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/* Copyright (c) 2009 Xilinx, Inc. All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are
met:
1. Redistributions source code must retain the above copyright notice,
this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.
3. Neither the name of Xilinx nor the names of its contributors may be
used to endorse or promote products derived from this software without
specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER AND CONTRIBUTORS "AS
IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
FUNCTION
<<strcmp>>---character string compare
INDEX
strcmp
ANSI_SYNOPSIS
#include <string.h>
int strcmp(const char *<[a]>, const char *<[b]>);
TRAD_SYNOPSIS
#include <string.h>
int strcmp(<[a]>, <[b]>)
char *<[a]>;
char *<[b]>;
DESCRIPTION
<<strcmp>> compares the string at <[a]> to
the string at <[b]>.
RETURNS
If <<*<[a]>>> sorts lexicographically after <<*<[b]>>>,
<<strcmp>> returns a number greater than zero. If the two
strings match, <<strcmp>> returns zero. If <<*<[a]>>>
sorts lexicographically before <<*<[b]>>>, <<strcmp>> returns a
number less than zero.
PORTABILITY
<<strcmp>> is ANSI C.
<<strcmp>> requires no supporting OS subroutines.
QUICKREF
strcmp ansi pure
*/
#include <string.h>
#include <limits.h>
/* Nonzero if either X or Y is not aligned on a "long" boundary. */
#define UNALIGNED(X, Y) \
(((long)X & (sizeof (long) - 1)) | ((long)Y & (sizeof (long) - 1)))
/* DETECTNULL returns nonzero if (long)X contains a NULL byte. */
#if LONG_MAX == 2147483647L
#define DETECTNULL(X) (((X) - 0x01010101) & ~(X) & 0x80808080)
#else
#if LONG_MAX == 9223372036854775807L
#define DETECTNULL(X) (((X) - 0x0101010101010101) & ~(X) & 0x8080808080808080)
#else
#error long int is not a 32bit or 64bit type.
#endif
#endif
#ifndef DETECTNULL
#error long int is not a 32bit or 64bit byte
#endif
int
_DEFUN (strcmp, (s1, s2),
_CONST char *s1 _AND
_CONST char *s2)
{
#ifndef HAVE_HW_PCMP
#if defined(PREFER_SIZE_OVER_SPEED) || defined(__OPTIMIZE_SIZE__)
while (*s1 != '\0' && *s1 == *s2)
{
s1++;
s2++;
}
return (*(unsigned char *) s1) - (*(unsigned char *) s2);
#else
unsigned long *a1;
unsigned long *a2;
/* If s1 or s2 are unaligned, then compare bytes. */
if (!UNALIGNED (s1, s2))
{
/* If s1 and s2 are word-aligned, compare them a word at a time. */
a1 = (unsigned long*)s1;
a2 = (unsigned long*)s2;
while (*a1 == *a2)
{
/* To get here, *a1 == *a2, thus if we find a null in *a1,
then the strings must be equal, so return zero. */
if (DETECTNULL (*a1))
return 0;
a1++;
a2++;
}
/* A difference was detected in last few bytes of s1, so search bytewise */
s1 = (char*)a1;
s2 = (char*)a2;
}
while (*s1 != '\0' && *s1 == *s2)
{
s1++;
s2++;
}
return (*(unsigned char *) s1) - (*(unsigned char *) s2);
#endif /* not PREFER_SIZE_OVER_SPEED */
#else
asm volatile (" \n\
or r9, r0, r0 /* Index register */ \n\
check_alignment: \n\
andi r3, r5, 3 \n\
andi r4, r6, 3 \n\
bnei r3, try_align_args \n\
bnei r4, regular_strcmp /* At this point we don't have a choice */ \n\
cmp_loop: \n\
lw r3, r5, r9 \n\
lw r4, r6, r9 \n\
pcmpbf r7, r3, r0 /* See if there is Null byte */ \n\
bnei r7, end_cmp_loop /* IF yes (r7 > 0) use byte compares in end_cmp_loop */ \n\
cmpu r7, r4, r3 /* ELSE compare whole word */ \n\
bnei r7, end_cmp \n\
brid cmp_loop \n\
addik r9, r9, 4 /* delay slot */ \n\
end_cmp_loop: \n\
lbu r3, r5, r9 /* byte compare loop */ \n\
lbu r4, r6, r9 \n\
cmpu r7, r4, r3 /* Compare bytes */ \n\
bnei r7, end_cmp_early \n\
bneid r3, end_cmp_loop /* If reached null on one string, terminate */ \n\
addik r9, r9, 1 /* delay slot */ \n\
end_cmp_early: \n\
rtsd r15, 8 \n\
or r3, r0, r7 \n\
try_align_args: \n\
xor r7, r4, r3 \n\
bnei r7, regular_strcmp /* cannot align args */ \n\
rsubik r10, r3, 4 /* Number of initial bytes to align */ \n\
align_loop: \n\
lbu r3, r5, r9 \n\
lbu r4, r6, r9 \n\
cmpu r7, r4, r3 \n\
bnei r7, end_cmp \n\
beqi r3, end_cmp \n\
addik r10, r10, -1 \n\
beqid r10, cmp_loop \n\
addik r9, r9, 1 \n\
bri align_loop \n\
regular_strcmp: \n\
lbu r3, r5, r9 \n\
lbu r4, r6, r9 \n\
cmpu r7, r4, r3 \n\
bnei r7, end_cmp \n\
beqi r3, end_cmp \n\
brid regular_strcmp \n\
addik r9, r9, 1 \n\
end_cmp: \n\
rtsd r15, 8 \n\
or r3, r0, r7 /* Return strcmp result */");
#endif /* ! HAVE_HW_PCMP */
}
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