glibc/sysdeps/arm/strlen.S
Roland McGrath 47f0752a48 2004-11-18 Daniel Jacobowitz <dan@codesourcery.com>
* sysdeps/arm/sysdep.h: Define __USE_BX__ if bx is available.
	Use it instead of __THUMB_INTERWORK__.  Make RETINSTR take
	only a condition and a register.
	* sysdeps/arm/dl-machine.h: Use __USE_BX__ instead of
	__THUMB_INTERWORK__.
	(_dl_start_user): Use BX.
	* sysdeps/arm/strlen.S: Use DO_RET.
	* sysdeps/unix/arm/brk.S, sysdeps/unix/arm/fork.S,
	sysdeps/unix/arm/sysdep.S, sysdeps/unix/arm/sysdep.h: Likewise.
	* sysdeps/unix/sysv/linux/arm/clone.S,
	sysdeps/unix/sysv/linux/arm/mmap.S,
	sysdeps/unix/sysv/linux/arm/mmap64.S,
	sysdeps/unix/sysv/linux/arm/socket.S,
	sysdeps/unix/sysv/linux/arm/sysdep.h,
	sysdeps/unix/sysv/linux/arm/vfork.S: Update uses of RETINSTR.
2004-12-04 21:20:17 +00:00

74 lines
3.0 KiB
ArmAsm

/* Copyright (C) 1998, 2003 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Code contributed by Matthew Wilcox <willy@odie.barnet.ac.uk>
The GNU C 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 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, write to the Free
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA. */
#include <sysdep.h>
/* size_t strlen(const char *S)
* entry: r0 -> string
* exit: r0 = len
*/
ENTRY(strlen)
bic r1, r0, $3 @ addr of word containing first byte
ldr r2, [r1], $4 @ get the first word
ands r3, r0, $3 @ how many bytes are duff?
rsb r0, r3, $0 @ get - that number into counter.
beq Laligned @ skip into main check routine if no
@ more
#ifdef __ARMEB__
orr r2, r2, $0xff000000 @ set this byte to non-zero
subs r3, r3, $1 @ any more to do?
orrgt r2, r2, $0x00ff0000 @ if so, set this byte
subs r3, r3, $1 @ more?
orrgt r2, r2, $0x0000ff00 @ then set.
#else
orr r2, r2, $0x000000ff @ set this byte to non-zero
subs r3, r3, $1 @ any more to do?
orrgt r2, r2, $0x0000ff00 @ if so, set this byte
subs r3, r3, $1 @ more?
orrgt r2, r2, $0x00ff0000 @ then set.
#endif
Laligned: @ here, we have a word in r2. Does it
tst r2, $0x000000ff @ contain any zeroes?
tstne r2, $0x0000ff00 @
tstne r2, $0x00ff0000 @
tstne r2, $0xff000000 @
addne r0, r0, $4 @ if not, the string is 4 bytes longer
ldrne r2, [r1], $4 @ and we continue to the next word
bne Laligned @
Llastword: @ drop through to here once we find a
#ifdef __ARMEB__
tst r2, $0xff000000 @ word that has a zero byte in it
addne r0, r0, $1 @
tstne r2, $0x00ff0000 @ and add up to 3 bytes on to it
addne r0, r0, $1 @
tstne r2, $0x0000ff00 @ (if first three all non-zero, 4th
addne r0, r0, $1 @ must be zero)
#else
tst r2, $0x000000ff @ word that has a zero byte in it
addne r0, r0, $1 @
tstne r2, $0x0000ff00 @ and add up to 3 bytes on to it
addne r0, r0, $1 @
tstne r2, $0x00ff0000 @ (if first three all non-zero, 4th
addne r0, r0, $1 @ must be zero)
#endif
DO_RET(lr)
END(strlen)
libc_hidden_builtin_def (strlen)