<p> # Code in C for Factorial: # main () 25 fact: # Subroutine "fact". First setup stack frame. # { Stack: 26 subu $sp,$sp,8 # Stack frame is 8 bytes long # printf ("The factorial of 3 is %d\n", 27 sw $ra,0($sp) # Save return address fact( 3 ) ); 28 sw $a0,4($sp) # Save argument (n) # } 29 # check for ending condition (n <= 0) # 30 lw $v0,4($sp) # Load n # int fact (int n) 31 bgtz $v0,recurse # Branch if n > 0 # { 32 li $v0,1 # Return 1 # if (n < 1) 33 jr return # Jump to code to return # return (1); 34 recurse: # else 35 # compute n-1 and make recursive call # return (n * fact (n - 1)); 36 lw $v1,4($sp) # Load n # } 37 subu $v0,$v1,1 # Compute n - 1 sp 38 move $a0,$v0 # Move value to $a0 1 .data 39 jal fact # Call factorial function 2 answer: 40 # upon returning from the recursion, compute the product 3 .asciiz "The factorial of 3 is: " 41 lw $v1,4($sp) # Load n 4 .text 42 mul $v0,$v0,$v1 # Compute fact(n-1) * n 5 main: 43 return: 6 # Setup stack frame for main() 44 # restore callee-saved registers and return the value in $v0 7 subu $sp,$sp,8 # Stack frame is 8 bytes long 45 lw $ra, 0($sp) # Restore $ra 8 sw $ra,0($sp) # Save return address 46 addiu $sp, $sp, 8 # Pop stack 9 # load parameter for factorial in a0 and call factorial function 47 jr $ra # Return to caller 10 li $a0,3 # Put argument in $a0 11 jal fact # Call factorial function Trace: (pretend addresses are decimal, not hex) 12 $v0 $v1 $a0 $ra $a1 13 # after returning from function, display result string and value 14 move $a1,$v0 # Move fact result to $a1 15 la $a0,answer # Put format string in $a0 16 li $v0, 4 # Code for Print String 17 syscall 18 move $a0,$a1 # Move fact result to $a0 for printing 19 li $v0, 1 # Code for Print Integer 20 syscall 21 # before exiting main(), restore saved reg. and pop stack frame 22 lw $ra,0($sp) # Restore return address 23 addiu $sp,$sp,8 # Pop stack frame 24 jr $ra # Return to caller</p>