Question

Write a SPIM program to find weather two numbers are relatively prime. Two integers are said to be relatively prime if there is no integer greater than one that divides them both. Sample I/O: Enter the first number: 14 Enter the second number: 15 The entered numbers are relatively prime. Sample I/O: Enter the first number: 12 Enter the second number: 15 The entered numbers are not relatively prime.

Answer 1

# is_prime.s

# Tells if a number is prime

                .data

num:     .word    743711                                                                  # This is the number we'll test to see

                                                                                                                # if it's prime.

                                                                                                                # It will be located by the label `num`

                .text

main:

                lw           $a0, num

                jal           is_prime                                                              # Send the number to the procedure!

                add        $a0, $zero, $v0                  # Send the result as an argument to...

                li              $v0, 1                                                    # ...print integer onscreen

                syscall

                li              $v0, 10                                                  # exit the program

                syscall  

## Tells if a number is prime

# $a0     The number to check if it's prime

# $v0     1 if the number is prime, 0 if it's not

is_prime:

                addi       $t0, $zero, 2                                                       # int x = 2

               

is_prime_test:

                slt           $t1, $t0, $a0                                                        # if (x > num)

                bne        $t1, $zero, is_prime_loop                           

                addi       $v0, $zero, 1                                                       # It's prime!

                jr             $ra                                                                                          # return 1

is_prime_loop:                                                                                 # else

                div          $a0, $t0                                                                               

                mfhi       $t3                                                                                          # c = (num % x)

                slti          $t4, $t3, 1                                                           

                beq        $t4, $zero, is_prime_loop_continue        # if (c == 0)

                add        $v0, $zero, $zero                                                              # its not a prime

                jr             $ra                                                                                                          # return 0

is_prime_loop_continue:                            

                addi $t0, $t0, 1                                                   # x++

                j               is_prime_test                                                    # continue the loop