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dnl x86 mpn_rshift -- mpn right shift.
dnl Copyright (C) 1992, 1994, 1996, 1999, 2000 Free Software Foundation,
dnl Inc.
dnl
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
dnl modify it under the terms of the GNU Library General Public License as
dnl published by the Free Software Foundation; either version 2 of the
dnl License, or (at your option) any later version.
dnl
dnl The GNU MP Library is distributed in the hope that it will be useful,
dnl but WITHOUT ANY WARRANTY; without even the implied warranty of
dnl MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
dnl Library General Public License for more details.
dnl
dnl You should have received a copy of the GNU Library General Public
dnl License along with the GNU MP Library; see the file COPYING.LIB. If
dnl not, write to the Free Software Foundation, Inc., 59 Temple Place -
dnl Suite 330, Boston, MA 02111-1307, USA.
include(`../config.m4')
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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