# strpbrk_P.S

/* Copyright (c) 2007  Dmitry Xmelkov

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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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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. */

/* $Id$ */

/** \file */
/** \ingroup avr_pgmspace
\fn char *strpbrk_P(const char *s, PGM_P accept)

The strpbrk_P() function locates the first occurrence in the string
\p s of any of the characters in the flash string \p accept. This
function is similar to strpbrk() except that \p accept is a pointer
to a string in program space.

\return  The strpbrk_P() function returns a pointer to the character
in \p s that matches one of the characters in \p accept, or \c NULL
if no such character is found. The terminating zero is not considered
as a part of string: if one or both args are empty, the result will
\c NULL.    */

#if !defined(__AVR_TINY__)

#ifndef __DOXYGEN__

#include "macros.inc"

#define str_lo  r24
#define acc_lo  r22

#define ret_lo  r24
#define ret_hi  r25

/* This realization is compact, but is not very fast: an accept string
is not cashed.       */

ASSEMBLY_CLIB_SECTION
.global _U(strpbrk_P)
.type   _U(strpbrk_P), @function

_U(strpbrk_P):
X_movw  XL, str_lo
clr     ret_hi          ; a trick to save 1 word
; get next symbol from s[]
1:      ld      ret_lo, X+      ; *s++
tst     ret_lo
breq    3f
; check an occurance
X_movw  ZL, acc_lo
2:      X_lpm   r0, Z+
cp      r0, ret_lo
cpse    r0, __zero_reg__
brne    2b
brne    1b              ; branch if end of accept[] is reached
; OK, is found
sbiw    XL, 1
X_movw  ret_lo, XL
3:      ret

.size _U(strpbrk_P), . - _U(strpbrk_P)
#endif  /* !__DOXYGEN__ */

#endif /* !defined(__AVR_TINY__) */