# strchr_P.S

/* Copyright (c) 2002, 2007 Marek Michalkiewicz
Copyright (c) 2007  Dmitry Xmelkov

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
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* Redistributions in binary form must reproduce the above copyright
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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
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INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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/* $Id$ */

/** \file */

/** \ingroup avr_pgmspace
\fn PGM_P strchr_P(PGM_P s, int val)
\brief Locate character in program space string.

The strchr_P() function locates the first occurrence of \p val
(converted to a char) in the string pointed to by \p s in program
space. The terminating null character is considered to be part of
the string.

The strchr_P() function is similar to strchr() except that \p s is
pointer to a string in program space.

\returns The strchr_P() function returns a pointer to the matched
character or \c NULL if the character is not found. */

#if !defined(__AVR_TINY__)

#if !defined(__DOXYGEN__)

#include "macros.inc"

#define str_hi  r25
#define str_lo  r24
#define val_lo  r22

#define ret_hi  r25
#define ret_lo  r24

ASSEMBLY_CLIB_SECTION
.global _U(strchr_P)
.type   _U(strchr_P), @function
_U(strchr_P):
X_movw  ZL, str_lo
1:
X_lpm   r0, Z+
cp      r0, val_lo
breq    2f
tst     r0
brne    1b