Question

(USING THE PROGRAM MARS) Using the MemoryAccess program we wrote in class as a starting point, write a program called LoadStore

# Title : Memory access.asm
#Desc: Practice initially memory,
#in val1 = 0x0a;
#int val2 = 0x0b;
#int result;
#string resultstring = " final answer : ";
#string returnchar = "\n";
#void main() {
#   result = val1 + val2;
#   cout<<< resultstring << returnchar;
#}
.data
val1: .word 0x0a   #store 0xa into variable val1
val2: .word 0x0b   #store 0xb into val2
result: .word 0 #destination
resultstring: .asciiz "final answer is: "
returnchar: .asciiz "\n"

.text
   .globl main
   main:
       #load our values into registers
       lw $t0, val1
       lw $t1, val2
  
       #do the math
       add $t0, $t0, $t1
       #store the total back into result
       sw $t0, result
       #series of 3 prints. string then number then string
       li $v0, 4   #syscode for printing a string
       la $a0, resultstring   #address of string to print
       syscall
       #print an integer
       li $v0, 1   #syscode for printing an int
       lw $a0, result    #we want the value in $a0
       syscall
       #print return charater
       li $v0, 4
       la $a0, returnchar
       syscall
      
       #get out of dodge
       li $v0, 10
       syscall

^^^^^^^^^^^^^^^^^^memory access program

The Algorithm for your program is as follows:

1. Ask the user for a first number
2. Get that number
3. Store that number to val1 in Data Storage
4. Ask the user for a second number
5. Get that number
6. Store that number to val2 in Data Storage
7. Ask the user for a third number
8. Get that number
9. Store that number to val3 in Data Storage
10. Load val1, val2 and val3 into $s0, $s1 and $s2
11. Set $s3 to $s0 + $s1 - $s2
12. Store $s3 into results
13. Print the final answer. This could be tricky
14. Exit cleanly as always.

Your output should look as follows (Example User Input is shown in bold):

Please enter the first number:  12
Please enter the second number:  13
Please enter the third number:  14
Result: 12 + 13 – 14 = 11

---------------------------------------

Hint: The operators are strings

Answer 1

PROGRAM:

.data
   val1: .space 4
   val2: .space 4
   val3: .space 4
   result: .space 4
   prompt1: .asciiz "Please enter first number: "
   prompt2: .asciiz "Please enter second number: "
   prompt3: .asciiz "Please enter third number: "
   output: .asciiz "Result: "
   plus: .asciiz " + "
   minus: .asciiz " - "
   equal_sign: .asciiz " = "
.text
.globl main
main:
   li $v0,4           # 4 is the print string syscall
   la $a0,prompt1           # Address of the string to be printed
   syscall               # Print the string
   li $v0,5           # 5 is the read integer syscall
   syscall               # Read the integer
   sw $v0,val1           # Store the integer in val1
  
   li $v0,4           # 4 is the print string syscall
   la $a0,prompt2           # Address of the string to be printed
   syscall               # Print the string
   li $v0,5           # 5 is the read integer syscall
   syscall               # Read the integer
   sw $v0,val2           # Store the integer in val2
  
   li $v0,4           # 4 is the print string syscall
   la $a0,prompt3           # Address of the string to be printed
   syscall               # Print the string
   li $v0,5           # 5 is the read integer syscall
   syscall               # Read the integer
   sw $v0,val3           # Store the integer in val3
  
   lw $s0,val1           # Load val1 into $s0
   lw $s1,val2           # Load val2 into $s1
   lw $s2,val3           # Load val3 into $s2
  
   add $s3,$s0,$s1           # $s3 = $s0 + $s1
   sub $s3,$s3,$s2           # $s3 = $s3 - $s2
   sw $s3,result           # Store $s3 into memory
  
   li $v0,4           # 4 is the print string syscall
   la $a0,output           # Address of the string to be printed
   syscall               # Print the string
   li $v0,1           # 1 is the print integer syscall
   lw $a0,val1           # Load integer to be printed
   syscall               # Print the integer
   li $v0,4           # 4 is the print string syscall
   la $a0,plus           # Address of the string to be printed
   syscall               # print the string
   li $v0,1           # 1 is the print integer syscall
   lw $a0,val2           # Load integer to be printed
   syscall               # Print the integer
   li $v0,4           # 4 is the print string syscall
   la $a0,minus           # Address of the string to be printed
   syscall               # Print the string
   li $v0,1           # 1 is the print integer syscall
   lw $a0,val3           # Load integer to be printed
   syscall               # Print the integer
   li $v0,4           # 4 is the print string syscall
   la $a0,equal_sign       # Address of the string to be printed
   syscall               # Print the string
   li $v0,1           # 1 is the print integer syscall
   lw $a0,result           # Load integer to be printed
   syscall               # Print the integer
  
   li $v0,10           # 10 is exit program syscall
   syscall               # Exit the program

Please refer to the following screenshot of the program for indentation of the code:

OUTPUT: