From 20dd72e40dc2728d3c5335d860e4b8ab8da14fcc Mon Sep 17 00:00:00 2001
From: Aleksa Vučković <aleksav013@gmail.com>
Date: Mon, 25 Oct 2021 00:36:33 +0200
Subject: Changing build system to recursive make

---
 src/as/boot.s | 82 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 82 insertions(+)
 create mode 100644 src/as/boot.s

(limited to 'src/as/boot.s')

diff --git a/src/as/boot.s b/src/as/boot.s
new file mode 100644
index 0000000..6fe5ab8
--- /dev/null
+++ b/src/as/boot.s
@@ -0,0 +1,82 @@
+.set ALIGN,    1<<0
+.set MEMINFO,  1<<1
+.set FLAGS,    ALIGN | MEMINFO
+.set MAGIC,    0x1BADB002
+.set CHECKSUM, -(MAGIC + FLAGS)
+ 
+.section .multiboot
+.align 4
+.long MAGIC
+.long FLAGS
+.long CHECKSUM
+
+.global _start
+.global load_gdt
+.global load_idt
+.global enable_interrupts
+.global keyboard_handler
+.global ioport_in
+.global ioport_out
+
+.extern init_gdt_table
+.extern handle_keyboard_interrupt
+.extern kernel_main
+
+load_gdt:
+    movl 4(%esp), %edx
+    lgdt (%edx)
+    ret
+
+load_idt:
+    movl 4(%esp), %edx
+    lidt (%edx)
+    sti
+    ret
+
+keyboard_handler:
+    pushal
+    cld
+    call handle_keyboard_interrupt
+    popal
+    iretl
+
+ioport_in:
+    movl 4(%esp),%edx
+    in %dx,%al
+    ret
+
+ioport_out:
+    movl 4(%esp),%edx
+    movl 8(%esp),%eax
+    outb %al,%dx
+    ret
+
+.set CODE_SEGMENT, 0x08
+.set DATA_SEGMENT, 0x10
+
+.section .bss
+.align 16
+stack_bottom:
+.skip 16384
+stack_top:
+
+.section .text
+.type _start, @function
+_start:
+	call init_gdt_table
+	ljmp $CODE_SEGMENT, $code
+	
+code:
+	movw $DATA_SEGMENT, %ax
+	movw %ax, %ds
+	movw %ax, %es
+	movw %ax, %fs
+	movw %ax, %gs
+	movw %ax, %ss
+	movl $stack_top, %esp
+	cli
+	call _init
+	call kernel_main
+	hlt
+ 
+.size _start, . - _start
-- 
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