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Implement push and refactor pop

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This commit is contained in:
Franco Colmenarez 2021-10-16 19:41:07 -05:00
parent 4dbcb4cb6c
commit 989971af8b
1 changed files with 36 additions and 17 deletions
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51
src/cpu.rs
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@ -437,21 +437,27 @@ impl CPU {
let pc = self.registers.get(Register::PC);
self.registers.decrement(Register::SP, 2);
let sp = self.registers.get(Register::SP);
bus.write_16bit(sp, pc);
bus.write_16bit(sp, pc + 3);
self.registers.set(Register::PC, address);
},
_ => {},
},
// RST, same as Call
Opcode::RST(address) => self.exec(Opcode::CALL(OpcodeParameter::U16(address as u16)), bus),
// POP
Opcode::POP(register) => {
if register.is_16bit() {
// PUSH onto the stack
Opcode::PUSH(register) => {
let val = self.registers.get(register).to_be_bytes();
let sp = self.registers.get(Register::SP);
let val = bus.read_16bit(sp);
self.registers.set(register, val);
bus.write(sp - 1, val[1]);
bus.write(sp - 2, val[0]);
self.registers.increment(Register::PC, 1);
self.registers.decrement(Register::SP, 2);
},
// POP onto the stack
Opcode::POP(register) => {
let sp = self.registers.get(Register::SP);
self.registers.set(register, bus.read_16bit(sp));
self.registers.increment(Register::SP, 2);
}
},
// RET, same as POP PC when no parameter is specified
Opcode::RET(params) => match params {
@ -985,7 +991,7 @@ mod tests {
cpu.registers.set(Register::SP, sp);
cpu.registers.set(Register::PC, 0x1234);
cpu.exec(Opcode::CALL(OpcodeParameter::U16(0xF0F0)), &mut bus);
assert_eq!(bus.read_16bit(sp - 2), 0x1234);
assert_eq!(bus.read_16bit(sp - 2), 0x1234 + 3);
assert_eq!(cpu.registers.get(Register::SP), sp - 2);
assert_eq!(cpu.registers.get(Register::PC), 0xF0F0);
@ -995,22 +1001,35 @@ mod tests {
cpu.registers.set(Register::SP, sp);
cpu.registers.set(Register::PC, 0x1234);
cpu.exec(Opcode::RST(0xF0), &mut bus);
assert_eq!(bus.read_16bit(sp - 2), 0x1234);
assert_eq!(bus.read_16bit(sp - 2), 0x1234 + 3);
assert_eq!(cpu.registers.get(Register::SP), sp - 2);
assert_eq!(cpu.registers.get(Register::PC), 0x00F0);
// PUSH
let mut cpu = CPU::new();
let mut bus = Bus::new();
let addr = 0xD000;
cpu.registers.set(Register::SP, addr);
cpu.registers.set(Register::AF, 0x1234);
cpu.exec(Opcode::PUSH(Register::AF), &mut bus);
assert_eq!(bus.read_16bit(addr - 2), 0x3412);
assert_eq!(cpu.registers.get(Register::SP), addr - 2);
assert_eq!(cpu.registers.get(Register::PC), 0x101);
// POP
let mut cpu = CPU::new();
let sp = 0xFFDF;
cpu.registers.set(Register::SP, sp);
bus.write_16bit(sp, 0x1234);
cpu.exec(Opcode::POP(Register::HL), &mut bus);
assert_eq!(cpu.registers.get(Register::HL), 0x1234);
assert_eq!(cpu.registers.get(Register::SP), sp + 2);
let mut bus = Bus::new();
let addr = 0xD000;
cpu.registers.set(Register::SP, addr);
bus.write_16bit(addr, 0x1234);
cpu.exec(Opcode::POP(Register::PC), &mut bus);
assert_eq!(cpu.registers.get(Register::PC), 0x1234);
assert_eq!(cpu.registers.get(Register::SP), addr + 2);
// RET
let mut cpu = CPU::new();
let sp = 0xFFDF;
let mut bus = Bus::new();
let sp = 0xD000;
cpu.registers.set(Register::SP, sp);
bus.write_16bit(sp, 0x1234);
cpu.exec(Opcode::RET(OpcodeParameter::NoParam), &mut bus);