dnl  ARM mpn_mul_1 optimised for A15.

dnl  Copyright 2012, 2013 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		best
C StrongARM:	 -
C XScale	 ?
C Cortex-A7	 ?
C Cortex-A8	 ?
C Cortex-A9	 5.25			3.25
C Cortex-A15	 2.25			this


C This runs well on A15 but very poorly on A9.  By scheduling loads and adds
C it is possible to get good A9 performance as well, but at the cost of using
C many more (callee-saves) registers.

C This is armv5 code, optimized for the armv7a cpu A15.  Its location in the
C GMP file structure might be misleading.


define(`rp', `r0')
define(`up', `r1')
define(`n',  `r2')
define(`v0', `r3')

ASM_START()
PROLOGUE(mpn_mul_1c)
	ldr	r12, [sp]
	b	L(ent)
EPILOGUE()
PROLOGUE(mpn_mul_1)
	mov	r12, #0
L(ent):	push	{r4-r7}

	ldr	r6, [up], #4
	tst	n, #1
	beq	L(bx0)

L(bx1):	umull	r4, r7, r6, v0
	adds	r4, r4, r12
	tst	n, #2
	beq	L(lo1)
	b	L(lo3)

L(bx0):	umull	r4, r5, r6, v0
	adds	r4, r4, r12
	tst	n, #2
	beq	L(lo0)
	b	L(lo2)

L(top):	ldr	r6, [up], #4
	str	r4, [rp], #4
	umull	r4, r5, r6, v0
	adds	r4, r4, r7
L(lo0):	ldr	r6, [up], #4
	str	r4, [rp], #4
	umull	r4, r7, r6, v0
	adcs	r4, r4, r5
L(lo3):	ldr	r6, [up], #4
	str	r4, [rp], #4
	umull	r4, r5, r6, v0
	adcs	r4, r4, r7
L(lo2):	ldr	r6, [up], #4
	str	r4, [rp], #4
	umull	r4, r7, r6, v0
	adcs	r4, r4, r5
L(lo1):	adc	r7, r7, #0
	subs	n, n, #4
	bgt	L(top)

	str	r4, [rp]
	mov	r0, r7
	pop	{r4-r7}
	bx	lr
EPILOGUE()