avr-libc-1.7.1/libc/pmstring/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: strsep_P.S 2191 2010-11-05 13:45:57Z arcanum $ */

/** \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__) */