pack.c

早期freebsd实现

/*-
 * Copyright (c) 1979, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#ifndef lint
static char sccsid[] = "@(#)PACK.c	8.1 (Berkeley) 6/6/93";
#endif /* not lint */

/*
 * pack(a,i,z)
 *
 * with:	a: array[m..n] of t
 *	z: packed array[u..v] of t
 *
 * semantics:	for j := u to v do
 *			z[j] := a[j-u+i];
 *
 * need to check:
 *	1. i >= m
 *	2. i+(v-u) <= n		(i.e. i-m <= (n-m)-(v-u))
 *
 * on stack:	lv(z), lv(a), rv(i) (len 4)
 *
 * move w(t)*(v-u+1) bytes from lv(a)+w(t)*(i-m) to lv(z)
 */

PACK(i, a, z, size_a, lb_a, ub_a, size_z)

	long	i;	/* subscript into a to begin packing */
	char	*a;	/* pointer to structure a */
	char	*z;	/* pointer to structure z */
	long	size_a;	/* sizeof(a_type) */
	long	lb_a;	/* lower bound of structure a */
	long	ub_a;	/* (upper bound of a) - (lb_a + sizeof(z_type)) */
	long	size_z;	/* sizeof(z_type) */
{
	int		subscr;
	register char	*cp;
	register char	*zp = z;
	register char	*limit;

	subscr = i - lb_a;
	if (subscr < 0 || subscr > ub_a) {
		ERROR("i = %D: Bad i to pack(a,i,z)\n", i);
		return;
	}
	cp = &a[subscr * size_a];
	limit = cp + size_z;
	do	{
		*zp++ = *cp++;
	} while (cp < limit);
}