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-rw-r--r--src/lib/libc/stdlib/qsort.c161
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1/* $OpenBSD: qsort.c,v 1.10 2005/08/08 08:05:37 espie Exp $ */
2/*-
3 * Copyright (c) 1992, 1993
4 * The Regents of the University of California. All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 * 3. Neither the name of the University nor the names of its contributors
15 * may be used to endorse or promote products derived from this software
16 * without specific prior written permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
28 * SUCH DAMAGE.
29 */
30
31#include <sys/types.h>
32#include <stdlib.h>
33
34static __inline char *med3(char *, char *, char *, int (*)(const void *, const void *));
35static __inline void swapfunc(char *, char *, int, int);
36
37#define min(a, b) (a) < (b) ? a : b
38
39/*
40 * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function".
41 */
42#define swapcode(TYPE, parmi, parmj, n) { \
43 long i = (n) / sizeof (TYPE); \
44 TYPE *pi = (TYPE *) (parmi); \
45 TYPE *pj = (TYPE *) (parmj); \
46 do { \
47 TYPE t = *pi; \
48 *pi++ = *pj; \
49 *pj++ = t; \
50 } while (--i > 0); \
51}
52
53#define SWAPINIT(a, es) swaptype = ((char *)a - (char *)0) % sizeof(long) || \
54 es % sizeof(long) ? 2 : es == sizeof(long)? 0 : 1;
55
56static __inline void
57swapfunc(char *a, char *b, int n, int swaptype)
58{
59 if (swaptype <= 1)
60 swapcode(long, a, b, n)
61 else
62 swapcode(char, a, b, n)
63}
64
65#define swap(a, b) \
66 if (swaptype == 0) { \
67 long t = *(long *)(a); \
68 *(long *)(a) = *(long *)(b); \
69 *(long *)(b) = t; \
70 } else \
71 swapfunc(a, b, es, swaptype)
72
73#define vecswap(a, b, n) if ((n) > 0) swapfunc(a, b, n, swaptype)
74
75static __inline char *
76med3(char *a, char *b, char *c, int (*cmp)(const void *, const void *))
77{
78 return cmp(a, b) < 0 ?
79 (cmp(b, c) < 0 ? b : (cmp(a, c) < 0 ? c : a ))
80 :(cmp(b, c) > 0 ? b : (cmp(a, c) < 0 ? a : c ));
81}
82
83void
84qsort(void *aa, size_t n, size_t es, int (*cmp)(const void *, const void *))
85{
86 char *pa, *pb, *pc, *pd, *pl, *pm, *pn;
87 int d, r, swaptype, swap_cnt;
88 char *a = aa;
89
90loop: SWAPINIT(a, es);
91 swap_cnt = 0;
92 if (n < 7) {
93 for (pm = (char *)a + es; pm < (char *) a + n * es; pm += es)
94 for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0;
95 pl -= es)
96 swap(pl, pl - es);
97 return;
98 }
99 pm = (char *)a + (n / 2) * es;
100 if (n > 7) {
101 pl = (char *)a;
102 pn = (char *)a + (n - 1) * es;
103 if (n > 40) {
104 d = (n / 8) * es;
105 pl = med3(pl, pl + d, pl + 2 * d, cmp);
106 pm = med3(pm - d, pm, pm + d, cmp);
107 pn = med3(pn - 2 * d, pn - d, pn, cmp);
108 }
109 pm = med3(pl, pm, pn, cmp);
110 }
111 swap(a, pm);
112 pa = pb = (char *)a + es;
113
114 pc = pd = (char *)a + (n - 1) * es;
115 for (;;) {
116 while (pb <= pc && (r = cmp(pb, a)) <= 0) {
117 if (r == 0) {
118 swap_cnt = 1;
119 swap(pa, pb);
120 pa += es;
121 }
122 pb += es;
123 }
124 while (pb <= pc && (r = cmp(pc, a)) >= 0) {
125 if (r == 0) {
126 swap_cnt = 1;
127 swap(pc, pd);
128 pd -= es;
129 }
130 pc -= es;
131 }
132 if (pb > pc)
133 break;
134 swap(pb, pc);
135 swap_cnt = 1;
136 pb += es;
137 pc -= es;
138 }
139 if (swap_cnt == 0) { /* Switch to insertion sort */
140 for (pm = (char *) a + es; pm < (char *) a + n * es; pm += es)
141 for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0;
142 pl -= es)
143 swap(pl, pl - es);
144 return;
145 }
146
147 pn = (char *)a + n * es;
148 r = min(pa - (char *)a, pb - pa);
149 vecswap(a, pb - r, r);
150 r = min(pd - pc, pn - pd - es);
151 vecswap(pb, pn - r, r);
152 if ((r = pb - pa) > es)
153 qsort(a, r / es, es, cmp);
154 if ((r = pd - pc) > es) {
155 /* Iterate rather than recurse to save stack space */
156 a = pn - r;
157 n = r / es;
158 goto loop;
159 }
160/* qsort(pn - r, r / es, es, cmp);*/
161}
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