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/* Pentium optimized __mpn_rshift --
Copyright (C) 1992, 94, 95, 96, 97, 98, 2000 Free Software Foundation, Inc.
This file is part of the GNU MP Library.
The GNU MP Library 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.
The GNU MP Library 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 the GNU MP Library; see the file COPYING.LIB. If not, write to
the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
MA 02111-1307, USA. */
#include "sysdep.h"
#include "asm-syntax.h"
#include "bp-sym.h"
#include "bp-asm.h"
#define PARMS LINKAGE+16 /* space for 4 saved regs */
#define RES PARMS
#define S RES+PTR_SIZE
#define SIZE S+PTR_SIZE
#define CNT SIZE+4
.text
ENTRY (BP_SYM (__mpn_rshift))
ENTER
pushl %edi
pushl %esi
pushl %ebp
pushl %ebx
movl RES(%esp),%edi
movl S(%esp),%esi
movl SIZE(%esp),%ebx
movl CNT(%esp),%ecx
#if __BOUNDED_POINTERS__
shll $2, %ebx /* convert limbs to bytes */
CHECK_BOUNDS_BOTH_WIDE (%edi, RES(%esp), %ebx)
CHECK_BOUNDS_BOTH_WIDE (%esi, S(%esp), %ebx)
shrl $2, %ebx
#endif
/* We can use faster code for shift-by-1 under certain conditions. */
cmp $1,%ecx
jne L(normal)
leal 4(%edi),%eax
cmpl %esi,%eax
jnc L(special) /* jump if res_ptr + 1 >= s_ptr */
leal (%edi,%ebx,4),%eax
cmpl %eax,%esi
jnc L(special) /* jump if s_ptr >= res_ptr + size */
L(normal):
movl (%esi),%edx
addl $4,%esi
xorl %eax,%eax
shrdl %cl,%edx,%eax /* compute carry limb */
pushl %eax /* push carry limb onto stack */
decl %ebx
pushl %ebx
shrl $3,%ebx
jz L(end)
movl (%edi),%eax /* fetch destination cache line */
ALIGN (2)
L(oop): movl 28(%edi),%eax /* fetch destination cache line */
movl %edx,%ebp
movl (%esi),%eax
movl 4(%esi),%edx
shrdl %cl,%eax,%ebp
shrdl %cl,%edx,%eax
movl %ebp,(%edi)
movl %eax,4(%edi)
movl 8(%esi),%ebp
movl 12(%esi),%eax
shrdl %cl,%ebp,%edx
shrdl %cl,%eax,%ebp
movl %edx,8(%edi)
movl %ebp,12(%edi)
movl 16(%esi),%edx
movl 20(%esi),%ebp
shrdl %cl,%edx,%eax
shrdl %cl,%ebp,%edx
movl %eax,16(%edi)
movl %edx,20(%edi)
movl 24(%esi),%eax
movl 28(%esi),%edx
shrdl %cl,%eax,%ebp
shrdl %cl,%edx,%eax
movl %ebp,24(%edi)
movl %eax,28(%edi)
addl $32,%esi
addl $32,%edi
decl %ebx
jnz L(oop)
L(end): popl %ebx
andl $7,%ebx
jz L(end2)
L(oop2):
movl (%esi),%eax
shrdl %cl,%eax,%edx /* compute result limb */
movl %edx,(%edi)
movl %eax,%edx
addl $4,%esi
addl $4,%edi
decl %ebx
jnz L(oop2)
L(end2):
shrl %cl,%edx /* compute most significant limb */
movl %edx,(%edi) /* store it */
popl %eax /* pop carry limb */
popl %ebx
popl %ebp
popl %esi
popl %edi
LEAVE
ret
/* We loop from least significant end of the arrays, which is only
permissible if the source and destination don't overlap, since the
function is documented to work for overlapping source and destination.
*/
L(special):
leal -4(%edi,%ebx,4),%edi
leal -4(%esi,%ebx,4),%esi
movl (%esi),%edx
subl $4,%esi
decl %ebx
pushl %ebx
shrl $3,%ebx
shrl $1,%edx
incl %ebx
decl %ebx
jz L(Lend)
movl (%edi),%eax /* fetch destination cache line */
ALIGN (2)
L(Loop):
movl -28(%edi),%eax /* fetch destination cache line */
movl %edx,%ebp
movl (%esi),%eax
movl -4(%esi),%edx
rcrl $1,%eax
movl %ebp,(%edi)
rcrl $1,%edx
movl %eax,-4(%edi)
movl -8(%esi),%ebp
movl -12(%esi),%eax
rcrl $1,%ebp
movl %edx,-8(%edi)
rcrl $1,%eax
movl %ebp,-12(%edi)
movl -16(%esi),%edx
movl -20(%esi),%ebp
rcrl $1,%edx
movl %eax,-16(%edi)
rcrl $1,%ebp
movl %edx,-20(%edi)
movl -24(%esi),%eax
movl -28(%esi),%edx
rcrl $1,%eax
movl %ebp,-24(%edi)
rcrl $1,%edx
movl %eax,-28(%edi)
leal -32(%esi),%esi /* use leal not to clobber carry */
leal -32(%edi),%edi
decl %ebx
jnz L(Loop)
L(Lend):
popl %ebx
sbbl %eax,%eax /* save carry in %eax */
andl $7,%ebx
jz L(Lend2)
addl %eax,%eax /* restore carry from eax */
L(Loop2):
movl %edx,%ebp
movl (%esi),%edx
rcrl $1,%edx
movl %ebp,(%edi)
leal -4(%esi),%esi /* use leal not to clobber carry */
leal -4(%edi),%edi
decl %ebx
jnz L(Loop2)
jmp L(L1)
L(Lend2):
addl %eax,%eax /* restore carry from eax */
L(L1): movl %edx,(%edi) /* store last limb */
movl $0,%eax
rcrl $1,%eax
popl %ebx
popl %ebp
popl %esi
popl %edi
LEAVE
ret
END (BP_SYM (__mpn_rshift))
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