ARM ASM nested loop hello world

smile.s

.global main
main:
MOV R4, #3	@ init outer line counter =3

_outerloop:
MOV R3, R4	@ init word loop counter with current value of outer counter

_wordloop:
MOV R7, #4 	@ syscall 4: output to stdout
MOV R0, #1	@ stdout
MOV R2, #6	@ length of string
LDR R1, =output
SWI 0
SUB R3, R3, #1	@ decrement word loop counter
CMP R3, #0
BNE _wordloop

@print newline
MOV R7, #4 	@ syscall 4: output to stdout
MOV R0, #1	@ stdout
MOV R2, #1	@ length of string
LDR R1, =eol
SWI 0

SUB R4, R4, #1	@ decrement outer counter
CMP R4, #0
BNE _outerloop

_exit:
MOV R1, #0
MOV R7, #1
SWI 0

.data
output:
	.asciz "Smile!"
eol:
	.asciz "\n"