; See the end of this file for copyright and license terms.

;
; We use a custom ABI because BIOS interrupts use ax for their parameter:
;
; register | usage
; ---------|--------------------
; ax       | BIOS parameter
; bx       | arg1, return value
; cx       | arg2
; dx       | arg3
;
; Registers ax-dx are saved by the caller, all others by the callee.
;
; To save space, strings are terminated by setting bit 7 of their last
; character to 1 (because ascii only uses bits 0-6) rather than appending a
; full NUL terminator byte.  This technique is stolen from FreeBSD.
;

[bits 16]
[org 0x7c00]

_start:
	mov	bp,	0x9000
	mov	sp,	bp

	mov	bx,	HELLO
	call	print

	; TODO: switch to protected mode and call kernel here
	jmp	$

; args:
; - bx: pointer to string
print:
	mov	ah,	0x0e
_print_loop:
	mov	al,	[bx]
	mov	cl,	al
	and	al,	0x7f
	int	0x10
	inc	bx
	and	cl,	0x80
	je	_print_loop
	ret

HELLO:	db "hi i'm gay uwu", 0x0d, 0x8a ; '\r', '\n'|0x80

; padding to 512 bytes (-2 for magic)
times 510 - ($-$$) db 0
; mbr magic
dw 0xaa55

; This file is part of GayBSD.
; Copyright (c) 2021 fef <owo@fef.moe>.
;
; GayBSD is nonviolent software: you may only use, redistribute, and/or
; modify it under the terms of the Cooperative Nonviolent Public License
; (CNPL) as found in the LICENSE file in the source code root directory
; or at <https://git.pixie.town/thufie/cnpl-builder>; either version 7
; of the license, or (at your option) any later version.
;
; GayBSD comes with ABSOLUTELY NO WARRANTY, to the extent
; permitted by applicable law.  See the CNPL for details.