEB23
2 changed files with 116 additions and 107 deletions
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src/cpu.rs
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@ -185,27 +185,27 @@ impl<M: Bus> CPU<M> {
match decoded_instr { match decoded_instr {
(Instruction::ADC, OpInput::UseImmediate(val)) => { (Instruction::ADC, OpInput::UseImmediate(val)) => {
debug!("add with carry immediate: {}", val); debug!("add with carry immediate: {}", val);
self.add_with_carry(val as i8); self.add_with_carry(val);
} }
(Instruction::ADC, OpInput::UseAddress(addr)) => { (Instruction::ADC, OpInput::UseAddress(addr)) => {
let val = self.memory.get_byte(addr) as i8; let val = self.memory.get_byte(addr);
debug!("add with carry. address: {:?}. value: {}", addr, val); debug!("add with carry. address: {:?}. value: {}", addr, val);
self.add_with_carry(val); self.add_with_carry(val);
} }
(Instruction::AND, OpInput::UseImmediate(val)) => { (Instruction::AND, OpInput::UseImmediate(val)) => {
self.and(val as i8); self.and(val);
} }
(Instruction::AND, OpInput::UseAddress(addr)) => { (Instruction::AND, OpInput::UseAddress(addr)) => {
let val = self.memory.get_byte(addr) as i8; let val = self.memory.get_byte(addr);
self.and(val); self.and(val);
} }
(Instruction::ASL, OpInput::UseImplied) => { (Instruction::ASL, OpInput::UseImplied) => {
// Accumulator mode // Accumulator mode
let mut val = self.registers.accumulator as u8; let mut val = self.registers.accumulator;
CPU::<M>::shift_left_with_flags(&mut val, &mut self.registers.status); CPU::<M>::shift_left_with_flags(&mut val, &mut self.registers.status);
self.registers.accumulator = val as i8; self.registers.accumulator = val;
} }
(Instruction::ASL, OpInput::UseAddress(addr)) => { (Instruction::ASL, OpInput::UseAddress(addr)) => {
let mut operand: u8 = self.memory.get_byte(addr); let mut operand: u8 = self.memory.get_byte(addr);
@ -234,7 +234,7 @@ impl<M: Bus> CPU<M> {
} }
(Instruction::BIT, OpInput::UseAddress(addr)) => { (Instruction::BIT, OpInput::UseAddress(addr)) => {
let a: u8 = self.registers.accumulator as u8; let a: u8 = self.registers.accumulator;
let m: u8 = self.memory.get_byte(addr); let m: u8 = self.memory.get_byte(addr);
let res = a & m; let res = a & m;
@ -372,12 +372,12 @@ impl<M: Bus> CPU<M> {
(Instruction::LDA, OpInput::UseImmediate(val)) => { (Instruction::LDA, OpInput::UseImmediate(val)) => {
debug!("load A immediate: {}", val); debug!("load A immediate: {}", val);
self.load_accumulator(val as i8); self.load_accumulator(val);
} }
(Instruction::LDA, OpInput::UseAddress(addr)) => { (Instruction::LDA, OpInput::UseAddress(addr)) => {
let val = self.memory.get_byte(addr); let val = self.memory.get_byte(addr);
debug!("load A. address: {:?}. value: {}", addr, val); debug!("load A. address: {:?}. value: {}", addr, val);
self.load_accumulator(val as i8); self.load_accumulator(val);
} }
(Instruction::LDX, OpInput::UseImmediate(val)) => { (Instruction::LDX, OpInput::UseImmediate(val)) => {
@ -402,9 +402,9 @@ impl<M: Bus> CPU<M> {
(Instruction::LSR, OpInput::UseImplied) => { (Instruction::LSR, OpInput::UseImplied) => {
// Accumulator mode // Accumulator mode
let mut val = self.registers.accumulator as u8; let mut val = self.registers.accumulator;
CPU::<M>::shift_right_with_flags(&mut val, &mut self.registers.status); CPU::<M>::shift_right_with_flags(&mut val, &mut self.registers.status);
self.registers.accumulator = val as i8; self.registers.accumulator = val;
} }
(Instruction::LSR, OpInput::UseAddress(addr)) => { (Instruction::LSR, OpInput::UseAddress(addr)) => {
let mut operand: u8 = self.memory.get_byte(addr); let mut operand: u8 = self.memory.get_byte(addr);
@ -422,7 +422,7 @@ impl<M: Bus> CPU<M> {
(Instruction::PHA, OpInput::UseImplied) => { (Instruction::PHA, OpInput::UseImplied) => {
// Push accumulator // Push accumulator
let val = self.registers.accumulator as u8; let val = self.registers.accumulator;
self.push_on_stack(val); self.push_on_stack(val);
} }
(Instruction::PHP, OpInput::UseImplied) => { (Instruction::PHP, OpInput::UseImplied) => {
@ -434,12 +434,12 @@ impl<M: Bus> CPU<M> {
// Pull accumulator // Pull accumulator
self.pull_from_stack(); self.pull_from_stack();
let val: u8 = self.fetch_from_stack(); let val: u8 = self.fetch_from_stack();
self.registers.accumulator = val as i8; self.registers.accumulator = val;
self.registers.status.set_with_mask( self.registers.status.set_with_mask(
Status::PS_ZERO | Status::PS_NEGATIVE, Status::PS_ZERO | Status::PS_NEGATIVE,
Status::new(StatusArgs { Status::new(StatusArgs {
zero: val == 0, zero: val == 0,
negative: self.registers.accumulator < 0, negative: self.registers.accumulator > 127,
..StatusArgs::none() ..StatusArgs::none()
}), }),
); );
@ -456,9 +456,9 @@ impl<M: Bus> CPU<M> {
(Instruction::ROL, OpInput::UseImplied) => { (Instruction::ROL, OpInput::UseImplied) => {
// Accumulator mode // Accumulator mode
let mut val = self.registers.accumulator as u8; let mut val = self.registers.accumulator;
CPU::<M>::rotate_left_with_flags(&mut val, &mut self.registers.status); CPU::<M>::rotate_left_with_flags(&mut val, &mut self.registers.status);
self.registers.accumulator = val as i8; self.registers.accumulator = val;
} }
(Instruction::ROL, OpInput::UseAddress(addr)) => { (Instruction::ROL, OpInput::UseAddress(addr)) => {
let mut operand: u8 = self.memory.get_byte(addr); let mut operand: u8 = self.memory.get_byte(addr);
@ -467,9 +467,9 @@ impl<M: Bus> CPU<M> {
} }
(Instruction::ROR, OpInput::UseImplied) => { (Instruction::ROR, OpInput::UseImplied) => {
// Accumulator mode // Accumulator mode
let mut val = self.registers.accumulator as u8; let mut val = self.registers.accumulator;
CPU::<M>::rotate_right_with_flags(&mut val, &mut self.registers.status); CPU::<M>::rotate_right_with_flags(&mut val, &mut self.registers.status);
self.registers.accumulator = val as i8; self.registers.accumulator = val;
} }
(Instruction::ROR, OpInput::UseAddress(addr)) => { (Instruction::ROR, OpInput::UseAddress(addr)) => {
let mut operand: u8 = self.memory.get_byte(addr); let mut operand: u8 = self.memory.get_byte(addr);
@ -497,10 +497,10 @@ impl<M: Bus> CPU<M> {
(Instruction::SBC, OpInput::UseImmediate(val)) => { (Instruction::SBC, OpInput::UseImmediate(val)) => {
debug!("subtract with carry immediate: {}", val); debug!("subtract with carry immediate: {}", val);
self.subtract_with_carry(val as i8); self.subtract_with_carry(val);
} }
(Instruction::SBC, OpInput::UseAddress(addr)) => { (Instruction::SBC, OpInput::UseAddress(addr)) => {
let val = self.memory.get_byte(addr) as i8; let val = self.memory.get_byte(addr);
debug!("subtract with carry. address: {:?}. value: {}", addr, val); debug!("subtract with carry. address: {:?}. value: {}", addr, val);
self.subtract_with_carry(val); self.subtract_with_carry(val);
} }
@ -516,7 +516,7 @@ impl<M: Bus> CPU<M> {
} }
(Instruction::STA, OpInput::UseAddress(addr)) => { (Instruction::STA, OpInput::UseAddress(addr)) => {
self.memory.set_byte(addr, self.registers.accumulator as u8); self.memory.set_byte(addr, self.registers.accumulator);
} }
(Instruction::STX, OpInput::UseAddress(addr)) => { (Instruction::STX, OpInput::UseAddress(addr)) => {
self.memory.set_byte(addr, self.registers.index_x); self.memory.set_byte(addr, self.registers.index_x);
@ -527,11 +527,11 @@ impl<M: Bus> CPU<M> {
(Instruction::TAX, OpInput::UseImplied) => { (Instruction::TAX, OpInput::UseImplied) => {
let val = self.registers.accumulator; let val = self.registers.accumulator;
self.load_x_register(val as u8); self.load_x_register(val);
} }
(Instruction::TAY, OpInput::UseImplied) => { (Instruction::TAY, OpInput::UseImplied) => {
let val = self.registers.accumulator; let val = self.registers.accumulator;
self.load_y_register(val as u8); self.load_y_register(val);
} }
(Instruction::TSX, OpInput::UseImplied) => { (Instruction::TSX, OpInput::UseImplied) => {
let StackPointer(val) = self.registers.stack_pointer; let StackPointer(val) = self.registers.stack_pointer;
@ -539,7 +539,7 @@ impl<M: Bus> CPU<M> {
} }
(Instruction::TXA, OpInput::UseImplied) => { (Instruction::TXA, OpInput::UseImplied) => {
let val = self.registers.index_x; let val = self.registers.index_x;
self.load_accumulator(val as i8); self.load_accumulator(val);
} }
(Instruction::TXS, OpInput::UseImplied) => { (Instruction::TXS, OpInput::UseImplied) => {
// Note that this is the only 'transfer' instruction that does // Note that this is the only 'transfer' instruction that does
@ -550,7 +550,7 @@ impl<M: Bus> CPU<M> {
} }
(Instruction::TYA, OpInput::UseImplied) => { (Instruction::TYA, OpInput::UseImplied) => {
let val = self.registers.index_y; let val = self.registers.index_y;
self.load_accumulator(val as i8); self.load_accumulator(val);
} }
(Instruction::NOP, OpInput::UseImplied) => { (Instruction::NOP, OpInput::UseImplied) => {
@ -671,11 +671,6 @@ impl<M: Bus> CPU<M> {
CPU::<M>::set_flags_from_u8(status, value); CPU::<M>::set_flags_from_u8(status, value);
} }
fn set_i8_with_flags(mem: &mut i8, status: &mut Status, value: i8) {
*mem = value;
CPU::<M>::set_flags_from_i8(status, value);
}
fn load_x_register(&mut self, value: u8) { fn load_x_register(&mut self, value: u8) {
CPU::<M>::set_u8_with_flags( CPU::<M>::set_u8_with_flags(
&mut self.registers.index_x, &mut self.registers.index_x,
@ -692,50 +687,50 @@ impl<M: Bus> CPU<M> {
); );
} }
fn load_accumulator(&mut self, value: i8) { fn load_accumulator(&mut self, value: u8) {
CPU::<M>::set_i8_with_flags( CPU::<M>::set_u8_with_flags(
&mut self.registers.accumulator, &mut self.registers.accumulator,
&mut self.registers.status, &mut self.registers.status,
value, value,
); );
} }
fn add_with_carry(&mut self, value: i8) { fn add_with_carry(&mut self, value: u8) {
let a_before: i8 = self.registers.accumulator; #[cfg(feature = "decimal_mode")]
let c_before: i8 = i8::from(self.registers.status.contains(Status::PS_CARRY)); fn decimal_adjust(result: u8) -> u8 {
let a_after: i8 = a_before.wrapping_add(c_before).wrapping_add(value); let bcd1: u8 = if (result & 0x0f) > 0x09 { 0x06 } else { 0x00 };
debug_assert_eq!( let bcd2: u8 = if (result.wrapping_add(bcd1) & 0xf0) > 0x90 {
a_after as u8,
a_before.wrapping_add(c_before).wrapping_add(value) as u8
);
let bcd1: i8 = if (a_after & 0x0f) as u8 > 0x09 {
0x06
} else {
0x00
};
let bcd2: i8 = if (a_after.wrapping_add(bcd1) as u8 & 0xf0) > 0x90 {
0x60 0x60
} else { } else {
0x00 0x00
}; };
result.wrapping_add(bcd1).wrapping_add(bcd2)
}
let a_before: u8 = self.registers.accumulator;
let c_before: u8 = u8::from(self.registers.status.contains(Status::PS_CARRY));
let a_after: u8 = a_before.wrapping_add(c_before).wrapping_add(value);
debug_assert_eq!(a_after, a_before.wrapping_add(c_before).wrapping_add(value));
#[cfg(feature = "decimal_mode")] #[cfg(feature = "decimal_mode")]
let result: i8 = if self.registers.status.contains(Status::PS_DECIMAL_MODE) { let result: u8 = if self.registers.status.contains(Status::PS_DECIMAL_MODE) {
a_after.wrapping_add(bcd1).wrapping_add(bcd2) decimal_adjust(a_after)
} else { } else {
a_after a_after
}; };
#[cfg(not(feature = "decimal_mode"))] #[cfg(not(feature = "decimal_mode"))]
let result: i8 = a_after; let result: u8 = a_after;
let did_carry = (result as u8) < (a_before as u8) || (c_before == 1 && value == -1); let did_carry = (result) < (a_before)
|| (a_after == 0 && c_before == 0x01)
|| (value == 0xff && c_before == 0x01);
let did_overflow = (a_before < 0 && value < 0 && a_after >= 0) let did_overflow = (a_before > 127 && value > 127 && a_after < 128)
|| (a_before > 0 && value > 0 && a_after <= 0); || (a_before < 128 && value < 128 && a_after > 127);
let mask = Status::PS_CARRY | Status::PS_OVERFLOW; let mask = Status::PS_CARRY | Status::PS_OVERFLOW;
@ -753,22 +748,22 @@ impl<M: Bus> CPU<M> {
debug!("accumulator: {}", self.registers.accumulator); debug!("accumulator: {}", self.registers.accumulator);
} }
fn and(&mut self, value: i8) { fn and(&mut self, value: u8) {
let a_after = self.registers.accumulator & value; let a_after = self.registers.accumulator & value;
self.load_accumulator(a_after); self.load_accumulator(a_after);
} }
fn subtract_with_carry(&mut self, value: i8) { fn subtract_with_carry(&mut self, value: u8) {
// A - M - (1 - C) // A - M - (1 - C)
// nc -- 'not carry' // nc -- 'not carry'
let nc: i8 = if self.registers.status.contains(Status::PS_CARRY) { let nc: u8 = if self.registers.status.contains(Status::PS_CARRY) {
0 0
} else { } else {
1 1
}; };
let a_before: i8 = self.registers.accumulator; let a_before = self.registers.accumulator;
let a_after = a_before.wrapping_sub(value).wrapping_sub(nc); let a_after = a_before.wrapping_sub(value).wrapping_sub(nc);
@ -778,40 +773,39 @@ impl<M: Bus> CPU<M> {
// range of - M - (1 - C) is -128 to 128 // range of - M - (1 - C) is -128 to 128
// -(127 + 1) to -(-128 + 0) // -(127 + 1) to -(-128 + 0)
// //
let over = let over = (nc == 0 && value > 127) && a_before < 128 && a_after > 127;
((nc == 0 && value < 0) || (nc == 1 && value < -1)) && a_before >= 0 && a_after < 0;
let under = let under =
(a_before < 0) && (0i8.wrapping_sub(value).wrapping_sub(nc) < 0) && a_after >= 0; (a_before > 127) && (0u8.wrapping_sub(value).wrapping_sub(nc) > 127) && a_after < 128;
let did_overflow = over || under; let did_overflow = over || under;
let mask = Status::PS_CARRY | Status::PS_OVERFLOW; let mask = Status::PS_CARRY | Status::PS_OVERFLOW;
let bcd1: i8 = if (a_before & 0x0f).wrapping_sub(nc) < (value & 0x0f) { let bcd1: u8 = if (a_before & 0x0f).wrapping_sub(nc) < (value & 0x0f) {
0x06 0x06
} else { } else {
0x00 0x00
}; };
let bcd2: i8 = if (a_after.wrapping_sub(bcd1) as u8 & 0xf0) > 0x90 { let bcd2: u8 = if (a_after.wrapping_sub(bcd1) & 0xf0) > 0x90 {
0x60 0x60
} else { } else {
0x00 0x00
}; };
#[cfg(feature = "decimal_mode")] #[cfg(feature = "decimal_mode")]
let result: i8 = if self.registers.status.contains(Status::PS_DECIMAL_MODE) { let result: u8 = if self.registers.status.contains(Status::PS_DECIMAL_MODE) {
a_after.wrapping_sub(bcd1).wrapping_sub(bcd2) a_after.wrapping_sub(bcd1).wrapping_sub(bcd2)
} else { } else {
a_after a_after
}; };
#[cfg(not(feature = "decimal_mode"))] #[cfg(not(feature = "decimal_mode"))]
let result: i8 = a_after; let result = a_after;
// The carry flag is set on unsigned overflow. // The carry flag is set on unsigned overflow.
let did_carry = (result as u8) > (a_before as u8); let did_carry = (result) > (a_before);
self.registers.status.set_with_mask( self.registers.status.set_with_mask(
mask, mask,
@ -918,20 +912,20 @@ impl<M: Bus> CPU<M> {
// If the C flag is 1, then A (unsigned) >= NUM (unsigned) and BCS will branch // If the C flag is 1, then A (unsigned) >= NUM (unsigned) and BCS will branch
// ... // ...
// The N flag contains most significant bit of the subtraction result. // The N flag contains most significant bit of the subtraction result.
fn compare(&mut self, r: i8, val: u8) { fn compare(&mut self, r: u8, val: u8) {
if r as u8 >= val { if r >= val {
self.registers.status.insert(Status::PS_CARRY); self.registers.status.insert(Status::PS_CARRY);
} else { } else {
self.registers.status.remove(Status::PS_CARRY); self.registers.status.remove(Status::PS_CARRY);
} }
if r == val as i8 { if r == val {
self.registers.status.insert(Status::PS_ZERO); self.registers.status.insert(Status::PS_ZERO);
} else { } else {
self.registers.status.remove(Status::PS_ZERO); self.registers.status.remove(Status::PS_ZERO);
} }
let diff: i8 = r.wrapping_sub(val as i8); let diff: i8 = (r as i8).wrapping_sub(val as i8);
if diff < 0 { if diff < 0 {
self.registers.status.insert(Status::PS_NEGATIVE); self.registers.status.insert(Status::PS_NEGATIVE);
} else { } else {
@ -948,21 +942,21 @@ impl<M: Bus> CPU<M> {
debug!("compare_with_x_register"); debug!("compare_with_x_register");
let x = self.registers.index_x; let x = self.registers.index_x;
self.compare(x as i8, val); self.compare(x, val);
} }
fn compare_with_y_register(&mut self, val: u8) { fn compare_with_y_register(&mut self, val: u8) {
let y = self.registers.index_y; let y = self.registers.index_y;
self.compare(y as i8, val); self.compare(y, val);
} }
fn exclusive_or(&mut self, val: u8) { fn exclusive_or(&mut self, val: u8) {
let a_after = self.registers.accumulator ^ (val as i8); let a_after = self.registers.accumulator ^ val;
self.load_accumulator(a_after); self.load_accumulator(a_after);
} }
fn inclusive_or(&mut self, val: u8) { fn inclusive_or(&mut self, val: u8) {
let a_after = self.registers.accumulator | (val as i8); let a_after = self.registers.accumulator | val;
self.load_accumulator(a_after); self.load_accumulator(a_after);
} }
@ -1006,14 +1000,14 @@ mod tests {
#[test] #[test]
fn dont_panic_for_overflow() { fn dont_panic_for_overflow() {
let mut cpu = CPU::new(Ram::new()); let mut cpu = CPU::new(Ram::new());
cpu.add_with_carry(-128); cpu.add_with_carry(0x80);
assert_eq!(cpu.registers.accumulator, -128); assert_eq!(cpu.registers.accumulator, 0x80);
cpu.add_with_carry(-128); cpu.add_with_carry(0x80);
assert_eq!(cpu.registers.accumulator, 0); assert_eq!(cpu.registers.accumulator, 0);
cpu.subtract_with_carry(-128); cpu.subtract_with_carry(0x80);
assert_eq!(cpu.registers.accumulator, -128); assert_eq!(cpu.registers.accumulator, 0x80);
cpu.subtract_with_carry(-128); cpu.subtract_with_carry(0x80);
assert_eq!(cpu.registers.accumulator, 0); assert_eq!(cpu.registers.accumulator, 0);
} }
@ -1053,7 +1047,7 @@ mod tests {
cpu.registers.accumulator = 0; cpu.registers.accumulator = 0;
cpu.subtract_with_carry(0x48); cpu.subtract_with_carry(0x48);
assert_eq!(cpu.registers.accumulator as u8, 0x52); assert_eq!(cpu.registers.accumulator, 0x52);
assert!(cpu.registers.status.contains(Status::PS_CARRY)); assert!(cpu.registers.status.contains(Status::PS_CARRY));
assert!(!cpu.registers.status.contains(Status::PS_ZERO)); assert!(!cpu.registers.status.contains(Status::PS_ZERO));
assert!(!cpu.registers.status.contains(Status::PS_NEGATIVE)); assert!(!cpu.registers.status.contains(Status::PS_NEGATIVE));
@ -1077,7 +1071,7 @@ mod tests {
assert!(!cpu.registers.status.contains(Status::PS_NEGATIVE)); assert!(!cpu.registers.status.contains(Status::PS_NEGATIVE));
assert!(!cpu.registers.status.contains(Status::PS_OVERFLOW)); assert!(!cpu.registers.status.contains(Status::PS_OVERFLOW));
cpu.add_with_carry(-1); cpu.add_with_carry(0xff);
assert_eq!(cpu.registers.accumulator, 0); assert_eq!(cpu.registers.accumulator, 0);
assert!(cpu.registers.status.contains(Status::PS_CARRY)); assert!(cpu.registers.status.contains(Status::PS_CARRY));
assert!(cpu.registers.status.contains(Status::PS_ZERO)); assert!(cpu.registers.status.contains(Status::PS_ZERO));
@ -1093,6 +1087,7 @@ mod tests {
let mut cpu = CPU::new(Ram::new()); let mut cpu = CPU::new(Ram::new());
assert_eq!(cpu.registers.accumulator, 0);
cpu.add_with_carry(127); cpu.add_with_carry(127);
assert_eq!(cpu.registers.accumulator, 127); assert_eq!(cpu.registers.accumulator, 127);
assert!(!cpu.registers.status.contains(Status::PS_CARRY)); assert!(!cpu.registers.status.contains(Status::PS_CARRY));
@ -1100,7 +1095,7 @@ mod tests {
assert!(!cpu.registers.status.contains(Status::PS_NEGATIVE)); assert!(!cpu.registers.status.contains(Status::PS_NEGATIVE));
assert!(!cpu.registers.status.contains(Status::PS_OVERFLOW)); assert!(!cpu.registers.status.contains(Status::PS_OVERFLOW));
cpu.add_with_carry(-127); cpu.add_with_carry(-127i8 as u8);
assert_eq!(cpu.registers.accumulator, 0); assert_eq!(cpu.registers.accumulator, 0);
assert!(cpu.registers.status.contains(Status::PS_CARRY)); assert!(cpu.registers.status.contains(Status::PS_CARRY));
assert!(cpu.registers.status.contains(Status::PS_ZERO)); assert!(cpu.registers.status.contains(Status::PS_ZERO));
@ -1108,15 +1103,15 @@ mod tests {
assert!(!cpu.registers.status.contains(Status::PS_OVERFLOW)); assert!(!cpu.registers.status.contains(Status::PS_OVERFLOW));
cpu.registers.status.remove(Status::PS_CARRY); cpu.registers.status.remove(Status::PS_CARRY);
cpu.add_with_carry(-128); cpu.add_with_carry(0x80);
assert_eq!(cpu.registers.accumulator, -128); assert_eq!(cpu.registers.accumulator, 0x80);
assert!(!cpu.registers.status.contains(Status::PS_CARRY)); assert!(!cpu.registers.status.contains(Status::PS_CARRY));
assert!(!cpu.registers.status.contains(Status::PS_ZERO)); assert!(!cpu.registers.status.contains(Status::PS_ZERO));
assert!(cpu.registers.status.contains(Status::PS_NEGATIVE)); assert!(cpu.registers.status.contains(Status::PS_NEGATIVE));
assert!(!cpu.registers.status.contains(Status::PS_OVERFLOW)); assert!(!cpu.registers.status.contains(Status::PS_OVERFLOW));
cpu.add_with_carry(127); cpu.add_with_carry(127);
assert_eq!(cpu.registers.accumulator, -1); assert_eq!(cpu.registers.accumulator, 0xff);
assert!(!cpu.registers.status.contains(Status::PS_CARRY)); assert!(!cpu.registers.status.contains(Status::PS_CARRY));
assert!(!cpu.registers.status.contains(Status::PS_ZERO)); assert!(!cpu.registers.status.contains(Status::PS_ZERO));
assert!(cpu.registers.status.contains(Status::PS_NEGATIVE)); assert!(cpu.registers.status.contains(Status::PS_NEGATIVE));
@ -1132,7 +1127,7 @@ mod tests {
assert!(!cpu.registers.status.contains(Status::PS_OVERFLOW)); assert!(!cpu.registers.status.contains(Status::PS_OVERFLOW));
cpu.add_with_carry(1); cpu.add_with_carry(1);
assert_eq!(cpu.registers.accumulator, -128); assert_eq!(cpu.registers.accumulator, 0x80);
assert!(!cpu.registers.status.contains(Status::PS_CARRY)); assert!(!cpu.registers.status.contains(Status::PS_CARRY));
assert!(!cpu.registers.status.contains(Status::PS_ZERO)); assert!(!cpu.registers.status.contains(Status::PS_ZERO));
assert!(cpu.registers.status.contains(Status::PS_NEGATIVE)); assert!(cpu.registers.status.contains(Status::PS_NEGATIVE));
@ -1140,36 +1135,50 @@ mod tests {
let mut cpu = CPU::new(Ram::new()); let mut cpu = CPU::new(Ram::new());
cpu.registers.status.or(Status::PS_CARRY); cpu.registers.status.or(Status::PS_CARRY);
cpu.add_with_carry(-1); cpu.add_with_carry(0xff);
assert_eq!(cpu.registers.accumulator, 0); assert_eq!(cpu.registers.accumulator, 0);
assert!(cpu.registers.status.contains(Status::PS_CARRY)); assert!(cpu.registers.status.contains(Status::PS_CARRY));
} }
#[test]
fn solid65_adc_immediate() {
let mut cpu = CPU::new(Ram::new());
// Adding $FF plus carry should be the same as adding $00 and no carry, so these three
// instructions should leave the carry flags unaffected, i.e. set.
cpu.execute_instruction((Instruction::LDA, OpInput::UseImmediate(0x9c)));
cpu.execute_instruction((Instruction::SEC, OpInput::UseImplied));
cpu.execute_instruction((Instruction::ADC, OpInput::UseImmediate(0xff)));
assert_eq!(cpu.registers.accumulator, 0x9c);
assert!(cpu.registers.status.contains(Status::PS_CARRY));
}
#[test] #[test]
fn and_test() { fn and_test() {
let mut cpu = CPU::new(Ram::new()); let mut cpu = CPU::new(Ram::new());
cpu.registers.accumulator = 0; cpu.registers.accumulator = 0;
cpu.and(-1); cpu.and(0xff);
assert_eq!(cpu.registers.accumulator, 0); assert_eq!(cpu.registers.accumulator, 0);
assert!(cpu.registers.status.contains(Status::PS_ZERO)); assert!(cpu.registers.status.contains(Status::PS_ZERO));
assert!(!cpu.registers.status.contains(Status::PS_NEGATIVE)); assert!(!cpu.registers.status.contains(Status::PS_NEGATIVE));
cpu.registers.accumulator = -1; cpu.registers.accumulator = 0xff;
cpu.and(0); cpu.and(0);
assert_eq!(cpu.registers.accumulator, 0); assert_eq!(cpu.registers.accumulator, 0);
assert!(cpu.registers.status.contains(Status::PS_ZERO)); assert!(cpu.registers.status.contains(Status::PS_ZERO));
assert!(!cpu.registers.status.contains(Status::PS_NEGATIVE)); assert!(!cpu.registers.status.contains(Status::PS_NEGATIVE));
cpu.registers.accumulator = -1; cpu.registers.accumulator = 0xff;
cpu.and(0x0f); cpu.and(0x0f);
assert_eq!(cpu.registers.accumulator, 0x0f); assert_eq!(cpu.registers.accumulator, 0x0f);
assert!(!cpu.registers.status.contains(Status::PS_ZERO)); assert!(!cpu.registers.status.contains(Status::PS_ZERO));
assert!(!cpu.registers.status.contains(Status::PS_NEGATIVE)); assert!(!cpu.registers.status.contains(Status::PS_NEGATIVE));
cpu.registers.accumulator = -1; cpu.registers.accumulator = 0xff;
cpu.and(-128); cpu.and(0x80);
assert_eq!(cpu.registers.accumulator, -128); assert_eq!(cpu.registers.accumulator, 0x80);
assert!(!cpu.registers.status.contains(Status::PS_ZERO)); assert!(!cpu.registers.status.contains(Status::PS_ZERO));
assert!(cpu.registers.status.contains(Status::PS_NEGATIVE)); assert!(cpu.registers.status.contains(Status::PS_NEGATIVE));
} }
@ -1182,14 +1191,14 @@ mod tests {
cpu.registers.accumulator = 0; cpu.registers.accumulator = 0;
cpu.subtract_with_carry(1); cpu.subtract_with_carry(1);
assert_eq!(cpu.registers.accumulator, -1); assert_eq!(cpu.registers.accumulator, 0xff);
assert!(cpu.registers.status.contains(Status::PS_CARRY)); assert!(cpu.registers.status.contains(Status::PS_CARRY));
assert!(!cpu.registers.status.contains(Status::PS_ZERO)); assert!(!cpu.registers.status.contains(Status::PS_ZERO));
assert!(cpu.registers.status.contains(Status::PS_NEGATIVE)); assert!(cpu.registers.status.contains(Status::PS_NEGATIVE));
assert!(!cpu.registers.status.contains(Status::PS_OVERFLOW)); assert!(!cpu.registers.status.contains(Status::PS_OVERFLOW));
cpu.execute_instruction((Instruction::SEC, OpInput::UseImplied)); cpu.execute_instruction((Instruction::SEC, OpInput::UseImplied));
cpu.registers.accumulator = -128; cpu.registers.accumulator = 0x80;
cpu.subtract_with_carry(1); cpu.subtract_with_carry(1);
assert_eq!(cpu.registers.accumulator, 127); assert_eq!(cpu.registers.accumulator, 127);
assert!(!cpu.registers.status.contains(Status::PS_CARRY)); assert!(!cpu.registers.status.contains(Status::PS_CARRY));
@ -1199,15 +1208,15 @@ mod tests {
cpu.execute_instruction((Instruction::SEC, OpInput::UseImplied)); cpu.execute_instruction((Instruction::SEC, OpInput::UseImplied));
cpu.registers.accumulator = 127; cpu.registers.accumulator = 127;
cpu.subtract_with_carry(-1); cpu.subtract_with_carry(0xff);
assert_eq!(cpu.registers.accumulator, -128); assert_eq!(cpu.registers.accumulator, 0x80);
assert!(cpu.registers.status.contains(Status::PS_CARRY)); assert!(cpu.registers.status.contains(Status::PS_CARRY));
assert!(!cpu.registers.status.contains(Status::PS_ZERO)); assert!(!cpu.registers.status.contains(Status::PS_ZERO));
assert!(cpu.registers.status.contains(Status::PS_NEGATIVE)); assert!(cpu.registers.status.contains(Status::PS_NEGATIVE));
assert!(cpu.registers.status.contains(Status::PS_OVERFLOW)); assert!(cpu.registers.status.contains(Status::PS_OVERFLOW));
cpu.execute_instruction((Instruction::CLC, OpInput::UseImplied)); cpu.execute_instruction((Instruction::CLC, OpInput::UseImplied));
cpu.registers.accumulator = -64; cpu.registers.accumulator = -64i8 as u8;
cpu.subtract_with_carry(64); cpu.subtract_with_carry(64);
assert_eq!(cpu.registers.accumulator, 127); assert_eq!(cpu.registers.accumulator, 127);
assert!(!cpu.registers.status.contains(Status::PS_CARRY)); assert!(!cpu.registers.status.contains(Status::PS_CARRY));
@ -1217,8 +1226,8 @@ mod tests {
cpu.execute_instruction((Instruction::SEC, OpInput::UseImplied)); cpu.execute_instruction((Instruction::SEC, OpInput::UseImplied));
cpu.registers.accumulator = 0; cpu.registers.accumulator = 0;
cpu.subtract_with_carry(-128); cpu.subtract_with_carry(0x80);
assert_eq!(cpu.registers.accumulator, -128); assert_eq!(cpu.registers.accumulator, 0x80);
assert!(cpu.registers.status.contains(Status::PS_CARRY)); assert!(cpu.registers.status.contains(Status::PS_CARRY));
assert!(!cpu.registers.status.contains(Status::PS_ZERO)); assert!(!cpu.registers.status.contains(Status::PS_ZERO));
assert!(cpu.registers.status.contains(Status::PS_NEGATIVE)); assert!(cpu.registers.status.contains(Status::PS_NEGATIVE));
@ -1227,7 +1236,7 @@ mod tests {
cpu.execute_instruction((Instruction::CLC, OpInput::UseImplied)); cpu.execute_instruction((Instruction::CLC, OpInput::UseImplied));
cpu.registers.accumulator = 0; cpu.registers.accumulator = 0;
cpu.subtract_with_carry(127); cpu.subtract_with_carry(127);
assert_eq!(cpu.registers.accumulator, -128); assert_eq!(cpu.registers.accumulator, 0x80);
assert!(cpu.registers.status.contains(Status::PS_CARRY)); assert!(cpu.registers.status.contains(Status::PS_CARRY));
assert!(!cpu.registers.status.contains(Status::PS_ZERO)); assert!(!cpu.registers.status.contains(Status::PS_ZERO));
assert!(cpu.registers.status.contains(Status::PS_NEGATIVE)); assert!(cpu.registers.status.contains(Status::PS_NEGATIVE));
@ -1583,7 +1592,7 @@ mod tests {
cpu.exclusive_or(val); cpu.exclusive_or(val);
let a_after = a_before ^ val; let a_after = a_before ^ val;
assert_eq!(cpu.registers.accumulator, a_after as i8); assert_eq!(cpu.registers.accumulator, a_after);
if a_after == 0 { if a_after == 0 {
assert!(cpu.registers.status.contains(Status::PS_ZERO)); assert!(cpu.registers.status.contains(Status::PS_ZERO));
@ -1611,7 +1620,7 @@ mod tests {
cpu.inclusive_or(val); cpu.inclusive_or(val);
let a_after = a_before | val; let a_after = a_before | val;
assert_eq!(cpu.registers.accumulator, a_after as i8); assert_eq!(cpu.registers.accumulator, a_after);
if a_after == 0 { if a_after == 0 {
assert!(cpu.registers.status.contains(Status::PS_ZERO)); assert!(cpu.registers.status.contains(Status::PS_ZERO));

2
src/registers.rs
View File

@ -162,7 +162,7 @@ impl StackPointer {
#[derive(Copy, Clone, PartialEq, Eq, Debug)] #[derive(Copy, Clone, PartialEq, Eq, Debug)]
pub struct Registers { pub struct Registers {
pub accumulator: i8, pub accumulator: u8,
pub index_x: u8, pub index_x: u8,
pub index_y: u8, pub index_y: u8,
pub stack_pointer: StackPointer, pub stack_pointer: StackPointer,