B main

value   DEFW 0 ;
enterI  DEFB "Please enter your integer: ",0
newline DEFB "\n",0
error   DEFB "\nerror",0

        ALIGN

main    ADR R0, enterI
        SWI 3

next    SWI 1
        SWI 4
        CMP R0, #'0'
        BLT skip
        CMP R0, #'9'
        BGT skip

        ADR R0, value
        SWI 4
        SWI 2

skip    ADR R0, error
        SWI 3
        B next