Chip-8 emulator

Complete Chip-8 instructions. However, the user still needs to modify the code to select the ROM. Next-step will be to insert SUPER-CHIP and OX-CHIP instructions, as well as to give menu options to the user.

.gitignore

@@ -2,3 +2,4 @@
 Cargo.lock
 
 /src/SDL2.dll
+/src/chip_8/roms

src/chip_8/chip_8_base_interpreter.rs

@@ -1,28 +1,42 @@
 // CHIP-8 means Compact Hexadecimal Interpretive Programming - 8-bit
 use ::sdl2;
 
-use crate::chip_8::display;
 use rand::Rng;
 
+use std::io::Read;
+
 const DISPLAY_WIDTH: usize = 64;
 const DISPLAY_HEIGHT: usize = 32;
 const DISPLAY_SCALE: u32 = 10;
 
 pub struct ProgramCounter(usize);
-pub struct Registers([u8; 16]);
+pub struct Registers([u8; 0x10]);
 pub struct Ram([u8; 4 * 1024]);
-pub struct Timer(u8);
-pub struct Timing(u16);
 pub struct DisplayBuffer([[bool; DISPLAY_HEIGHT]; DISPLAY_WIDTH]);
+
+pub struct Timer{
+    tick: u8,
+    clock_hz: u128,
+    elapsed: std::time::SystemTime
+}
+
 pub struct Keypad { 
-    keys: [bool; 0xF],
+    keys: [bool; 0x10], 
-    layout: String
+    // layout: String 
+}
+
+pub struct OpCodes { 
+    opcode: u16, 
+    nible_1: u8, 
+    nible_2: u8, 
+    nible_3: u8, 
+    nible_4: u8 
 }
 
 impl ProgramCounter {
     fn init() -> ProgramCounter {
         ProgramCounter {
-            0: 0
+            0: 0x200
         }
     }
 
@@ -30,6 +44,10 @@ impl ProgramCounter {
         self.0 += 2;
     }
 
+    fn decrement(&mut self) {
+        self.0 -= 2;
+    }
+
     fn set(&mut self, value: usize) {
         self.0 = value;
     }
@@ -47,17 +65,11 @@ impl Registers {
     }
 
     fn get(&self, register: usize) -> u8 {
-        if register <= 0xF {
+        self.0[register]
-            self.0[register]
-        } else {
-            0
-        }
     }
 
     fn set(&mut self, register: usize, value: u8) {
-        if register <= 0xF {
+        self.0[register] = value;
-            self.0[register] = value;
-        }
     }
 }
 
@@ -69,7 +81,8 @@ impl Ram {
     }
 
     fn init_fonts(&mut self) {
-        const FONTS: [u8; 80] = [
+        let font_address = 0x50;
+        let fonts: [u8; 80] = [
             0xF0, 0x90, 0x90, 0x90, 0xF0,  // 0
             0x20, 0x60, 0x20, 0x20, 0x70,  // 1
             0xF0, 0x10, 0xF0, 0x80, 0xF0,  // 2
@@ -86,8 +99,8 @@ impl Ram {
             0xE0, 0x90, 0x90, 0x90, 0xE0,  // D
             0xF0, 0x80, 0xF0, 0x80, 0xF0,  // E
             0xF0, 0x80, 0xF0, 0x80, 0x80]; // F
-        for i in 0x50..0x80 {
+        for i in 0..fonts.len() {
-            self.0[i] = FONTS[i];
+            self.0[i + font_address] = fonts[i];
         }
     }
 
@@ -99,70 +112,114 @@ impl Ram {
     }
 
     fn read8(&self, addr: usize) -> u8 {
-        assert!(addr <= self.0.len());
+        assert!(addr <= self.0.len(), "addr = {}, self.0.len() = {}", addr, self.0.len());
         self.0[addr]
     }
 
     fn read16(&self, addr: usize) -> u16 {
-        assert!(addr < self.0.len());
+        assert!(addr < self.0.len(), "addr = {}, self.0.len() = {}", addr, self.0.len());
-        // byteorder::LittleEndiar::read_u16(&self.ram[addr])
+        // byteorder::LittleEndian::read_u16(&self.0[addr]);
         
         // u16::from_le_bytes(self.ram[addr..addr+2])
         // self.ram[addr..addr+2]
         (self.0[addr] as u16) << 8 | self.0[addr+1] as u16
     }
+
+    fn write8(&mut self, addr: usize, value: u8) {
+        assert!(addr < self.0.len());
+        self.0[addr] = value;
+    }
 }
 
 impl Timer {
     fn init() -> Timer {
         Timer {
-            0: 0
+            tick: 255,
+            clock_hz: 60,
+            elapsed: std::time::SystemTime::now()
         }
     }
 
     fn tick(&mut self) -> bool {
-        self.0 -= 1;
+        let mut res: bool = false;
-        self.0 == 0
+        match self.elapsed.elapsed() {
+            Ok(elapsed) => {
+                if elapsed.as_secs_f32() >= 1./(self.clock_hz as f32)  {
+                    if self.tick > 0 { self.tick -= 1; }
+                    self.reset_elapsed();
+                    res = true;
+                }
+            }
+            Err(e) => {
+                println!("Error: {:?}", e);
+            }
+        }
+        res
+    }
+
+    fn reset_elapsed(&mut self) {
+        self.elapsed = std::time::SystemTime::now();
     }
 }
 
 impl Keypad {
     fn init() -> Keypad {
         Keypad {
-            keys: [false; 0xF],
+            keys: [false; 0x10],
-            layout: String::from("123C456D789EA0BF")
+            // layout: String::from("123C456D789EA0BF")
         }
     }
 
-    fn set_layout(&mut self, layout: &str) {
+    fn compute_keycode(&self, keycode: sdl2::keyboard::Keycode) -> Option<usize> {
-        assert_eq!(layout.len(), self.layout.len());
+        match keycode {
-        self.layout = layout.to_string();
+            sdl2::keyboard::Keycode::Num1 => Some(0x1),
-    }
+            sdl2::keyboard::Keycode::Num2 => Some(0x2),
-}
+            sdl2::keyboard::Keycode::Num3 => Some(0x3),
+            sdl2::keyboard::Keycode::Num4 => Some(0xC),
 
-impl Timing {
+            sdl2::keyboard::Keycode::Q => Some(0x4),
-    fn init() -> Timing {
+            sdl2::keyboard::Keycode::W => Some(0x5),
-        Timing {
+            sdl2::keyboard::Keycode::E => Some(0x6),
-            0: 1000 // 1 MHz
+            sdl2::keyboard::Keycode::R => Some(0xD),
+
+            sdl2::keyboard::Keycode::A => Some(0x7),
+            sdl2::keyboard::Keycode::S => Some(0x8),
+            sdl2::keyboard::Keycode::D => Some(0x9),
+            sdl2::keyboard::Keycode::F => Some(0xE),
+
+            sdl2::keyboard::Keycode::Z => Some(0xA),
+            sdl2::keyboard::Keycode::X => Some(0x0),
+            sdl2::keyboard::Keycode::C => Some(0xB),
+            sdl2::keyboard::Keycode::V => Some(0xF),
+
+            _ => Option::None,
         }
     }
 
-    fn increase(&mut self) {
+    // fn set_layout(&mut self, layout: &str) {
-        self.0 += 10;
+    //     assert_eq!(layout.len(), self.layout.len());
+    //     self.layout = layout.to_string();
+    // }
+
+    fn get(&mut self, pos: usize) -> bool {
+        self.keys[pos]
     }
 
-    fn decrease(&mut self) {
+    fn being_pressed(&self) -> u8 {
-        self.0 -= 10;
+        for key in 0x0..0x10 {
-    }
+            if self.keys[key] {
-
+                return key as u8
-    fn format(&self) -> String {
+            }
-        let mut res = String::new();
-        if self.0 >= 1000 {
-            res = format!("{:.2}{}", self.0/1000, "MHz");
-        } else {
-            res = format!("{}{}", self.0, "Hz");
         }
-        res
+        return 0x10
+    }
+
+    fn press(&mut self, key: usize) {
+        self.keys[key] = true;
+    }
+
+    fn release(&mut self, key: usize) {
+        self.keys[key] = false;
     }
 }
 
@@ -176,57 +233,455 @@ impl DisplayBuffer {
     fn clear(&mut self) {
         self.0 = [[false; DISPLAY_HEIGHT]; DISPLAY_WIDTH];
     }
+}
 
-    fn random(&mut self) {
+impl OpCodes {
-        for (x, col) in self.0.iter_mut().enumerate() {
+    fn init(opcode: u16) -> OpCodes {
-            for (y, pixel) in col.iter_mut().enumerate() {
+        OpCodes {
-                let mut rng = rand::thread_rng();
+            opcode: opcode,
-                *pixel = rng.gen_range(0..2) == 0;
+            nible_1: ((opcode & 0xF000) >> 12) as u8,
-            }
+            nible_2: ((opcode & 0x0F00) >> 8) as u8,
+            nible_3: ((opcode & 0x00F0) >> 4) as u8,
+            nible_4: (opcode & 0x000F) as u8
+        }
+    }
+
+    fn get_x(&self) -> usize {
+        self.nible_2 as usize
+    }
+
+    fn get_y(&self) -> usize {
+        self.nible_3 as usize
+    }
+
+    fn get_nnn(&self) -> u16 {
+        self.opcode & 0xFFF
+    }
+
+    fn get_nn(&self) -> u8 {
+        (self.opcode & 0xFF) as u8
+    }
+
+    fn get_n(&self) -> u8 {
+        (self.opcode & 0xF) as  u8
+    }
+}
+
+struct CPU {
+    pc: ProgramCounter,
+    index_register: usize,
+    stack: Vec<usize>,
+    delay_timer: Timer,
+    sound_timer: Timer,
+    clock: Timer,
+    registers: Registers,
+    ram: Ram,
+    keypad: Keypad,
+    display_buffer: DisplayBuffer
+}
+
+impl CPU {
+    fn init() -> CPU {
+        CPU {
+            pc: ProgramCounter::init(),
+            index_register: 0,
+            stack: vec![],
+            delay_timer: Timer::init(),
+            sound_timer: Timer::init(),
+            clock: Timer::init(),
+            registers: Registers::init(),
+            ram: Ram::init(),
+            keypad: Keypad::init(),
+            display_buffer: DisplayBuffer::init()
         }
     }
 }
 
 pub fn run() {
-    let mut pc = ProgramCounter::init();
+    let mut cpu = CPU::init();
-    let mut index_register: u16 = 0;
+    cpu.ram.init_fonts();
-    let mut stack: Vec<u16>;
+    // load_rom("src/chip_8/roms/ibm_logo.ch8", &mut cpu);
-    let mut delay_timer = Timer::init();
+    load_rom("src/chip_8/roms/BC_test.ch8", &mut cpu);
-    let mut sound_timer = Timer::init();
+    // load_rom("src/chip_8/roms/test_opcode.ch8", &mut cpu);
-    let mut registers = Registers::init();
+    // load_rom("src/chip_8/roms/HIDDEN.ch8", &mut cpu); // Good to test keyboard
-    let mut ram = Ram::init();
+    // load_rom("src/chip_8/roms/CAVE.ch8", &mut cpu); // Good to test keyboard
-    let mut keypad = Keypad::init();
+    // load_rom("src/chip_8/roms/TRON.ch8", &mut cpu); // Good to test keyboard
-    let mut timing = Timing::init();
+    // load_rom("src/chip_8/roms/PUZZLE.ch8", &mut cpu); // Good to test keyboard?
-    let mut display_buffer = DisplayBuffer::init();
+    // load_rom("src/chip_8/roms/TETRIS.ch8", &mut cpu); // Good to test keyboard? 
+    // load_rom("src/chip_8/roms/delay_timer_test.ch8", &mut cpu);
+    // load_rom("src/chip_8/roms/random_number_test.ch8", &mut cpu);
 
     let sdl_context = sdl2::init().unwrap();
-
     let mut display = crate::chip_8::display::Display::init(&sdl_context, DISPLAY_SCALE);
-
     let mut event_listener = sdl_context.event_pump().unwrap();
-    let mut is_running = true;
+    cpu.clock.clock_hz = 60;
+
     'runner: loop {
         for event in event_listener.poll_iter() {
             match event {
-                sdl2::event::Event::Quit {..} | sdl2::event::Event::KeyDown { 
+                sdl2::event::Event::Quit {..} => break 'runner,
+                sdl2::event::Event::KeyDown { 
                     keycode: Some(sdl2::keyboard::Keycode::Escape), .. } => {break 'runner},
+                sdl2::event::Event::KeyDown { 
+                    keycode: Some(sdl2::keyboard::Keycode::RightBracket), .. } => {
+                    println!("Increasing cpu clock from {} Hz to {} Hz", cpu.clock.clock_hz, cpu.clock.clock_hz + 10);
+                    cpu.clock.clock_hz += 10;
+                },
+                sdl2::event::Event::KeyDown { 
+                    keycode: Some(sdl2::keyboard::Keycode::LeftBracket), .. } => {
+                    println!("Decreasing cpu clock from {} Hz to {} Hz", cpu.clock.clock_hz, cpu.clock.clock_hz - 10);
+                    cpu.clock.clock_hz -= 10;
+                },
+                sdl2::event::Event::KeyDown { keycode: Some(keycode), ..} => {
+                    if let Some(key_index) = cpu.keypad.compute_keycode(keycode) {
+                        cpu.keypad.press(key_index);
+                    }
+                },
+                sdl2::event::Event::KeyUp { keycode: Some(keycode), ..} => {
+                    if let Some(key_index) = cpu.keypad.compute_keycode(keycode) {
+                        cpu.keypad.release(key_index);
+                    }
+                },
                 _ => {}
             }
         }
 
-        display_buffer.random();
+        cpu.delay_timer.tick();
-        display.draw(&display_buffer.0)
+        cpu.sound_timer.tick();
+        if cpu.clock.tick() {
+            let opcode = OpCodes::init(fetch(&mut cpu));
+            decode(&opcode, &mut cpu);
+            if opcode.nible_1 == 0xD {
+                display.draw(&cpu.display_buffer.0)
+            }
+        }
     }
 }
 
-pub fn fetch(ram: Ram, pc: &mut ProgramCounter) -> u16{
+fn load_rom(filename: &str, cpu: &mut CPU) {
-    let opcode = ram.read16(pc.get());
+    let mut f = std::fs::File::open(&filename).expect("no file found");
-    pc.increase();
+    let metadata = std::fs::metadata(&filename).expect("unable to read metadata");
+    let mut buffer = vec![0; metadata.len() as usize];
+    f.read(&mut buffer).expect("buffer overflow");
+    cpu.ram.load_rom(&buffer);
+}
+
+fn fetch(cpu: &mut CPU) -> u16 {
+    let opcode = cpu.ram.read16(cpu.pc.get());
+    cpu.pc.increase();
     opcode
 }
 
-pub fn decode() {}
+fn decode(opcode: &OpCodes, cpu: &mut CPU) {
+    if opcode.opcode == 0x00E0 {
+        op_00e0(cpu);
+    } else if opcode.nible_1 == 0x1 {
+        op1nnn(cpu, opcode.get_nnn() as usize);
+    } else if opcode.opcode == 0x00EE {
+        op00ee(cpu);
+    } else if opcode.nible_1 == 0x2 {
+        op2nnn(cpu, opcode.get_nnn() as usize);
+    } else if opcode.nible_1 == 0x3 {
+        op3xnn(cpu, opcode.get_x(), opcode.get_nn());
+    } else if opcode.nible_1 == 0x4 {
+        op4xnn(cpu, opcode.get_x(), opcode.get_nn());
+    } else if opcode.nible_1 == 0x5 {
+        op5xy0(cpu, opcode.get_x(), opcode.get_y());
+    } else if opcode.nible_1 == 0x9 {
+        op9xy0(cpu, opcode.get_x(), opcode.get_y());
+    } else if opcode.nible_1 == 0x6 {
+        op6xnn(cpu, opcode.get_x(), opcode.get_nn());
+    } else if opcode.nible_1 == 0x7 {
+        op7xnn(cpu, opcode.get_x(), opcode.get_nn());
+    } else if opcode.nible_1 == 0x8 && opcode.nible_4 == 0x0 {
+        op8xy0(cpu, opcode.get_x(), opcode.get_y());
+    } else if opcode.nible_1 == 0x8 && opcode.nible_4 == 0x1 {
+        op8xy1(cpu, opcode.get_x(), opcode.get_y());
+    } else if opcode.nible_1 == 0x8 && opcode.nible_4 == 0x2 {
+        op8xy2(cpu, opcode.get_x(), opcode.get_y());
+    } else if opcode.nible_1 == 0x8 && opcode.nible_4 == 0x3 {
+        op8xy3(cpu, opcode.get_x(), opcode.get_y());
+    } else if opcode.nible_1 == 0x8 && opcode.nible_4 == 0x4 {
+        op8xy4(cpu, opcode.get_x(), opcode.get_y());
+    } else if opcode.nible_1 == 0x8 && opcode.nible_4 == 0x5 {
+        op8xy5(cpu, opcode.get_x(), opcode.get_y());
+    } else if opcode.nible_1 == 0x8 && opcode.nible_4 == 0x6 {
+        op8xy6(cpu, opcode.get_x(), opcode.get_y());
+    } else if opcode.nible_1 == 0x8 && opcode.nible_4 == 0x7 {
+        op8xy7(cpu, opcode.get_x(), opcode.get_y());
+    } else if opcode.nible_1 == 0x8 && opcode.nible_4 == 0xE {
+        op8xye(cpu, opcode.get_x(), opcode.get_y());
+    } else if opcode.nible_1 == 0xA {
+        opannn(cpu, opcode.get_nnn() as usize);
+    } else if opcode.nible_1 == 0xB {
+        opbnnn(cpu, opcode.get_nnn() as usize);
+    } else if opcode.nible_1 == 0xC {
+        opcxnn(cpu, opcode.get_x(), opcode.get_nn());
+    } else if opcode.nible_1 == 0xD {
+        opdxyn(cpu, opcode.get_x(), opcode.get_y(), opcode.get_n());
+    } else if opcode.nible_1 == 0xE && opcode.nible_3 == 0x9 && opcode.nible_4 == 0xE {
+        opex9e(cpu, opcode.get_x());
+    } else if opcode.nible_1 == 0xE && opcode.nible_3 == 0x9 && opcode.nible_4 == 0xE {
+        opex9e(cpu, opcode.get_x());
+    } else if opcode.nible_1 == 0xE && opcode.nible_3 == 0xA && opcode.nible_4 == 0x1 {
+        opexa1(cpu, opcode.get_x());
+    } else if opcode.nible_1 == 0xF && opcode.nible_3 == 0x0 && opcode.nible_4 == 0x7 {
+        opfx07(cpu, opcode.get_x());
+    } else if opcode.nible_1 == 0xF && opcode.nible_3 == 0x1 && opcode.nible_4 == 0x5 {
+        opfx15(cpu, opcode.get_x());
+    } else if opcode.nible_1 == 0xF && opcode.nible_3 == 0x1 && opcode.nible_4 == 0x8 {
+        opfx18(cpu, opcode.get_x());
+    } else if opcode.nible_1 == 0xF && opcode.nible_3 == 0x1 && opcode.nible_4 == 0xE {
+        opfx1e(cpu, opcode.get_x());
+    } else if opcode.nible_1 == 0xF && opcode.nible_3 == 0x0 && opcode.nible_4 == 0xA {
+        opfx0a(cpu, opcode.get_x());
+    } else if opcode.nible_1 == 0xF && opcode.nible_3 == 0x2 && opcode.nible_4 == 0x9 {
+        opfx29(cpu, opcode.get_x());
+    } else if opcode.nible_1 == 0xF && opcode.nible_3 == 0x3 && opcode.nible_4 == 0x3 {
+        opfx33(cpu, opcode.get_x());
+    } else if opcode.nible_1 == 0xF && opcode.nible_3 == 0x5 && opcode.nible_4 == 0x5 {
+        opfx55(cpu, opcode.get_x());
+    } else if opcode.nible_1 == 0xF && opcode.nible_3 == 0x6 && opcode.nible_4 == 0x5 {
+        opfx65(cpu, opcode.get_x());
+    } else {
+        println!{"Unknown instruction: {:04x}", opcode.opcode};
+    }
+}
+// fn execute() {}
 
-pub fn execute() {}
+// fn op_0NNN() {}//ignore
 
+// CLS
+// Clear the display, turning all pixels off
+fn op_00e0(cpu: &mut CPU) {
+    cpu.display_buffer.clear();
+}
 
+// JMP
+// Set PC to NNN, causing the program to jump to that memory location
+fn op1nnn(cpu: &mut CPU, value: usize) {
+    cpu.pc.set(value);
+}
+
+fn op00ee(cpu: &mut CPU) {
+    let value = cpu.stack.pop();
+    match value {
+        Some(value) => {
+            cpu.pc.set(value);
+        }
+        _ => {}
+    }
+}
+
+fn op2nnn(cpu: &mut CPU, value: usize) {
+    cpu.stack.push(cpu.pc.get());
+    cpu.pc.set(value);
+}
+
+fn op3xnn(cpu: &mut CPU, register_x: usize, value: u8) {
+    if cpu.registers.get(register_x) == value {
+        cpu.pc.increase();
+    }
+}
+
+fn op4xnn(cpu: &mut CPU, register_x: usize, value: u8) {
+    if cpu.registers.get(register_x) != value {
+        cpu.pc.increase();
+    }
+}
+
+fn op5xy0(cpu: &mut CPU, register_x: usize, register_y: usize) {
+    if cpu.registers.get(register_x) == cpu.registers.get(register_y) {
+        cpu.pc.increase();
+    }
+}
+
+fn op9xy0(cpu: &mut CPU, register_x: usize, register_y: usize) {
+    if cpu.registers.get(register_x) != cpu.registers.get(register_y) {
+        cpu.pc.increase();
+    }
+}
+
+// SET
+// Set the register VX to the value NN
+fn op6xnn(cpu: &mut CPU, register: usize, value: u8) {
+    cpu.registers.set(register, value);
+}
+
+// ADD
+// Add the value NN to VX. VF is ignored
+fn op7xnn(cpu: &mut CPU, register: usize, value: u8) {
+    let nn = value as u16;
+    let vx = cpu.registers.get(register) as u16;
+    let value = (nn + vx) & 0xFF;
+    let value = value as u8;
+    cpu.registers.set(register, value);
+}
+
+fn op8xy0(cpu: &mut CPU, register_x: usize, register_y: usize) {
+    cpu.registers.set(register_x, cpu.registers.get(register_y));
+}
+
+fn op8xy1(cpu: &mut CPU, register_x: usize, register_y: usize) {
+    let vx = cpu.registers.get(register_x);
+    let vy = cpu.registers.get(register_y);
+    cpu.registers.set(register_x, vx | vy);
+}
+
+fn op8xy2(cpu: &mut CPU, register_x: usize, register_y: usize) {
+    let vx = cpu.registers.get(register_x);
+    let vy = cpu.registers.get(register_y);
+    cpu.registers.set(register_x, vx & vy);
+}
+
+fn op8xy3(cpu: &mut CPU, register_x: usize, register_y: usize) {
+    let vx = cpu.registers.get(register_x);
+    let vy = cpu.registers.get(register_y);
+    cpu.registers.set(register_x, vx ^ vy);
+}
+
+fn op8xy4(cpu: &mut CPU, register_x: usize, register_y: usize) {
+    let vx = cpu.registers.get(register_x) as u16;
+    let vy = cpu.registers.get(register_y) as u16;
+    let value = (vx + vy) & 0xFF;
+    cpu.registers.set(register_x, value as u8);
+}
+
+fn op8xy5(cpu: &mut CPU, register_x: usize, register_y: usize) {
+    let vx = cpu.registers.get(register_x);
+    let vy = cpu.registers.get(register_y);
+    cpu.registers.set(register_x, vx.wrapping_sub(vy));
+    cpu.registers.set(0xF, if vx > vy {1} else {0});
+}
+
+fn op8xy6(cpu: &mut CPU, register_x: usize, register_y: usize) {
+    let vy = cpu.registers.get(register_y);
+    let vx = cpu.registers.get(register_x);
+    cpu.registers.set(register_x, vy >> 1);
+    cpu.registers.set(0xF, vx & 0x1);
+}
+
+fn op8xy7(cpu: &mut CPU, register_x: usize, register_y: usize) {
+    let vx = cpu.registers.get(register_x);
+    let vy = cpu.registers.get(register_y);
+    cpu.registers.set(register_x, vy.wrapping_sub(vx));
+    cpu.registers.set(0xF, if vy > vx {1} else {0});
+}
+
+fn op8xye(cpu: &mut CPU, register_x: usize, register_y: usize) {
+    let vy = cpu.registers.get(register_y);
+    let vx = cpu.registers.get(register_x);
+    cpu.registers.set(register_x, vy << 1);
+    cpu.registers.set(0xF, (vx & 0x80) >> 7);
+    
+}
+
+// IND
+// Set index register I to the value NNN
+fn opannn(cpu: &mut CPU, value: usize) {
+    cpu.index_register = value;
+}
+
+fn opbnnn(cpu: &mut CPU, value: usize) {
+    let v0 = cpu.registers.get(0x0) as usize;
+    cpu.pc.set(value + v0);
+}
+
+fn opcxnn(cpu: &mut CPU, register_x: usize, value: u8) {
+    let mut rng = rand::thread_rng();
+    cpu.registers.set(register_x,rng.gen_range(0x0..0xFF) & value);
+}
+
+// DIS
+// Display
+fn opdxyn(cpu: &mut CPU, register_x: usize, register_y: usize, value: u8) {
+    let mut vf: bool = false;
+    let value = value as usize;
+    let ori_x = cpu.registers.get(register_x) as usize % DISPLAY_WIDTH;
+    let ori_y = cpu.registers.get(register_y) as usize % DISPLAY_HEIGHT;
+
+    for row in 0..value {
+        let y = ori_y + row;
+        if y >= DISPLAY_HEIGHT {
+            break;
+        }
+
+        let sprite = cpu.ram.read8(cpu.index_register + row);
+        for pixel_position in 0..8 {
+            let x = ori_x + pixel_position;
+            if x >= DISPLAY_WIDTH {
+                break;
+            }
+
+            let memory_pixel: bool = (sprite & (1 << (7 - pixel_position))) > 0;
+            let display_pixel: bool = cpu.display_buffer.0[x][y];
+            cpu.display_buffer.0[x][y] = memory_pixel ^ display_pixel;
+            vf = (memory_pixel && display_pixel) || vf;
+        }
+    }
+    cpu.registers.set(0xF, if vf {1} else {0});
+}
+
+fn opex9e(cpu: &mut CPU, register_x: usize) {
+    if cpu.keypad.get(cpu.registers.get(register_x) as usize) {
+        cpu.pc.increase();
+    }
+}
+
+fn opexa1(cpu: &mut CPU, register_x: usize) {
+    if !cpu.keypad.get(cpu.registers.get(register_x) as usize) {
+        cpu.pc.increase();
+    }
+}
+
+fn opfx07(cpu: &mut CPU, register_x: usize) {
+    cpu.registers.set(register_x, cpu.delay_timer.tick);
+}
+
+fn opfx15(cpu: &mut CPU, register_x: usize) {
+    cpu.delay_timer.tick = cpu.registers.get(register_x);
+}
+
+fn opfx18(cpu: &mut CPU, register_x: usize) {
+    cpu.sound_timer.tick = cpu.registers.get(register_x);
+}
+
+fn opfx1e(cpu: &mut CPU, register_x: usize) {
+    cpu.index_register += cpu.registers.get(register_x) as usize;
+}
+
+fn opfx0a(cpu: &mut CPU, register_x: usize) {
+    if cpu.keypad.being_pressed() == 0x10 {
+        cpu.pc.decrement();
+    } else {
+        cpu.registers.set(register_x, cpu.keypad.being_pressed());
+    }
+}
+
+fn opfx29(cpu: &mut CPU, register_x: usize) {
+    let char = (cpu.registers.get(register_x) & 0xF) as usize;
+    cpu.index_register = 0x50 + char * 5;
+}
+
+fn opfx33(cpu: &mut CPU, register_x: usize) {
+    let vx = cpu.registers.get(register_x);
+    cpu.ram.write8(cpu.index_register, vx / 100);
+    cpu.ram.write8(cpu.index_register + 1, vx / 10 % 10);
+    cpu.ram.write8(cpu.index_register + 2, vx % 10);
+}
+
+fn opfx55(cpu: &mut CPU, register_x: usize) {
+    let i = cpu.index_register;
+    for regs in 0x0..(register_x + 1) {
+        cpu.ram.write8(i + regs, cpu.registers.get(regs));
+    }
+    // cpu.index_register += register_x + 1;
+}
+
+fn opfx65(cpu: &mut CPU, register_x: usize) {
+    let i = cpu.index_register;
+    for regs in 0x0..(register_x + 1) {
+        cpu.registers.set(regs, cpu.ram.read8(i + regs));
+    }
+    // cpu.index_register += register_x + 1;
+}

src/chip_8/display.rs

@@ -1,21 +1,15 @@
-use sdl2::pixels::Color;
-use sdl2::rect::Rect;
-use sdl2::render::Canvas;
-use sdl2::Sdl;
-use sdl2::video::Window;
-
 const WIDTH: usize = 64;
 const HEIGHT: usize = 32;
 
 pub struct Display {
-    canvas: Canvas<Window>,
+    canvas: sdl2::render::Canvas<sdl2::video::Window>,
     scale: u32,
-    off_color: Color,
+    off_color: sdl2::pixels::Color,
-    on_color: Color
+    on_color: sdl2::pixels::Color
 }
 
 impl Display {
-    pub fn init(sdl_context: &Sdl, scale: u32) -> Display {
+    pub fn init(sdl_context: &sdl2::Sdl, scale: u32) -> Display {
         let video_subsystem = sdl_context.video().unwrap();
         
         let window = video_subsystem.window("Chip-8", WIDTH as u32 * scale,  
@@ -29,8 +23,8 @@ impl Display {
         Display {
             canvas: canvas,
             scale: scale,
-            off_color: Color::RGB(0, 0, 0),
+            off_color: sdl2::pixels::Color::RGB(0, 0, 0),
-            on_color: Color::RGB(255, 255, 255)
+            on_color: sdl2::pixels::Color::RGB(255, 255, 255)
         }
     }
 
@@ -46,7 +40,7 @@ impl Display {
                     let y = (y as u32 * self.scale) as i32;
                     let width = self.scale;
                     let height = self.scale;
-                    self.canvas.fill_rect(Rect::new(x, y, width, height))
+                    self.canvas.fill_rect(sdl2::rect::Rect::new(x, y, width, height))
                         .expect("Failed to draw pixel");
                 }
             }