Adding to an array in a subroutine(MIPS/Assembly) - arrays

Question

I'm trying to add values to an array inside a subroutine. I can get the first valid value(positive number and divisible by 3) into the array, but the next valid entries don't work. I can enter a valid number and then enter an invalid number and the program works fine, but two valid numbers makes Spim stop working. I've spent a few hours trying to figure it out but no luck. The jumping from one subroutine is a requirement for the assignment, I have a working program but lacks all the unnecessary(in my opinion) subroutines.
.data
array1: .word 80
EnterARVal: .asciiz "Please enter a number:\t"
space: .asciiz " "
errormessage: .asciiz "*****Error: "
notpos: .asciiz " is not a positive number.\n"
notdiv3: .asciiz " is not divisible by 3.\n"
numadded: .asciiz " added to array.\n"
EnterElem: .asciiz "Enter number "
ARReverse: .asciiz "The contents of the array in reverse orders is:\n"
InvalidAR: .asciiz "Invalid number of array elements, please try again.\n"
.text
main:
la $s0, array1 #array1 pointer
li $t0, 1
begin:
jal readNum #go to readNum subroutine
add $a0, $0, $v0 #stores readNum input to $a0
jal verifySize #jumps to verifySize subroutine
add $t1, $v1, $0 #stores 0 or 1 value to $t1
beq $t1, $0, begin #starts over if t1 is 0 or false
beq $t1, $t0, numok #goes to numok if t1 is 1 or true
numok: add $a0, $0, $a0
add $a1, $0, $s0
jal createArray
j exit
readNum: li $v0, 4
la $a0, EnterARVal
syscall
li $v0, 5
syscall
add $v0, $v0, $0
j $ra
verifySize: add $t1, $0, $a0
li $t2, 20
li $t3, 1
li $t4, 0
li $t5, 1
slt $t6, $t1, $t3
beq $t6, $t3, toolow
sgt $t7, $t1, $t2
beq $t7, $t3, toohigh
beq $t7, $t4, oknum
oknum:
add $v1, $t5, $0
j $ra
toolow:
li $v0, 4
la $a0, InvalidAR
syscall
add $v1, $t4, $0
j $ra
toohigh:
li $v0, 4
la $a0, InvalidAR
syscall
add $v1, $t4, $0
j $ra
createArray: add $s1, $a0, $0
add $s0, $a1, $0
li $t0, 0 #counter
li $t2, 1
add $a0, $s1, $0
li $v0, 1
syscall
makingarray: beq $t0, $s1, arraydone
jal readNum #go to readNum subroutine
add $a0, $v0, $0 #stores number from readNum to $a0
jal checkNumPositive #jump to checkNumPositive subroutine
add $t1, $v0, $0
beq $t1, $0, positivenum #if number is positive go to positivenum
beq $t1, $t2, notpositive
positivenum:
jal divisibleBy3
add $t4, $v0, $0
beq $t4, $0, notdivisibleby3
sw $a0, 0($s0)
li $v0, 1
syscall
li $v0, 4
la $a0, numadded
syscall
add $s0, $s0, 4
add $t0, $t0, 1
j makingarray
arraydone:
add $v0, $s0, $0
j $ra
notpositive:
li $v0, 4
la $a0, notpos
syscall
j makingarray
notdivisibleby3:
li $v0, 4
la $a0, notdiv3
syscall
j makingarray
#reverseArray:
divisibleBy3: add $t0, $a0, $0
li $t1, 3
div $t0, $t1
mfhi $t2
mflo $t3
seq $t4, $t2, $0
add $v0, $t4, $0
j $ra
checkNumPositive: li $t0, 0
slt $t1, $a0, $0 #set t1 to 1 if number is less than 0
add $v0, $t1, $t0
j $ra
exit: li $v0, 10
syscall
Any tips with how I can fix createArray is appreciated, thanks.

Answer 1

Your primary problem is you used .word 80 which only reserves a single word with value 80. You probably meant .space 80 to reserve space for up to 20 words (which seems to be the limit enforced in your code).
Further problem is you are not following conventions about which registers need to be preserved.
For example, you use $t0 as counter in createArray and that's not preserved across subroutines, not by convention and de facto not by your code (both divisibleBy3 and checkNumPositive destroy it).
Similar problem with not properly preserving $ra in nested subroutine calls, as such the return address for createArray is overwritten by the subroutines invoked from there.
I assume the intent of the assignment was to teach you about these nuances.