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 * $FreeBSD$
34 */
35
36 #include <sys/libkern.h>
37
38 typedef int cmp_t __P((const void *, const void *));
39 static __inline char *med3 __P((char *, char *, char *, cmp_t *));
40 static __inline void swapfunc __P((char *, char *, int, int));
41
42 #define min(a, b) (a) < (b) ? a : b
43
44 /*
45 * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function".
46 */
47 #define swapcode(TYPE, parmi, parmj, n) { \
48 long i = (n) / sizeof (TYPE); \
49 register TYPE *pi = (TYPE *) (parmi); \
50 register TYPE *pj = (TYPE *) (parmj); \
51 do { \
52 register TYPE t = *pi; \
53 *pi++ = *pj; \
54 *pj++ = t; \
55 } while (--i > 0); \
56 }
57
58 #define SWAPINIT(a, es) swaptype = ((char *)a - (char *)0) % sizeof(long) || \
59 es % sizeof(long) ? 2 : es == sizeof(long)? 0 : 1;
60
61 static __inline void
62 swapfunc(a, b, n, swaptype)
63 char *a, *b;
64 int n, swaptype;
65 {
66 if(swaptype <= 1)
67 swapcode(long, a, b, n)
68 else
69 swapcode(char, a, b, n)
70 }
71
72 #define swap(a, b) \
73 if (swaptype == 0) { \
74 long t = *(long *)(a); \
75 *(long *)(a) = *(long *)(b); \
76 *(long *)(b) = t; \
77 } else \
78 swapfunc(a, b, es, swaptype)
79
80 #define vecswap(a, b, n) if ((n) > 0) swapfunc(a, b, n, swaptype)
81
82 static __inline char *
83 med3(a, b, c, cmp)
84 char *a, *b, *c;
85 cmp_t *cmp;
86 {
87 return cmp(a, b) < 0 ?
88 (cmp(b, c) < 0 ? b : (cmp(a, c) < 0 ? c : a ))
89 :(cmp(b, c) > 0 ? b : (cmp(a, c) < 0 ? a : c ));
90 }
91
92 void
93 qsort(a, n, es, cmp)
94 void *a;
95 size_t n, es;
96 cmp_t *cmp;
97 {
98 char *pa, *pb, *pc, *pd, *pl, *pm, *pn;
99 int d, r, swaptype, swap_cnt;
100
101 loop: SWAPINIT(a, es);
102 swap_cnt = 0;
103 if (n < 7) {
104 for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es)
105 for (pl = pm; pl > (char *)a && cmp(pl - es, pl) > 0;
106 pl -= es)
107 swap(pl, pl - es);
108 return;
109 }
110 pm = (char *)a + (n / 2) * es;
111 if (n > 7) {
112 pl = a;
113 pn = (char *)a + (n - 1) * es;
114 if (n > 40) {
115 d = (n / 8) * es;
116 pl = med3(pl, pl + d, pl + 2 * d, cmp);
117 pm = med3(pm - d, pm, pm + d, cmp);
118 pn = med3(pn - 2 * d, pn - d, pn, cmp);
119 }
120 pm = med3(pl, pm, pn, cmp);
121 }
122 swap(a, pm);
123 pa = pb = (char *)a + es;
124
125 pc = pd = (char *)a + (n - 1) * es;
126 for (;;) {
127 while (pb <= pc && (r = cmp(pb, a)) <= 0) {
128 if (r == 0) {
129 swap_cnt = 1;
130 swap(pa, pb);
131 pa += es;
132 }
133 pb += es;
134 }
135 while (pb <= pc && (r = cmp(pc, a)) >= 0) {
136 if (r == 0) {
137 swap_cnt = 1;
138 swap(pc, pd);
139 pd -= es;
140 }
141 pc -= es;
142 }
143 if (pb > pc)
144 break;
145 swap(pb, pc);
146 swap_cnt = 1;
147 pb += es;
148 pc -= es;
149 }
150 if (swap_cnt == 0) { /* Switch to insertion sort */
151 for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es)
152 for (pl = pm; pl > (char *)a && cmp(pl - es, pl) > 0;
153 pl -= es)
154 swap(pl, pl - es);
155 return;
156 }
157
158 pn = (char *)a + n * es;
159 r = min(pa - (char *)a, pb - pa);
160 vecswap(a, pb - r, r);
161 r = min(pd - pc, pn - pd - es);
162 vecswap(pb, pn - r, r);
163 if ((r = pb - pa) > es)
164 qsort(a, r / es, es, cmp);
165 if ((r = pd - pc) > es) {
166 /* Iterate rather than recurse to save stack space */
167 a = pn - r;
168 n = r / es;
169 goto loop;
170 }
171 /* qsort(pn - r, r / es, es, cmp);*/
172 }
Cache object: c05c8995828f2896e1d0c97904fb5819
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