#![no_std]
#![feature(ptr_internals)]
#![feature(const_option)]
use core::{fmt::{self, Write}, ptr::Unique};
use volatile::Volatile;
#[cfg(target_arch = "x86_64")] const VGA_BUFFER_VIRTUAL_ADDR: usize = 0xb8000;
const BUFFER_HEIGHT: usize = 25;
const BUFFER_WIDTH: usize = 80;
type VgaTextBufferLine = [Volatile<ScreenChar>; BUFFER_WIDTH];
type VgaTextBuffer = [VgaTextBufferLine; BUFFER_HEIGHT];
pub struct VgaBuffer {
column_position: usize,
buffer: Unique<VgaTextBuffer>,
}
impl VgaBuffer {
pub const fn new() -> Self {
VgaBuffer {
column_position: 0,
buffer: Unique::new((VGA_BUFFER_VIRTUAL_ADDR) as *mut _).unwrap(),
}
}
pub fn write_byte(&mut self, byte: u8) {
match byte {
b'\n' => self.new_line(),
byte => {
if self.column_position >= BUFFER_WIDTH {
self.new_line();
}
let row = BUFFER_HEIGHT - 1;
let col = self.column_position;
self.buffer()[row][col].write(
ScreenChar {
ascii_character: byte,
color_code: ColorCode::default(),
}
);
self.column_position += 1;
}
}
}
fn new_line(&mut self) {
for row in 1..BUFFER_HEIGHT {
for col in 0..BUFFER_WIDTH {
let character = self.buffer()[row][col].read();
self.buffer()[row - 1][col].write(character);
}
}
self.clear_row(BUFFER_HEIGHT - 1);
self.column_position = 0;
}
fn clear_row(&mut self, row: usize) {
let blank = ScreenChar {
ascii_character: b' ',
color_code: ColorCode::default()
};
for col in 0..BUFFER_WIDTH {
self.buffer()[row][col].write(blank);
}
}
fn buffer(&mut self) -> &mut [VgaTextBufferLine] {
unsafe { self.buffer.as_mut() }
}
}
impl Write for VgaBuffer {
fn write_str(&mut self, s: &str) -> fmt::Result {
for byte in s.bytes() {
self.write_byte(byte)
}
Ok(())
}
}
#[allow(dead_code)]
#[derive(Debug, Clone, Copy)]
#[repr(u8)]
pub enum Color {
Black = 0,
Blue = 1,
Green = 2,
Cyan = 3,
Red = 4,
Magenta = 5,
Brown = 6,
LightGray = 7,
DarkGray = 8,
LightBlue = 9,
LightGreen = 10,
LightCyan = 11,
LightRed = 12,
Pink = 13,
Yellow = 14,
White = 15,
}
#[derive(Debug, Clone, Copy)]
pub struct ColorCode(u8);
impl ColorCode {
pub const fn new(foreground: Color, background: Color) -> ColorCode {
ColorCode((background as u8) << 4 | (foreground as u8))
}
}
impl Default for ColorCode {
fn default() -> ColorCode {
ColorCode::new(Color::LightGreen, Color::Black)
}
}
#[derive(Debug, Clone, Copy)]
#[repr(C)]
pub struct ScreenChar {
ascii_character: u8,
color_code: ColorCode,
}
impl ScreenChar {
pub const fn new(ascii: u8, color: ColorCode) -> ScreenChar {
ScreenChar {
ascii_character: ascii,
color_code: color,
}
}
}