I keep getting 0 as an answer for my mips code where I'm supposed to find the gcd of two numbers - mips

Question

.data
n1:.asciiz"Enter the first number:"
n2: .asciiz"Enter the second number:"
.text
.globl main
main:
li $v0,4
la $a0,n1
syscall
li $v0, 5 # get input from user
syscall
move $a0,$s0
li $v0,4
la $a0,n2
syscall
li $v0, 5 # get second input from user
syscall
move $a0,$s1
jal calcGCD # call function calcGCD
add $a0,$v0,$zero
li $v0,1
syscall # print result
li $v0, 10 # exit program
syscall
calcGCD:
#GCD(n1, n2)
# n1 = $a0
# n2 = $a1
addi $sp, $sp, -12
sw $ra, 0($sp) # save function into stack
sw $s0, 4($sp) # save value $s0 into stack
sw $s1, 8($sp) # save value $s1 into stack
add $s0, $a0, $zero # s0 = a0 ( value n1 )
add $s1, $a1, $zero # s1 = a1 ( value n2 )
addi $t1, $zero, 0 # $t1 = 0
beq $s1, $t1, return # if s1 == 0 return
add $a0, $zero, $s1 # make a0 = $s1
div $s0, $s1 # n1/n2
mfhi $a1 # reminder of n1/n2 which is equal to n1%n2
jal calcGCD
exitGCD:
lw $ra, 0 ($sp) # read registers from stack
lw $s0, 4 ($sp)
lw $s1, 8 ($sp)
addi $sp,$sp , 12 # bring back stack pointer
jr $ra
return:
add $v0, $zero, $s0 # return $v0 = $s0 ( n1)
j exitGCD

Answer 1

The main issue with your code is with the part where you store the user input in the registers. In move $a0,$s0, you are moving the value at $s0 into $a0 when the user input is stored in $v0, therefore, it should be move $a0,$v0, and from your function, you seem to have stored the second input in $a1 but in your code, both the inputs are being stored in the same register so the next command should be move $a1,$v0. Here is one version of your code.
.data
n1:.asciiz"Enter the first number:"
n2: .asciiz"Enter the second number:"
.text
.globl main
main:
li $v0,4
la $a0,n1
syscall
li $v0, 5 # get input from user
syscall
move $t0,$v0 #temporarily store the user input in another register because $a0 is having another value stored in it in the next command
li $v0,4
la $a0,n2
syscall
li $v0, 5 # get second input from user
syscall
move $a1,$v0
move $a0,$t0 #transfer the first user input into $a0 to be used in the function
jal calcGCD # call function calcGCD
add $a0,$v0,$zero
li $v0,1
syscall # print result
li $v0, 10 # exit program
syscall
calcGCD:
#GCD(n1, n2)
# n1 = $a0
# n2 = $a1
addi $sp, $sp, -12
sw $ra, 0($sp) # save function into stack
sw $s0, 4($sp) # save value $s0 into stack
sw $s1, 8($sp) # save value $s1 into stack
add $s0, $a0, $zero # s0 = a0 ( value n1 )
add $s1, $a1, $zero # s1 = a1 ( value n2 )
addi $t1, $zero, 0 # $t1 = 0
beq $s1, $t1, return # if s1 == 0 return
add $a0, $zero, $s1 # make a0 = $s1
div $s0, $s1 # n1/n2
mfhi $a1 # reminder of n1/n2 which is equal to n1%n2
jal calcGCD
exitGCD:
lw $ra, 0 ($sp) # read registers from stack
lw $s0, 4 ($sp)
lw $s1, 8 ($sp)
addi $sp,$sp , 12 # bring back stack pointer
jr $ra
return:
add $v0, $zero, $s0 # return $v0 = $s0 ( n1)
j exitGCD