bits 32
	section .startup

	extern _bss_start
	extern _bss_size
	extern kmain

MB_MAGIC equ 0x1badb002
MB_FLAGS equ 0


	global start
start:
	jmp .skip_mboot_hdr

	; multiboot header
	align 4
	dd MB_MAGIC
	dd MB_FLAGS
	dd -(MB_MAGIC + MB_FLAGS)	; checksum
	times 5 dd 0

.skip_mboot_hdr:
	; init temporary kernel stack at the top of conventional memory
	mov esp, 0xa0000

	; clear .bss (if it's not empty)
	; due to the ALIGN(4) statements in the linker script, it's guaranteed
	; that _bss_start and _bss_end will be 32bit-aligned, so we can use
	; rep stosd to clear it
	mov ecx, _bss_size
	test ecx, ecx
	jz .skip_bss
	xor eax, eax
	mov edi, _bss_start
	shr ecx, 2	; _bss_size is in bytes, we need count in "dwords"
	rep stosd
.skip_bss:

	call kmain
	; kmain shouldn't ever return, but we'll enter a hlt loop just in case
.inf:	hlt
	jmp .inf

; vi:ft=nasm: