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-rw-r--r--src/lib/libc/stdlib/qsort.c238
1 files changed, 0 insertions, 238 deletions
diff --git a/src/lib/libc/stdlib/qsort.c b/src/lib/libc/stdlib/qsort.c
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--- a/src/lib/libc/stdlib/qsort.c
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1/* $OpenBSD: qsort.c,v 1.18 2017/05/30 14:54:09 millert 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 *, size_t, 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 * This version differs from Bentley & McIlroy in the following ways:
43 * 1. The partition value is swapped into a[0] instead of being
44 * stored out of line.
45 *
46 * 2. The swap function can swap 32-bit aligned elements on 64-bit
47 * platforms instead of swapping them as byte-aligned.
48 *
49 * 3. It uses David Musser's introsort algorithm to fall back to
50 * heapsort(3) when the recursion depth reaches 2*lg(n + 1).
51 * This avoids quicksort's quadratic behavior for pathological
52 * input without appreciably changing the average run time.
53 *
54 * 4. Tail recursion is eliminated when sorting the larger of two
55 * subpartitions to save stack space.
56 */
57#define SWAPTYPE_BYTEV 1
58#define SWAPTYPE_INTV 2
59#define SWAPTYPE_LONGV 3
60#define SWAPTYPE_INT 4
61#define SWAPTYPE_LONG 5
62
63#define TYPE_ALIGNED(TYPE, a, es) \
64 (((char *)a - (char *)0) % sizeof(TYPE) == 0 && es % sizeof(TYPE) == 0)
65
66#define swapcode(TYPE, parmi, parmj, n) { \
67 size_t i = (n) / sizeof (TYPE); \
68 TYPE *pi = (TYPE *) (parmi); \
69 TYPE *pj = (TYPE *) (parmj); \
70 do { \
71 TYPE t = *pi; \
72 *pi++ = *pj; \
73 *pj++ = t; \
74 } while (--i > 0); \
75}
76
77static __inline void
78swapfunc(char *a, char *b, size_t n, int swaptype)
79{
80 switch (swaptype) {
81 case SWAPTYPE_INT:
82 case SWAPTYPE_INTV:
83 swapcode(int, a, b, n);
84 break;
85 case SWAPTYPE_LONG:
86 case SWAPTYPE_LONGV:
87 swapcode(long, a, b, n);
88 break;
89 default:
90 swapcode(char, a, b, n);
91 break;
92 }
93}
94
95#define swap(a, b) do { \
96 switch (swaptype) { \
97 case SWAPTYPE_INT: { \
98 int t = *(int *)(a); \
99 *(int *)(a) = *(int *)(b); \
100 *(int *)(b) = t; \
101 break; \
102 } \
103 case SWAPTYPE_LONG: { \
104 long t = *(long *)(a); \
105 *(long *)(a) = *(long *)(b); \
106 *(long *)(b) = t; \
107 break; \
108 } \
109 default: \
110 swapfunc(a, b, es, swaptype); \
111 } \
112} while (0)
113
114#define vecswap(a, b, n) if ((n) > 0) swapfunc(a, b, n, swaptype)
115
116static __inline char *
117med3(char *a, char *b, char *c, int (*cmp)(const void *, const void *))
118{
119 return cmp(a, b) < 0 ?
120 (cmp(b, c) < 0 ? b : (cmp(a, c) < 0 ? c : a ))
121 :(cmp(b, c) > 0 ? b : (cmp(a, c) < 0 ? a : c ));
122}
123
124static void
125introsort(char *a, size_t n, size_t es, size_t maxdepth, int swaptype,
126 int (*cmp)(const void *, const void *))
127{
128 char *pa, *pb, *pc, *pd, *pl, *pm, *pn;
129 int cmp_result;
130 size_t r, s;
131
132loop: if (n < 7) {
133 for (pm = a + es; pm < a + n * es; pm += es)
134 for (pl = pm; pl > a && cmp(pl - es, pl) > 0;
135 pl -= es)
136 swap(pl, pl - es);
137 return;
138 }
139 if (maxdepth == 0) {
140 if (heapsort(a, n, es, cmp) == 0)
141 return;
142 }
143 maxdepth--;
144 pm = a + (n / 2) * es;
145 if (n > 7) {
146 pl = a;
147 pn = a + (n - 1) * es;
148 if (n > 40) {
149 s = (n / 8) * es;
150 pl = med3(pl, pl + s, pl + 2 * s, cmp);
151 pm = med3(pm - s, pm, pm + s, cmp);
152 pn = med3(pn - 2 * s, pn - s, pn, cmp);
153 }
154 pm = med3(pl, pm, pn, cmp);
155 }
156 swap(a, pm);
157 pa = pb = a + es;
158 pc = pd = a + (n - 1) * es;
159 for (;;) {
160 while (pb <= pc && (cmp_result = cmp(pb, a)) <= 0) {
161 if (cmp_result == 0) {
162 swap(pa, pb);
163 pa += es;
164 }
165 pb += es;
166 }
167 while (pb <= pc && (cmp_result = cmp(pc, a)) >= 0) {
168 if (cmp_result == 0) {
169 swap(pc, pd);
170 pd -= es;
171 }
172 pc -= es;
173 }
174 if (pb > pc)
175 break;
176 swap(pb, pc);
177 pb += es;
178 pc -= es;
179 }
180
181 pn = a + n * es;
182 r = min(pa - a, pb - pa);
183 vecswap(a, pb - r, r);
184 r = min(pd - pc, pn - pd - es);
185 vecswap(pb, pn - r, r);
186 /*
187 * To save stack space we sort the smaller side of the partition first
188 * using recursion and eliminate tail recursion for the larger side.
189 */
190 r = pb - pa;
191 s = pd - pc;
192 if (r < s) {
193 /* Recurse for 1st side, iterate for 2nd side. */
194 if (s > es) {
195 if (r > es) {
196 introsort(a, r / es, es, maxdepth,
197 swaptype, cmp);
198 }
199 a = pn - s;
200 n = s / es;
201 goto loop;
202 }
203 } else {
204 /* Recurse for 2nd side, iterate for 1st side. */
205 if (r > es) {
206 if (s > es) {
207 introsort(pn - s, s / es, es, maxdepth,
208 swaptype, cmp);
209 }
210 n = r / es;
211 goto loop;
212 }
213 }
214}
215
216void
217qsort(void *a, size_t n, size_t es, int (*cmp)(const void *, const void *))
218{
219 size_t i, maxdepth = 0;
220 int swaptype;
221
222 /* Approximate 2*ceil(lg(n + 1)) */
223 for (i = n; i > 0; i >>= 1)
224 maxdepth++;
225 maxdepth *= 2;
226
227 if (TYPE_ALIGNED(long, a, es))
228 swaptype = es == sizeof(long) ? SWAPTYPE_LONG : SWAPTYPE_LONGV;
229 else if (sizeof(int) != sizeof(long) && TYPE_ALIGNED(int, a, es))
230 swaptype = es == sizeof(int) ? SWAPTYPE_INT : SWAPTYPE_INTV;
231 else
232 swaptype = SWAPTYPE_BYTEV;
233
234 introsort(a, n, es, maxdepth, swaptype, cmp);
235
236}
237
238DEF_STRONG(qsort);
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