create vga text buffer

Cargo.lock

@@ -8,9 +8,39 @@ version = "0.9.34"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "13f6a8a495d2f93fe3d6eb3a224f9aa749a63cfd746ed03eb5ddcbd00ade7d8f"
 
+[[package]]
+name = "lazy_static"
+version = "1.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bbd2bcb4c963f2ddae06a2efc7e9f3591312473c50c6685e1f298068316e66fe"
+dependencies = [
+ "spin 0.9.8",
+]
+
 [[package]]
 name = "rust-kernel"
 version = "0.1.0"
 dependencies = [
  "bootloader",
+ "lazy_static",
+ "spin 0.5.2",
+ "volatile",
 ]
+
+[[package]]
+name = "spin"
+version = "0.5.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6e63cff320ae2c57904679ba7cb63280a3dc4613885beafb148ee7bf9aa9042d"
+
+[[package]]
+name = "spin"
+version = "0.9.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6980e8d7511241f8acf4aebddbb1ff938df5eebe98691418c4468d0b72a96a67"
+
+[[package]]
+name = "volatile"
+version = "0.2.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f6b06ad3ed06fef1713569d547cdbdb439eafed76341820fb0e0344f29a41945"

Cargo.toml

@@ -18,3 +18,6 @@ bench = false
 
 [dependencies]
 bootloader = "0.9"
+volatile = "0.2.6"
+lazy_static = { version = "1.5", features = ["spin_no_std"] }
+spin = "0.5.2"

src/main.rs

@@ -1,30 +1,19 @@
 #![no_std]
 #![no_main]
 
-static HELLLO: &[u8] = b"Hello World!";
+mod vga_buffer;
-
-#[unsafe(no_mangle)]
-pub extern "C" fn _start() -> ! {
-    let vga_buffer = 0xb8000 as *mut u8;
-    
-    for (i, &byte) in HELLLO.iter().enumerate() {
-        unsafe {
-            *vga_buffer.offset(i as isize * 2) = byte;
-            *vga_buffer.offset(i as isize * 2 +1) = 0xb;
-        }
-    }
-    
-    loop {
-        
-    }
-}
-
 
 use core::panic::PanicInfo;
 
-#[panic_handler]
+#[unsafe(no_mangle)]
-fn panic(_info: &PanicInfo) -> ! {
+pub extern "C" fn _start() -> ! {
-    loop {
+    println!("Hello World{}", "!");
-        
+    panic!("Some panic message");
-    }
+    loop {}
+}
+
+#[panic_handler]
+fn panic(info: &PanicInfo) -> ! {
+    println!("{info}");
+    loop {}
 }

src/vga_buffer.rs

@@ -0,0 +1,144 @@
+use core::fmt;
+
+use lazy_static::lazy_static;
+use spin::Mutex;
+use volatile::Volatile;
+
+#[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)]
+struct ColorCode(u8);
+
+impl ColorCode {
+    fn new(foreground: Color, background: Color) -> Self {
+        Self((background as u8) << 4 | foreground as u8)
+    }
+}
+
+#[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)]
+struct Buffer {
+    chars: [[Volatile<ScreenChar>; BUFFER_WIDTH]; BUFFER_HEIGHT],
+}
+
+pub struct Writer {
+    column_position: usize,
+    color_code: ColorCode,
+    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].write(ScreenChar {
+                    ascii_character: byte,
+                    color_code,
+                });
+
+                self.column_position += 1;
+            }
+        }
+    }
+
+    pub fn write_string(&mut self, s: &str) {
+        for byte in s.bytes() {
+            match byte {
+                0x20..=0x7e | b'\n' => self.write_byte(byte),
+                _ => self.write_byte(0xfe),
+            }
+        }
+    }
+
+    fn new_line(&mut self) {
+        for row in 1..BUFFER_HEIGHT {
+            for col in 0..BUFFER_WIDTH {
+                let char = self.buffer.chars[row][col].read();
+                self.buffer.chars[row - 1][col].write(char);
+            }
+        }
+        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: self.color_code,
+        };
+        for col in 0..BUFFER_WIDTH {
+            self.buffer.chars[row][col].write(blank);
+        }
+    }
+}
+
+impl fmt::Write for Writer {
+    fn write_str(&mut self, s: &str) -> fmt::Result {
+        self.write_string(s);
+        Ok(())
+    }
+}
+
+lazy_static! {
+    pub static ref WRITER: Mutex<Writer> = Mutex::new(Writer {
+        column_position: 0,
+        color_code: ColorCode::new(Color::White, Color::Black),
+        buffer: unsafe { &mut *(0xb8000 as *mut Buffer) },
+    });
+}
+
+#[macro_export]
+macro_rules! print {
+    ($($arg:tt)*) => ($crate::vga_buffer::_print(format_args!($($arg)*)));
+}
+
+#[macro_export]
+macro_rules! println {
+    () => ($crate::print!("\n"));
+    ($($arg:tt)*) => ($crate::print!("{}\n", format_args!($($arg)*)));
+}
+
+#[doc(hidden)]
+pub fn _print(args: fmt::Arguments) {
+    use core::fmt::Write;
+    WRITER.lock().write_fmt(args).unwrap();
+}