LENGTH OF NULL TERMINATED STRING

 ;Program to find the length of a null terminated string
 AREA data1,data,readonly
strr DCB "Advanced",'0'
 AREA data2,data
 SPACE 1
 AREA progq,code,readonly
 ENTRY
 ldr r0,=strr
up ldrb r2,[r0],#1
 cmp r2,#'0'
 beq done
 add r1,r1,#1
 b up
done ldr r0,=data2
 str r1,[r0]
s b s

 END