Need in ARM assembly language

2. Write a program length.s that reads a string from stdin and prints the length of the string. You cannot use the C library function "strlen" in this assignment. The length of the string is guaranteed to be less than 100 characters long, and there will be no white space. Type the string in the terminal and output the length to the terminal. An example output is shown below. pi@raspberypi:r/cs250/lab7-src$ ./length HelloWorld! i@raspberrypi:~/cs250/lab7-src$ ./length 12345678901234567890 20