From 00d3a1de7206cde88f17011ee4ca595df4202a79 Mon Sep 17 00:00:00 2001
From: Jacob Hinchliffe <jacob@nullndvoid.xyz>
Date: Mon, 24 Feb 2025 23:24:03 +0000
Subject: [PATCH] fb: Added support for typing backspaces.

---
 libk/src/drivers/io/ascii/mod.rs | 27 ++++++++++++++++++++++-----
 libk/src/drivers/io/keyboard.rs  |  5 ++---
 libk/src/lib.rs                  |  1 +
 3 files changed, 25 insertions(+), 8 deletions(-)

diff --git a/libk/src/drivers/io/ascii/mod.rs b/libk/src/drivers/io/ascii/mod.rs
index 56e5199..949aa22 100644
--- a/libk/src/drivers/io/ascii/mod.rs
+++ b/libk/src/drivers/io/ascii/mod.rs
@@ -64,13 +64,19 @@ impl Writer {
         self.font = font;
     }
 
+    /// This is sent when the user types a backspace.
+    const BACKSPACE: u16 = 8;
+
     pub fn write_glyph(&mut self, c: u16) {
-        if c as u8 == b'\n' {
+        if c == b'\n' as u16 {
             self.newline();
             return;
+        } else if c == Self::BACKSPACE {
+            self.backspace();
+            return;
         }
 
-        // get the character data from the font array. -- each byte is a row of pixels
+        // Get the character data from the font array. -- each byte is a row of pixels
         let data: &[u8] = &self.font.0[c as usize];
 
         if let Some(writer) = FRAMEBUFFER_WRITER.lock().as_mut() {
@@ -80,17 +86,17 @@ impl Writer {
                     let pixel_y: u32 = self.text_line * FONT_HEIGHT + row as u32;
 
                     if line & (0x80 >> col) != 0 {
-                        // write the foreground color
+                        // Write the foreground color
                         writer.write_pixel(pixel_x as usize, pixel_y as usize, self.fg_color);
                     } else {
-                        // write the background color
+                        // Write the background color
                         writer.write_pixel(pixel_x as usize, pixel_y as usize, self.bg_color);
                     }
                 }
             }
         }
 
-        // go to next position
+        // Go to next position
         if self.text_col + 1 >= self.screen_width {
             self.newline();
         } else {
@@ -121,6 +127,17 @@ impl Writer {
         }
     }
 
+    /// Handles the backspace character. TODO: Implement VT-100 style terminal control
+    /// codes alongside a shell. Not simple.
+    pub fn backspace(&mut self) {
+        if self.text_col > 0 {
+            self.text_col -= 1;
+            // Blank out the previous char.
+            self.write_glyph(' ' as u16);
+            self.text_col -= 1;
+        }
+    }
+
     pub fn write_string(&mut self, s: &str) {
         for c in s.chars() {
             self.write_glyph(c as u16);
diff --git a/libk/src/drivers/io/keyboard.rs b/libk/src/drivers/io/keyboard.rs
index 87ce346..e2e9da2 100644
--- a/libk/src/drivers/io/keyboard.rs
+++ b/libk/src/drivers/io/keyboard.rs
@@ -11,9 +11,7 @@ use pc_keyboard::{
 };
 use spin::{Lazy, Mutex, Once};
 
-use crate::println;
-
-use super::print;
+use crate::prelude::*;
 
 static KBD_QUEUE: Once<ArrayQueue<u8>> = Once::new();
 static WAKER: AtomicWaker = AtomicWaker::new();
@@ -21,6 +19,7 @@ static WAKER: AtomicWaker = AtomicWaker::new();
 pub static KEYBOARD: Lazy<Mutex<Keyboard<Uk105Key, ScancodeSet1>>> = Lazy::new(|| {
     Mutex::new(Keyboard::new(
         ScancodeSet1::new(),
+        // TODO: Expose an API to change the default KB layout.
         layouts::Uk105Key,
         HandleControl::Ignore,
     ))
diff --git a/libk/src/lib.rs b/libk/src/lib.rs
index 56a5118..a139d5b 100644
--- a/libk/src/lib.rs
+++ b/libk/src/lib.rs
@@ -26,6 +26,7 @@ pub mod resources;
 pub mod std;
 
 /// Re-exports most of the IO macros as well as standard allocation stuff
+#[allow(unused)]
 pub mod prelude {
     pub use crate::std::io::*;
     pub use alloc::{