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/* Copyright (c) 2002, 2007 Philip Soeberg
Copyright (c) 2007 Dmitry Xmelkov
All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
* Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
* 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.
* Neither the name of the copyright holders nor the names of
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 HOLDERS 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 OWNER 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. */
/* $Id: strstr.S,v 1.13.2.1 2009/04/01 23:12:19 arcanum Exp $ */
/*
strstr.S
Search string contained in a string
Contributed by:
Philip Soeberg <philip@soeberg.net>
*/
/** \file */
/** \ingroup avr_string
\fn char *strstr(const char *s1, const char *s2)
\brief Locate a substring.
The strstr() function finds the first occurrence of the substring \p
s2 in the string \p s1. The terminating '\\0' characters are not
compared.
\returns The strstr() function returns a pointer to the beginning of
the substring, or \c NULL if the substring is not found. If \p s2
points to a string of zero length, the function returns \p s1. */
#if !defined(__DOXYGEN__)
#include "macros.inc"
#define s1_hi r25
#define s1_lo r24
#define s2_hi r23
#define s2_lo r22
#define chr1 r20
#define beg2 r21 /* begin of s2: s2[0] */
#define chr2 r0
ASSEMBLY_CLIB_SECTION
.global _U(strstr)
.type _U(strstr), @function
_U(strstr):
X_movw ZL, s2_lo
ld beg2, Z+
tst beg2 ; is str2 empty?
breq .L_ret ; return original string (req'd by standard)
X_movw s2_lo, ZL ; save: address of second s2 byte
0: X_movw XL, s1_lo
1: ld chr1, X+ ; Find first char
cp chr1, beg2
cpse chr1, __zero_reg__
brne 1b
brne .L_no_match ; end of s1
X_movw s1_lo, XL ; store return value
2: ld chr2, Z+ ; compare strings
tst chr2
breq .L_match ; end of s2
ld chr1, X+
cp chr1, chr2
cpse chr1, __zero_reg__ ; break, if end of s1
breq 2b
X_movw ZL, s2_lo ; restore s2+1
cpse chr1, __zero_reg__
rjmp 0b
.L_no_match:
ldi s1_lo, lo8(1)
ldi s1_hi, hi8(1)
.L_match:
sbiw s1_lo, 1 ; restore after post-increment
.L_ret:
ret
.size _U(strstr), . - _U(strstr)
#endif /* not __DOXYGEN__ */
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