From 46d47f8d2ee0b9eee478e6bcd3eaa69a08a5dea4 Mon Sep 17 00:00:00 2001
From: Philipp Oppermann <dev@phil-opp.com>
Date: Wed, 12 Apr 2017 19:20:15 +0200
Subject: [PATCH] Create a Writer struct with a `write_byte` function

---
 src/lib.rs        |  1 +
 src/vga_buffer.rs | 40 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 41 insertions(+)

diff --git a/src/lib.rs b/src/lib.rs
index ffb8853b..87889a41 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,5 +1,6 @@
 #![feature(lang_items)]
 #![feature(const_fn)]
+#![feature(unique)]
 #![no_std]
 
 extern crate rlibc;
diff --git a/src/vga_buffer.rs b/src/vga_buffer.rs
index eaa8896b..8b807fb4 100644
--- a/src/vga_buffer.rs
+++ b/src/vga_buffer.rs
@@ -1,4 +1,7 @@
+use core::ptr::Unique;
+
 #[allow(dead_code)]
+#[derive(Debug, Clone, Copy)]
 #[repr(u8)]
 pub enum Color {
     Black      = 0,
@@ -19,6 +22,7 @@ pub enum Color {
     White      = 15,
 }
 
+#[derive(Debug, Clone, Copy)]
 struct ColorCode(u8);
 
 impl ColorCode {
@@ -27,6 +31,7 @@ impl ColorCode {
     }
 }
 
+#[derive(Debug, Clone, Copy)]
 #[repr(C)]
 struct ScreenChar {
     ascii_character: u8,
@@ -39,3 +44,38 @@ const BUFFER_WIDTH: usize = 80;
 struct Buffer {
     chars: [[ScreenChar; BUFFER_WIDTH]; BUFFER_HEIGHT],
 }
+
+pub struct Writer {
+    column_position: usize,
+    color_code: ColorCode,
+    buffer: Unique<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: color_code,
+                };
+                self.column_position += 1;
+            }
+        }
+    }
+
+    fn buffer(&mut self) -> &mut Buffer {
+        unsafe{ self.buffer.as_mut() }
+    }
+
+    fn new_line(&mut self) {/* TODO */}
+}