FreeBSD/Linux Kernel Cross Reference
sys/libkern/qsort.c
1 /*-
2 * Copyright (c) 1992, 1993
3 * The Regents of the University of California. All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 3. All advertising materials mentioning features or use of this software
14 * must display the following acknowledgement:
15 * This product includes software developed by the University of
16 * California, Berkeley and its contributors.
17 * 4. 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/cdefs.h>
35 __FBSDID("$FreeBSD: releng/5.2/sys/libkern/qsort.c 116189 2003-06-11 05:37:42Z obrien $");
36
37 #include <sys/libkern.h>
38
39 typedef int cmp_t(const void *, const void *);
40 static __inline char *med3(char *, char *, char *, cmp_t *);
41 static __inline void swapfunc(char *, char *, int, int);
42
43 #define min(a, b) (a) < (b) ? (a) : (b)
44
45 /*
46 * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function".
47 */
48 #define swapcode(TYPE, parmi, parmj, n) { \
49 long i = (n) / sizeof (TYPE); \
50 register TYPE *pi = (TYPE *) (parmi); \
51 register TYPE *pj = (TYPE *) (parmj); \
52 do { \
53 register TYPE t = *pi; \
54 *pi++ = *pj; \
55 *pj++ = t; \
56 } while (--i > 0); \
57 }
58
59 #define SWAPINIT(a, es) swaptype = ((char *)a - (char *)0) % sizeof(long) || \
60 es % sizeof(long) ? 2 : es == sizeof(long)? 0 : 1;
61
62 static __inline void
63 swapfunc(a, b, n, swaptype)
64 char *a, *b;
65 int n, swaptype;
66 {
67 if(swaptype <= 1)
68 swapcode(long, a, b, n)
69 else
70 swapcode(char, a, b, n)
71 }
72
73 #define swap(a, b) \
74 if (swaptype == 0) { \
75 long t = *(long *)(a); \
76 *(long *)(a) = *(long *)(b); \
77 *(long *)(b) = t; \
78 } else \
79 swapfunc(a, b, es, swaptype)
80
81 #define vecswap(a, b, n) if ((n) > 0) swapfunc(a, b, n, swaptype)
82
83 static __inline char *
84 med3(a, b, c, cmp)
85 char *a, *b, *c;
86 cmp_t *cmp;
87 {
88 return cmp(a, b) < 0 ?
89 (cmp(b, c) < 0 ? b : (cmp(a, c) < 0 ? c : a ))
90 :(cmp(b, c) > 0 ? b : (cmp(a, c) < 0 ? a : c ));
91 }
92
93 void
94 qsort(a, n, es, cmp)
95 void *a;
96 size_t n, es;
97 cmp_t *cmp;
98 {
99 char *pa, *pb, *pc, *pd, *pl, *pm, *pn;
100 int d, r, swaptype, swap_cnt;
101
102 loop: SWAPINIT(a, es);
103 swap_cnt = 0;
104 if (n < 7) {
105 for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es)
106 for (pl = pm; pl > (char *)a && cmp(pl - es, pl) > 0;
107 pl -= es)
108 swap(pl, pl - es);
109 return;
110 }
111 pm = (char *)a + (n / 2) * es;
112 if (n > 7) {
113 pl = a;
114 pn = (char *)a + (n - 1) * es;
115 if (n > 40) {
116 d = (n / 8) * es;
117 pl = med3(pl, pl + d, pl + 2 * d, cmp);
118 pm = med3(pm - d, pm, pm + d, cmp);
119 pn = med3(pn - 2 * d, pn - d, pn, cmp);
120 }
121 pm = med3(pl, pm, pn, cmp);
122 }
123 swap(a, pm);
124 pa = pb = (char *)a + es;
125
126 pc = pd = (char *)a + (n - 1) * es;
127 for (;;) {
128 while (pb <= pc && (r = cmp(pb, a)) <= 0) {
129 if (r == 0) {
130 swap_cnt = 1;
131 swap(pa, pb);
132 pa += es;
133 }
134 pb += es;
135 }
136 while (pb <= pc && (r = cmp(pc, a)) >= 0) {
137 if (r == 0) {
138 swap_cnt = 1;
139 swap(pc, pd);
140 pd -= es;
141 }
142 pc -= es;
143 }
144 if (pb > pc)
145 break;
146 swap(pb, pc);
147 swap_cnt = 1;
148 pb += es;
149 pc -= es;
150 }
151 if (swap_cnt == 0) { /* Switch to insertion sort */
152 for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es)
153 for (pl = pm; pl > (char *)a && cmp(pl - es, pl) > 0;
154 pl -= es)
155 swap(pl, pl - es);
156 return;
157 }
158
159 pn = (char *)a + n * es;
160 r = min(pa - (char *)a, pb - pa);
161 vecswap(a, pb - r, r);
162 r = min(pd - pc, pn - pd - es);
163 vecswap(pb, pn - r, r);
164 if ((r = pb - pa) > es)
165 qsort(a, r / es, es, cmp);
166 if ((r = pd - pc) > es) {
167 /* Iterate rather than recurse to save stack space */
168 a = pn - r;
169 n = r / es;
170 goto loop;
171 }
172 /* qsort(pn - r, r / es, es, cmp);*/
173 }
Cache object: 1ddca1e38612f2b0626040e6e7bb101c
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