1/* Copyright (c) 2002, 2007 Reiner Patommel 2 Copyright (c) 2007 Dmitry Xmelkov 3 All rights reserved. 4 5 Redistribution and use in source and binary forms, with or without 6 modification, are permitted provided that the following conditions are met: 7 8 * Redistributions of source code must retain the above copyright 9 notice, this list of conditions and the following disclaimer. 10 * Redistributions in binary form must reproduce the above copyright 11 notice, this list of conditions and the following disclaimer in 12 the documentation and/or other materials provided with the 13 distribution. 14 * Neither the name of the copyright holders nor the names of 15 contributors may be used to endorse or promote products derived 16 from this software without specific prior written permission. 17 18 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" 19 AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20 IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21 ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE 22 LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 23 CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 24 SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 25 INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 26 CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 27 ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 28 POSSIBILITY OF SUCH DAMAGE. */ 29 30/* $Id: strrev.S 2191 2010-11-05 13:45:57Z arcanum $ */ 31 32/* 33 strrev.S 34 Reverse a string 35 36 Contributors: 37 Created by Reiner Patommel 38*/ 39/** \file */ 40 41/** \ingroup avr_string 42 \fn char *strrev(char *s) 43 \brief Reverse a string. 44 45 The strrev() function reverses the order of the string. 46 47 \returns The strrev() function returns a pointer to the beginning of the 48 reversed string. */ 49 50#if !defined(__AVR_TINY__) 51 52#if !defined(__DOXYGEN__) 53 54#include "macros.inc" 55 56#define str_hi r25 57#define str_lo r24 58#define ltemp r23 59#define rtemp r22 60 61 ASSEMBLY_CLIB_SECTION 62 .global _U(strrev) 63 .type _U(strrev), @function 64 65_U(strrev): 66 X_movw XL, str_lo ; X is start of string 67 X_movw ZL, str_lo ; Z becomes end of string 68 ; find end of string 691: mov rtemp, ltemp ; to obtain right nonzero character 70 ld ltemp, Z+ 71 tst ltemp 72 brne 1b 73 sbiw ZL, 2 ; to last nonzero byte 74 rjmp 3f 75 ; swap bytes 762: ld ltemp, X 77 st X+, rtemp 78 st Z, ltemp 79 ld rtemp, -Z 803: cp XL, ZL 81 cpc XH, ZH 82 brlo 2b 83 84 ret 85 86 .size _U(strrev), . - _U(strrev) 87 88#endif /* not __DOXYGEN__ */ 89 90#endif /* !defined(__AVR_TINY__) */ 91