From 649ff9636fe7289749c91141bbf32b2dcbe6dde4 Mon Sep 17 00:00:00 2001
From: Benji Dial <benji@benjidial.net>
Date: Sun, 19 May 2024 13:27:11 -0400
Subject: add serial logging for exceptions, fix virtualbox issue

---
 kernel/source/serial.asm | 58 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 58 insertions(+)
 create mode 100644 kernel/source/serial.asm

(limited to 'kernel/source/serial.asm')

diff --git a/kernel/source/serial.asm b/kernel/source/serial.asm
new file mode 100644
index 0000000..071e525
--- /dev/null
+++ b/kernel/source/serial.asm
@@ -0,0 +1,58 @@
+bits 64
+
+global serial_init
+global serial_putchar
+
+section .text
+
+serial_init:
+
+  xor al, al
+  mov dx, 0x03f9
+  out dx, al
+
+  mov al, 0x80
+  mov dx, 0x03fb
+  out dx, al
+
+  mov al, 0x03
+  mov dx, 0x03f8
+  out dx, al
+
+  xor al, al
+  mov dx, 0x03f9
+  out dx, al
+
+  mov al, 0x03
+  mov dx, 0x03fb
+  out dx, al
+
+  mov al, 0xc7
+  mov dx, 0x03fa
+  out dx, al
+
+  ret
+
+serial_putchar:
+
+  cmp dil, 0x0a
+  je .do_cr
+.cr_ret:
+
+  mov dx, 0x03fd
+
+.loop:
+  in al, dx
+  test al, 0x20
+  jz .loop
+
+  mov al, dil
+  mov dx, 0x03f8
+  out dx, al
+  ret
+
+.do_cr:
+  mov dil, 0x0d
+  call serial_putchar
+  mov dil, 0x0a
+  jmp .cr_ret
-- 
cgit v1.2.3