Update to latest bootloader prototype

src/framebuffer.rs

@@ -0,0 +1,172 @@
+use bootloader::boot_info::PixelFormat;
+use core::{fmt, slice};
+use font8x8::UnicodeFonts;
+use spin::Mutex;
+use volatile::Volatile;
+
+pub static WRITER: Mutex<Option<Writer>> = Mutex::new(None);
+
+pub fn init(framebuffer: &'static mut bootloader::boot_info::FrameBuffer) {
+    let mut writer = Writer {
+        info: framebuffer.info(),
+        buffer: Volatile::new(framebuffer.buffer()),
+        x_pos: 0,
+        y_pos: 0,
+    };
+    writer.clear();
+
+    // global writer should not be locked here
+    let mut global_writer = WRITER.try_lock().unwrap();
+    assert!(global_writer.is_none(), "Global writer already initialized");
+    *global_writer = Some(writer);
+}
+
+pub struct Writer {
+    buffer: Volatile<&'static mut [u8]>,
+    info: bootloader::boot_info::FrameBufferInfo,
+    x_pos: usize,
+    y_pos: usize,
+}
+
+impl Writer {
+    fn newline(&mut self) {
+        self.y_pos += 8;
+        self.carriage_return();
+    }
+
+    fn carriage_return(&mut self) {
+        self.x_pos = 0;
+    }
+
+    /// Erases all text on the screen
+    pub fn clear(&mut self) {
+        self.x_pos = 0;
+        self.y_pos = 0;
+        self.buffer.fill(0);
+    }
+
+    fn width(&self) -> usize {
+        self.info.horizontal_resolution
+    }
+
+    fn height(&self) -> usize {
+        self.info.vertical_resolution
+    }
+
+    fn write_char(&mut self, c: char) {
+        match c {
+            '\n' => self.newline(),
+            '\r' => self.carriage_return(),
+            c => {
+                if self.x_pos >= self.width() {
+                    self.newline();
+                }
+                if self.y_pos >= (self.height() - 8) {
+                    self.clear();
+                }
+                let rendered = font8x8::BASIC_FONTS
+                    .get(c)
+                    .expect("character not found in basic font");
+                self.write_rendered_char(rendered);
+            }
+        }
+    }
+
+    fn write_rendered_char(&mut self, rendered_char: [u8; 8]) {
+        for (y, byte) in rendered_char.iter().enumerate() {
+            for (x, bit) in (0..8).enumerate() {
+                let on = *byte & (1 << bit) != 0;
+                self.write_pixel(self.x_pos + x, self.y_pos + y, on);
+            }
+        }
+        self.x_pos += 8;
+    }
+
+    fn write_pixel(&mut self, x: usize, y: usize, on: bool) {
+        let pixel_offset = y * self.info.stride + x;
+        let color = if on {
+            match self.info.pixel_format {
+                PixelFormat::RGB => [0x33, 0xff, 0x66, 0],
+                other => panic!("unknown pixel format {:?}", other),
+            }
+        } else {
+            [0, 0, 0, 0]
+        };
+        let bytes_per_pixel = self.info.bytes_per_pixel;
+        let byte_offset = pixel_offset * bytes_per_pixel;
+        self.buffer
+            .index_mut(byte_offset..(byte_offset + bytes_per_pixel))
+            .copy_from_slice(&color[..bytes_per_pixel]);
+    }
+
+    /// Writes the given ASCII string to the buffer.
+    ///
+    /// Wraps lines at `BUFFER_WIDTH`. Supports the `\n` newline character. Does **not**
+    /// support strings with non-ASCII characters, since they can't be printed in the VGA text
+    /// mode.
+    fn write_string(&mut self, s: &str) {
+        for char in s.chars() {
+            self.write_char(char);
+        }
+    }
+}
+
+impl fmt::Write for Writer {
+    fn write_str(&mut self, s: &str) -> fmt::Result {
+        self.write_string(s);
+        Ok(())
+    }
+}
+
+/// Like the `print!` macro in the standard library, but prints to the VGA text buffer.
+#[macro_export]
+macro_rules! print {
+    ($($arg:tt)*) => ($crate::framebuffer::_print(format_args!($($arg)*)));
+}
+
+/// Like the `println!` macro in the standard library, but prints to the VGA text buffer.
+#[macro_export]
+macro_rules! println {
+    () => ($crate::print!("\n"));
+    ($($arg:tt)*) => ($crate::print!("{}\n", format_args!($($arg)*)));
+}
+
+/// Prints the given formatted string to the VGA text buffer
+/// through the global `WRITER` instance.
+#[doc(hidden)]
+pub fn _print(args: fmt::Arguments) {
+    use core::fmt::Write;
+    use x86_64::instructions::interrupts;
+
+    interrupts::without_interrupts(|| {
+        WRITER.lock().as_mut().unwrap().write_fmt(args).unwrap();
+    });
+}
+
+#[test_case]
+fn test_println_simple() {
+    println!("test_println_simple output");
+}
+
+#[test_case]
+fn test_println_many() {
+    for _ in 0..200 {
+        println!("test_println_many output");
+    }
+}
+
+#[test_case]
+fn test_println_output() {
+    use core::fmt::Write;
+    use x86_64::instructions::interrupts;
+
+    let s = "Some test string that fits on a single line";
+    interrupts::without_interrupts(|| {
+        let mut writer = WRITER.lock();
+        writeln!(writer, "\n{}", s).expect("writeln failed");
+        for (i, c) in s.chars().enumerate() {
+            let screen_char = writer.buffer.chars[BUFFER_HEIGHT - 2][i].read();
+            assert_eq!(char::from(screen_char.ascii_character), c);
+        }
+    });
+}