Initial Commit

src/io/mod.rs

@@ -0,0 +1 @@
+pub mod vga;

src/io/vga/buffer.rs

@@ -0,0 +1,64 @@
+use crate::io::vga::colors::ColorCode;
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+#[repr(C)]
+struct ScreenChar {
+    ascii_character: u8,
+    color_code: ColorCode,
+}
+
+const BUFFER_HEIGHT: usize = 25;
+const BUFFER_WIDTH: usize = 80;
+
+#[repr(transparent)]
+pub struct Buffer {
+    chars: [[ScreenChar; BUFFER_WIDTH]; BUFFER_HEIGHT],
+}
+
+pub struct Writer {
+    pub(crate) column_position: usize,
+    pub(crate) color_code: ColorCode,
+    pub(crate) buffer: &'static mut Buffer,
+}
+
+impl Writer {
+    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;
+
+                let color_code = self.color_code;
+                self.buffer.chars[row][col] = ScreenChar {
+                    ascii_character: byte,
+                    color_code,
+                };
+                self.column_position += 1;
+            }
+        }
+    }
+
+    fn new_line(&mut self) {
+        unimplemented!();
+    }
+}
+
+
+impl Writer {
+    pub fn write_string(&mut self, s: &str) {
+        for byte in s.bytes() {
+            match byte {
+                // printable ASCII byte or newline
+                0x20..=0x7e | b'\n' => self.write_byte(byte),
+                // not part of printable ASCII range
+                _ => self.write_byte(0xfe),
+            }
+
+        }
+    }
+}

src/io/vga/colors.rs

@@ -0,0 +1,31 @@
+#[allow(dead_code)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+#[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, PartialEq, Eq)]
+#[repr(transparent)]
+pub struct ColorCode(u8);
+
+impl ColorCode {
+    pub(crate) fn new(foreground: Color, background: Color) -> ColorCode {
+        ColorCode((background as u8) << 4 | (foreground as u8))
+    }
+}

src/io/vga/mod.rs

@@ -0,0 +1,2 @@
+pub mod colors;
+pub mod buffer;

src/main.rs

@@ -0,0 +1,27 @@
+#![no_std]
+#![no_main]
+
+use core::panic::PanicInfo;
+use crate::io::vga::buffer::{Buffer, Writer};
+use crate::io::vga::colors::{Color, ColorCode};
+
+mod io;
+
+#[no_mangle]
+#[panic_handler]
+pub extern "C" fn panic_handler(_info: &PanicInfo) -> ! {
+    loop {}
+}
+
+#[no_mangle]
+pub extern "C" fn _start() -> ! {
+    let mut writer = Writer {
+        column_position: 0,
+        color_code: ColorCode::new(Color::Yellow, Color::Black),
+        buffer: unsafe { &mut *(0xb8000 as *mut Buffer) }
+    };
+
+    writer.write_string("Hello World\n");
+
+    loop {}
+}