added a basic vga buffer

2 files changed, 111 insertions, 0 deletions

diff --git a/StrixKernel/src/main.rs b/StrixKernel/src/main.rs
index 0376946..36783d1 100644
--- a/StrixKernel/src/main.rs
+++ b/StrixKernel/src/main.rs
@@ -3,6 +3,8 @@
 #![no_std] // don't link the Rust standard library
 #![no_main] // disable all Rust-level entry points
 
+mod vga_buffer; 
+
 use core::panic::PanicInfo;
 
 static HELLO: &[u8] = b"Hello World!";
@@ -24,5 +26,7 @@ pub extern "C" fn _start() -> ! {
 /// This function is called on panic.
 #[panic_handler]
 fn panic(_info: &PanicInfo) -> ! {
+    vga_buffer::print_something();
+
     loop {}
 }
diff --git a/StrixKernel/src/vga_buffer.rs b/StrixKernel/src/vga_buffer.rs
new file mode 100644
index 0000000..311187e
--- /dev/null
+++ b/StrixKernel/src/vga_buffer.rs
@@ -0,0 +1,107 @@
+// vga_buffer.rs
+
+#[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) -> ColorCode {
+        ColorCode((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: [[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] = ScreenChar {
+                    ascii_character: byte,
+                    color_code,
+                };
+                self.column_position += 1;
+            }
+        }
+    }
+
+    fn new_line(&mut self) {/* TODO */}
+}
+
+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),
+            }
+
+        }
+    }
+}
+
+pub fn print_something() {
+    let mut writer = Writer {
+        column_position: 0,
+        color_code: ColorCode::new(Color::Yellow, Color::Black),
+        buffer: unsafe { &mut *(0xb8000 as *mut Buffer) },
+    };
+
+    writer.write_byte(b'H');
+    writer.write_string("ello ");
+    writer.write_string("Wörld!");
+}