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dnl ARM v4 mpn_bdiv_q_1, mpn_pi1_bdiv_q_1 -- Hensel division by 1-limb divisor.
dnl Contributed to the GNU project by Torbjörn Granlund.
dnl Copyright 2012, 2017 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 norm unorm
C 1176 13 18
C Cortex-A5 8 12
C Cortex-A7 10.5 18
C Cortex-A8 14 15
C Cortex-A9 10 12 not measured since latest edits
C Cortex-A15 9 9
C Cortex-A53 14 20
C Architecture requirements:
C v5 -
C v5t -
C v5te -
C v6 -
C v6t2 -
C v7a -
define(`rp', `r0')
define(`up', `r1')
define(`n', `r2')
define(`d', `r3')
define(`di_arg', `sp[0]') C just mpn_pi1_bdiv_q_1
define(`cnt_arg', `sp[4]') C just mpn_pi1_bdiv_q_1
define(`cy', `r7')
define(`cnt', `r6')
define(`tnc', `r8')
ASM_START()
PROLOGUE(mpn_bdiv_q_1)
tst d, #1
push {r6-r11}
mov cnt, #0
bne L(inv)
C count trailing zeros
movs r10, d, lsl #16
moveq d, d, lsr #16
moveq cnt, #16
tst d, #0xff
moveq d, d, lsr #8
addeq cnt, cnt, #8
LEA( r10, ctz_tab)
and r11, d, #0xff
ldrb r10, [r10, r11]
mov d, d, lsr r10
add cnt, cnt, r10
C binvert limb
L(inv): LEA( r10, binvert_limb_table)
and r12, d, #254
ldrb r10, [r10, r12, lsr #1]
mul r12, r10, r10
mul r12, d, r12
rsb r12, r12, r10, lsl #1
mul r10, r12, r12
mul r10, d, r10
rsb r10, r10, r12, lsl #1 C r10 = inverse
b L(pi1)
EPILOGUE()
PROLOGUE(mpn_pi1_bdiv_q_1)
push {r6-r11}
ldr cnt, [sp, #28]
ldr r10, [sp, #24]
L(pi1): ldr r11, [up], #4 C up[0]
cmp cnt, #0
mov cy, #0
bne L(unorm)
L(norm):
subs n, n, #1 C set carry as side-effect
beq L(edn)
ALIGN(16)
L(tpn): sbcs cy, r11, cy
ldr r11, [up], #4
sub n, n, #1
mul r9, r10, cy
tst n, n
umull r12, cy, d, r9
str r9, [rp], #4
bne L(tpn)
L(edn): sbc cy, r11, cy
mul r9, r10, cy
str r9, [rp]
pop {r6-r11}
return r14
L(unorm):
rsb tnc, cnt, #32
mov r11, r11, lsr cnt
subs n, n, #1 C set carry as side-effect
beq L(edu)
ALIGN(16)
L(tpu): ldr r12, [up], #4
orr r9, r11, r12, lsl tnc
mov r11, r12, lsr cnt
sbcs cy, r9, cy C critical path ->cy->cy->
sub n, n, #1
mul r9, r10, cy C critical path ->cy->r9->
tst n, n
umull r12, cy, d, r9 C critical path ->r9->cy->
str r9, [rp], #4
bne L(tpu)
L(edu): sbc cy, r11, cy
mul r9, r10, cy
str r9, [rp]
pop {r6-r11}
return r14
EPILOGUE()
RODATA
ctz_tab:
.byte 8,0,1,0,2,0,1,0,3,0,1,0,2,0,1,0,4,0,1,0,2,0,1,0,3,0,1,0,2,0,1,0
.byte 5,0,1,0,2,0,1,0,3,0,1,0,2,0,1,0,4,0,1,0,2,0,1,0,3,0,1,0,2,0,1,0
.byte 6,0,1,0,2,0,1,0,3,0,1,0,2,0,1,0,4,0,1,0,2,0,1,0,3,0,1,0,2,0,1,0
.byte 5,0,1,0,2,0,1,0,3,0,1,0,2,0,1,0,4,0,1,0,2,0,1,0,3,0,1,0,2,0,1,0
.byte 7,0,1,0,2,0,1,0,3,0,1,0,2,0,1,0,4,0,1,0,2,0,1,0,3,0,1,0,2,0,1,0
.byte 5,0,1,0,2,0,1,0,3,0,1,0,2,0,1,0,4,0,1,0,2,0,1,0,3,0,1,0,2,0,1,0
.byte 6,0,1,0,2,0,1,0,3,0,1,0,2,0,1,0,4,0,1,0,2,0,1,0,3,0,1,0,2,0,1,0
.byte 5,0,1,0,2,0,1,0,3,0,1,0,2,0,1,0,4,0,1,0,2,0,1,0,3,0,1,0,2,0,1,0
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