strpbrk_P.S

/* Copyright (c) 2007  Dmitry Xmelkov
   All rights reserved.

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   modification, are permitted provided that the following conditions are met:

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     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
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/* $Id$ */

/** \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__) */