From a78033acc941fc4bcf6188f1d48fd8e012673fff Mon Sep 17 00:00:00 2001
From: EmulatedSeasons <89668582+EmulatedSeasons@users.noreply.github.com>
Date: Thu, 15 Jun 2023 22:36:39 -0400
Subject: initial commit

---
 kernel/arch/i386/boot.asm | 82 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 82 insertions(+)
 create mode 100644 kernel/arch/i386/boot.asm

(limited to 'kernel/arch/i386/boot.asm')

diff --git a/kernel/arch/i386/boot.asm b/kernel/arch/i386/boot.asm
new file mode 100644
index 0000000..a2dccce
--- /dev/null
+++ b/kernel/arch/i386/boot.asm
@@ -0,0 +1,82 @@
+; multiboot header constants
+MBALIGN equ 1 << 0
+MEMINFO equ 1 << 1
+MBFLAGS equ MBALIGN | MEMINFO
+MAGIC    equ  0x1BADB002
+CHECKSUM equ -(MAGIC+MBFLAGS)
+
+; multiboot header
+section .multiboot
+align 4
+    dd MAGIC
+    dd MBFLAGS
+    dd CHECKSUM
+
+section .data
+%include "arch/i386/gdt.asm"
+
+; defines the stack
+section .bss
+align 16
+stack_bottom:
+resb 16384 ; 16 KiB
+stack_top:
+
+
+section .text
+global _start:function (_start.end - _start)
+_start:
+    cli
+    ; setup stack
+    mov esp, stack_top
+
+    extern _init
+    call _init
+
+    lgdt [gdt_descriptor]
+    jmp 0x08:.gdt_jmp
+
+.gdt_jmp:
+	mov ax, DATA_SEG
+	mov ds, ax
+	mov es, ax
+	mov fs, ax
+	mov gs, ax
+	mov ss, ax
+	jmp .gdt_jmp2
+
+.gdt_jmp2:
+
+    ; setup idt
+    extern idt_setup
+    call idt_setup
+    extern idtr
+    lidt [idtr]
+    
+    ; initialize pic
+    push ebp
+    mov ebp, esp
+    mov ebx, 0x28
+    push ebx
+    mov ebx, 0x20
+    push ebx
+
+    extern pic_remap
+    call pic_remap
+
+    pop ebx
+    pop ebx
+    mov esp, ebp
+    pop ebp
+
+    sti
+
+    ; enter the kernel
+    extern kernel_main
+    call kernel_main
+
+    ; indefinite loop once system exits
+    ;cli
+.hang: hlt
+    jmp .hang
+.end:
\ No newline at end of file
-- 
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