Add editorconfig file

Things still need to be ironed out, mainly in the display crate, but the system
is working

.editorconfig

@@ -0,0 +1,5 @@
+[*.rs]
+indent_style = tab
+indent_size = 4
+max_line_length = 100
+

.gitignore

@@ -1 +1,15 @@
 /target
+/cgmath
+*.log
+*.bin
+*.bin.*
+*.bkp
+*.perf
+*.svg
+*.lock
+perf.*
+tags
+
+
+
+

Cargo.toml

@@ -1,8 +1,19 @@
 [package]
 name = "nes_emulator"
 version = "0.1.0"
-edition = "2018"
+edition = "2021"
 
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
+log = "0.4.14"
+chrono = "0.4.19"
+fern = "0.6.0"
+bitflags = "1.3.2"
+rusttype = "0.9.2"
+canvas = "0.1.0"
+
+[patch.crates-io]
+canvas = { git = "https://git.steins7.ovh/Steins7/canvas.git", branch = "dev" }
+cgmath = { path = "cgmath" }
+

doc/nes_architecture

@@ -0,0 +1 @@
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src/bus.rs

@@ -0,0 +1,165 @@
+use std::{
+	fmt,
+	rc::Rc,
+	cell::RefCell,
+};
+
+use crate::{
+	utils::DisplayBuffer,
+	peripherals::{Peripheral, Ram, Mapper, Ppu},
+};
+
+pub struct Bus<M: Mapper> {
+	ram: Ram<0x800>,
+	ppu: Ppu<M>,
+	apu: Ram<0x1F>,//TODO
+	cartridge: Rc<RefCell<M>>,
+}
+
+impl<M: Mapper> fmt::Debug for Bus<M> {
+
+	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+		f.debug_struct("Bus")
+			.field("ram", &self.ram)
+			.finish_non_exhaustive()
+	}
+}
+
+impl<M: Mapper> Peripheral for Bus<M> {
+
+	fn read_addr(&self, addr: u16) -> u8 {
+
+		match addr {
+			0x0000..=0x1FFF => self.ram.read_addr(addr % 0x0800),    //RAM is mirrored 3 times
+			0x2000..=0x3FFF => self.ppu.read_addr(addr % 0x8),       //PPU is mirrored every 8 bytes
+			0x4000..=0x401F => self.apu.read_addr(addr),
+			0x4020..=0xFFFF => self.cartridge.borrow().read_addr(addr),
+		}
+	}
+
+	fn write_addr(&mut self, addr: u16, data: u8) {
+
+		match addr {
+			0x0000..=0x1FFF => self.ram.write_addr(addr % 0x0800, data),
+			0x2000..=0x3FFF => self.ppu.write_addr(addr % 0x8, data),
+			0x4000..=0x401F => self.apu.write_addr(addr, data),
+			0x4020..=0xFFFF => self.cartridge.borrow_mut().write_addr(addr, data),
+		};
+	}
+}
+
+impl<M: Mapper> Bus<M> {
+
+	pub fn new(mapper: Rc<RefCell<M>>,
+		screen: Rc<RefCell<DisplayBuffer>>,
+		pattern_table: Rc<RefCell<DisplayBuffer>>)
+		-> Self {
+
+			let mut ram = Ram::<0x800>::new();
+
+			//TODO temporary for instruction tests
+			ram.buffer[0x01] = 0xE9; //sbc
+			ram.buffer[0x02] = (-3 as i8) as u8;
+			ram.buffer[0x03] = 0x09;
+			ram.buffer[0x04] = 0x00;
+			ram.buffer[0x05] = 0xA9; //lda
+			ram.buffer[0x06] = 0x01;
+			ram.buffer[0x07] = 0x4C; //jmp
+			ram.buffer[0x08] = 0x00;
+			ram.buffer[0x09] = 0x00;
+			ram.buffer[0x0A] = 0x2A; //fn rol
+			ram.buffer[0x0B] = 0x90; //bcc
+			ram.buffer[0x0C] = (-3 as i8) as u8;
+			ram.buffer[0x0D] = 0x60; //rts
+			ram.buffer[0x0E] = 0xFD;
+			ram.buffer[0x0F] = 0x01;
+			ram.buffer[0x10] = 0x21;
+			ram.buffer[0x11] = 0x9F;
+			ram.buffer[0x12] = 0x31;
+			ram.buffer[0x13] = 0xB0;
+
+			// boundary
+			ram.buffer[0x14] = 0x3D;
+			ram.buffer[0x15] = 0xFF;
+			ram.buffer[0x16] = 0x02;
+			ram.buffer[0x17] = 0x39;
+			ram.buffer[0x18] = 0xFE;
+			ram.buffer[0x19] = 0x02;
+			ram.buffer[0x1A] = 0x31;
+			ram.buffer[0x1B] = 0xB2;
+
+
+			// ptr to val
+			ram.buffer[0xA0] = 0xFF;
+			ram.buffer[0xA1] = 0x01;
+
+			// ptr to val as table
+			ram.buffer[0xB0] = 0xFD;
+			ram.buffer[0xB1] = 0x01;
+			ram.buffer[0xB2] = 0xFE; //boundary
+			ram.buffer[0xB3] = 0x02;
+
+			// zero page val
+			ram.buffer[0xFF] = 0x01;
+
+			// val
+			ram.buffer[0x01FF] = 0x01;
+			ram.buffer[0x02FF] = 0xFF; //boundary
+			ram.buffer[0x0300] = 0x03;
+
+			// ptr to test
+			ram.buffer[0x030F] = 0xFF;
+			ram.buffer[0x0310] = 0x03;
+
+			// jmp test
+			ram.buffer[0x0400] = 0xE6;
+
+			Bus {
+				ram,
+				ppu: Ppu::new(mapper.clone(), screen, pattern_table),
+				apu: Ram::<0x1F>::new(),
+				cartridge: mapper,
+			}
+		}
+
+	pub fn tick(&mut self) {
+		self.ppu.tick();
+	}
+}
+
+/// special Bus only used for testing the emulator
+pub struct FileBus {
+	mem: Ram<0x10000>,
+}
+
+impl fmt::Debug for FileBus {
+
+	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+		f.debug_struct("Bus")
+			.field("mem", &self.mem)
+			.finish()
+	}
+}
+
+impl Peripheral for FileBus {
+
+	fn read_addr(&self, addr: u16) -> u8 {
+		self.mem.read_addr(addr)    //RAM is mirrored 3 times
+	}
+
+	fn write_addr(&mut self, addr: u16, data: u8) {
+		self.mem.write_addr(addr % 0x0800, data)
+	}
+}
+
+impl FileBus {
+
+	#[allow(dead_code)]
+	pub fn new() -> Self {
+		FileBus {
+			mem: Ram::from_file("6502_functional_test.bin"),
+		}
+	}
+}
+
+

src/main.rs

@@ -1,3 +1,261 @@
-fn main() {
-    println!("Hello, world!");
+#[allow(unused_imports)]
+use log::{debug, error, info, trace, warn};
+
+use std::{
+	rc::Rc,
+	cell::RefCell,
+	time::Instant,
+	fmt::Write,
+};
+
+mod cpu;
+use cpu::Cpu;
+
+mod bus;
+mod peripherals;
+use peripherals::mapper::Nrom128;
+
+mod utils;
+
+use canvas::{
+	Application,
+	Canvas,
+	sprite::{Sprite, TextureSprite, TextSprite, Center},
+	utils::{Size, Color, Position},
+};
+use utils::DisplayBuffer;
+
+struct EmulatorState {
+	pub screen: Rc<RefCell<DisplayBuffer>>,
+	pub screen_sprite: TextureSprite,
+
+	#[allow(dead_code)]
+	pub pattern_table: Rc<RefCell<DisplayBuffer>>,
+	pub pattern_sprite: TextureSprite,
+
+	pub fps_text: TextSprite,
+	pub debug_text: TextSprite,
+
+	pub cpu: Cpu<Nrom128>,
+
+	pub start: Instant,
 }
+
+struct NesEmulator {}
+
+impl Application<EmulatorState> for NesEmulator {
+
+	fn init(canvas: &mut Canvas) -> Result<EmulatorState, &'static str> {
+
+		let start = Instant::now();
+
+		let screen_texture = canvas
+			.create_texture(Size {w: 256, h: 240}, Some(Color::RED.into()))
+			.unwrap();
+		let mut screen_sprite = canvas.create_texture_sprite(Size {w: 256 * 2, h: 240 * 2});
+		screen_sprite.set_texture(screen_texture.clone(), None, 0.5);
+		screen_sprite.set_center(Center::BotLeft);
+		screen_sprite.set_position(Position {x: 100, y: 200});
+		let screen = Rc::new(RefCell::new(DisplayBuffer::from_texture(screen_texture)));
+
+		let pattern_texture = canvas
+			.create_texture(Size {w: 256, h: 128}, Some(Color::BLUE.into()))
+			.unwrap();
+		let mut pattern_sprite = canvas.create_texture_sprite(Size {w: 256, h: 128});
+		pattern_sprite.set_texture(pattern_texture.clone(), None, 1.0);
+		pattern_sprite.set_center(Center::BotLeft);
+		pattern_sprite.set_position(Position {x: 100, y: 50});
+		let pattern_table = Rc::new(RefCell::new(DisplayBuffer::from_texture(pattern_texture)));
+
+		let mut fps_text = canvas.create_text_sprite("00", Size {w: 30, h: 20}, 20.0);
+		fps_text.set_center(Center::TopLeft);
+		fps_text.set_position(Position {x:0, y:720});
+
+		let mut debug_text = canvas.create_text_sprite("00", Size {w: 300, h: 600}, 20.0);
+		debug_text.set_center(Center::BotLeft);
+		debug_text.set_position(Position {x:700, y:50});
+
+		let mapper = Rc::new(RefCell::new(Nrom128::new(false)));
+		let cpu = Cpu::new(mapper, screen.clone(), pattern_table.clone());
+
+		canvas.clear();
+		canvas.update();
+
+		Ok(EmulatorState {
+			screen,
+			screen_sprite,
+			pattern_table,
+			pattern_sprite,
+			fps_text,
+			debug_text,
+			cpu,
+			start,
+		})
+	}
+
+	fn tick(state: &mut EmulatorState, canvas: &mut Canvas) -> Result<(), &'static str> {
+
+		let frame_time = state.start.elapsed().as_secs_f32();
+		state.start = Instant::now();
+		canvas.clear();
+		state.cpu.tick();
+
+		if state.screen.borrow_mut().is_ready {
+			state.screen.borrow_mut().is_ready = false;
+		}
+
+		canvas.draw(&mut state.screen_sprite);
+		canvas.draw(&mut state.pattern_sprite);
+
+		let mut fps_str = String::new();
+		write!(fps_str, "{} fps", 1.0/frame_time).unwrap();
+		state.fps_text.set_text(&fps_str);
+		canvas.draw(&mut state.fps_text);
+
+		let mut debug_str = String::new();
+		write!(debug_str, "{:#?}", state.cpu).unwrap();
+		state.debug_text.set_text(&debug_str);
+		canvas.draw(&mut state.debug_text);
+
+		canvas.update();
+
+		Ok(())
+	}
+}
+
+fn main() -> Result<(), &'static str> {
+
+	setup_logger()
+		.map_err(|_| "Failed to setup logger")?;
+	canvas::run_canvas("NES emulator", Size {w: 1280, h: 720}, NesEmulator {});
+}
+
+//    use utils::{Pixel, PixelBuffer, FontRenderer, DisplayBuffer};
+//	use glutin::{
+//		dpi::LogicalSize,
+//        event_loop::EventLoop,
+//	};
+//    use mini_gl_fb::config;
+//    use std::{
+//        fmt::Write,
+//        rc::Rc,
+//        cell::RefCell,
+//        time::Instant,
+//    };
+//    use peripherals::mapper::Nrom128;
+//	use std::ops::Deref;
+//
+//    // setup
+//    setup_logger().map_err(|_| "Failed to setup logger")?;
+//
+//    let mut event_loop = EventLoop::new();
+//    let config = config! {
+//        window_title: "Test".to_string(),
+//        window_size: LogicalSize::new(1280.0, 720.0),
+//        invert_y: false,
+//    };
+//    let mut fb = mini_gl_fb::get_fancy(config, event_loop.deref());
+//    let mut buffer = PixelBuffer::new(1280, 720);
+//    let mut renderer = FontRenderer::new(20.0, [0u8, 0, 0]);
+//
+//    // first image
+//    let mapper = Rc::new(RefCell::new(Nrom128::new(false)));
+//    let mut screen = Rc::new(RefCell::new(DisplayBuffer::new(256, 240)));
+//    let pattern_table = Rc::new(RefCell::new(DisplayBuffer::new(256, 128)));
+//    let mut cpu = Cpu::new(mapper, screen.clone(), pattern_table.clone());
+//    let mut debug_str = String::new();
+//    //write!(debug_str, "{:#?}", cpu).unwrap();
+//    buffer.fill([0, 0], [1280, 720], Pixel::rgba(255, 255, 255, 255));
+//    //renderer.draw(&mut buffer, &debug_str, [20, 20], [760, 560]);
+//
+//    let vec: Vec<[u8; 4]> = (&buffer).into();
+//    fb.update_buffer(&vec);
+//    let mut update = false;
+//    let mut refresh = true;
+//    let mut start = Instant::now();
+//
+//    // event loop
+//    fb.glutin_handle_basic_input(&mut event_loop, |fb, input| {
+//        use glutin::event::VirtualKeyCode;
+//
+//        // wait for input before updating
+//
+//        // close if escape is pressed
+//        if input.key_pressed(VirtualKeyCode::Escape) {
+//            return false
+//        }
+//
+//        // execute next cpu instruction (step mode)
+//        if input.key_pressed(VirtualKeyCode::S) {
+//            cpu.tick();
+//            refresh = true;
+//        }
+//
+//        if input.key_pressed(VirtualKeyCode::R) {
+//            update = true;
+//        }
+//
+//        if input.key_pressed(VirtualKeyCode::C) {
+//            update = false;
+//            refresh = true;
+//        }
+//
+//        if update {
+//            cpu.tick();
+//
+//            if screen.borrow_mut().is_ready {
+//                screen.borrow_mut().is_ready = false;
+//                refresh = true;
+//            }
+//
+//            input.wait = false;
+//        } else {
+//            input.wait = true;
+//        }
+//
+//        if refresh {
+//            refresh = false;
+//
+//            let frame_time = start.elapsed().as_secs_f32();
+//            start = Instant::now();
+//
+//            let mut debug_str = String::new();
+//            buffer.fill([0, 0], [1280, 720], Pixel::rgba(255, 255, 255, 255));
+//            write!(debug_str, "{} fps", 1.0/frame_time);
+//            renderer.draw(&mut buffer, &debug_str, [1, 1], [20, 20]);
+//            debug_str = String::new();
+//            write!(debug_str, "{:#?}", cpu).unwrap();
+//            renderer.draw(&mut buffer, &debug_str, [600, 20], [760, 560]);
+//            buffer.embbed([20, 20], &screen.borrow().buffer, 2);
+//
+//            let vec: Vec<[u8; 4]> = (&buffer).into();
+//            fb.update_buffer(&vec);
+//        }
+//
+//        true
+//    });
+//
+//    Ok(())
+//}
+
+fn setup_logger() -> Result<(), fern::InitError> {
+
+	fern::Dispatch::new()
+		.format(|out, message, record| {
+			out.finish(format_args!(
+					"{}[{}][{}] {}",
+					chrono::Local::now().format("[%H:%M:%S]"),
+					record.target(),
+					//record.file(),
+					record.level(),
+					message
+			))
+		})
+	.level(log::LevelFilter::Error)
+		.chain(std::io::stdout())
+		.chain(fern::log_file("output.log")?)
+		.apply()?;
+
+	Ok(())
+}
+

src/peripherals.rs

@@ -0,0 +1,17 @@
+
+mod ram;
+mod ppu;
+pub mod mapper;
+
+pub use ram::Ram;
+pub use ppu::Ppu;
+pub use mapper::Mapper;
+
+//--------------------------------------------------------------------------------------------------
+pub trait Peripheral {
+
+    fn read_addr(&self, addr: u16) -> u8;
+
+    fn write_addr(&mut self, addr: u16, data: u8);
+}
+

src/peripherals/mapper.rs

@@ -0,0 +1,17 @@
+use super::Peripheral;
+
+mod nrom;
+pub use nrom::Nrom128;
+
+//--Mapper struct-----------------------------------------------------------------------------------
+///A trait used as API for the different implementations of mappers in cartridges
+///
+///A Mapper is a special `Peripheral` that can also be read by the `Ppu`. The exact memory layout
+///is defined by the implementation
+pub trait Mapper: Peripheral {
+
+    ///read the specified 16 bits address using the ppu bus
+    fn ppu_read_addr(&self, addr: u16) -> u8;
+}
+
+

src/peripherals/mapper/nrom.rs

@@ -0,0 +1,71 @@
+use super::{
+    Mapper,
+    super::{
+        Peripheral,
+        Ram,
+    },
+};
+
+pub struct Nrom128 {
+    prg_rom: Ram<0x4000>,   //16KiB
+    prg_ram: Ram<0x2000>,   //8KiB
+    chr_rom: Ram<0x2000>,   //8KiB
+    v_ram: Ram<0x0800>,     //2KiB
+    vertical: bool,
+}
+
+impl Peripheral for Nrom128 {
+
+    fn read_addr(&self, addr: u16) -> u8 {
+
+        match addr {
+            0x6000..=0x7FFF => self.prg_ram.read_addr(addr - 0x6000),
+            0x8000..=0xFFFF => self.prg_rom.read_addr((addr - 0x8000) % 0x4000),
+            //mirrored every 16KiB
+            _ => panic!("{}: Invalid address", addr),
+        }
+    }
+
+    fn write_addr(&mut self, addr: u16, data: u8) {
+
+        match addr {
+            0x6000..=0x7FFF => self.prg_ram.write_addr(addr - 0x6000, data),
+            _ => (), //writes are ignored for rom or invald addresses
+        }
+   }
+}
+
+impl Mapper for Nrom128 {
+
+    fn ppu_read_addr(&self, addr: u16) -> u8 {
+
+        match addr {
+            0x0000..=0x1FFF => self.chr_rom.read_addr(addr),
+            0x2000..=0x3EFF => {
+                match self.vertical {
+                    false => match (addr - 0x2000) % 0x0FFF {
+                        0x0000..=0x07FF => self.v_ram.read_addr(addr % 0x0400),
+                        0x0800..=0x0FFF => self.v_ram.read_addr((addr % 0x0400) + 0x0800),
+                        _ => panic!("Unexpected behaviour"),
+                    },
+                    true => self.v_ram.read_addr(addr % 0x0800),
+                }},
+            _ => panic!("{}: Invalid ppu address", addr),
+        }
+    }
+}
+
+impl Nrom128 {
+
+    pub fn new(vertical: bool) -> Self {
+
+        Self {
+            prg_rom: Ram::<0x4000>::new(),
+            prg_ram: Ram::<0x2000>::new(),
+            chr_rom: Ram::<0x2000>::new(),
+            v_ram: Ram::<0x0800>::new(),
+            vertical,
+        }
+    }
+}
+

src/peripherals/ppu.rs

@@ -0,0 +1,174 @@
+#[allow(unused_imports)]
+use log::{debug, error, info, trace, warn};
+
+use std::{
+    rc::Rc,
+    cell::RefCell,
+};
+
+use bitflags::bitflags;
+
+use crate::{
+    peripherals::{Peripheral, Ram, Mapper},
+    utils::DisplayBuffer,
+};
+
+//--------------------------------------------------------------------------------------------------
+bitflags! {
+    struct PpuCtrl: u8 {
+        const Nl = 0x1 << 0;
+        const Nh = 0x1 << 1;
+        const I = 0x1 << 2;
+        const S = 0x1 << 3;
+        const B = 0x1 << 4;
+        const H = 0x1 << 5;
+        const P = 0x1 << 6;
+        const V = 0x1 << 7;
+    }
+}
+
+bitflags! {
+    struct PpuMask: u8 {
+        const Gr = 0x1 << 0;
+        const m = 0x1 << 1;
+        const M = 0x1 << 2;
+        const b = 0x1 << 3;
+        const s = 0x1 << 4;
+        const R = 0x1 << 5;
+        const G = 0x1 << 6;
+        const B = 0x1 << 7;
+    }
+}
+
+bitflags! {
+    struct PpuStatus: u8 {
+        const O = 0x1 << 5;
+        const S = 0x1 << 6;
+        const V = 0x1 << 7;
+    }
+}
+
+#[allow(dead_code)]
+pub struct Ppu<M: Mapper> {
+    vbus: Rc<RefCell<M>>,
+    ppu_ctrl: PpuCtrl,
+    ppu_mask: PpuMask,
+    ppu_status: PpuStatus,
+    scroll: u8,
+    addr: u8,
+    data: u8,
+    oam_addr: u8,
+    oam_data: u8,
+    oam_dma: u8,
+    oam: Ram<0x100>,
+    blanking: bool,
+    line: u16,
+    dot: u16,
+    nmi: bool,
+
+    // outputs
+    screen: Rc<RefCell<DisplayBuffer>>,
+    pattern_table: Rc<RefCell<DisplayBuffer>>,
+}
+
+impl<M: Mapper> Peripheral for Ppu<M> {
+
+    fn read_addr(&self, _addr: u16) -> u8 {
+        unimplemented!();
+    }
+
+    fn write_addr(&mut self, _addr: u16, _data: u8) {
+        unimplemented!();
+    }
+}
+
+impl<M: Mapper> Ppu<M> {
+
+    pub fn new(mapper: Rc<RefCell<M>>,
+               screen: Rc<RefCell<DisplayBuffer>>,
+               pattern_table: Rc<RefCell<DisplayBuffer>>)
+        -> Self {
+
+        Self {
+            vbus: mapper,
+            ppu_ctrl: PpuCtrl::from_bits(0).unwrap(),
+            ppu_mask: PpuMask::from_bits(0).unwrap(),
+            ppu_status: PpuStatus::from_bits(0).unwrap(),
+            scroll: 0,
+            addr: 0,
+            data: 0,
+            oam_addr: 0,
+            oam_data: 0,
+            oam_dma: 0,
+            oam: Ram::<0x100>::new(),
+            blanking: false,
+            line: 0,
+            dot: 0,
+            nmi: false,
+
+            screen,
+            pattern_table,
+        }
+    }
+
+    pub fn poll_nmi(&mut self) -> bool {
+        let ret = self.nmi;
+        if self.nmi {
+            self.nmi = false;
+        }
+        ret
+    }
+
+    pub fn tick(&mut self) {
+        use crate::utils::Pixel;
+
+        self.screen.borrow_mut()
+            .set_pixel(
+                self.dot.into(),
+                self.line.into(),
+                Pixel::rgba(self.data.into(), 0, 0, 255));
+
+        self.execute();
+    }
+
+    fn execute(&mut self) {
+
+        match self.line {
+            0..=239 => self.render_frame(),
+            241 => {
+                if self.dot == 1 {
+                    self.ppu_status.set(PpuStatus::V, true);
+                }
+            }
+            261 => {
+                if self.dot == 1 {
+                    self.ppu_status.set(PpuStatus::V | PpuStatus::S | PpuStatus::O, false);
+                }
+                self.render_frame();
+
+                //last line, got back to first line
+                self.line = 0;
+            }
+            240..=260 => (), //vertical blank
+            _ => panic!("{}: Invalid line number", self.line),
+        }
+
+        self.dot = (self.dot + 1) % 256;
+        if self.dot == 0 {
+            self.line = (self.line + 1) % 240;
+            if self.line == 0 {
+                self.screen.borrow_mut().is_ready = true;
+                self.data = (self.data + 1) % 255;
+            }
+        }
+    }
+
+    fn render_frame(&mut self) {
+
+        match self.dot {
+            0 => (),
+            33..=40 => (),
+            _ => (),
+        }
+    }
+}

src/peripherals/ram.rs

@@ -0,0 +1,59 @@
+use std::fmt;
+
+use super::Peripheral;
+
+//--------------------------------------------------------------------------------------------------
+pub struct Ram<const SIZE: usize> {
+    pub buffer: [u8; SIZE],
+}
+
+impl<const SIZE: usize> fmt::Debug for Ram<SIZE> {
+
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        for i in 0x100..=0x1FF {
+            if i%0x10 == 0 {
+                f.write_fmt(format_args!("\n    {:0>4X}", i))?;
+            }
+            f.write_fmt(format_args!(" {:0>2X}", self.buffer[i]))?
+        }
+
+        Ok(())
+    }
+}
+
+impl<const SIZE: usize> Peripheral for Ram<SIZE> {
+
+    fn read_addr(&self, addr: u16) -> u8 {
+        self.buffer[addr as usize]
+    }
+
+    fn write_addr(&mut self, addr: u16, data: u8) {
+        self.buffer[addr as usize] = data;
+    }
+}
+
+impl<const SIZE: usize> Ram<SIZE> {
+
+    pub fn new() -> Self {
+
+        Ram {
+            buffer: [0u8; SIZE],
+        }
+    }
+
+    pub fn from_file(file: &str) -> Self {
+        use std::{
+            fs::File,
+            io::Read,
+        };
+
+        let mut f = File::open(file).unwrap();
+        let mut buffer = [0u8; SIZE];
+        f.read_exact(&mut buffer).unwrap();
+
+        Ram {
+            buffer,
+        }
+    }
+}
+

src/utils.rs

@@ -0,0 +1,124 @@
+#[allow(unused_imports)]
+use log::{debug, error, info, trace, warn};
+
+mod display_buffer;
+pub use display_buffer::DisplayBuffer;
+
+//--------------------------------------------------------------------------------------------------
+/* Pixel struct */
+
+#[derive(Clone, Copy)]
+pub struct Pixel {
+    r: u8,
+    g: u8,
+    b: u8,
+    a: u8,
+}
+
+impl Pixel {
+
+    pub fn rgba(r: u8, g: u8, b: u8, a: u8) -> Self {
+        Pixel {r, g, b, a, }
+    }
+}
+
+impl std::ops::Add for Pixel {
+    type Output = Self;
+
+    fn add(self, other: Self) -> Self {
+
+        let alpha = other.a as f32 / 255.0;
+        let inv_alpha = 1.0 - alpha;
+
+        Pixel {
+            r: ((self.r as f32)*inv_alpha + (other.r as f32)*alpha) as u8,
+            g: ((self.g as f32)*inv_alpha + (other.g as f32)*alpha) as u8,
+            b: ((self.b as f32)*inv_alpha + (other.b as f32)*alpha) as u8,
+            a: 255,
+        }
+    }
+}
+
+impl std::ops::AddAssign for Pixel {
+
+    fn add_assign(&mut self, other: Self) {
+
+        let alpha = other.a as f32 / 255.0;
+        let inv_alpha = 1.0 - alpha;
+
+        self.r = ((self.r as f32)*inv_alpha + (other.r as f32)*alpha) as u8;
+        self.g = ((self.g as f32)*inv_alpha + (other.g as f32)*alpha) as u8;
+        self.b = ((self.b as f32)*inv_alpha + (other.b as f32)*alpha) as u8;
+    }
+}
+
+impl From<&Pixel> for [u8; 4] {
+    fn from(pixel: &Pixel) -> Self {
+        [pixel.r, pixel.g, pixel.b, pixel.a]
+    }
+}
+
+impl From<[u8; 4]> for Pixel {
+    fn from(array: [u8; 4]) -> Self {
+        Pixel::rgba(array[0], array[1], array[2], array[3])
+    }
+}
+
+//--------------------------------------------------------------------------------------------------
+/* PixelBuffer struct */
+
+pub struct PixelBuffer {
+    buffer: Vec<Pixel>,
+    w: usize,
+    h: usize,
+}
+
+impl PixelBuffer {
+
+    pub fn new(w: usize, h: usize) -> Self {
+        PixelBuffer {
+            buffer: vec![Pixel::rgba(255u8, 255u8, 255u8, 255); h * w],
+            w,
+            h,
+        }
+    }
+
+    pub fn put_pixel(&mut self, x: usize, y: usize, pixel: Pixel) {
+        self.buffer[x + y*self.w] += pixel
+    }
+
+    pub fn get_pixel(&self, x: usize, y: usize) -> Pixel {
+        self.buffer[x + y*self.w]
+    }
+
+    pub fn fill(&mut self, origin: [usize; 2], size: [usize; 2], pixel: Pixel) {
+        for x in origin[0]..(origin[0] + size[0]) {
+            for y in origin[1]..(origin[1] + size[1]) {
+                self.buffer[x + y*self.w] = pixel;
+            }
+        }
+    }
+
+    pub fn embbed(&mut self, origin: [usize; 2], buffer: &Self, scale: usize) {
+        let [w, h] = buffer.get_dimensions();
+
+        for y in 0..(h*scale) {
+            for x in 0..(w*scale) {
+                self.put_pixel(x + origin[0], y + origin[1], buffer.get_pixel(x/scale, y/scale));
+            }
+        }
+    }
+
+    pub fn get_dimensions(&self) -> [usize; 2] {
+        [self.w, self.h]
+    }
+}
+
+impl From<&PixelBuffer> for Vec<[u8; 4]> {
+    fn from(buffer: &PixelBuffer) -> Self {
+       buffer.buffer.iter()
+           .map(|pixel| pixel.into())
+           .collect()
+    }
+}
+

src/utils/display_buffer.rs

@@ -0,0 +1,33 @@
+use super::Pixel;
+
+use canvas::texture::TextureHandle;
+
+//--------------------------------------------------------------------------------------------------
+pub struct DisplayBuffer {
+	pub is_ready: bool,
+
+	texture: TextureHandle,
+}
+
+impl DisplayBuffer {
+
+	pub fn from_texture(texture: TextureHandle) -> Self {
+
+		Self {
+			texture,
+			is_ready: false,
+		}
+	}
+
+	pub fn set_pixel(&mut self, x: usize, y: usize, pixel: Pixel) {
+		self.texture.set_pixel(
+			canvas::utils::Position {x: x.try_into().unwrap(), y: y.try_into().unwrap()},
+			canvas::utils::Pixel {
+				r: pixel.r,
+				g: pixel.g,
+				b: pixel.b,
+				a: pixel.a,
+			});
+	}
+}
+