strsep_P.S

/* Copyright (c) 2003, 2007 Reiner Patommel
   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.

 */

/* $Id$ */

/** \file */

/** \ingroup avr_pgmspace
    \fn char *strsep_P(char **sp, PGM_P delim)
    \brief Parse a string into tokens.

    The strsep_P() function locates, in the string referenced by \p *sp,
    the first occurrence of any character in the string \p delim (or the
    terminating '\\0' character) and replaces it with a '\\0'.  The
    location of the next character after the delimiter character (or \c
    NULL, if the end of the string was reached) is stored in \p *sp. An
    ``empty'' field, i.e. one caused by two adjacent delimiter
    characters, can be detected by comparing the location referenced by
    the pointer returned in \p *sp to '\\0'. This function is similar to
    strsep() except that \p delim is a pointer to a string in program
    space.
   
    \return The strsep_P() function returns a pointer to the original
    value of \p *sp. If \p *sp is initially \c NULL, strsep_P() returns
    \c NULL.    */
     

#if !defined(__AVR_TINY__)

#if !defined(__DOXYGEN__)

#include "macros.inc"

#define strp_lo r24
#define dlm_lo  r22
#define str_lo  r20
#define chr     r19

#define ret_lo  r24

        ASSEMBLY_CLIB_SECTION
        .global _U(strsep_P)
        .type   _U(strsep_P),@function
_U(strsep_P):
  ; check a NULL pointer
        X_movw  ZL, strp_lo
        ld      XL, Z                   ; str address
        ldd     XH, Z+1
        X_movw  str_lo, XL              ; save for return
        adiw    XL, 0
        breq    5f                      ; return NULL
  ; get a symbol from str
1:      ld      chr, X+
  ; scan delim[]
        X_movw  ZL, dlm_lo
2:      X_lpm   r0, Z+
        cp      r0, chr
        cpse    r0, __zero_reg__
        brne    2b      ; if symbol is't match && no delim end
        brne    1b      ; if symbol is absent in delim[] && not a zero
  ; chr is founded in delim[] (possible, it is a terminating zero of str)
        tst     r0                      ; the same, as chr
        brne    3f
        X_movw  XL, r0                  ; __zero_reg__ is r1
        rjmp    4f
  ; OK, delimeter symbol is founded
3:      st      -X, __zero_reg__        ; replace by '\0'
        adiw    XL, 1                   ; address of next token
  ; save result to *sp and return
4:      X_movw  ZL, strp_lo
        st      Z, XL
        std     Z+1, XH
5:      X_movw  ret_lo, str_lo          ; return original address
        ret

        .size   _U(strsep_P), . - _U(strsep_P)
#endif /* not __DOXYGEN__ */

#endif /* !defined(__AVR_TINY__) */