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mod cpu;
mod instructions;
mod memory;
use cpu::CPU;
use memory::Memory;
use instructions::Instruction;
fn main() {
let mut cpu = CPU::default();
let mut mem = Memory::new();
// a = 10
mem.write(0x0000, Instruction::MOV as u8);
mem.write(0x0001, 0);
mem.write(0x0002, 5);
// b = 2
mem.write(0x0003, Instruction::MOV as u8);
mem.write(0x0004, 1);
mem.write(0x0005, 10);
// a = a + b
mem.write(0x0006, Instruction::SUB as u8);
mem.write(0x0007, 0);
mem.write(0x0008, 1);
// set b = 0
mem.write(0x0009, Instruction::MOV as u8);
mem.write(0x000a, 1);
mem.write(0x000b, 0);
// halt
mem.write(0x000c, Instruction::HLT as u8);
while !cpu.halted {
let opcode = mem.read(cpu.pc);
cpu.inc_cp();
match opcode {
x if x == Instruction::MOV as u8 => {
let reg = mem.read(cpu.pc); cpu.inc_cp();
let val = mem.read(cpu.pc); cpu.inc_cp();
match reg {
0 => cpu.a = val,
1 => cpu.b = val,
2 => cpu.c = val,
3 => cpu.d = val,
_ => {}
}
}
x if x == Instruction::ADD as u8 => {
let dest = mem.read(cpu.pc); cpu.pc += 1;
let src = mem.read(cpu.pc); cpu.pc += 1;
let (result, carry) = match (dest, src) {
// What the fuck do these tuples mean?
// so basically they are the numbers assigned to register
// 0 => A, 1 => B ....
// so when it is (0, 0), it basically says add the
// value of register B into register A,
// thats exactly whats replicated in the code below
(0, 0) => cpu.a.overflowing_add(cpu.a),
(0, 1) => cpu.a.overflowing_add(cpu.b),
(0, 2) => cpu.a.overflowing_add(cpu.c),
(0, 3) => cpu.a.overflowing_add(cpu.d),
(1, 0) => cpu.b.overflowing_add(cpu.a),
(1, 1) => cpu.b.overflowing_add(cpu.b),
(1, 2) => cpu.b.overflowing_add(cpu.c),
(1, 3) => cpu.b.overflowing_add(cpu.d),
(2, 0) => cpu.c.overflowing_add(cpu.a),
(2, 1) => cpu.c.overflowing_add(cpu.b),
(2, 2) => cpu.c.overflowing_add(cpu.c),
(2, 3) => cpu.c.overflowing_add(cpu.d),
(3, 0) => cpu.d.overflowing_add(cpu.a),
(3, 1) => cpu.d.overflowing_add(cpu.b),
(3, 2) => cpu.d.overflowing_add(cpu.c),
(3, 3) => cpu.d.overflowing_add(cpu.d),
_ => (0, false),
};
match dest {
0 => cpu.a = result,
1 => cpu.b = result,
2 => cpu.c = result,
3 => cpu.d = result,
_ => {}
}
cpu.zero = result == 0;
cpu.carry = carry;
}
x if x == Instruction::SUB as u8 => {
let dest = mem.read(cpu.pc); cpu.pc += 1;
let src = mem.read(cpu.pc); cpu.pc += 1;
let (result, borrow) = match (dest, src) {
// What the fuck do these tuples mean?
// so basically they are the numbers assigned to register
// 0 => A, 1 => B ....
// so when it is (0, 0), it basically says add the
// value of register B into register A,
// thats exactly whats replicated in the code below
(0, 0) => cpu.a.overflowing_sub(cpu.a),
(0, 1) => cpu.a.overflowing_sub(cpu.b),
(0, 2) => cpu.a.overflowing_sub(cpu.c),
(0, 3) => cpu.a.overflowing_sub(cpu.d),
(1, 0) => cpu.b.overflowing_sub(cpu.a),
(1, 1) => cpu.b.overflowing_sub(cpu.b),
(1, 2) => cpu.b.overflowing_sub(cpu.c),
(1, 3) => cpu.b.overflowing_sub(cpu.d),
(2, 0) => cpu.c.overflowing_sub(cpu.a),
(2, 1) => cpu.c.overflowing_sub(cpu.b),
(2, 2) => cpu.c.overflowing_sub(cpu.c),
(2, 3) => cpu.c.overflowing_sub(cpu.d),
(3, 0) => cpu.d.overflowing_sub(cpu.a),
(3, 1) => cpu.d.overflowing_sub(cpu.b),
(3, 2) => cpu.d.overflowing_sub(cpu.c),
(3, 3) => cpu.d.overflowing_sub(cpu.d),
_ => (0, false),
};
match dest {
0 => cpu.a = result,
1 => cpu.b = result,
2 => cpu.c = result,
3 => cpu.d = result,
_ => {}
}
cpu.zero = result == 0;
cpu.carry = borrow;
}
x if x == Instruction::JMP as u8 => {}
x if x == Instruction::JZ as u8 => {}
x if x == Instruction::HLT as u8 => {
cpu.halted = true;
}
_ => panic!("Unknown opcode {:02X}", opcode),
}
}
println!("{:#?}", cpu);
}
|
