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 __FBSDID("$FreeBSD$");
37
38 #include <errno.h>
39 #include <stdint.h>
40 #include <stdlib.h>
41 #include <string.h>
42 #include "libc_private.h"
43
44 #if defined(I_AM_QSORT_R)
45 typedef int cmp_t(void *, const void *, const void *);
46 #elif defined(I_AM_QSORT_S)
47 typedef int cmp_t(const void *, const void *, void *);
48 #else
49 typedef int cmp_t(const void *, const void *);
50 #endif
51 static inline char *med3(char *, char *, char *, cmp_t *, void *);
52
53 #define MIN(a, b) ((a) < (b) ? a : b)
54
55 /*
56 * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function".
57 */
58
59 static inline void
swapfunc(char * a,char * b,size_t es)60 swapfunc(char *a, char *b, size_t es)
61 {
62 char t;
63
64 do {
65 t = *a;
66 *a++ = *b;
67 *b++ = t;
68 } while (--es > 0);
69 }
70
71 #define vecswap(a, b, n) \
72 if ((n) > 0) swapfunc(a, b, n)
73
74 #if defined(I_AM_QSORT_R)
75 #define CMP(t, x, y) (cmp((t), (x), (y)))
76 #elif defined(I_AM_QSORT_S)
77 #define CMP(t, x, y) (cmp((x), (y), (t)))
78 #else
79 #define CMP(t, x, y) (cmp((x), (y)))
80 #endif
81
82 static inline char *
med3(char * a,char * b,char * c,cmp_t * cmp,void * thunk __unused)83 med3(char *a, char *b, char *c, cmp_t *cmp, void *thunk
84 #if !defined(I_AM_QSORT_R) && !defined(I_AM_QSORT_S)
85 __unused
86 #endif
87 )
88 {
89 return CMP(thunk, a, b) < 0 ?
90 (CMP(thunk, b, c) < 0 ? b : (CMP(thunk, a, c) < 0 ? c : a ))
91 :(CMP(thunk, b, c) > 0 ? b : (CMP(thunk, a, c) < 0 ? a : c ));
92 }
93
94 /*
95 * The actual qsort() implementation is static to avoid preemptible calls when
96 * recursing. Also give them different names for improved debugging.
97 */
98 #if defined(I_AM_QSORT_R)
99 #define local_qsort local_qsort_r
100 #elif defined(I_AM_QSORT_S)
101 #define local_qsort local_qsort_s
102 #endif
103 static void
local_qsort(void * a,size_t n,size_t es,cmp_t * cmp,void * thunk)104 local_qsort(void *a, size_t n, size_t es, cmp_t *cmp, void *thunk)
105 {
106 char *pa, *pb, *pc, *pd, *pl, *pm, *pn;
107 size_t d1, d2;
108 int cmp_result;
109 int swap_cnt;
110
111 if (__predict_false(n == 0))
112 return;
113 loop:
114 swap_cnt = 0;
115 if (n < 7) {
116 for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es)
117 for (pl = pm;
118 pl > (char *)a && CMP(thunk, pl - es, pl) > 0;
119 pl -= es)
120 swapfunc(pl, pl - es, es);
121 return;
122 }
123 pm = (char *)a + (n / 2) * es;
124 if (n > 7) {
125 pl = a;
126 pn = (char *)a + (n - 1) * es;
127 if (n > 40) {
128 size_t d = (n / 8) * es;
129
130 pl = med3(pl, pl + d, pl + 2 * d, cmp, thunk);
131 pm = med3(pm - d, pm, pm + d, cmp, thunk);
132 pn = med3(pn - 2 * d, pn - d, pn, cmp, thunk);
133 }
134 pm = med3(pl, pm, pn, cmp, thunk);
135 }
136 swapfunc(a, pm, es);
137 pa = pb = (char *)a + es;
138
139 pc = pd = (char *)a + (n - 1) * es;
140 for (;;) {
141 while (pb <= pc && (cmp_result = CMP(thunk, pb, a)) <= 0) {
142 if (cmp_result == 0) {
143 swap_cnt = 1;
144 swapfunc(pa, pb, es);
145 pa += es;
146 }
147 pb += es;
148 }
149 while (pb <= pc && (cmp_result = CMP(thunk, pc, a)) >= 0) {
150 if (cmp_result == 0) {
151 swap_cnt = 1;
152 swapfunc(pc, pd, es);
153 pd -= es;
154 }
155 pc -= es;
156 }
157 if (pb > pc)
158 break;
159 swapfunc(pb, pc, es);
160 swap_cnt = 1;
161 pb += es;
162 pc -= es;
163 }
164 if (swap_cnt == 0) { /* Switch to insertion sort */
165 for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es)
166 for (pl = pm;
167 pl > (char *)a && CMP(thunk, pl - es, pl) > 0;
168 pl -= es)
169 swapfunc(pl, pl - es, es);
170 return;
171 }
172
173 pn = (char *)a + n * es;
174 d1 = MIN(pa - (char *)a, pb - pa);
175 vecswap(a, pb - d1, d1);
176 d1 = MIN(pd - pc, pn - pd - es);
177 vecswap(pb, pn - d1, d1);
178
179 d1 = pb - pa;
180 d2 = pd - pc;
181 if (d1 <= d2) {
182 /* Recurse on left partition, then iterate on right partition */
183 if (d1 > es) {
184 local_qsort(a, d1 / es, es, cmp, thunk);
185 }
186 if (d2 > es) {
187 /* Iterate rather than recurse to save stack space */
188 /* qsort(pn - d2, d2 / es, es, cmp); */
189 a = pn - d2;
190 n = d2 / es;
191 goto loop;
192 }
193 } else {
194 /* Recurse on right partition, then iterate on left partition */
195 if (d2 > es) {
196 local_qsort(pn - d2, d2 / es, es, cmp, thunk);
197 }
198 if (d1 > es) {
199 /* Iterate rather than recurse to save stack space */
200 /* qsort(a, d1 / es, es, cmp); */
201 n = d1 / es;
202 goto loop;
203 }
204 }
205 }
206
207 #if defined(I_AM_QSORT_R)
208 void
qsort_r(void * a,size_t n,size_t es,void * thunk,cmp_t * cmp)209 qsort_r(void *a, size_t n, size_t es, void *thunk, cmp_t *cmp)
210 {
211 local_qsort_r(a, n, es, cmp, thunk);
212 }
213 #elif defined(I_AM_QSORT_S)
214 errno_t
qsort_s(void * a,rsize_t n,rsize_t es,cmp_t * cmp,void * thunk)215 qsort_s(void *a, rsize_t n, rsize_t es, cmp_t *cmp, void *thunk)
216 {
217 if (n > RSIZE_MAX) {
218 __throw_constraint_handler_s("qsort_s : n > RSIZE_MAX", EINVAL);
219 return (EINVAL);
220 } else if (es > RSIZE_MAX) {
221 __throw_constraint_handler_s("qsort_s : es > RSIZE_MAX",
222 EINVAL);
223 return (EINVAL);
224 } else if (n != 0) {
225 if (a == NULL) {
226 __throw_constraint_handler_s("qsort_s : a == NULL",
227 EINVAL);
228 return (EINVAL);
229 } else if (cmp == NULL) {
230 __throw_constraint_handler_s("qsort_s : cmp == NULL",
231 EINVAL);
232 return (EINVAL);
233 }
234 }
235
236 local_qsort_s(a, n, es, cmp, thunk);
237 return (0);
238 }
239 #else
240 void
qsort(void * a,size_t n,size_t es,cmp_t * cmp)241 qsort(void *a, size_t n, size_t es, cmp_t *cmp)
242 {
243 local_qsort(a, n, es, cmp, NULL);
244 }
245 #endif
246