;; Author: Ben Weiner
;;
;; This program reads in a nonnegative integer n and prints out the sum of the digits
;; in its decimal representation.  For instance, for n = 1203 it prints out 6.

    allocate-registers n, ten, test, return, digit, sum, zero, sumDigit

    li ten 10
    li zero 0
    li sum 0
    li return Lreturn
    li sumDigit LsumDigit

    read n
    
LsumDigit:
    sgt test n zero
    jeqz test return
    rem digit n ten
    div n n ten
    add sum sum digit
    j sumDigit
Lreturn:
    write sum
    halt