dnl  PowerPC-64 mpn_sublsh1_n -- rp[] = up[] - (vp[] << 1)

dnl  Copyright 2003, 2005 Free Software Foundation, Inc.

dnl  This file is part of the GNU MP Library.

dnl  The GNU MP Library is free software; you can redistribute it and/or modify
dnl  it under the terms of the GNU Lesser General Public License as published
dnl  by the Free Software Foundation; either version 3 of the License, or (at
dnl  your option) any later version.

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 Lesser General Public
dnl  License for more details.

dnl  You should have received a copy of the GNU Lesser General Public License
dnl  along with the GNU MP Library.  If not, see http://www.gnu.org/licenses/.

include(`../config.m4')

C		cycles/limb
C POWER3/PPC630:     2		(1.5 c/l should be possible)
C POWER4/PPC970:     4		(2.0 c/l should be possible)

C INPUT PARAMETERS
C rp	r3
C up	r4
C vp	r5
C n	r6

define(`rp',`r3')
define(`up',`r4')
define(`vp',`r5')

define(`s0',`r6')
define(`s1',`r7')
define(`u0',`r8')
define(`v0',`r10')
define(`v1',`r11')

ASM_START()
PROLOGUE(mpn_sublsh1_n)
	mtctr	r6		C put n in ctr

	ld	v0, 0(vp)	C load v limb
	ld	u0, 0(up)	C load u limb
	addic	up, up, -8	C update up; set cy
	addi	rp, rp, -8	C update rp
	sldi	s1, v0, 1
	bdz	L(end)		C If done, skip loop

L(oop):	ld	v1, 8(vp)	C load v limb
	subfe	s1, s1, u0	C add limbs with cy, set cy
	std	s1, 8(rp)	C store result limb
	srdi	s0, v0, 63	C shift down previous v limb
	ldu	u0, 16(up)	C load u limb and update up
	rldimi	s0, v1, 1, 0	C left shift v limb and merge with prev v limb

	bdz	L(exit)		C decrement ctr and exit if done

	ldu	v0, 16(vp)	C load v limb and update vp
	subfe	s0, s0, u0	C add limbs with cy, set cy
	stdu	s0, 16(rp)	C store result limb and update rp
	srdi	s1, v1, 63	C shift down previous v limb
	ld	u0, 8(up)	C load u limb
	rldimi	s1, v0, 1, 0	C left shift v limb and merge with prev v limb

	bdnz	L(oop)		C decrement ctr and loop back

L(end):	subfe	r7, s1, u0
	std	r7, 8(rp)	C store last result limb
	srdi	r3, v0, 63
	subfze	r3, r3
	neg	r3, r3
	blr
L(exit):	subfe	r7, s0, u0
	std	r7, 16(rp)	C store last result limb
	srdi	r3, v1, 63
	subfze	r3, r3
	neg	r3, r3
	blr
EPILOGUE()