1 files changed, 59 insertions, 0 deletions
diff --git a/src/boot/boot.s b/src/boot/boot.s
new file mode 100644
index 0000000..aba32ff
--- /dev/null
+++ b/src/boot/boot.s
@@ -0,0 +1,59 @@
+MBALIGN   equ 1<<0  ; Align loaded modules on page boundries */
+MBMEMINFO equ 1<<1  ; Provide memory map*/
+MBFLAGS equ MBALIGN | MBMEMINFO ; Multiboot flag field*/
+MAGIC equ 0x1BADB002 ;Lets bootloader find header*/
+CHECKSUM equ -(MAGIC + MBFLAGS) ; Proves we are multiboot via checksum*/
+CODESEG equ 0x08
+DATASEG equ 0x10
+
+section .multiboot
+align 4
+  dd MAGIC
+  dd MBFLAGS
+  dd CHECKSUM
+
+section .bss
+align 16
+stack_bottom:
+resb 16384
+stack_top:
+
+section .text
+global gdtr
+gdtr:
+  dw 0
+  dd 0
+global _start:function (_start.end - _start)
+_start:
+  mov esp, stack_top
+
+  extern get_gdtr
+  call get_gdtr
+  cli
+  lgdt	[gdtr]
+  mov eax, cr0
+  or al, 1
+  mov cr0, eax
+
+  call reloadSegments
+
+  [bits 32]
+  extern kernel_main
+  call kernel_main
+
+
+	cli
+.hang:	hlt
+	jmp .hang
+.end:
+
+reloadSegments:
+  JMP   CODESEG:.reload_CS ; should def define a CODESEG
+.reload_CS:
+   MOV   AX, DATASEG
+   MOV   DS, AX
+   MOV   ES, AX ; TODO: Setup proper extra segment
+   MOV   FS, AX ; TODO: Setup proper General purpose segments
+   MOV   GS, AX ; ...
+   MOV   SS, AX ; TODO: Setup proper stack segment
+   RET