strtok_r.S

/* Copyright (c) 2003, 2007 Reiner Patommel
   Copyright (c) 2009  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_string
    \fn char *strtok_r(char *string, const char *delim, char **last)
    \brief Parses string into tokens.

    strtok_r parses string into tokens. The first call to strtok_r
    should have string as its first argument. Subsequent calls should have
    the first argument set to NULL. If a token ends with a delimiter, this
    delimiting character is overwritten with a '\\0' and a pointer to the next
    character is saved for the next call to strtok_r. The delimiter string
    \p delim may be different for each call. \p last is a user allocated char*
    pointer. It must be the same while parsing the same string. strtok_r is
    a reentrant version of strtok().

    \returns The strtok_r() function returns a pointer to the next token or
    NULL when no more tokens are found. */

#if !defined(__AVR_TINY__)

#if !defined(__DOXYGEN__)

#include "asmdef.h"

/*  char *strtok_r (char *s, const char *delim, char **last)
    {
        char *p = *last;
        const char *q;
        char c, d;

        if (!s) {
            if (!p) return s;           // end of string
            s = p;                      // continue parsing
        }

        p = s;
        for (;;) {                      // skip delimeters
            s = p;                      // space optimization (vs. s = p-1)
            if (!(c = *p++)) {
                s = 0;
                p = 0;
                goto ret;
            }
            q = delim;
            do {
                if (!(d = *q++))
                    goto find_end;
            } while (d != c);
        }

      find_end:
        do {
            q = delim;
            do {
                d = *q++;
                if (c == d) {
                    *--p = 0;
                    p++;
                    goto ret;
                }
            } while (d);
        } while ((c = *p++) != 0);
        p = 0;                          // stop parsing
      ret:
        *last = p;
        return s;
    }
 */

#define str_lo  r24
#define dlm_lo  r22
#define lst_lo  r20
#define dch     r18

ENTRY strtok_r
        X_movw  ZL, lst_lo
        ld      XL, Z+                  ; X = *last
        ld      XH, Z
  ; check str
        sbiw    str_lo, 0
        brne    1f
        sbiw    XL, 0
        breq    .Lret                   ; end of string
        X_movw  str_lo, XL              ; continue parsing

  ; skip delimeters
1:      X_movw  XL, str_lo              ; p = str
2:      X_movw  str_lo, XL
        ld      __tmp_reg__, X+
        tst     __tmp_reg__
        brne    3f
        X_movw  str_lo, __tmp_reg__     ; <r0,r1>
        rjmp    .Lclr
3:      X_movw  ZL, dlm_lo
4:      ld      dch, Z+
        tst     dch
        breq    5f                      ; goto find
        cp      dch, __tmp_reg__
        brne    4b
        rjmp    2b                      ; skip 1 byte

  ; find new token end
5:      X_movw  ZL, dlm_lo
6:      ld      dch, Z+
        cp      dch, __tmp_reg__        ; __tmp_reg__ != 0
        brne    7f
        st      -X, __zero_reg__
        adiw    XL, 1
        rjmp    .Lret
7:      tst     dch
        brne    6b
  ; next str byte
        ld      __tmp_reg__, X+
        tst     __tmp_reg__
        brne    5b

  ; stop parsing
.Lclr:  X_movw  XL, __tmp_reg__         ; <r0,r1>
  ; save last pointer
.Lret:  X_movw  ZL, lst_lo              ; *last = X
        st      Z+, XL
        st      Z, XH
        ret

ENDFUNC

#endif /* not __DOXYGEN__ */

#endif /* !defined(__AVR_TINY__) */