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/* Determine the length of a string.
For SPARC v7.
Copyright (C) 1996, 1999, 2003 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Jakub Jelinek <jj@ultra.linux.cz>.
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>
/* Normally, this uses ((xword - 0x01010101) & 0x80808080) test
to find out if any byte in xword could be zero. This is fast, but
also gives false alarm for any byte in range 0x81-0xff. It does
not matter for correctness, as if this test tells us there could
be some zero byte, we check it byte by byte, but if bytes with
high bits set are common in the strings, then this will give poor
performance. You can #define EIGHTBIT_NOT_RARE and the algorithm
will use one tick slower, but more precise test
((xword - 0x01010101) & (~xword) & 0x80808080),
which does not give any false alarms (but if some bits are set,
one cannot assume from it which bytes are zero and which are not).
It is yet to be measured, what is the correct default for glibc
in these days for an average user.
*/
.text
.align 4
ENTRY(strlen)
mov %o0, %o1
andcc %o0, 3, %g0
be 20f
sethi %hi(0x80808080), %o4
ldub [%o0], %o5
cmp %o5, 0
be 21f
add %o0, 1, %o0
andcc %o0, 3, %g0
be 4f
or %o4, %lo(0x80808080), %o3
ldub [%o0], %o5
cmp %o5, 0
be 22f
add %o0, 1, %o0
andcc %o0, 3, %g0
be 5f
sethi %hi(0x01010101), %o4
ldub [%o0], %o5
cmp %o5, 0
be 23f
add %o0, 1, %o0
b 11f
or %o4, %lo(0x01010101), %o2
21: retl
mov 0, %o0
22: retl
mov 1, %o0
23: retl
mov 2, %o0
20: or %o4, %lo(0x80808080), %o3
4: sethi %hi(0x01010101), %o4
5: or %o4, %lo(0x01010101), %o2
11: ld [%o0], %o5
12: sub %o5, %o2, %o4
#ifdef EIGHTBIT_NOT_RARE
andn %o4, %o5, %o4
#endif
andcc %o4, %o3, %g0
be 11b
add %o0, 4, %o0
srl %o5, 24, %g5
andcc %g5, 0xff, %g0
be 13f
add %o0, -4, %o4
srl %o5, 16, %g5
andcc %g5, 0xff, %g0
be 13f
add %o4, 1, %o4
srl %o5, 8, %g5
andcc %g5, 0xff, %g0
be 13f
add %o4, 1, %o4
andcc %o5, 0xff, %g0
bne,a 12b
ld [%o0], %o5
add %o4, 1, %o4
13: retl
sub %o4, %o1, %o0
END(strlen)
libc_hidden_builtin_def (strlen)
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