134 lines
3.2 KiB
Rust
134 lines
3.2 KiB
Rust
use core::fmt;
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use volatile::Volatile;
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use spin::Mutex;
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#[allow(dead_code)]
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#[derive(Debug, Clone, Copy, PartialEq, Eq)]
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#[repr(u8)]
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pub enum Color {
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Black = 0,
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Blue = 1,
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Green = 2,
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Cyan = 3,
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Red = 4,
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Magenta = 5,
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Brown = 6,
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LightGray = 7,
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DarkGray = 8,
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LightBlue = 9,
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LightGreen = 10,
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LightCyan = 11,
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LightRed = 12,
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Pink = 13,
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Yellow = 14,
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White = 15,
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}
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// represents a color by combining foreground and background
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#[derive(Debug, Clone, Copy, Eq, PartialEq)]
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pub struct ColorCode(u8);
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impl ColorCode {
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pub fn new(foreground: Color, background: Color) -> ColorCode {
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// foreground/background use 4 bits
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// u8 is used because there is no u4 in rust
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// The 4 most significant bits in ColorCode store background
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// and 4 least significant bits store foreground color
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ColorCode((background as u8) << 4 | (foreground as u8))
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}
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}
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#[derive(Debug, Clone, Eq, PartialEq, Copy)]
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#[repr(C)]
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struct ScreenChar {
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ascii_character: u8,
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color_code: ColorCode,
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}
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const BUFFER_HEIGHT: usize = 25;
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const BUFFER_WIDTH: usize = 80;
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// This represents the vga buffer of size 25 * 80.
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pub struct Buffer {
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chars: [[Volatile<ScreenChar>; BUFFER_WIDTH]; BUFFER_HEIGHT],
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}
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pub struct Writer {
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pub column_position: usize,
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pub color_code: ColorCode,
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pub buffer: &'static mut Buffer,
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}
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lazy_static! {
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pub static ref WRITER: Mutex<Writer> = Mutex::new(Writer {
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column_position: 0,
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color_code: ColorCode::new(Color::Yellow, Color::Black),
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buffer: unsafe { &mut *(0xb8000 as *mut Buffer) },
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});
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}
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impl Writer {
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pub fn write_byte(&mut self, byte: u8) {
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match byte {
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b'\n' => self.new_line(),
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byte => {
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if self.column_position >= BUFFER_WIDTH {
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self.new_line();
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}
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let row = BUFFER_HEIGHT - 1;
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let col = self.column_position;
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let color_code = self.color_code;
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self.buffer.chars[row][col].write(ScreenChar {
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ascii_character: byte,
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color_code: color_code,
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});
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self.column_position += 1;
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}
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}
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}
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pub fn write_string(&mut self, ip: &str) {
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for byte in ip.bytes() {
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match byte {
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0x20...0x7e | b'\n' => self.write_byte(byte),
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_ => self.write_byte(0xfe),
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}
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}
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}
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fn new_line(&mut self) {
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for row in 1..BUFFER_HEIGHT {
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for col in 1..BUFFER_WIDTH {
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let character = self.buffer.chars[row][col].read();
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self.buffer.chars[row - 1][col].write(character);
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}
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}
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self.clear_row(BUFFER_HEIGHT - 1);
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self.column_position = 0;
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}
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fn clear_row(&mut self, row: usize) {
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let blank = ScreenChar {
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ascii_character: b' ',
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color_code: self.color_code,
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};
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for col in 0..BUFFER_WIDTH {
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self.buffer.chars[row][col].write(blank);
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}
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}
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}
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impl fmt::Write for Writer {
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fn write_str(&mut self, s: &str) -> fmt::Result {
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self.write_string(s);
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Ok(())
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}
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}
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