##############################################################################
#
#  inst-examples.s
#
#  This "program" is really just a collection of instruction examples to
#  illustrate what instructions do and how they are encoded in machine 
#  language.  
#
###############################################################################

		.text				# TEXT SEGMENT FOLLOWS

# The main() function is called from the simple SPIM runtime environment
# (coded in the exceptions.s file).  It should do the work of the program.

main:	# ADD instruction example

	li	$s1, 3			# Two numbers to add:  3 and 5
	li	$s2, 5

	add	$t8, $s2, $s1		# ADD example: $t8 = $s2 + $s1
	
	# Expression evaluation example:  Let g = (b + c) - (e + f)
	
	li	$s2, 7			# Let b ($s2) = 7
	li	$s3, 11			# Let c ($s3) = 11
	li	$s5, 13			# Let e ($s5) = 13
	li	$s6, 17			# Let f ($s6) = 17
	
	add	$t8, $s2, $s3		# $t8 = $s2 + $s3 = b + c = 18
	add	$t9, $s5, $s6		# $t9 = $s5 + $s6 = e + f = 30
	sub	$s7, $t8, $t9		# $s7 = $t8 - $t9 = (b+c)-(e+f) = 18-30 = -22
	
	# At this point, g ($s7) should contain the result, -22.
	
	# lui/ori example: Load 0xCafeDada into register $s0
	li	$s0, 0xDeadBeef		# Initial garbage in $s0
	lui	$s0, 0xCafe		# Load $s0 with 0xcafe0000
	ori	$s0, $s0, 0xDada	# Logical-OR 0x0000dada into $s0.
	
	jr	$ra			# Return to runtime environment.