Question

Write MIPS code that emulates a simple calculator. The calculator initially has the
value 0. Prompt the user to enter a command. A command is a number, where 0 is add,
1 is subtract, 2 is multiply, 3 is divide, 4 is clear, and 5 is exit. When the user enters 0,
1, 2, or 3, prompt the user for a number to add, subtract, multiply or divide from the
current value. If the user enters 4, then clear the current value (set it to 0). If the user
enters 5, exit the program. Give useful prompts.

(MARS)

Answer 1

calculator.asm:

.data
string1: .asciiz "\nEnter command 0 - add 1- subtract 2 - multiply 3 - Divide 4 - clear 5 - exit: "
string2: .asciiz "Enter number: "
string3: .asciiz "\n result = "
string4: .asciiz "\n******* result cleared *******"
string5: .asciiz "\n******* Terminating Program *******"

.text
   li $t0,0 #result variable initially result = 0
  
loop:  
   li $v0,4   
   la $a0,string3 #print string 3
   syscall
  
   li $v0,1
   move $a0,$t0   #print result
   syscall
  
   li $v0,4   
   la $a0,string1 #print string 1
   syscall      
  
   li $v0, 5
   syscall
   move $s0,$v0 #store user choice
  
   beq $s0,4,clear #check user choice if 4 clear
   beq $s0,5,exit   #check user choice if 5 exit
  
   li $v0,4   
   la $a0,string2 #print string 2
   syscall      
  
   li $v0, 5
   syscall
   move $t1,$v0 #store user numberand perform valid operation
  
    beqz $s0,addition   #check user choice if 0 add
   beq $s0,1,subtraction   #check user choice if 1 subtract
   beq $s0,2,multiplication#check user choice if 2 multiply
   beq $s0,3,division   #check user choice if 3 divide
  
addition:    add $t0,$t0,$t1 # add number to result
      j loop  
  
subtraction:    sub $t0,$t0,$t1 # subtract number to result
      j loop      
  
multiplication:   mul $t0,$t0,$t1 # multiply result with number
       j loop  
      
division:   div $t0,$t0,$t1 # divide result with number
       j loop
  
clear:       li $t0,0
       li $v0,4   
       la $a0,string4 #print string 4
       syscall  
       j loop

exit:       li $v0,4   
       la $a0,string5 #print string 5
       syscall  
      
       li $v0, 10#stop the program and exit
             syscall

Output:

Mars Messages Run l/O result- Enter command add 1- subtract 2 multiply 3 - Divide 4 clear 5 - exit:0 Enter number: 400 Clear result 400 Enter command - add 1- subtract 2 multiply 3 - Divide 4 clear 5 - exit: 1 Enter number: 21 result - 379

Mars MessagesRun l/O Enter command -add1-subtract 2 - multiply 3 - Divide 4 - clear 5 - exit: 2 Enter number: 3 result - 1137 Enter command - add 1- subtract 2 multiply 3 - Divide 4 clear 5 - exit: 4 Clear result clearedxx*** result -0

Mars Messages Run Vo Enter commandadd1-subtract 2-multipty 3-Divide 4 clear 5- exit: O nter number: 123 result 123 nter number 2 result 61 - Enter coband 2 . add i. Subtract 2 . multiply 3 . Divide 4 . clear 5 . ent: 3 Clear ter command 0 add 1- subtract 2 - multiply 3 Divide 4 - clear 5 - exit: 5