1 /*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1992, 1993
5 * The Regents of the University of California. All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 * 3. Neither the name of the University nor the names of its contributors
16 * may be used to endorse or promote products derived from this software
17 * without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 */
31
32 #if defined(LIBC_SCCS) && !defined(lint)
33 static char sccsid[] = "@(#)qsort.c 8.1 (Berkeley) 6/4/93";
34 #endif /* LIBC_SCCS and not lint */
35 // #include <sys/cdefs.h>
36
37 #if defined(__GNUC__)
38 #define __IDSTRING(name,string) __asm__(".ident\t\"" string "\"")
39 #else
40 /*
41 * The following definition might not work well if used in header files,
42 * but it should be better than nothing. If you want a "do nothing"
43 * version, then it should generate some harmless declaration, such as:
44 * #define __IDSTRING(name,string) struct __hack
45 */
46 #define __IDSTRING(name,string) static const char name[] __unused = string
47 #endif
48
49 /*
50 * Embed the rcs id of a source file in the resulting library. Note that in
51 * more recent ELF binutils, we use .ident allowing the ID to be stripped.
52 * Usage:
53 * __FBSDID("$FreeBSD$");
54 */
55 #ifndef __FBSDID
56 #if !defined(STRIP_FBSDID)
57 #define __FBSDID(s) __IDSTRING(__CONCAT(__rcsid_,__LINE__),s)
58 #else
59 #define __FBSDID(s) struct __hack
60 #endif
61 #endif
62
63 #if defined(__GNUC__)
64 #define __GNUC_PREREQ__(ma, mi) \
65 (__GNUC__ > (ma) || __GNUC__ == (ma) && __GNUC_MINOR__ >= (mi))
66 #else
67 #define __GNUC_PREREQ__(ma, mi) 0
68 #endif
69
70 #if !__GNUC_PREREQ__(2, 5)
71 #define __unused
72 #endif
73 #if __GNUC__ == 2 && __GNUC_MINOR__ >= 5 && __GNUC_MINOR__ < 7
74 #define __unused
75 /* XXX Find out what to do for __packed, __aligned and __section */
76 #endif
77 #if __GNUC_PREREQ__(2, 7)
78 #define __unused __attribute__((__unused__))
79 #endif
80
81 #if __GNUC_PREREQ__(2, 96)
82 #define __predict_false(exp) __builtin_expect((exp), 0)
83 #else
84 #define __predict_false(exp) (exp)
85 #endif
86
87 __FBSDID("$FreeBSD$");
88
89 #include <errno.h>
90 #include <stdint.h>
91 #include <stdlib.h>
92 #include <string.h>
93 // #include "libc_private.h"
94
95 #if defined(I_AM_QSORT_R)
96 typedef int cmp_t(void *, const void *, const void *);
97 #elif defined(I_AM_QSORT_S)
98 typedef int cmp_t(const void *, const void *, void *);
99 #else
100 typedef int cmp_t(const void *, const void *);
101 #endif
102 static inline char *med3(char *, char *, char *, cmp_t *, void *);
103
104 #define MIN(a, b) ((a) < (b) ? a : b)
105
106 /*
107 * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function".
108 */
109
110 static inline void
swapfunc(char * a,char * b,size_t es)111 swapfunc(char *a, char *b, size_t es)
112 {
113 char t;
114
115 do {
116 t = *a;
117 *a++ = *b;
118 *b++ = t;
119 } while (--es > 0);
120 }
121
122 #define vecswap(a, b, n) \
123 if ((n) > 0) swapfunc(a, b, n)
124
125 #if defined(I_AM_QSORT_R)
126 #define CMP(t, x, y) (cmp((t), (x), (y)))
127 #elif defined(I_AM_QSORT_S)
128 #define CMP(t, x, y) (cmp((x), (y), (t)))
129 #else
130 #define CMP(t, x, y) (cmp((x), (y)))
131 #endif
132
133 static inline char *
med3(char * a,char * b,char * c,cmp_t * cmp,void * thunk __unused)134 med3(char *a, char *b, char *c, cmp_t *cmp, void *thunk
135 #if !defined(I_AM_QSORT_R) && !defined(I_AM_QSORT_S)
136 __unused
137 #endif
138 )
139 {
140 return CMP(thunk, a, b) < 0 ?
141 (CMP(thunk, b, c) < 0 ? b : (CMP(thunk, a, c) < 0 ? c : a ))
142 :(CMP(thunk, b, c) > 0 ? b : (CMP(thunk, a, c) < 0 ? a : c ));
143 }
144
145 /*
146 * The actual qsort() implementation is static to avoid preemptible calls when
147 * recursing. Also give them different names for improved debugging.
148 */
149 #if defined(I_AM_QSORT_R)
150 #define local_qsort local_qsort_r
151 #elif defined(I_AM_QSORT_S)
152 #define local_qsort local_qsort_s
153 #endif
154 static void
local_qsort(void * a,size_t n,size_t es,cmp_t * cmp,void * thunk)155 local_qsort(void *a, size_t n, size_t es, cmp_t *cmp, void *thunk)
156 {
157 char *pa, *pb, *pc, *pd, *pl, *pm, *pn;
158 size_t d1, d2;
159 int cmp_result;
160 int swap_cnt;
161
162 if (__predict_false(n == 0))
163 return;
164 loop:
165 swap_cnt = 0;
166 if (n < 7) {
167 for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es)
168 for (pl = pm;
169 pl > (char *)a && CMP(thunk, pl - es, pl) > 0;
170 pl -= es)
171 swapfunc(pl, pl - es, es);
172 return;
173 }
174 pm = (char *)a + (n / 2) * es;
175 if (n > 7) {
176 pl = a;
177 pn = (char *)a + (n - 1) * es;
178 if (n > 40) {
179 size_t d = (n / 8) * es;
180
181 pl = med3(pl, pl + d, pl + 2 * d, cmp, thunk);
182 pm = med3(pm - d, pm, pm + d, cmp, thunk);
183 pn = med3(pn - 2 * d, pn - d, pn, cmp, thunk);
184 }
185 pm = med3(pl, pm, pn, cmp, thunk);
186 }
187 swapfunc(a, pm, es);
188 pa = pb = (char *)a + es;
189
190 pc = pd = (char *)a + (n - 1) * es;
191 for (;;) {
192 while (pb <= pc && (cmp_result = CMP(thunk, pb, a)) <= 0) {
193 if (cmp_result == 0) {
194 swap_cnt = 1;
195 swapfunc(pa, pb, es);
196 pa += es;
197 }
198 pb += es;
199 }
200 while (pb <= pc && (cmp_result = CMP(thunk, pc, a)) >= 0) {
201 if (cmp_result == 0) {
202 swap_cnt = 1;
203 swapfunc(pc, pd, es);
204 pd -= es;
205 }
206 pc -= es;
207 }
208 if (pb > pc)
209 break;
210 swapfunc(pb, pc, es);
211 swap_cnt = 1;
212 pb += es;
213 pc -= es;
214 }
215 if (swap_cnt == 0) { /* Switch to insertion sort */
216 for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es)
217 for (pl = pm;
218 pl > (char *)a && CMP(thunk, pl - es, pl) > 0;
219 pl -= es)
220 swapfunc(pl, pl - es, es);
221 return;
222 }
223
224 pn = (char *)a + n * es;
225 d1 = MIN(pa - (char *)a, pb - pa);
226 vecswap(a, pb - d1, d1);
227 d1 = MIN(pd - pc, pn - pd - es);
228 vecswap(pb, pn - d1, d1);
229
230 d1 = pb - pa;
231 d2 = pd - pc;
232 if (d1 <= d2) {
233 /* Recurse on left partition, then iterate on right partition */
234 if (d1 > es) {
235 local_qsort(a, d1 / es, es, cmp, thunk);
236 }
237 if (d2 > es) {
238 /* Iterate rather than recurse to save stack space */
239 /* qsort(pn - d2, d2 / es, es, cmp); */
240 a = pn - d2;
241 n = d2 / es;
242 goto loop;
243 }
244 } else {
245 /* Recurse on right partition, then iterate on left partition */
246 if (d2 > es) {
247 local_qsort(pn - d2, d2 / es, es, cmp, thunk);
248 }
249 if (d1 > es) {
250 /* Iterate rather than recurse to save stack space */
251 /* qsort(a, d1 / es, es, cmp); */
252 n = d1 / es;
253 goto loop;
254 }
255 }
256 }
257
258 #if defined(I_AM_QSORT_R)
259 void
qsort_r(void * a,size_t n,size_t es,void * thunk,cmp_t * cmp)260 qsort_r(void *a, size_t n, size_t es, void *thunk, cmp_t *cmp)
261 {
262 local_qsort_r(a, n, es, cmp, thunk);
263 }
264 #elif defined(I_AM_QSORT_S)
265 errno_t
qsort_s(void * a,rsize_t n,rsize_t es,cmp_t * cmp,void * thunk)266 qsort_s(void *a, rsize_t n, rsize_t es, cmp_t *cmp, void *thunk)
267 {
268 if (n > RSIZE_MAX) {
269 __throw_constraint_handler_s("qsort_s : n > RSIZE_MAX", EINVAL);
270 return (EINVAL);
271 } else if (es > RSIZE_MAX) {
272 __throw_constraint_handler_s("qsort_s : es > RSIZE_MAX",
273 EINVAL);
274 return (EINVAL);
275 } else if (n != 0) {
276 if (a == NULL) {
277 __throw_constraint_handler_s("qsort_s : a == NULL",
278 EINVAL);
279 return (EINVAL);
280 } else if (cmp == NULL) {
281 __throw_constraint_handler_s("qsort_s : cmp == NULL",
282 EINVAL);
283 return (EINVAL);
284 }
285 }
286
287 local_qsort_s(a, n, es, cmp, thunk);
288 return (0);
289 }
290 #else
291 void
qsort(void * a,size_t n,size_t es,cmp_t * cmp)292 qsort(void *a, size_t n, size_t es, cmp_t *cmp)
293 {
294 local_qsort(a, n, es, cmp, NULL);
295 }
296 #endif