main:
	# Args:	void
	# Returns:
	#	- int
	#
	# Locals:
	#	- $s0:	int input
	#	- $t0:	int f
	#
	# Stack:	[$ra, $s0]
	# Uses:		[$s0, $a0, $v0, $t0]
	# Clobbers:	[$t0, $a0, $v0]
	#
	# Structure:
	# -> main
	#	-> [prologue]
	#	-> [body]
	#	-> [epilogue]

main__prologue:
	begin
	push	$ra
	push	$s0

main__body:
	li	$v0, 5				# syscall 5: read_int
	syscall					#
	move	$s0, $v0			# scanf("%d", &input);

	# TODO: call factorial, and put the result somewhere useful
	move	$a0, $s0			#
	jal	factorial			#
	move	$t0, $v0			# int f = factorial(input);


	li	$v0, 1				# syscall 1: print_int
	move	$a0, $s0			#
	syscall					# printf("%d", input);

	li	$v0, 4				# syscall 4: print_string
	la	$a0, main__result_msg		#
	syscall					# printf("!= ");

	li	$v0, 1				# syscall 1: print_int
	move	$a0, $t0				#
	syscall					# printf("%d", f);

	li	$v0, 11				# syscall 11: print_char
	li	$a0, '\n'			#
	syscall					# putchar('\n');


main__epilogue:
	pop	$s0
	pop	$ra
	end

	li	$v0, 0				#
	jr	$ra				# return 0;

factorial:
	# Args:	
	#	- $a0:	int n
	# Returns:
	#	- int
	#
	# Locals:
	#	- $s0: int n
	#
	# Stack:	[$ra, $s0]
	# Uses:		[$s0, $a0, $v0]
	# Clobbers:	[$a0, $v0]
	#
	# Structure:
	# -> factorial 
	#	-> [prologue]
	#	-> [body]
	#		-> read_loop
	#			-> init
	#			-> cond
	#			-> body
	#		-> n_le_0
	#	-> [epilogue]
factorial__prologue:
	begin
	push	$ra
	push	$s0

factorial__body:
	move	$s0, $a0
	blez	$a0, factorial__n_le_0

	addi	$a0, $s0, -1
	jal	factorial
	mul	$v0, $s0, $v0	# retval = n * factorial(n - 1)
	j	factorial__epilogue
	
factorial__read_loop_init:
factorial__read_loop_cond:
factorial__read_loop_body:
factorial__read_loop_step:
factorial__read_loop_end:

	
factorial__n_le_0:
	li	$v0, 1		# retval = 1

factorial__epilogue:
	pop	$s0
	pop	$ra
	end

	jr	$ra


	.data
main__result_msg:
	.asciiz	"! = "