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Optimized memset version.

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This commit is contained in:
Ulrich Drepper 1998-03-18 14:29:09 +00:00
parent 2c2c129dd4
commit d024bf59e6
1 changed files with 68 additions and 0 deletions
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sysdeps/arm/memset.S Normal file
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/* Copyright (C) 1998 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Philip Blundell <philb@gnu.org>
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.
The GNU C 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
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with the GNU C 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>
/* void *memset (dstpp, c, len) */
ENTRY(memset)
mov a4, a1
cmp a3, $8 @ at least 8 bytes to do?
blt 2f
orr a2, a2, a2, lsl $8
orr a2, a2, a2, lsl $16
1:
tst a4, $3 @ aligned yet?
strneb a2, [a4], $1
subne a3, a3, $1
bne 1b
mov ip, a2
1:
cmp a3, $8 @ 8 bytes still to do?
blt 2f
stmia a4!, {a2, ip}
sub a3, a3, $8
cmp a3, $8 @ 8 bytes still to do?
blt 2f
stmia a4!, {a2, ip}
sub a3, a3, $8
cmp a3, $8 @ 8 bytes still to do?
blt 2f
stmia a4!, {a2, ip}
sub a3, a3, $8
cmp a3, $8 @ 8 bytes still to do?
stmgeia a4!, {a2, ip}
subge a3, a3, $8
bge 1b
2:
movs a3, a3 @ anything left?
RETINSTR(moveq,pc,lr) @ nope
rsb a3, a3, $7
add pc, pc, a3, lsl $2
mov r0, r0
strb a2, [a4], $1
strb a2, [a4], $1
strb a2, [a4], $1
strb a2, [a4], $1
strb a2, [a4], $1
strb a2, [a4], $1
strb a2, [a4], $1
strb a2, [a4], $1
RETINSTR(mov,pc,lr)
END(memset)