174 lines
4.1 KiB
Rust
174 lines
4.1 KiB
Rust
const MEMORY_SIZE: usize = 4096;
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const WIDTH: u32 = 64;
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const HEIGHT: u32 = 32;
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const DATA_REGISTERS: usize = 16;
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pub const SCALE_FACTOR: u32 = 10;
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pub const WINDOW_WIDTH: u32 = WIDTH * SCALE_FACTOR;
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pub const WINDOW_HEIGHT: u32 = HEIGHT * SCALE_FACTOR;
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type Memory = [u8; MEMORY_SIZE];
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pub enum Register {
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V0,
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V1,
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V2,
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V3,
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V4,
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V5,
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V6,
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V7,
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V8,
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V9,
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VA,
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VB,
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VC,
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VD,
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VE,
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VF,
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I,
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DT,
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ST,
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PC,
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SP,
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}
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struct Registers {
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data: [u8; DATA_REGISTERS],
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i: u16,
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delay_timer: u8,
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sound_timer: u8,
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pc: u16,
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sp: u8,
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}
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pub struct Chip8 {
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memory: Memory,
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registers: Registers,
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}
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fn data_register_to_index(register: Register) -> usize {
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match register {
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Register::V0 => 0,
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Register::V1 => 1,
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Register::V2 => 2,
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Register::V3 => 3,
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Register::V4 => 4,
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Register::V5 => 5,
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Register::V6 => 6,
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Register::V7 => 7,
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Register::V8 => 8,
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Register::V9 => 9,
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Register::VA => 10,
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Register::VB => 11,
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Register::VC => 12,
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Register::VD => 13,
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Register::VE => 14,
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Register::VF => 15,
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_ => panic!("invalid data register"),
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}
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}
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impl Chip8 {
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pub fn new() -> Chip8 {
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Chip8 {
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memory: [0; MEMORY_SIZE],
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registers: Registers {
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data: [0; DATA_REGISTERS],
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i: 0,
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delay_timer: 0,
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sound_timer: 0,
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pc: 0,
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sp: 0,
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},
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}
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}
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pub fn memory_set(&mut self, index: usize, value: u8) -> () {
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self.memory[index] = value;
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}
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pub fn memory_get(&self, index: usize) -> u8 {
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self.memory[index]
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}
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pub fn register_set(&mut self, register: Register, value: u16) -> () {
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match register {
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Register::I => self.registers.i = value,
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Register::DT => self.registers.delay_timer = value as u8,
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Register::ST => self.registers.sound_timer = value as u8,
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Register::PC => self.registers.pc = value,
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Register::SP => self.registers.sp = value as u8,
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_ => self.registers.data[data_register_to_index(register)] = value as u8,
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}
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}
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pub fn register_get(&mut self, register: Register) -> u16 {
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match register {
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Register::I => self.registers.i,
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Register::DT => self.registers.delay_timer as u16,
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Register::ST => self.registers.sound_timer as u16,
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Register::PC => self.registers.pc,
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Register::SP => self.registers.sp as u16,
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_ => self.registers.data[data_register_to_index(register)] as u16,
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}
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}
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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#[test]
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fn it_has_the_correct_memory_size() {
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assert_eq!(Chip8::new().memory.len(), MEMORY_SIZE);
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}
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#[test]
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fn it_can_write_the_memory() {
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let mut chip8 = Chip8::new();
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chip8.memory_set(2, 42);
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assert_eq!(chip8.memory[0..3], [0, 0, 42]);
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}
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#[test]
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fn it_can_read_the_memory() {
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let mut chip8 = Chip8::new();
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chip8.memory_set(2, 42);
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assert_eq!(chip8.memory_get(2), 42);
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}
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#[test]
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fn it_has_the_correct_number_of_data_registers() {
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assert_eq!(Chip8::new().registers.data.len(), DATA_REGISTERS);
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}
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#[test]
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fn it_can_write_data_registers() {
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let mut chip8 = Chip8::new();
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chip8.register_set(Register::VA, 42);
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assert_eq!(chip8.registers.data[10], 42);
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}
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#[test]
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fn it_can_read_data_registers() {
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let mut chip8 = Chip8::new();
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chip8.register_set(Register::VA, 42);
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assert_eq!(chip8.register_get(Register::VA), 42);
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}
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#[test]
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fn it_can_write_special_registers() {
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let mut chip8 = Chip8::new();
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chip8.register_set(Register::PC, 42);
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assert_eq!(chip8.registers.pc, 42);
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}
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#[test]
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fn it_can_read_special_registers() {
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let mut chip8 = Chip8::new();
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chip8.register_set(Register::PC, 42);
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assert_eq!(chip8.register_get(Register::PC), 42);
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}
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}
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