# Sum - calculates the sum of the integers between zero and a value taken from the input stream
#     - the result is put on the output stream

lc r1 main

main:
    ldin r2 sin                    # Load a value from the input stream into r2...
    jmp r0 r1                      # ...but repeat if the stream was not ready (sin)
    
    lc r3 0                        # Initialise result register
    lc r4 loop
    
loop:                       
    add r3 r3 r2 sez               # Add the current number to the result...
    dec r2                         # ...and decrement if non-zero (sez)
    bnez r0 r2 r4                  # Repeat if the current number is non-zero
    
stout r2                           # Otherwise, put the result on the output stream

jmp r0 r1                          # Restart program