usr/src/lib/libc/string/swab.c

/*
 * Copyright (c) 1988 Regents of the University of California.
 * All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Jeffrey Mogul.
 *
 * %sccs.include.redist.c%
 */

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)swab.c      5.8 (Berkeley) %G%";
#endif /* LIBC_SCCS and not lint */

#include <string.h>

void
swab(from, to, n)
        register char *from, *to;
        register int n;
{
        register unsigned long temp;

        n >>= 1; n++;
#define STEP    temp = *from++,*to++ = *from++,*to++ = temp
        /* round to multiple of 8 */
        while ((--n) & 07)
                STEP;
        n >>= 3;
        while (--n >= 0) {
                STEP; STEP; STEP; STEP;
                STEP; STEP; STEP; STEP;
        }
}