# memchr.S

/* Copyright (c) 2002, 2007 Marek Michalkiewicz

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 void *memchr(const void *src, int val, size_t len)
\brief Scan memory for a character.

The memchr() function scans the first len bytes of the memory area pointed
to by src for the character val.  The first byte to match val (interpreted
as an unsigned character) stops the operation.

\returns The memchr() function returns a pointer to the matching byte or
NULL if the character does not occur in the given memory area.  */

#if !defined(__AVR_TINY__)

#if !defined(__DOXYGEN__)

#include "macros.inc"

#define src_hi r25
#define src_lo r24
; #define val_hi r23
#define val_lo r22
#define len_hi r21
#define len_lo r20

#define ret_hi r25
#define ret_lo r24

ASSEMBLY_CLIB_SECTION
.global _U(memchr)
.type   _U(memchr), @function
_U(memchr):
X_movw  ZL, src_lo
.L_memchr_loop:
subi    len_lo, lo8(1)
sbci    len_hi, hi8(1)
brcs    .L_memchr_notfound
ld      __tmp_reg__, Z+
cp      __tmp_reg__, val_lo
brne    .L_memchr_loop
sbiw    ZL, 1           ; undo post-increment
X_movw  ret_lo, ZL
ret
.L_memchr_notfound:
clr     ret_lo
clr     ret_hi
ret
.L_memchr_end:
.size   _U(memchr), .L_memchr_end - _U(memchr)

#endif /* not __DOXYGEN__ */

#endif /* !defined(__AVR_TINY__) */