PROGRAM3.DNKMMS

SMA 1
LW	$r0
SMA	2
LW	$r4
SMA 0
MOVA $ma
MOVR $r1
MOVR $r12
MOVR $r13
CMP $r0, $r4
STBR 2
BR greater

less_or_eq:
SMA	1
LW	$r4
SMA	2
LW	$r4

greater:
STBR 2
BREVEN	less_eq_even

less_eq_odd:		# Odd first number
MOVA	$r12		#
ADD	$r0		# lowproduct = lowproduct + r0
MOVR $r12		# 
MOVA $r13		# 
ADD	$r1		# highproduct = highproduct + r1 (has overflow carry from r0)
MOVR $r13		# 


less_eq_even:		# 
MOVA	$r0		# 
SLL	$acc		# Shift left low bits of A	(MULT BY 2) A*2
MOVR	$r0		# 
MOVA $r1		# 
SLL	$acc		# Shift left high bits of A (has overflow carry from r0)
MOVR	$r1		# 


SLR	$r4,		# Shift right	(DIVIDE BY 2)	
MOVR	$r4
CMP	$acc, $one	# B > 0
STBR 3
BR	greater	# Relative jump to code for smaller first number

SMA	3		# 
LW	$r4		# load C
SMA	4		# 
SW	$r12		# save low bits of product
SMA	5		# 
SW	$r13		# save high bits of product


MOVA    $r12		# 
MOVR    $r0		# Set low bits of A to previous product low
MOVA	$r13		# 
MOVR    $r1		# Set high bits of A to previous product high

SMA 0
MOVA $ma
MOVR $r12
MOVR $r13

loop:
STBR 2
BREVEN even	# Detect if first number is even (and branch to that code if so)


odd:			# Odd first number
MOVA	$r12		# 
ADD	$r0		# low product bits = low product bits + r2
MOVR $r12		# 
MOVA $r13		# 
ADD	$r1		# high product bits = high product bits +r3 + ov
MOVR $r13		# 
ADD $zero

even:			# 
MOVA	$r0		# 
SLL	$acc,		# lowA*2 Shift left	(MULT BY 2)
MOVR	$r0		# 
MOVA $r1		# 
SLL	$acc		# highA*2 
MOVR	$r1		# 
ADD $zero
MOVA $r1


SLR	$r4,		# C/2 Shift right	(DIVIDE BY 2)
MOVR	$r4
CMP	$acc, $zero	# C > 0
STBR 3
BR	loop		# Relative jump to code for smaller first number


SMA	4		# 
SW	$r12		# store low bits of product
SMA	5		# 
SW	$r13		# store high bits of product


HALT			# End of Program