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dnl x86 mpn_rshift -- mpn right shift.
dnl Copyright 1992, 1994, 1996, 1999-2002 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 P54 7.5
C P55 7.0
C P6 2.5
C K6 4.5
C K7 5.0
C P4 16.5
C mp_limb_t mpn_rshift (mp_ptr dst, mp_srcptr src, mp_size_t size,
C unsigned shift);
defframe(PARAM_SHIFT,16)
defframe(PARAM_SIZE, 12)
defframe(PARAM_SRC, 8)
defframe(PARAM_DST, 4)
TEXT
ALIGN(8)
PROLOGUE(mpn_rshift)
pushl %edi
pushl %esi
pushl %ebx
deflit(`FRAME',12)
movl PARAM_DST,%edi
movl PARAM_SRC,%esi
movl PARAM_SIZE,%edx
movl PARAM_SHIFT,%ecx
leal -4(%edi,%edx,4),%edi
leal (%esi,%edx,4),%esi
negl %edx
movl (%esi,%edx,4),%ebx C read least significant limb
xorl %eax,%eax
shrdl( %cl, %ebx, %eax) C compute carry limb
incl %edx
jz L(end)
pushl %eax C push carry limb onto stack
testb $1,%dl
jnz L(1) C enter loop in the middle
movl %ebx,%eax
ALIGN(8)
L(oop): movl (%esi,%edx,4),%ebx C load next higher limb
shrdl( %cl, %ebx, %eax) C compute result limb
movl %eax,(%edi,%edx,4) C store it
incl %edx
L(1): movl (%esi,%edx,4),%eax
shrdl( %cl, %eax, %ebx)
movl %ebx,(%edi,%edx,4)
incl %edx
jnz L(oop)
shrl %cl,%eax C compute most significant limb
movl %eax,(%edi) C store it
popl %eax C pop carry limb
popl %ebx
popl %esi
popl %edi
ret
L(end): shrl %cl,%ebx C compute most significant limb
movl %ebx,(%edi) C store it
popl %ebx
popl %esi
popl %edi
ret
EPILOGUE()
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