#
# File: for1_mod.s
# Author: William T Krieger, Oct 2003
#
# My modification of the for1 test case demonstrating a simple for loop.

.text
FMT0:	.ascii "Enter summation number: \0"
FMT1:	.ascii "%d\0"
FMT2:	.ascii "Summation is %d\12\0"

#
# Function: _main()
# void _main()
# Demonstrates a simple for loop. The function queries the user for
# a number (N) and then prints the summation of 1 to N.

.globl _main
_main:
	pushl %ebp			# enter _main()
	movl %esp, %ebp

	subl $12, %esp		# adjust stack for 3 local vars
						# num = -4(%ebp)
						# sum = -8(%ebp)
						# i = -12(%ebp)

	movl $0,-8(%ebp)	# sum = 0

	pushl $FMT0			# call printf( fmt0)
	call _printf
	addl $4,%esp

	leal -4(%ebp),%eax	# call scanf( fmt1, &num)
	pushl %eax
	pushl $FMT1
	call _scanf
	addl $8,%esp

	movl -4(%ebp),%eax	# eax = num
	movl %eax,-12(%ebp)	# i = eax

LOOP1_HEAD:
	cmpl $0,-12(%ebp)	# compare( 0, i)
	jg LOOP1_BODY		# if > then jump LOOP1_BODY
	jmp LOOP1_TAIL		# else jump LOOP1_TAIL

LOOP1_BODY:
	movl -12(%ebp),%eax	# eax = i
	addl %eax,-8(%ebp)	# sum = sum + eax

	decl -12(%ebp)		# i--
	jmp LOOP1_HEAD

LOOP1_TAIL:
	movl -8(%ebp),%eax	# call printf( fmt2, sum)
	pushl %eax
	pushl $FMT2
	call _printf
	addl $8,%esp

	movl %ebp, %esp		# exit _main()
	pop %ebp
	ret