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

/*
 * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_LICENSE_HEADER_START@
 * 
 * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
 * 
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this
 * file.
 * 
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 * 
 * @APPLE_LICENSE_HEADER_END@
 */
/*
 * 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.
 */


#include <sys/types.h>
#include <errno.h>
#include <stdlib.h>
#include <stddef.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) __P((const void *, const void *));
{
	register int cnt, i, j, l;
	register 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
e9ce8d39 A	1	/*
	2	* Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
	3	*
	4	* @APPLE_LICENSE_HEADER_START@
	5	*
734aad71	6	* Copyright (c) 1999-2003 Apple Computer, Inc. All Rights Reserved.
e9ce8d39	7	*
734aad71 A	8	* This file contains Original Code and/or Modifications of Original Code
	9	* as defined in and that are subject to the Apple Public Source License
	10	* Version 2.0 (the 'License'). You may not use this file except in
	11	* compliance with the License. Please obtain a copy of the License at
	12	* http://www.opensource.apple.com/apsl/ and read it before using this
	13	* file.
	14	*
	15	* The Original Code and all software distributed under the License are
	16	* distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
e9ce8d39 A	17	* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
e9ce8d39 A	18	* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
734aad71 A	19	* FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
	20	* Please see the License for the specific language governing rights and
	21	* limitations under the License.
e9ce8d39 A	22	*
	23	* @APPLE_LICENSE_HEADER_END@
	24	*/
	25	/*
	26	* Copyright (c) 1991, 1993
	27	* The Regents of the University of California. All rights reserved.
	28	*
	29	* This code is derived from software contributed to Berkeley by
	30	* Ronnie Kon at Mindcraft Inc., Kevin Lew and Elmer Yglesias.
	31	*
	32	* Redistribution and use in source and binary forms, with or without
	33	* modification, are permitted provided that the following conditions
	34	* are met:
	35	* 1. Redistributions of source code must retain the above copyright
	36	* notice, this list of conditions and the following disclaimer.
	37	* 2. Redistributions in binary form must reproduce the above copyright
	38	* notice, this list of conditions and the following disclaimer in the
	39	* documentation and/or other materials provided with the distribution.
	40	* 3. All advertising materials mentioning features or use of this software
	41	* must display the following acknowledgement:
	42	* This product includes software developed by the University of
	43	* California, Berkeley and its contributors.
	44	* 4. Neither the name of the University nor the names of its contributors
	45	* may be used to endorse or promote products derived from this software
	46	* without specific prior written permission.
	47	*
	48	* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
	49	* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	50	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	51	* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
	52	* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	53	* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	54	* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	55	* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	56	* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	57	* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	58	* SUCH DAMAGE.
	59	*/
	60
	61
	62	#include <sys/types.h>
	63	#include <errno.h>
	64	#include <stdlib.h>
	65	#include <stddef.h>
	66
	67	/*
	68	* Swap two areas of size number of bytes. Although qsort(3) permits random
	69	* blocks of memory to be sorted, sorting pointers is almost certainly the
	70	* common case (and, were it not, could easily be made so). Regardless, it
	71	* isn't worth optimizing; the SWAP's get sped up by the cache, and pointer
	72	* arithmetic gets lost in the time required for comparison function calls.
	73	*/
	74	#define SWAP(a, b, count, size, tmp) { \
	75	count = size; \
	76	do { \
	77	tmp = *a; \
	78	a++ = b; \
	79	*b++ = tmp; \
	80	} while (--count); \
	81	}
	82
	83	/* Copy one block of size size to another. */
	84	#define COPY(a, b, count, size, tmp1, tmp2) { \
	85	count = size; \
86	tmp1 = a; \
87	tmp2 = b; \
88	do { \
89	tmp1++ = tmp2++; \
90	} while (--count); \
91	}
92
93	/*
94	* Build the list into a heap, where a heap is defined such that for
95	* the records K1 ... KN, Kj/2 >= Kj for 1 <= j/2 <= j <= N.
96	*
97	* There two cases. If j == nmemb, select largest of Ki and Kj. If
98	* j < nmemb, select largest of Ki, Kj and Kj+1.
99	*/
100	#define CREATE(initval, nmemb, par_i, child_i, par, child, size, count, tmp) { \
101	for (par_i = initval; (child_i = par_i * 2) <= nmemb; \
102	par_i = child_i) { \
103	child = base + child_i * size; \
104	if (child_i < nmemb && compar(child, child + size) < 0) { \
105	child += size; \
106	++child_i; \
107	} \
108	par = base + par_i * size; \
109	if (compar(child, par) <= 0) \
110	break; \
111	SWAP(par, child, count, size, tmp); \
112	} \
113	}
114
115	/*
116	* Select the top of the heap and 'heapify'. Since by far the most expensive
117	* action is the call to the compar function, a considerable optimization
118	* in the average case can be achieved due to the fact that k, the displaced
119	* elememt, is ususally quite small, so it would be preferable to first
120	* heapify, always maintaining the invariant that the larger child is copied
121	* over its parent's record.
122	*
123	* Then, starting from the bottom of the heap, finding k's correct place,
124	* again maintianing the invariant. As a result of the invariant no element
125	* is 'lost' when k is assigned its correct place in the heap.
126	*
127	* The time savings from this optimization are on the order of 15-20% for the
128	* average case. See Knuth, Vol. 3, page 158, problem 18.
129	*
130	* XXX Don't break the #define SELECT line, below. Reiser cpp gets upset.
131	*/
132	#define SELECT(par_i, child_i, nmemb, par, child, size, k, count, tmp1, tmp2) { \
133	for (par_i = 1; (child_i = par_i * 2) <= nmemb; par_i = child_i) { \
134	child = base + child_i * size; \
135	if (child_i < nmemb && compar(child, child + size) < 0) { \
136	child += size; \
137	++child_i; \
138	} \
139	par = base + par_i * size; \
140	COPY(par, child, count, size, tmp1, tmp2); \
141	} \
142	for (;;) { \
143	child_i = par_i; \
144	par_i = child_i / 2; \
145	child = base + child_i * size; \
146	par = base + par_i * size; \
147	if (child_i == 1 \|\| compar(k, par) < 0) { \
148	COPY(child, k, count, size, tmp1, tmp2); \
149	break; \
150	} \
151	COPY(child, par, count, size, tmp1, tmp2); \
152	} \
153	}
154
155	/*
156	* Heapsort -- Knuth, Vol. 3, page 145. Runs in O (N lg N), both average
157	* and worst. While heapsort is faster than the worst case of quicksort,
158	* the BSD quicksort does median selection so that the chance of finding
159	* a data set that will trigger the worst case is nonexistent. Heapsort's
160	* only advantage over quicksort is that it requires little additional memory.
161	*/
162	int
163	heapsort(vbase, nmemb, size, compar)
164	void *vbase;
165	size_t nmemb, size;
166	int (compar) __P((const void , const void *));
167	{
168	register int cnt, i, j, l;
169	register char tmp, tmp1, tmp2;
170	char base, k, p, t;
171
172	if (nmemb <= 1)
173	return (0);
174
175	if (!size) {
176	errno = EINVAL;
177	return (-1);
178	}
179
180	if ((k = malloc(size)) == NULL)
181	return (-1);
182
183	/*
184	* Items are numbered from 1 to nmemb, so offset from size bytes
185	* below the starting address.
186	*/
187	base = (char *)vbase - size;
188
189	for (l = nmemb / 2 + 1; --l;)
190	CREATE(l, nmemb, i, j, t, p, size, cnt, tmp);
191
192	/*
193	* For each element of the heap, save the largest element into its
194	* final slot, save the displaced element (k), then recreate the
195	* heap.
196	*/
197	while (nmemb > 1) {
198	COPY(k, base + nmemb * size, cnt, size, tmp1, tmp2);
199	COPY(base + nmemb * size, base + size, cnt, size, tmp1, tmp2);
200	--nmemb;
201	SELECT(i, j, nmemb, t, p, size, k, cnt, tmp1, tmp2);
202	}
203	free(k);
204	return (0);
205	}