raspberry pi 1 model bで、アセンブラ その２

#概要
raspberry pi 1 model bで、アセンブラでzundokoやってみた。
#開発環境
raspberry pi 1 model b
raspbian 2016_09_23 jessie lite
#実行
nano zundoko.s
gcc zundoko.s -nostdlib
./a.out
#サンプルコード
https://lowreal.net/2016/03/16/2

.text
.global _start
_start:
	ldr r8, =0x02020000
	mov r6, #0
loop:
	eor r8, r8, r8, lsl #13
	eor r8, r8, r8, lsr #17
	eor r8, r8, r8, lsl #15
	tst r8, $0x80
	adreq r1, zun
	moveq r2, #zun_len
	addeq r6, #1
	adrne r1, doko
	movne r2, #doko_len
	mov r0, #1
	mov r7, #4
	svc #0
	bne check_kiyoshi
	b loop
check_kiyoshi:
	cmp r6, #4
	bge call_kiyoshi
	mov r6, #0
	b loop
call_kiyoshi:
	adr r1, kiyoshi
	mov r2, #kiyoshi_len
	mov r0, #1
	mov r7, #4
	svc #0
	mov r0, #0
	mov r7, #1
	svc #0
zun:
	.string "ズン\n"
zun_len = . - zun
	.align 2
doko:
	.string "ドコ\n"
doko_len = . - doko
	.align 2
kiyoshi:
	.string "キヨシ\n"
kiyoshi_len = . - kiyoshi
	.align 2