dnl  AMD64 mpn_rsh1add_n -- rp[] = (up[] + vp[]) >> 1

dnl  AMD64 mpn_rsh1sub_n -- rp[] = (up[] - vp[]) >> 1

dnl  Copyright 2003, 2005, 2009, 2011, 2012 Free Software Foundation, Inc.

dnl  This file is part of the GNU MP Library.

dnl

dnl  The GNU MP Library is free software; you can redistribute it and/or modify

dnl  it under the terms of either:

dnl

dnl    * the GNU Lesser General Public License as published by the Free

dnl      Software Foundation; either version 3 of the License, or (at your

dnl      option) any later version.

dnl

dnl  or

dnl

dnl    * the GNU General Public License as published by the Free Software

dnl      Foundation; either version 2 of the License, or (at your option) any

dnl      later version.

dnl

dnl  or both in parallel, as here.

dnl

dnl  The GNU MP Library is distributed in the hope that it will be useful, but

dnl  WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY

dnl  or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

dnl  for more details.

dnl

dnl  You should have received copies of the GNU General Public License and the

dnl  GNU Lesser General Public License along with the GNU MP Library.  If not,

dnl  see https://www.gnu.org/licenses/.

include(`../config.m4')

C	     cycles/limb

C AMD K8,K9	 2.14	(mpn_add_n + mpn_rshift need 4.125)

C AMD K10	 2.14	(mpn_add_n + mpn_rshift need 4.125)

C Intel P4	12.75

C Intel core2	 3.75

C Intel NMH	 4.4

C Intel SBR	 ?

C Intel atom	 ?

C VIA nano	 3.25

C TODO

C  * Rewrite to use indexed addressing, like addlsh1.asm and sublsh1.asm.

C INPUT PARAMETERS

define(`rp', `%rdi')

define(`up', `%rsi')

define(`vp', `%rdx')

define(`n',`  %rcx')

ifdef(`OPERATION_rsh1add_n', `

	define(ADDSUB,	      add)

	define(ADCSBB,	      adc)

	define(func_n,	      mpn_rsh1add_n)

	define(func_nc,	      mpn_rsh1add_nc)')

ifdef(`OPERATION_rsh1sub_n', `

	define(ADDSUB,	      sub)

	define(ADCSBB,	      sbb)

	define(func_n,	      mpn_rsh1sub_n)

	define(func_nc,	      mpn_rsh1sub_nc)')

MULFUNC_PROLOGUE(mpn_rsh1add_n mpn_rsh1add_nc mpn_rsh1sub_n mpn_rsh1sub_nc)

ABI_SUPPORT(DOS64)

ABI_SUPPORT(STD64)

ASM_START()

	TEXT

	ALIGN(16)

PROLOGUE(func_nc)

	FUNC_ENTRY(4)

IFDOS(`	mov	56(%rsp), %r8	')

	push	%rbx

	xor	R32(%rax), R32(%rax)

	neg	%r8			C set C flag from parameter

	mov	(up), %rbx

	ADCSBB	(vp), %rbx

	jmp	L(ent)

EPILOGUE()

	ALIGN(16)

PROLOGUE(func_n)

	FUNC_ENTRY(4)

	push	%rbx

	xor	R32(%rax), R32(%rax)

	mov	(up), %rbx

	ADDSUB	(vp), %rbx

L(ent):

	rcr	%rbx			C rotate, save acy

	adc	R32(%rax), R32(%rax)	C return value

	mov	R32(n), R32(%r11)

	and	$3, R32(%r11)

	cmp	$1, R32(%r11)

	je	L(do)			C jump if n = 1 5 9 ...

L(n1):	cmp	$2, R32(%r11)

	jne	L(n2)			C jump unless n = 2 6 10 ...

	add	%rbx, %rbx		C rotate carry limb, restore acy

	mov	8(up), %r10

	ADCSBB	8(vp), %r10

	lea	8(up), up

	lea	8(vp), vp

	lea	8(rp), rp

	rcr	%r10

	rcr	%rbx

	mov	%rbx, -8(rp)

	jmp	L(cj1)

L(n2):	cmp	$3, R32(%r11)

	jne	L(n3)			C jump unless n = 3 7 11 ...

	add	%rbx, %rbx		C rotate carry limb, restore acy

	mov	8(up), %r9

	mov	16(up), %r10

	ADCSBB	8(vp), %r9

	ADCSBB	16(vp), %r10

	lea	16(up), up

	lea	16(vp), vp

	lea	16(rp), rp

	rcr	%r10

	rcr	%r9

	rcr	%rbx

	mov	%rbx, -16(rp)

	jmp	L(cj2)

L(n3):	dec	n			C come here for n = 4 8 12 ...

	add	%rbx, %rbx		C rotate carry limb, restore acy

	mov	8(up), %r8

	mov	16(up), %r9

	ADCSBB	8(vp), %r8

	ADCSBB	16(vp), %r9

	mov	24(up), %r10

	ADCSBB	24(vp), %r10

	lea	24(up), up

	lea	24(vp), vp

	lea	24(rp), rp

	rcr	%r10

	rcr	%r9

	rcr	%r8

	rcr	%rbx

	mov	%rbx, -24(rp)

	mov	%r8, -16(rp)

L(cj2):	mov	%r9, -8(rp)

L(cj1):	mov	%r10, %rbx

L(do):

	shr	$2, n			C				4

	je	L(end)			C				2

	ALIGN(16)

L(top):	add	%rbx, %rbx		C rotate carry limb, restore acy

	mov	8(up), %r8

	mov	16(up), %r9

	ADCSBB	8(vp), %r8

	ADCSBB	16(vp), %r9

	mov	24(up), %r10

	mov	32(up), %r11

	ADCSBB	24(vp), %r10

	ADCSBB	32(vp), %r11

	lea	32(up), up

	lea	32(vp), vp

	rcr	%r11			C rotate, save acy

	rcr	%r10

	rcr	%r9

	rcr	%r8

	rcr	%rbx

	mov	%rbx, (rp)

	mov	%r8, 8(rp)

	mov	%r9, 16(rp)

	mov	%r10, 24(rp)

	mov	%r11, %rbx

	lea	32(rp), rp

	dec	n

	jne	L(top)

L(end):	mov	%rbx, (rp)

	pop	%rbx

	FUNC_EXIT()

	ret

EPILOGUE()