[apple/libc.git] / stdlib / FreeBSD / heapsort.c

/*-
 * Copyright (c) 1991, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Ronnie Kon at Mindcraft Inc., Kevin Lew and Elmer Yglesias.
 *
 * 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.
 */

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)heapsort.c	8.1 (Berkeley) 6/4/93";
#endif /* LIBC_SCCS and not lint */
#include <sys/cdefs.h>
__FBSDID("$FreeBSD: src/lib/libc/stdlib/heapsort.c,v 1.4 2002/03/21 22:48:41 obrien Exp $");

#include <errno.h>
#include <stddef.h>
#include <stdlib.h>

/*
 * Swap two areas of size number of bytes.  Although qsort(3) permits random
 * blocks of memory to be sorted, sorting pointers is almost certainly the
 * common case (and, were it not, could easily be made so).  Regardless, it
 * isn't worth optimizing; the SWAP's get sped up by the cache, and pointer
 * arithmetic gets lost in the time required for comparison function calls.
 */
#define	SWAP(a, b, count, size, tmp) { \
	count = size; \
	do { \
		tmp = *a; \
		*a++ = *b; \
		*b++ = tmp; \
	} while (--count); \
}

/* Copy one block of size size to another. */
#define COPY(a, b, count, size, tmp1, tmp2) { \
	count = size; \
	tmp1 = a; \
	tmp2 = b; \
	do { \
		*tmp1++ = *tmp2++; \
	} while (--count); \
}

/*
 * Build the list into a heap, where a heap is defined such that for
 * the records K1 ... KN, Kj/2 >= Kj for 1 <= j/2 <= j <= N.
 *
 * There two cases.  If j == nmemb, select largest of Ki and Kj.  If
 * j < nmemb, select largest of Ki, Kj and Kj+1.
 */
#define CREATE(initval, nmemb, par_i, child_i, par, child, size, count, tmp) { \
	for (par_i = initval; (child_i = par_i * 2) <= nmemb; \
	    par_i = child_i) { \
		child = base + child_i * size; \
		if (child_i < nmemb && compar(child, child + size) < 0) { \
			child += size; \
			++child_i; \
		} \
		par = base + par_i * size; \
		if (compar(child, par) <= 0) \
			break; \
		SWAP(par, child, count, size, tmp); \
	} \
}

/*
 * Select the top of the heap and 'heapify'.  Since by far the most expensive
 * action is the call to the compar function, a considerable optimization
 * in the average case can be achieved due to the fact that k, the displaced
 * elememt, is ususally quite small, so it would be preferable to first
 * heapify, always maintaining the invariant that the larger child is copied
 * over its parent's record.
 *
 * Then, starting from the *bottom* of the heap, finding k's correct place,
 * again maintianing the invariant.  As a result of the invariant no element
 * is 'lost' when k is assigned its correct place in the heap.
 *
 * The time savings from this optimization are on the order of 15-20% for the
 * average case. See Knuth, Vol. 3, page 158, problem 18.
 *
 * XXX Don't break the #define SELECT line, below.  Reiser cpp gets upset.
 */
#define SELECT(par_i, child_i, nmemb, par, child, size, k, count, tmp1, tmp2) { \
	for (par_i = 1; (child_i = par_i * 2) <= nmemb; par_i = child_i) { \
		child = base + child_i * size; \
		if (child_i < nmemb && compar(child, child + size) < 0) { \
			child += size; \
			++child_i; \
		} \
		par = base + par_i * size; \
		COPY(par, child, count, size, tmp1, tmp2); \
	} \
	for (;;) { \
		child_i = par_i; \
		par_i = child_i / 2; \
		child = base + child_i * size; \
		par = base + par_i * size; \
		if (child_i == 1 || compar(k, par) < 0) { \
			COPY(child, k, count, size, tmp1, tmp2); \
			break; \
		} \
		COPY(child, par, count, size, tmp1, tmp2); \
	} \
}

/*
 * Heapsort -- Knuth, Vol. 3, page 145.  Runs in O (N lg N), both average
 * and worst.  While heapsort is faster than the worst case of quicksort,
 * the BSD quicksort does median selection so that the chance of finding
 * a data set that will trigger the worst case is nonexistent.  Heapsort's
 * only advantage over quicksort is that it requires little additional memory.
 */
int
heapsort(vbase, nmemb, size, compar)
	void *vbase;
	size_t nmemb, size;
	int (*compar)(const void *, const void *);
{
	int cnt, i, j, l;
	char tmp, *tmp1, *tmp2;
	char *base, *k, *p, *t;

	if (nmemb <= 1)
		return (0);

	if (!size) {
		errno = EINVAL;
		return (-1);
	}

	if ((k = malloc(size)) == NULL)
		return (-1);

	/*
	 * Items are numbered from 1 to nmemb, so offset from size bytes
	 * below the starting address.
	 */
	base = (char *)vbase - size;

	for (l = nmemb / 2 + 1; --l;)
		CREATE(l, nmemb, i, j, t, p, size, cnt, tmp);

	/*
	 * For each element of the heap, save the largest element into its
	 * final slot, save the displaced element (k), then recreate the
	 * heap.
	 */
	while (nmemb > 1) {
		COPY(k, base + nmemb * size, cnt, size, tmp1, tmp2);
		COPY(base + nmemb * size, base + size, cnt, size, tmp1, tmp2);
		--nmemb;
		SELECT(i, j, nmemb, t, p, size, k, cnt, tmp1, tmp2);
	}
	free(k);
	return (0);
}
Commit	Line	Data
9385eb3d	1	/*-
e9ce8d39 A	2	* Copyright (c) 1991, 1993
	3	* The Regents of the University of California. All rights reserved.
	4	*
	5	* This code is derived from software contributed to Berkeley by
	6	* Ronnie Kon at Mindcraft Inc., Kevin Lew and Elmer Yglesias.
	7	*
	8	* Redistribution and use in source and binary forms, with or without
	9	* modification, are permitted provided that the following conditions
	10	* are met:
	11	* 1. Redistributions of source code must retain the above copyright
	12	* notice, this list of conditions and the following disclaimer.
	13	* 2. Redistributions in binary form must reproduce the above copyright
	14	* notice, this list of conditions and the following disclaimer in the
	15	* documentation and/or other materials provided with the distribution.
	16	* 3. All advertising materials mentioning features or use of this software
	17	* must display the following acknowledgement:
	18	* This product includes software developed by the University of
	19	* California, Berkeley and its contributors.
	20	* 4. Neither the name of the University nor the names of its contributors
	21	* may be used to endorse or promote products derived from this software
	22	* without specific prior written permission.
	23	*
	24	* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
	25	* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	26	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	27	* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
	28	* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	29	* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	30	* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	31	* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	32	* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	33	* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	34	* SUCH DAMAGE.
	35	*/
	36
9385eb3d A	37	#if defined(LIBC_SCCS) && !defined(lint)
	38	static char sccsid[] = "@(#)heapsort.c 8.1 (Berkeley) 6/4/93";
	39	#endif /* LIBC_SCCS and not lint */
	40	#include <sys/cdefs.h>
	41	__FBSDID("$FreeBSD: src/lib/libc/stdlib/heapsort.c,v 1.4 2002/03/21 22:48:41 obrien Exp $");
e9ce8d39	42
e9ce8d39	43	#include <errno.h>
e9ce8d39	44	#include <stddef.h>
9385eb3d	45	#include <stdlib.h>
e9ce8d39 A	46
	47	/*
	48	* Swap two areas of size number of bytes. Although qsort(3) permits random
	49	* blocks of memory to be sorted, sorting pointers is almost certainly the
	50	* common case (and, were it not, could easily be made so). Regardless, it
	51	* isn't worth optimizing; the SWAP's get sped up by the cache, and pointer
	52	* arithmetic gets lost in the time required for comparison function calls.
	53	*/
	54	#define SWAP(a, b, count, size, tmp) { \
	55	count = size; \
	56	do { \
	57	tmp = *a; \
	58	a++ = b; \
	59	*b++ = tmp; \
	60	} while (--count); \
	61	}
	62
	63	/* Copy one block of size size to another. */
	64	#define COPY(a, b, count, size, tmp1, tmp2) { \
	65	count = size; \
	66	tmp1 = a; \
	67	tmp2 = b; \
	68	do { \
	69	tmp1++ = tmp2++; \
	70	} while (--count); \
	71	}
	72
	73	/*
	74	* Build the list into a heap, where a heap is defined such that for
	75	* the records K1 ... KN, Kj/2 >= Kj for 1 <= j/2 <= j <= N.
	76	*
	77	* There two cases. If j == nmemb, select largest of Ki and Kj. If
	78	* j < nmemb, select largest of Ki, Kj and Kj+1.
	79	*/
	80	#define CREATE(initval, nmemb, par_i, child_i, par, child, size, count, tmp) { \
	81	for (par_i = initval; (child_i = par_i * 2) <= nmemb; \
	82	par_i = child_i) { \
	83	child = base + child_i * size; \
	84	if (child_i < nmemb && compar(child, child + size) < 0) { \
	85	child += size; \
	86	++child_i; \
	87	} \
	88	par = base + par_i * size; \
	89	if (compar(child, par) <= 0) \
	90	break; \
	91	SWAP(par, child, count, size, tmp); \
	92	} \
	93	}
	94
	95	/*
	96	* Select the top of the heap and 'heapify'. Since by far the most expensive
	97	* action is the call to the compar function, a considerable optimization
	98	* in the average case can be achieved due to the fact that k, the displaced
	99	* elememt, is ususally quite small, so it would be preferable to first
	100	* heapify, always maintaining the invariant that the larger child is copied
	101	* over its parent's record.
	102	*
	103	* Then, starting from the bottom of the heap, finding k's correct place,
	104	* again maintianing the invariant. As a result of the invariant no element
	105	* is 'lost' when k is assigned its correct place in the heap.
	106	*
	107	* The time savings from this optimization are on the order of 15-20% for the
	108	* average case. See Knuth, Vol. 3, page 158, problem 18.
	109	*
110	* XXX Don't break the #define SELECT line, below. Reiser cpp gets upset.
111	*/
112	#define SELECT(par_i, child_i, nmemb, par, child, size, k, count, tmp1, tmp2) { \
113	for (par_i = 1; (child_i = par_i * 2) <= nmemb; par_i = child_i) { \
114	child = base + child_i * size; \
115	if (child_i < nmemb && compar(child, child + size) < 0) { \
116	child += size; \
117	++child_i; \
118	} \
119	par = base + par_i * size; \
120	COPY(par, child, count, size, tmp1, tmp2); \
121	} \
122	for (;;) { \
123	child_i = par_i; \
124	par_i = child_i / 2; \
125	child = base + child_i * size; \
126	par = base + par_i * size; \
127	if (child_i == 1 \|\| compar(k, par) < 0) { \
128	COPY(child, k, count, size, tmp1, tmp2); \
129	break; \
130	} \
131	COPY(child, par, count, size, tmp1, tmp2); \
132	} \
133	}
134
135	/*
136	* Heapsort -- Knuth, Vol. 3, page 145. Runs in O (N lg N), both average
137	* and worst. While heapsort is faster than the worst case of quicksort,
138	* the BSD quicksort does median selection so that the chance of finding
139	* a data set that will trigger the worst case is nonexistent. Heapsort's
140	* only advantage over quicksort is that it requires little additional memory.
141	*/
142	int
143	heapsort(vbase, nmemb, size, compar)
144	void *vbase;
145	size_t nmemb, size;
9385eb3d	146	int (compar)(const void , const void *);
e9ce8d39	147	{
9385eb3d A	148	int cnt, i, j, l;
9385eb3d A	149	char tmp, tmp1, tmp2;
e9ce8d39 A	150	char base, k, p, t;
	151
	152	if (nmemb <= 1)
	153	return (0);
	154
	155	if (!size) {
	156	errno = EINVAL;
	157	return (-1);
	158	}
	159
	160	if ((k = malloc(size)) == NULL)
	161	return (-1);
	162
	163	/*
	164	* Items are numbered from 1 to nmemb, so offset from size bytes
	165	* below the starting address.
	166	*/
	167	base = (char *)vbase - size;
	168
	169	for (l = nmemb / 2 + 1; --l;)
	170	CREATE(l, nmemb, i, j, t, p, size, cnt, tmp);
	171
	172	/*
	173	* For each element of the heap, save the largest element into its
	174	* final slot, save the displaced element (k), then recreate the
	175	* heap.
	176	*/
	177	while (nmemb > 1) {
	178	COPY(k, base + nmemb * size, cnt, size, tmp1, tmp2);
	179	COPY(base + nmemb * size, base + size, cnt, size, tmp1, tmp2);
	180	--nmemb;
	181	SELECT(i, j, nmemb, t, p, size, k, cnt, tmp1, tmp2);
	182	}
	183	free(k);
	184	return (0);
	185	}