Head

GCC Code Coverage Report

Directory:	./		Exec	Total	Coverage
File:	lib/libc/stdlib/heapsort.c	Lines:	14	18	77.8 %
Date:	2017-11-07	Branches:	37	40	92.5 %


/*	$OpenBSD: heapsort.c,v 1.11 2017/05/20 12:48:56 millert Exp $ */
/*-
 * 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. 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>

/*
 * 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 are 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
 * element, is usually 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 maintaining 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(void *vbase, size_t nmemb, size_t size,
    int (*compar)(const void *, const void *))
{
	size_t 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);
}
DEF_WEAK(heapsort);


Generated by: GCOVR (Version 3.3)

Line	Branch	Exec	Source
1			/* $OpenBSD: heapsort.c,v 1.11 2017/05/20 12:48:56 millert Exp $ */
2			/*-
3			* Copyright (c) 1991, 1993
4			* The Regents of the University of California. All rights reserved.
5			*
6			* This code is derived from software contributed to Berkeley by
7			* Ronnie Kon at Mindcraft Inc., Kevin Lew and Elmer Yglesias.
8			*
9			* Redistribution and use in source and binary forms, with or without
10			* modification, are permitted provided that the following conditions
11			* are met:
12			* 1. Redistributions of source code must retain the above copyright
13			* notice, this list of conditions and the following disclaimer.
14			* 2. Redistributions in binary form must reproduce the above copyright
15			* notice, this list of conditions and the following disclaimer in the
16			* documentation and/or other materials provided with the distribution.
17			* 3. Neither the name of the University nor the names of its contributors
18			* may be used to endorse or promote products derived from this software
19			* without specific prior written permission.
20			*
21			* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22			* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23			* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24			* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25			* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26			* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27			* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28			* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29			* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30			* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31			* SUCH DAMAGE.
32			*/
33
34			#include <sys/types.h>
35			#include <errno.h>
36			#include <stdlib.h>
37
38			/*
39			* Swap two areas of size number of bytes. Although qsort(3) permits random
40			* blocks of memory to be sorted, sorting pointers is almost certainly the
41			* common case (and, were it not, could easily be made so). Regardless, it
42			* isn't worth optimizing; the SWAP's get sped up by the cache, and pointer
43			* arithmetic gets lost in the time required for comparison function calls.
44			*/
45			#define SWAP(a, b, count, size, tmp) { \
46			count = size; \
47			do { \
48			tmp = *a; \
49			a++ = b; \
50			*b++ = tmp; \
51			} while (--count); \
52			}
53
54			/* Copy one block of size size to another. */
55			#define COPY(a, b, count, size, tmp1, tmp2) { \
56			count = size; \
57			tmp1 = a; \
58			tmp2 = b; \
59			do { \
60			tmp1++ = tmp2++; \
61			} while (--count); \
62			}
63
64			/*
65			* Build the list into a heap, where a heap is defined such that for
66			* the records K1 ... KN, Kj/2 >= Kj for 1 <= j/2 <= j <= N.
67			*
68			* There are two cases. If j == nmemb, select largest of Ki and Kj. If
69			* j < nmemb, select largest of Ki, Kj and Kj+1.
70			*/
71			#define CREATE(initval, nmemb, par_i, child_i, par, child, size, count, tmp) { \
72			for (par_i = initval; (child_i = par_i * 2) <= nmemb; \
73			par_i = child_i) { \
74			child = base + child_i * size; \
75			if (child_i < nmemb && compar(child, child + size) < 0) { \
76			child += size; \
77			++child_i; \
78			} \
79			par = base + par_i * size; \
80			if (compar(child, par) <= 0) \
81			break; \
82			SWAP(par, child, count, size, tmp); \
83			} \
84			}
85
86			/*
87			* Select the top of the heap and 'heapify'. Since by far the most expensive
88			* action is the call to the compar function, a considerable optimization
89			* in the average case can be achieved due to the fact that k, the displaced
90			* element, is usually quite small, so it would be preferable to first
91			* heapify, always maintaining the invariant that the larger child is copied
92			* over its parent's record.
93			*
94			* Then, starting from the bottom of the heap, finding k's correct place,
95			* again maintaining the invariant. As a result of the invariant no element
96			* is 'lost' when k is assigned its correct place in the heap.
97			*
98			* The time savings from this optimization are on the order of 15-20% for the
99			* average case. See Knuth, Vol. 3, page 158, problem 18.
100			*
101			* XXX Don't break the #define SELECT line, below. Reiser cpp gets upset.
102			*/
103			#define SELECT(par_i, child_i, nmemb, par, child, size, k, count, tmp1, tmp2) { \
104			for (par_i = 1; (child_i = par_i * 2) <= nmemb; par_i = child_i) { \
105			child = base + child_i * size; \
106			if (child_i < nmemb && compar(child, child + size) < 0) { \
107			child += size; \
108			++child_i; \
109			} \
110			par = base + par_i * size; \
111			COPY(par, child, count, size, tmp1, tmp2); \
112			} \
113			for (;;) { \
114			child_i = par_i; \
115			par_i = child_i / 2; \
116			child = base + child_i * size; \
117			par = base + par_i * size; \
118			if (child_i == 1 \|\| compar(k, par) < 0) { \
119			COPY(child, k, count, size, tmp1, tmp2); \
120			break; \
121			} \
122			COPY(child, par, count, size, tmp1, tmp2); \
123			} \
124			}
125
126			/*
127			* Heapsort -- Knuth, Vol. 3, page 145. Runs in O (N lg N), both average
128			* and worst. While heapsort is faster than the worst case of quicksort,
129			* the BSD quicksort does median selection so that the chance of finding
130			* a data set that will trigger the worst case is nonexistent. Heapsort's
131			* only advantage over quicksort is that it requires little additional memory.
132			*/
133			int
134			heapsort(void *vbase, size_t nmemb, size_t size,
135			int (compar)(const void , const void *))
136			{
137			size_t cnt, i, j, l;
138			char tmp, tmp1, tmp2;
139			char base, k, p, t;
140
141	✗✓	584	if (nmemb <= 1)
142			return (0);
143
144	✗✓	292	if (!size) {
145			errno = EINVAL;
146			return (-1);
147			}
148
149	✗✓	292	if ((k = malloc(size)) == NULL)
150			return (-1);
151
152			/*
153			* Items are numbered from 1 to nmemb, so offset from size bytes
154			* below the starting address.
155			*/
156		292	base = (char *)vbase - size;
157
158	✓✓	1752	for (l = nmemb / 2 + 1; --l;)
159	✓✓✓✓ ✓✓✓✓ ✓✓	19710	CREATE(l, nmemb, i, j, t, p, size, cnt, tmp);
160
161			/*
162			* For each element of the heap, save the largest element into its
163			* final slot, save the displaced element (k), then recreate the
164			* heap.
165			*/
166	✓✓	2482	while (nmemb > 1) {
167	✓✓	19710	COPY(k, base + nmemb * size, cnt, size, tmp1, tmp2);
168	✓✓	19710	COPY(base + nmemb * size, base + size, cnt, size, tmp1, tmp2);
169		2190	--nmemb;
170	✓✓✓✓ ✓✓✓✓ ✓✓✓✓ ✓✓✓✓	72416	SELECT(i, j, nmemb, t, p, size, k, cnt, tmp1, tmp2);
171			}
172		292	free(k);
173		292	return (0);
174		292	}
175			DEF_WEAK(heapsort);