子程序/函数来计算乘法

Question

# name :
# EE:361, DATE
 .data
msga : .asciiz "enter number a:/n"
msgb : .asciiz "enter number b:/n"
msg : .asciiz "the product is : "
 .text 
 .globl main 
 .globl mymul
main :
  addi $sp , $sp ,-8
  sw $ra ,4($sp)
  sw $fp ,0($sp)
  la $a0, msg 
  li $v1,4
  syscall 
  li $v1,5
  syscall 
  add $s1 , $v1 , $0
  la $a0,msgb 
  li $v1, 4
  syscall
  li $v1,5
  syscall
  add $a1 ,$v1 ,$0
  add $a0,$1,$0
  add $fp,$sp,$0
  jal mymul 
  add $1,$v1,$0
  la $a0 ,msg 
  li $v1,4
  syscall 
  add  $a0 ,$1,$0
  li $v1,1
  syscall 
  lw $fp ,0($sp) 
   lw $ra,4($sp)
   addi $sp,$sp,8 
  li $v1, 10
  syscall 
  mymul:
  addi $sp ,$sp ,-4
  sw $s0,0($sp)
  add $s0 , $a1 ,$0
  add $v1 ,$0, $0
  beq $s0 , $0, multEol
  add $v1,$v1,$a0
  addi $s0,$s0,-1
  j multloop 
  multEol:
  lw $s0,0($sp)
  jr $ra  
  
     
   

我编写了以下代码，但是它不起作用，并且没有o / p

我使用称为火星的mips模拟器

 .data
msga : .asciiz "enter number a:/n"
msgb : .asciiz "enter number b:/n"
msg : .asciiz "the product is : "
 .text 
 .globl main 
 .globl mymul
main :
  addi $sp , $sp ,-8
  sw $ra ,4($sp)
  sw $fp ,0($sp)
  la $a0, msg 
  li $v1,4
  syscall 
  li $v1,5
  syscall 
  add $s1 , $v1 , $0
  la $a0,msgb 
  li $v1, 4
  syscall
  li $v1,5
  syscall
  add $a1 ,$v1 ,$0
  add $a0,$1,$0
  add $fp,$sp,$0
  jal mymul 
  add $1,$v1,$0
  la $a0 ,msg 
  li $v1,4
  syscall 
  add  $a0 ,$1,$0
  li $v1,1
  syscall 
  lw $fp ,0($sp) 
   lw $ra,4($sp)
   addi $sp,$sp,8 
  li $v1, 10
  syscall 
  mymul:
  addi $sp ,$sp ,-4
  sw $s0,0($sp)
  add $s0 , $a1 ,$0
  add $v1 ,$0, $0
  beq $s0 , $0, multEol
  add $v1,$v1,$a0
  addi $s0,$s0,-1
  j multloop 
  multEol:
  lw $s0,0($sp)
  jr $ra  

黑屏出现很多错误，甚至字符串也没有显示