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dnl RISC-V/64 mpn_sec_tabselect
dnl Copyright 2021 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')
dnl This is compiler output, mildly edited. We don't expect this to be faster
dnl than the C fallback code, but providing this in assembly avoids problems
dnl with compilers which generate side channel leaky code.
define(`rp', `a0')
define(`tp', `a1')
define(`n', `a2')
define(`nents', `a3')
define(`which', `a4')
ASM_START()
PROLOGUE(mpn_sec_tabselect)
slli n, n, 3
add t4, a0, n
L(cpy): ld a7, 0(tp)
addi tp, tp, 8
addi rp, rp, 8
sd a7, -8(rp)
bne rp, t4, L(cpy)
li t5, 1
ble nents, t5, L(ret)
L(outer):
xor t3, which, t5
neg t3, t3
srai t3, t3, 63
sub rp, rp, n
L(top): ld a5, 0(rp)
ld t1, 0(tp)
addi rp, rp, 8
addi tp, tp, 8
xor a5, a5, t1
and a5, a5, t3
xor a5, a5, t1
sd a5, -8(rp)
bne t4, rp, L(top)
addi t5, t5, 1
bne nents, t5, L(outer)
L(ret): ret
EPILOGUE()
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