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/* Copyright (c) 2007 Dmitry Xmelkov
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions are met:
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* Redistributions of source code must retain the above copyright
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notice, this list of conditions and the following disclaimer.
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* Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions and the following disclaimer in
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the documentation and/or other materials provided with the
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* Neither the name of the copyright holders nor the names of
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contributors may be used to endorse or promote products derived
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from this software without specific prior written permission.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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POSSIBILITY OF SUCH DAMAGE. */
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/* $Id: memmem.S,v 1.1.2.1 2007/03/31 13:23:16 dmix Exp $ */
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/** \ingroup avr_string
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\fn void *memmem(const void *s1, size_t len1, const void *s2, size_t len2)
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The memmem() function finds the start of the first occurrence of the
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substring \p s2 of length \p len2 in the memory area \p s1 of length
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\return The memmem() function returns a pointer to the beginning of
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the substring, or \c NULL if the substring is not found. If \p len2
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is zero, the function returns \p s1. */
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/** \ingroup avr_pgmspace
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\fn void *memmem_P(const void *s1, size_t len1, PGM_VOID_P s2, size_t len2)
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The memmem_P() function is similar to memmem() except that \p s2 is
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pointer to a string in program space. */
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#if !defined(__DOXYGEN__)
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#define beg2 r17 /* begin of s2: s2[0] */
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#define c1 r16 /* char from s1[] */
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#define c2 r0 /* char from s2[]: tuned for classic lpm instr. */
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# define memmem memmem_P
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cp len2_lo, __zero_reg__
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cpc len2_hi, __zero_reg__
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breq .L_ret ; s2[] is empty
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add len2_lo, s2_lo ; len2 = &(s2[len2])
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add len1_lo, s1_lo ; len1 = &(s1[len1])
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LOAD beg2, Z+ ; beg2 = s2[0]
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X_movw s2_lo, ZL ; save: address of s2[1]
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1: X_movw XL, s1_lo ; goto to begin of s1[]
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2: cp XL, len1_lo ; find first char that is matched
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X_movw s1_lo, XL ; store address
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3: cp ZL, len2_lo ; compare strings
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brsh .L_match ; end of s2[] --> OK
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brsh .L_nomatch ; s1[] tail is too short
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sbiw s1_lo, 1 ; restore after post-increment
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#endif /* not __DOXYGEN__ */
added
removed
libc/string/memmem.S
