.text
.globl  __start
      
__start:
       li      $v0, 4           # mesg1 asking for a number
       la      $a0, msg1
       syscall
       li      $v0,5           # system call that reads an integer
       syscall
       move $a0, $v0
       jal fact        

        move $a0, $v0
        li      $v0,1           # print factorial
        syscall
        li      $v0,4           # print an end of line
        la      $a0, cr
        syscall
        li      $v0,10          # exit
        syscall
        
fact: slti $t1, $a0, 1
      bne $t1, $zero, done
      addi $sp, $sp, -8
      sw $a0, 0 ($sp)
      sw $ra, 4 ($sp)
      addi $a0, $a0, -1
      jal fact
      lw $t0, 0 ($sp)
      lw $ra, 4 ($sp)
      addi $sp, $sp, 8
      mul $t0, $v0, $t0
      move $v0, $t0
      j done1 
done: 
      addi $v0, $zero, 1
done1:jr $ra
        
.data

msg1:   .asciiz "Enter a integer number:  "
msg2:   .asciiz "Factorial of the number  =   "
cr:     .asciiz "\n"