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mre-mos6502/README.md
2018-10-30 01:23:39 +01:00

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# mos6502
[![Build Status](https://travis-ci.org/mre/mos6502.svg?branch=master)](https://travis-ci.org/mre/mos6502)
An emulator for the MOS 6502 CPU written in Rust.
## Features
* Builds on stable Rust.
* Runs on [`#[no_std]`](https://doc.rust-lang.org/1.7.0/book/no-stdlib.html), which means it works without the standard library. It is
portable, has very few dependencies, and doesn't depend on a full-fledged
`libc`.
## Usage example
```rust
#![no_std]
extern crate mos6502;
use mos6502::cpu;
use mos6502::address::Address;
fn main() {
let mut cpu = cpu::CPU::new();
let zero_page_data = [
// ZeroPage data start
0x00,
0x02, // ADC ZeroPage target
0x00,
0x04, // ADC ZeroPageX target
0x00,
0x00,
0x00,
0x00,
0x10, // ADC IndexedIndirectX address
0x80, // ADC IndexedIndirectX address
0x00,
0x00,
0x00,
0x00,
0x00,
0x08, // ADC IndirectIndexedY address
0x80, // ADC IndirectIndexedY address
];
let program = [
// Code start
0xA9, // LDA Immediate
0x01, // Immediate operand
0x69, // ADC Immediate
0x07, // Immediate operand
0x65, // ADC ZeroPage
0x01, // ZeroPage operand
0xA2, // LDX Immediate
0x01, // Immediate operand
0x75, // ADC ZeroPageX
0x02, // ZeroPageX operand
0x6D, // ADC Absolute
0x01, // Absolute operand
0x80, // Absolute operand
0xA2, // LDX immediate
0x08, // Immediate operand
0x7D, // ADC AbsoluteX
0x00, // AbsoluteX operand
0x80, // AbsoluteX operand
0xA0, // LDY immediate
0x04, // Immediate operand
0x79, // ADC AbsoluteY
0x00, // AbsoluteY operand
0x80, // AbsoluteY operand
0xA2, // LDX immediate
0x05, // Immediate operand
0x61, // ADC IndexedIndirectX
0x03, // IndexedIndirectX operand
0xA0, // LDY immediate
0x10, // Immediate operand
0x71, // ADC IndirectIndexedY
0x0F, // IndirectIndexedY operand
0xEA, // NOP :)
0xFF, // Something invalid -- the end!
];
let data: [u8; 25] = [
0x00,
0x09, // ADC Absolute target
0x00,
0x00,
0x40, // ADC AbsoluteY target
0x00,
0x00,
0x00,
0x11, // ADC AbsoluteX target
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x12, // ADC IndexedIndirectX target
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x00,
0x06, // ADC IndirectIndexedY target
];
// "Load" a program
cpu.memory.set_bytes(Address(0x0000), &zero_page_data);
cpu.memory.set_bytes(Address(0x4000), &program);
cpu.memory.set_bytes(Address(0x8000), &data);
cpu.registers.program_counter = Address(0x4000);
cpu.run();
}
```
## Credits
This started off as a fork of [6502-rs](https://github.com/amw-zero/6502-rs),
which seems to be unmaintained at this point.