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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#if defined(LIBC_SCCS) && !defined(lint)
35static char *rcsid = "$OpenBSD: qsort.c,v 1.7 2002/02/17 19:42:24 millert Exp $";
36#endif /* LIBC_SCCS and not lint */
37
38#include <sys/types.h>
39#include <stdlib.h>
40
41static __inline char *med3(char *, char *, char *, int (*)());
42static __inline void swapfunc(char *, char *, int, int);
43
44#define min(a, b) (a) < (b) ? a : b
45
46/*
47 * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function".
48 */
49#define swapcode(TYPE, parmi, parmj, n) { \
50 long i = (n) / sizeof (TYPE); \
51 register TYPE *pi = (TYPE *) (parmi); \
52 register TYPE *pj = (TYPE *) (parmj); \
53 do { \
54 register TYPE t = *pi; \
55 *pi++ = *pj; \
56 *pj++ = t; \
57 } while (--i > 0); \
58}
59
60#define SWAPINIT(a, es) swaptype = ((char *)a - (char *)0) % sizeof(long) || \
61 es % sizeof(long) ? 2 : es == sizeof(long)? 0 : 1;
62
63static __inline void
64swapfunc(a, b, n, swaptype)
65 char *a, *b;
66 int n, swaptype;
67{
68 if (swaptype <= 1)
69 swapcode(long, a, b, n)
70 else
71 swapcode(char, a, b, n)
72}
73
74#define swap(a, b) \
75 if (swaptype == 0) { \
76 long t = *(long *)(a); \
77 *(long *)(a) = *(long *)(b); \
78 *(long *)(b) = t; \
79 } else \
80 swapfunc(a, b, es, swaptype)
81
82#define vecswap(a, b, n) if ((n) > 0) swapfunc(a, b, n, swaptype)
83
84static __inline char *
85med3(a, b, c, cmp)
86 char *a, *b, *c;
87 int (*cmp)();
88{
89 return cmp(a, b) < 0 ?
90 (cmp(b, c) < 0 ? b : (cmp(a, c) < 0 ? c : a ))
91 :(cmp(b, c) > 0 ? b : (cmp(a, c) < 0 ? a : c ));
92}
93
94void
95qsort(aa, n, es, cmp)
96 void *aa;
97 size_t n, es;
98 int (*cmp)();
99{
100 char *pa, *pb, *pc, *pd, *pl, *pm, *pn;
101 int d, r, swaptype, swap_cnt;
102 register char *a = aa;
103
104loop: SWAPINIT(a, es);
105 swap_cnt = 0;
106 if (n < 7) {
107 for (pm = (char *)a + es; pm < (char *) a + n * es; pm += es)
108 for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0;
109 pl -= es)
110 swap(pl, pl - es);
111 return;
112 }
113 pm = (char *)a + (n / 2) * es;
114 if (n > 7) {
115 pl = (char *)a;
116 pn = (char *)a + (n - 1) * es;
117 if (n > 40) {
118 d = (n / 8) * es;
119 pl = med3(pl, pl + d, pl + 2 * d, cmp);
120 pm = med3(pm - d, pm, pm + d, cmp);
121 pn = med3(pn - 2 * d, pn - d, pn, cmp);
122 }
123 pm = med3(pl, pm, pn, cmp);
124 }
125 swap(a, pm);
126 pa = pb = (char *)a + es;
127
128 pc = pd = (char *)a + (n - 1) * es;
129 for (;;) {
130 while (pb <= pc && (r = cmp(pb, a)) <= 0) {
131 if (r == 0) {
132 swap_cnt = 1;
133 swap(pa, pb);
134 pa += es;
135 }
136 pb += es;
137 }
138 while (pb <= pc && (r = cmp(pc, a)) >= 0) {
139 if (r == 0) {
140 swap_cnt = 1;
141 swap(pc, pd);
142 pd -= es;
143 }
144 pc -= es;
145 }
146 if (pb > pc)
147 break;
148 swap(pb, pc);
149 swap_cnt = 1;
150 pb += es;
151 pc -= es;
152 }
153 if (swap_cnt == 0) { /* Switch to insertion sort */
154 for (pm = (char *) a + es; pm < (char *) a + n * es; pm += es)
155 for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0;
156 pl -= es)
157 swap(pl, pl - es);
158 return;
159 }
160
161 pn = (char *)a + n * es;
162 r = min(pa - (char *)a, pb - pa);
163 vecswap(a, pb - r, r);
164 r = min(pd - pc, pn - pd - es);
165 vecswap(pb, pn - r, r);
166 if ((r = pb - pa) > es)
167 qsort(a, r / es, es, cmp);
168 if ((r = pd - pc) > es) {
169 /* Iterate rather than recurse to save stack space */
170 a = pn - r;
171 n = r / es;
172 goto loop;
173 }
174/* qsort(pn - r, r / es, es, cmp);*/
175}
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