# strsep.S

/* Copyright (c) 2003, 2007 Reiner Patommel

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the documentation and/or other materials provided with the
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* Neither the name of the copyright holders nor the names of
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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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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 *strsep(char **sp, const char *delim)
\brief Parse a string into tokens.

The strsep() 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'.

\return The strsep() function returns a pointer to the original
value of \p *sp. If \p *sp is initially \c NULL, strsep() 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)
.type   _U(strsep),@function
_U(strsep):
; 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
breq    5f                      ; return NULL
; get a symbol from str
1:      ld      chr, X+
; scan delim[]
X_movw  ZL, dlm_lo
2:      ld      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'