#*****
#
#	Michael Riff
#	Multiprecision addition version 1.0  Februar 2022.
#	128 bits addition.
#
#****/
				dialect	PowerPC

					file	'lib_128.s'

# Only the sections can be exported (dos not work with labels)
#				export Add_128[DS]
				export .Add_128[PR] => 'add_128'
#				export Subt_128[DS]
				export .Subt_128[PR] => 'sub_128'

# 128 bit signed & unsigned addition 
		csect	Add_128[DS]
		csect	.Add_128[PR]

# Reset OFW in XER TBC
	addis r10,r0,0x3FFF
	addi r10,r10,0xFFFF
	mfspr r0,XER
	and r0,r0,r10
	mtspr xer,r0
	
#	mfspr r0,XER
#	stw r0,0(r6)

	lwz r12,12(r3)
	lwz r11,8(r3)
	lwz r10,4(r3)
	lwz r3,0(r3)

	lwz r9,12(r4)
	lwz r8,8(r4)
	lwz r7,4(r4)
	lwz r4,0(r4)

	addco r9,r9,r12
	addeo r8,r8,r11
	addeo r7,r7,r10
	addeo r10,r3,r4

	stw r10,0(r5)
	stw r7,4(r5)
	stw r8,8(r5)
	stw r9,12(r5)

# Handle overflow (and carry)
	mfspr r5,XER
	andis. r5,r5,0x6000
	
	stw r5,0(r6)

	blr


# 128 bit subtraction abcd - efgh
		csect	Subt_128[DS]
		csect	.Subt_128[PR]

# Reset OFW in XER ToDo

	lwz r12,12(r3)	# d
	lwz r11,8(r3)	# c
	lwz r10,4(r3)	# b
	lwz r3,0(r3)	# a

	# Clear carry bit
	addic	r0,r0,0

	lwz r9,12(r4)	# h
	lwz r8,8(r4)	# g
	lwz r7,4(r4)	# f
	lwz r4,0(r4)	# e

	
	subfc	r9,r9,r12
	subfe	r8,r8,r11
	subfe	r7,r7,r10
	subfe	r10,r4,r3
	
	stw	r9,12(r5)
	stw	r8,8(r5)
	stw	r7,4(r5)
	stw	r10,0(r5)

# Handle overflow ToDo

	blr