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dnl PowerPC-64 mpn_invert_limb -- Invert a normalized limb.
dnl Copyright 2004-2006, 2008, 2010, 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 (approximate)
C POWER3/PPC630 80
C POWER4/PPC970 86
C POWER5 86
C POWER6 170
C POWER7 66
ASM_START()
PROLOGUE(mpn_invert_limb,toc)
LEAL( r12, approx_tab)
srdi r9, r3, 32
rlwinm r9, r9, 10, 23, 30 C (d >> 55) & 0x1fe
srdi r10, r3, 24 C d >> 24
lis r11, 0x1000
rldicl r8, r3, 0, 63 C d mod 2
addi r10, r10, 1 C d40
sldi r11, r11, 32 C 2^60
srdi r7, r3, 1 C d/2
add r7, r7, r8 C d63 = ceil(d/2)
neg r8, r8 C mask = -(d mod 2)
lhzx r0, r9, r12
mullw r9, r0, r0 C v0*v0
sldi r6, r0, 11 C v0 << 11
addi r0, r6, -1 C (v0 << 11) - 1
mulld r9, r9, r10 C v0*v0*d40
srdi r9, r9, 40 C v0*v0*d40 >> 40
subf r9, r9, r0 C v1 = (v0 << 11) - (v0*v0*d40 >> 40) - 1
mulld r0, r9, r10 C v1*d40
sldi r6, r9, 13 C v1 << 13
subf r0, r0, r11 C 2^60 - v1*d40
mulld r0, r0, r9 C v1 * (2^60 - v1*d40)
srdi r0, r0, 47 C v1 * (2^60 - v1*d40) >> 47
add r0, r0, r6 C v2 = (v1 << 13) + (v1 * (2^60 - v1*d40) >> 47)
mulld r11, r0, r7 C v2 * d63
srdi r10, r0, 1 C v2 >> 1
sldi r9, r0, 31 C v2 << 31
and r8, r10, r8 C (v2 >> 1) & mask
subf r8, r11, r8 C ((v2 >> 1) & mask) - v2 * d63
mulhdu r0, r8, r0 C p1 = v2 * (((v2 >> 1) & mask) - v2 * d63)
srdi r0, r0, 1 C p1 >> 1
add r0, r0, r9 C v3 = (v2 << 31) + (p1 >> 1)
nop
mulld r11, r0, r3
mulhdu r9, r0, r3
addc r10, r11, r3
adde r3, r9, r3
subf r3, r3, r0
blr
EPILOGUE()
DEF_OBJECT(approx_tab)
forloop(i,256,512-1,dnl
` .short eval(0x7fd00/i)
')dnl
END_OBJECT(approx_tab)
ASM_END()
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