; Here is our entry point to the kernel
; A very simple assembly file
; We set up some parameters and then pass the execution to our kmain

global loader 				; entry symbol for ELF
extern kmain
extern gdt_init

MAGIC_NUMBER 	equ 0x1BADB002		; magic number constant
FLAGS		equ 0x3
CHECKSUM	equ -(MAGIC_NUMBER + FLAGS)	; calculate the checksum
KERNEL_STACK_SIZE equ 4096

; The multiboot section is a semi requirement for grub
; All this is doing is placing the required magic number, flags, and the checksum into the file first
; This lets grub know if this is a valid multiboot kernel or not
section .multiboot
align 4 				; code must be 4 byte aligned
	dd MAGIC_NUMBER
	dd FLAGS
	dd CHECKSUM

; Here we're setting up the stack
; Giving us 4096 bytes (resb)
section .bss
align 4
kernel_stack:
	resb KERNEL_STACK_SIZE

section .text
loader:
	mov esp, kernel_stack + KERNEL_STACK_SIZE ; move the top of the stack into esp

	call kmain ; pass execution over to our kmain function, where all of the real stuff is done

	; Should the system exit, we clear the interrupt flag
	; and do an infinite loop of nothing
	cli 
loop:	hlt
	jmp loop