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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()
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