usr/src/lib/libc/port/gen/swab.c

   1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License (the "License").
   6  * You may not use this file except in compliance with the License.
   7  *
   8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9  * or http://www.opensolaris.org/os/licensing.
  10  * See the License for the specific language governing permissions
  11  * and limitations under the License.
  12  *
  13  * When distributing Covered Code, include this CDDL HEADER in each
  14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15  * If applicable, add the following below this CDDL HEADER, with the
  16  * fields enclosed by brackets "[]" replaced with your own identifying
  17  * information: Portions Copyright [yyyy] [name of copyright owner]
  18  *
  19  * CDDL HEADER END
  20  */
  21
  22 /*
  23  * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
  24  * Use is subject to license terms.
  25  */
  26
  27 /*      Copyright (c) 1988 AT&T */
  28 /*        All Rights Reserved   */
  29
  30 #pragma ident   "%Z%%M% %I%     %E% SMI"
  31
  32 /*
  33  * Swab bytes
  34  */
  35
  36 #pragma weak _swab = swab
  37
  38 #include "lint.h"
  39 #include <sys/types.h>
  40 #include <stdlib.h>
  41
  42
  43 #define STEP    (void)((temp = *from++), (*to++ = *from++), (*to++ = temp))
  44
  45 void
  46 swab(const char *src, char *dest, ssize_t n)
  47 {
  48         char temp;
  49         const char *from = (const char *)src;
  50         char *to = (char *)dest;
  51
  52         if (n <= 1)
  53                 return;
  54         n >>= 1; n++;
  55         /* round to multiple of 8 */
  56         while ((--n) & 07)
  57                 STEP;
  58         n >>= 3;
  59         while (--n >= 0) {
  60                 STEP; STEP; STEP; STEP;
  61                 STEP; STEP; STEP; STEP;
  62         }
  63 }