1 /* $OpenBSD: swab.c,v 1.8 2008/03/15 21:54:09 ray Exp $ */ 2 /* 3 * Copyright (c) 1988 Regents of the University of California. 4 * All rights reserved. 5 * 6 * This code is derived from software contributed to Berkeley by 7 * Jeffrey Mogul. 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 2. Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in the 16 * documentation and/or other materials provided with the distribution. 17 * 3. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 */ 33 34 #include <unistd.h> 35 36 void 37 swab(const void *from, void *to, size_t len) 38 { 39 size_t n; 40 char *fp, *tp; 41 char temp; 42 43 n = (len / 2) + 1; 44 fp = (char *)from; 45 tp = (char *)to; 46 #define STEP do { \ 47 temp = *fp++; \ 48 *tp++ = *fp++; \ 49 *tp++ = temp; \ 50 } while (0) 51 /* round to multiple of 8 */ 52 while ((--n) & 07) 53 STEP; 54 n >>= 3; 55 if (n == 0) 56 return; 57 while (n-- != 0) { 58 STEP; STEP; STEP; STEP; 59 STEP; STEP; STEP; STEP; 60 } 61 } 62