mre-mos6502/examples/euclidean_algo.rs

extern crate mos6502;

use mos6502::cpu;

fn main() {
    println!("Enter two numbers (< 128) to know their GCD:");
    let mut input = String::new();
    std::io::stdin().read_line(&mut input).unwrap();

    let zero_page_data = input
        .split_whitespace()
        .map(|s| s.parse::<u8>().unwrap())
        .collect::<Vec<u8>>();

    let program = [
        // (F)irst | (S)econd
        // .algo
        0xa5, 0x00, // Load from F to A
        // .algo_
        0x38, // Set carry flag
        0xe5, 0x01, // Substract S from number in A (from F)
        0xf0, 0x07, // Jump to .end if diff is zero
        0x30, 0x08, // Jump to .swap if diff is negative
        0x85, 0x00, // Load A to F
        0x4c, 0x12, 0x00, // Jump to .algo_
        // .end
        0xa5, 0x00, // Load from S to A
        0xff, // .swap
        0xa6, 0x00, // load F to X
        0xa4, 0x01, // load S to Y
        0x86, 0x01, // Store X to F
        0x84, 0x00, // Store Y to S
        0x4c, 0x10, 0x00, // Jump to .algo
    ];

    let mut cpu = cpu::CPU::new();

    cpu.memory.set_bytes(0x00, &zero_page_data);
    cpu.memory.set_bytes(0x10, &program);
    cpu.registers.program_counter = 0x10;

    cpu.run();

    println!("GCD is {}", cpu.registers.accumulator);
}