usr/src/lib/libbc/libc/gen/common/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, Version 1.0 only
   6  * (the "License").  You may not use this file except in compliance
   7  * with the License.
   8  *
   9  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
  10  * or http://www.opensolaris.org/os/licensing.
  11  * See the License for the specific language governing permissions
  12  * and limitations under the License.
  13  *
  14  * When distributing Covered Code, include this CDDL HEADER in each
  15  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  16  * If applicable, add the following below this CDDL HEADER, with the
  17  * fields enclosed by brackets "[]" replaced with your own identifying
  18  * information: Portions Copyright [yyyy] [name of copyright owner]
  19  *
  20  * CDDL HEADER END
  21  */
  22 /*
  23  * Copyright 1989 Sun Microsystems, Inc.  All rights reserved.
  24  * Use is subject to license terms.
  25  */
  26
  27 #pragma ident   "%Z%%M% %I%     %E% SMI"
  28           /* from UCB 4.2 83/06/27 */
  29
  30 /*
  31  * Swab bytes
  32  * Jeffrey Mogul, Stanford
  33  */
  34
  35 void
  36 swab(from, to, n)
  37         register char *from, *to;
  38         register int n;
  39 {
  40         register unsigned long temp;
  41
  42         if (n <= 1)
  43                 return;
  44         n >>= 1; n++;
  45 #define STEP    temp = *from++,*to++ = *from++,*to++ = temp
  46         /* round to multiple of 8 */
  47         while ((--n) & 07)
  48                 STEP;
  49         n >>= 3;
  50         while (--n >= 0) {
  51                 STEP; STEP; STEP; STEP;
  52                 STEP; STEP; STEP; STEP;
  53         }
  54 }