1 /* $NetBSD: swab.c,v 1.18 2011/01/04 17:14:07 martin Exp $ */ 2 3 /* 4 * Copyright (c) 1988, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * This code is derived from software contributed to Berkeley by 8 * Jeffrey Mogul. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 */ 34 35 #include <sys/cdefs.h> 36 #if defined(LIBC_SCCS) && !defined(lint) 37 #if 0 38 static char sccsid[] = "@(#)swab.c 8.1 (Berkeley) 6/4/93"; 39 #else 40 __RCSID("$NetBSD: swab.c,v 1.18 2011/01/04 17:14:07 martin Exp $"); 41 #endif 42 #endif /* LIBC_SCCS and not lint */ 43 44 #include <assert.h> 45 #include <unistd.h> 46 47 void swab(const void * __restrict from,void * __restrict to,ssize_t len)48 swab(const void * __restrict from, void * __restrict to, ssize_t len) 49 { 50 char temp; 51 const char *fp; 52 char *tp; 53 54 if (len <= 1) 55 return; 56 57 _DIAGASSERT(from != NULL); 58 _DIAGASSERT(to != NULL); 59 60 len /= 2; 61 fp = (const char *)from; 62 tp = (char *)to; 63 #define STEP temp = *fp++,*tp++ = *fp++,*tp++ = temp 64 65 if (__predict_false(len == 1)) { 66 STEP; 67 return; 68 } 69 70 /* round to multiple of 8 */ 71 while ((--len % 8) != 0) 72 STEP; 73 len /= 8; 74 if (len == 0) 75 return; 76 while (len-- != 0) { 77 STEP; STEP; STEP; STEP; 78 STEP; STEP; STEP; STEP; 79 } 80 } 81