dnl ARM mpn_addlsh1_n and mpn_sublsh1_n
dnl Contributed to the GNU project by Torbjörn Granlund.
dnl Copyright 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 addlsh1_n sublsh1_n
C cycles/limb cycles/limb
C StrongARM ? ?
C XScale ? ?
C Cortex-A7 ? ?
C Cortex-A8 ? ?
C Cortex-A9 3.12 3.7
C Cortex-A15 ? ?
C TODO
C * The addlsh1_n code runs well, but is only barely faster than mpn_addmul_1.
C The sublsh1_n code could surely be tweaked, its REVCY slows down things
C very much. If two insns are really needed, it might help to separate them
C for better micro-parallelism.
define(`rp', `r0')
define(`up', `r1')
define(`vp', `r2')
define(`n', `r3')
ifdef(`OPERATION_addlsh1_n', `
define(`ADDSUB', adds)
define(`ADDSUBC', adcs)
define(`SETCY', `cmp $1, #1')
define(`RETVAL', `adc r0, $1, #2')
define(`SAVECY', `sbc $1, $2, #0')
define(`RESTCY', `cmn $1, #1')
define(`REVCY', `')
define(`INICYR', `mov $1, #0')
define(`r10r11', `r11')
define(`func', mpn_addlsh1_n)
define(`func_nc', mpn_addlsh1_nc)')
ifdef(`OPERATION_sublsh1_n', `
define(`ADDSUB', subs)
define(`ADDSUBC', sbcs)
define(`SETCY', `rsbs $1, $1, #0')
define(`RETVAL', `adc r0, $1, #1')
define(`SAVECY', `sbc $1, $1, $1')
define(`RESTCY', `cmn $1, #1')
define(`REVCY', `sbc $1, $1, $1
cmn $1, #1')
define(`INICYR', `mvn $1, #0')
define(`r10r11', `r10')
define(`func', mpn_sublsh1_n)
define(`func_nc', mpn_sublsh1_nc)')
MULFUNC_PROLOGUE(mpn_addlsh1_n mpn_sublsh1_n)
ASM_START()
PROLOGUE(func)
push {r4-r10r11, r14}
ifdef(`OPERATION_addlsh1_n', `
mvn r11, #0
')
INICYR( r14)
subs n, n, #3
blt L(le2) C carry clear on branch path
cmn r0, #0 C clear carry
ldmia vp!, {r8, r9, r10}
b L(mid)
L(top): RESTCY( r14)
ADDSUBC r4, r4, r8
ADDSUBC r5, r5, r9
ADDSUBC r6, r6, r10
ldmia vp!, {r8, r9, r10}
stmia rp!, {r4, r5, r6}
REVCY(r14)
adcs r8, r8, r8
adcs r9, r9, r9
adcs r10, r10, r10
ldmia up!, {r4, r5, r6}
SAVECY( r14, r11)
subs n, n, #3
blt L(exi)
RESTCY( r12)
ADDSUBC r4, r4, r8
ADDSUBC r5, r5, r9
ADDSUBC r6, r6, r10
ldmia vp!, {r8, r9, r10}
stmia rp!, {r4, r5, r6}
REVCY(r12)
L(mid): adcs r8, r8, r8
adcs r9, r9, r9
adcs r10, r10, r10
ldmia up!, {r4, r5, r6}
SAVECY( r12, r11)
subs n, n, #3
bge L(top)
mov r7, r12 C swap alternating...
mov r12, r14 C ...carry-save...
mov r14, r7 C ...registers
L(exi): RESTCY( r12)
ADDSUBC r4, r4, r8
ADDSUBC r5, r5, r9
ADDSUBC r6, r6, r10
stmia rp!, {r4, r5, r6}
REVCY(r12)
L(le2): tst n, #1 C n = {-1,-2,-3} map to [2], [1], [0]
beq L(e1)
L(e02): tst n, #2
beq L(rt0)
ldm vp, {r8, r9}
adcs r8, r8, r8
adcs r9, r9, r9
ldm up, {r4, r5}
SAVECY( r12, r11)
RESTCY( r14)
ADDSUBC r4, r4, r8
ADDSUBC r5, r5, r9
stm rp, {r4, r5}
b L(rt1)
L(e1): ldr r8, [vp]
adcs r8, r8, r8
ldr r4, [up]
SAVECY( r12, r11)
RESTCY( r14)
ADDSUBC r4, r4, r8
str r4, [rp]
L(rt1): mov r14, r12
REVCY(r12)
L(rt0): RETVAL( r14)
pop {r4-r10r11, r14}
ret r14
EPILOGUE()