From c9ec8f7a07d6e456bc1493dd90374c05cfd80eed Mon Sep 17 00:00:00 2001
From: Jeremy Soller <jackpot51@gmail.com>
Date: Tue, 1 Feb 2022 19:50:15 -0700
Subject: [PATCH] WIP: VGA

---
 src/lib.rs             | 56 ++++++++++++++++++++++++++++++++++++++++++
 x86/startup-common.asm |  2 +-
 2 files changed, 57 insertions(+), 1 deletion(-)

diff --git a/src/lib.rs b/src/lib.rs
index 001513e716..5a2f6c7eee 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -2,9 +2,65 @@
 #![feature(lang_items)]
 #![feature(llvm_asm)]
 
+use core::slice;
+
 mod panic;
 
+#[repr(packed)]
+pub struct VgaTextBlock {
+    char: u8,
+    color: u8,
+}
+
+#[repr(u8)]
+pub enum VgaTextColor {
+    Black = 0,
+    Blue = 1,
+    Green = 2,
+    Cyan = 3,
+    Red = 4,
+    Purple = 5,
+    Brown = 6,
+    Gray = 7,
+    DarkGray = 8,
+    LightBlue = 9,
+    LightGreen = 10,
+    LightCyan = 11,
+    LightRed = 12,
+    LightPurple = 13,
+    Yellow = 14,
+    White = 15,
+}
+
 #[no_mangle]
 pub unsafe extern "C" fn kstart() -> ! {
+    let vga = slice::from_raw_parts_mut(
+        0xb8000 as *mut VgaTextBlock,
+        80 * 25
+    );
+
+    for i in 0..vga.len() {
+        vga[i].char = 0;
+        vga[i].color =
+            ((VgaTextColor::DarkGray as u8) << 4) |
+            (VgaTextColor::White as u8);
+    }
+
+    let draw_text = |vga: &mut [VgaTextBlock], x: usize, y: usize, text: &str| {
+        let mut i = y * 80 + x;
+        for c in text.chars() {
+            if let Some(block) = vga.get_mut(i) {
+                block.char = c as u8;
+            }
+            i += 1;
+        }
+    };
+
+    draw_text(
+        vga,
+        10, 1,
+        "Arrow keys and space select mode, enter to continue"
+    );
+
     loop {}
 }
diff --git a/x86/startup-common.asm b/x86/startup-common.asm
index 34c8189c44..81def6a5f7 100644
--- a/x86/startup-common.asm
+++ b/x86/startup-common.asm
@@ -46,7 +46,7 @@ startup:
 
     call memory_map
 
-    call vesa
+    ;TODO call vesa
 
     mov si, init_fpu_msg
     call print