1/* Copyright (c) 2007 Dmitry Xmelkov 2 All rights reserved. 3 4 Redistribution and use in source and binary forms, with or without 5 modification, are permitted provided that the following conditions are met: 6 7 * Redistributions of source code must retain the above copyright 8 notice, this list of conditions and the following disclaimer. 9 * Redistributions in binary form must reproduce the above copyright 10 notice, this list of conditions and the following disclaimer in 11 the documentation and/or other materials provided with the 12 distribution. 13 * Neither the name of the copyright holders nor the names of 14 contributors may be used to endorse or promote products derived 15 from this software without specific prior written permission. 16 17 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" 18 AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE 21 LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 22 CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 23 SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 24 INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 25 CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 26 ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 27 POSSIBILITY OF SUCH DAMAGE. */ 28 29/* $Id: memrchr.S 2191 2010-11-05 13:45:57Z arcanum $ */ 30 31/** \file */ 32/** \ingroup avr_string 33 \fn void *memrchr(const void *src, int val, size_t len) 34 35 The memrchr() function is like the memchr() function, except that it 36 searches backwards from the end of the \p len bytes pointed to by \p 37 src instead of forwards from the front. (Glibc, GNU extension.) 38 39 \return The memrchr() function returns a pointer to the matching 40 byte or \c NULL if the character does not occur in the given memory 41 area. */ 42 43#if !defined(__AVR_TINY__) 44 45#if !defined(__DOXYGEN__) 46 47#include "asmdef.h" 48 49#define src_hi r25 50#define src_lo r24 51#define val r22 52#define len_hi r21 53#define len_lo r20 54 55#define ret_lo r24 56 57ENTRY memrchr 58 X_movw ZL, len_lo 59 adiw ZL, 0 60 breq 2f ; len is 0, return NULL 61 add ZL, src_lo 62 adc ZH, src_hi 63 641: ld r0, -Z 65 cp r0, val 66 breq 2f ; val is found 67 subi len_lo, lo8(1) 68 sbci len_hi, hi8(1) 69 brne 1b 70 71 X_movw ZL, len_lo ; is zero 722: X_movw ret_lo, ZL 73 ret 74ENDFUNC 75 76#endif /* not __DOXYGEN__ */ 77 78#endif /* !defined(__AVR_TINY__) */ 79