; Framework for strlen question

    B main
; you'll need a few more string declarations here to get the answer `looking right'.
text1   DEFB    "Hello World. Goodbye Universe\0"
text2   DEFB    "1234567890 are the ten decimal digits\0"
nulltxt DEFB    "\0"
    ALIGN

main    ADR R0, text1   ; get address of starting byte of string
    MOV R2, #0  ; Initialise the counter in Register 2
    ADR R3, nulltxt ; load R3 with null for comparison later on

again   LDRB R1, [R0]   ; this loads into r1 the byte whose address is currently in R0
    LDRB R4, [R3]
    CMP R1, R4  ; performs comparison to check if R1 is null
    BEQ end     ; if equal, must have come to end of string - branch to end
    ADD R2, R2, #1  ;add 1 to counter if not the null
    ADD R0, R0, #1      ;add 1 to the byte address
    B again

end MOV R0, R2  ;move counter value
    SWI 4       ;print out counter value
    SWI 2       ;end program