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* Copyright (C) 1992, 1994, 1998,
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* 2001 Free Software Foundation, Inc.
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* This file is part of GnuPG.
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* GnuPG is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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* GnuPG is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
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* Note: This code is heavily based on the GNU MP Library.
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* Actually it's the same code with only minor changes in the
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* way the data is stored; this is to support the abstraction
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* of an optional secure memory allocation which may be used
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* to avoid revealing of sensitive data due to paging etc.
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* The GNU MP Library itself is published under the LGPL;
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* however I decided to publish this code under the plain GPL.
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#include "asm-syntax.h"
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* mpihelp_rshift( mpi_ptr_t wp, (sp + 4)
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* mpi_ptr_t up, (sp + 8)
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* mpi_size_t usize, (sp + 12)
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* unsigned cnt) (sp + 16)
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.globl C_SYMBOL_NAME(mpihelp_rshift)
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C_SYMBOL_NAME(mpihelp_rshift:)
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movl 20(%esp),%edi /* res_ptr */
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movl 24(%esp),%esi /* s_ptr */
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movl 28(%esp),%ebp /* size */
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movl 32(%esp),%ecx /* cnt */
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/* We can use faster code for shift-by-1 under certain conditions. */
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jnc Rspecial /* jump if res_ptr + 1 >= s_ptr */
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leal (%edi,%ebp,4),%eax
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jnc Rspecial /* jump if s_ptr >= res_ptr + size */
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shrdl %cl,%edx,%eax /* compute carry limb */
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pushl %eax /* push carry limb onto stack */
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movl (%edi),%eax /* fetch destination cache line */
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Roop: movl 28(%edi),%eax /* fetch destination cache line */
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Roop2: movl (%esi),%eax
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shrdl %cl,%eax,%edx /* compute result limb */
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Rend2: shrl %cl,%edx /* compute most significant limb */
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movl %edx,(%edi) /* store it */
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popl %eax /* pop carry limb */
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/* We loop from least significant end of the arrays, which is only
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permissable if the source and destination don't overlap, since the
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function is documented to work for overlapping source and destination.
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leal -4(%edi,%ebp,4),%edi
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leal -4(%esi,%ebp,4),%esi
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movl (%edi),%eax /* fetch destination cache line */
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RLoop: movl -28(%edi),%eax /* fetch destination cache line */
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leal -32(%esi),%esi /* use leal not to clobber carry */
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sbbl %eax,%eax /* save carry in %eax */
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addl %eax,%eax /* restore carry from eax */
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RLoop2: movl %edx,%ebx
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leal -4(%esi),%esi /* use leal not to clobber carry */
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RLend2: addl %eax,%eax /* restore carry from eax */
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RL1: movl %edx,(%edi) /* store last limb */
added
removed
mpi/i586/mpih-rshift.S
