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/* i80386 sub_n -- Sub two limb vectors of the same length > 0 and store
* sum in a third limb vector.
*
* Copyright (C) 1992, 1994, 1995, 1998,
* 2001, 2002 Free Software Foundation, Inc.
*
* This file is part of Libgcrypt.
*
* Libgcrypt is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation; either version 2.1 of
* the License, or (at your option) any later version.
*
* Libgcrypt is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
*
* Note: This code is heavily based on the GNU MP Library.
* Actually it's the same code with only minor changes in the
* way the data is stored; this is to support the abstraction
* of an optional secure memory allocation which may be used
* to avoid revealing of sensitive data due to paging etc.
*/
#include "sysdep.h"
#include "asm-syntax.h"
/*******************
* mpi_limb_t
* _gcry_mpih_sub_n( mpi_ptr_t res_ptr, (sp + 4)
* mpi_ptr_t s1_ptr, (sp + 8)
* mpi_ptr_t s2_ptr, (sp + 12)
* mpi_size_t size) (sp + 16)
*/
.text
ALIGN (3)
.globl C_SYMBOL_NAME(_gcry_mpih_sub_n)
C_SYMBOL_NAME(_gcry_mpih_sub_n:)
pushl %edi
pushl %esi
movl 12(%esp),%edi /* res_ptr */
movl 16(%esp),%esi /* s1_ptr */
movl 20(%esp),%edx /* s2_ptr */
movl 24(%esp),%ecx /* size */
movl %ecx,%eax
shrl $3,%ecx /* compute count for unrolled loop */
negl %eax
andl $7,%eax /* get index where to start loop */
jz Loop /* necessary special case for 0 */
incl %ecx /* adjust loop count */
shll $2,%eax /* adjustment for pointers... */
subl %eax,%edi /* ... since they are offset ... */
subl %eax,%esi /* ... by a constant when we ... */
subl %eax,%edx /* ... enter the loop */
shrl $2,%eax /* restore previous value */
#ifdef PIC
/* Calculate start address in loop for PIC. Due to limitations in some
assemblers, Loop-L0-3 cannot be put into the leal */
call L0
L0: leal (%eax,%eax,8),%eax
addl (%esp),%eax
addl $(Loop-L0-3),%eax
addl $4,%esp
#else
/* Calculate start address in loop for non-PIC. */
leal (Loop - 3)(%eax,%eax,8),%eax
#endif
jmp *%eax /* jump into loop */
ALIGN (3)
Loop: movl (%esi),%eax
sbbl (%edx),%eax
movl %eax,(%edi)
movl 4(%esi),%eax
sbbl 4(%edx),%eax
movl %eax,4(%edi)
movl 8(%esi),%eax
sbbl 8(%edx),%eax
movl %eax,8(%edi)
movl 12(%esi),%eax
sbbl 12(%edx),%eax
movl %eax,12(%edi)
movl 16(%esi),%eax
sbbl 16(%edx),%eax
movl %eax,16(%edi)
movl 20(%esi),%eax
sbbl 20(%edx),%eax
movl %eax,20(%edi)
movl 24(%esi),%eax
sbbl 24(%edx),%eax
movl %eax,24(%edi)
movl 28(%esi),%eax
sbbl 28(%edx),%eax
movl %eax,28(%edi)
leal 32(%edi),%edi
leal 32(%esi),%esi
leal 32(%edx),%edx
decl %ecx
jnz Loop
sbbl %eax,%eax
negl %eax
popl %esi
popl %edi
ret
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