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. Neither the name of the University nor the names of its contributors
14 * may be used to endorse or promote products derived from this software
15 * without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 */
29
30 #if defined(LIBC_SCCS) && !defined(lint)
31 static char sccsid[] = "@(#)qsort.c 8.1 (Berkeley) 6/4/93";
32 #endif /* LIBC_SCCS and not lint */
33 #include <sys/cdefs.h>
34 __FBSDID("$FreeBSD$");
35
36 #include <stdlib.h>
37
38 #ifdef I_AM_QSORT_R
39 typedef int cmp_t(void *, const void *, const void *);
40 #else
41 typedef int cmp_t(const void *, const void *);
42 #endif
43 static inline char *med3(char *, char *, char *, cmp_t *, void *);
44 static inline void swapfunc(char *, char *, size_t, int, int);
45
46 #define MIN(a, b) ((a) < (b) ? a : b)
47
48 /*
49 * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function".
50 */
51 #define swapcode(TYPE, parmi, parmj, n) { \
52 size_t i = (n) / sizeof (TYPE); \
53 TYPE *pi = (TYPE *) (parmi); \
54 TYPE *pj = (TYPE *) (parmj); \
55 do { \
56 TYPE t = *pi; \
57 *pi++ = *pj; \
58 *pj++ = t; \
59 } while (--i > 0); \
60 }
61
62 #define SWAPINIT(TYPE, a, es) swaptype_ ## TYPE = \
63 ((char *)a - (char *)0) % sizeof(TYPE) || \
64 es % sizeof(TYPE) ? 2 : es == sizeof(TYPE) ? 0 : 1;
65
66 static inline void
swapfunc(char * a,char * b,size_t n,int swaptype_long,int swaptype_int)67 swapfunc(char *a, char *b, size_t n, int swaptype_long, int swaptype_int)
68 {
69 if (swaptype_long <= 1)
70 swapcode(long, a, b, n)
71 else if (swaptype_int <= 1)
72 swapcode(int, a, b, n)
73 else
74 swapcode(char, a, b, n)
75 }
76
77 #define swap(a, b) \
78 if (swaptype_long == 0) { \
79 long t = *(long *)(a); \
80 *(long *)(a) = *(long *)(b); \
81 *(long *)(b) = t; \
82 } else if (swaptype_int == 0) { \
83 int t = *(int *)(a); \
84 *(int *)(a) = *(int *)(b); \
85 *(int *)(b) = t; \
86 } else \
87 swapfunc(a, b, es, swaptype_long, swaptype_int)
88
89 #define vecswap(a, b, n) \
90 if ((n) > 0) swapfunc(a, b, n, swaptype_long, swaptype_int)
91
92 #ifdef I_AM_QSORT_R
93 #define CMP(t, x, y) (cmp((t), (x), (y)))
94 #else
95 #define CMP(t, x, y) (cmp((x), (y)))
96 #endif
97
98 static inline char *
med3(char * a,char * b,char * c,cmp_t * cmp,void * thunk __unused)99 med3(char *a, char *b, char *c, cmp_t *cmp, void *thunk
100 #ifndef I_AM_QSORT_R
101 __unused
102 #endif
103 )
104 {
105 return CMP(thunk, a, b) < 0 ?
106 (CMP(thunk, b, c) < 0 ? b : (CMP(thunk, a, c) < 0 ? c : a ))
107 :(CMP(thunk, b, c) > 0 ? b : (CMP(thunk, a, c) < 0 ? a : c ));
108 }
109
110 #ifdef I_AM_QSORT_R
111 void
qsort_r(void * a,size_t n,size_t es,void * thunk,cmp_t * cmp)112 qsort_r(void *a, size_t n, size_t es, void *thunk, cmp_t *cmp)
113 #else
114 #define thunk NULL
115 void
116 qsort(void *a, size_t n, size_t es, cmp_t *cmp)
117 #endif
118 {
119 char *pa, *pb, *pc, *pd, *pl, *pm, *pn;
120 size_t d1, d2;
121 int cmp_result;
122 int swaptype_long, swaptype_int, swap_cnt;
123
124 loop: SWAPINIT(long, a, es);
125 SWAPINIT(int, a, es);
126 swap_cnt = 0;
127 if (n < 7) {
128 for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es)
129 for (pl = pm;
130 pl > (char *)a && CMP(thunk, pl - es, pl) > 0;
131 pl -= es)
132 swap(pl, pl - es);
133 return;
134 }
135 pm = (char *)a + (n / 2) * es;
136 if (n > 7) {
137 pl = a;
138 pn = (char *)a + (n - 1) * es;
139 if (n > 40) {
140 size_t d = (n / 8) * es;
141
142 pl = med3(pl, pl + d, pl + 2 * d, cmp, thunk);
143 pm = med3(pm - d, pm, pm + d, cmp, thunk);
144 pn = med3(pn - 2 * d, pn - d, pn, cmp, thunk);
145 }
146 pm = med3(pl, pm, pn, cmp, thunk);
147 }
148 swap(a, pm);
149 pa = pb = (char *)a + es;
150
151 pc = pd = (char *)a + (n - 1) * es;
152 for (;;) {
153 while (pb <= pc && (cmp_result = CMP(thunk, pb, a)) <= 0) {
154 if (cmp_result == 0) {
155 swap_cnt = 1;
156 swap(pa, pb);
157 pa += es;
158 }
159 pb += es;
160 }
161 while (pb <= pc && (cmp_result = CMP(thunk, pc, a)) >= 0) {
162 if (cmp_result == 0) {
163 swap_cnt = 1;
164 swap(pc, pd);
165 pd -= es;
166 }
167 pc -= es;
168 }
169 if (pb > pc)
170 break;
171 swap(pb, pc);
172 swap_cnt = 1;
173 pb += es;
174 pc -= es;
175 }
176 if (swap_cnt == 0) { /* Switch to insertion sort */
177 for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es)
178 for (pl = pm;
179 pl > (char *)a && CMP(thunk, pl - es, pl) > 0;
180 pl -= es)
181 swap(pl, pl - es);
182 return;
183 }
184
185 pn = (char *)a + n * es;
186 d1 = MIN(pa - (char *)a, pb - pa);
187 vecswap(a, pb - d1, d1);
188 d1 = MIN(pd - pc, pn - pd - es);
189 vecswap(pb, pn - d1, d1);
190
191 d1 = pb - pa;
192 d2 = pd - pc;
193 if (d1 <= d2) {
194 /* Recurse on left partition, then iterate on right partition */
195 if (d1 > es) {
196 #ifdef I_AM_QSORT_R
197 qsort_r(a, d1 / es, es, thunk, cmp);
198 #else
199 qsort(a, d1 / es, es, cmp);
200 #endif
201 }
202 if (d2 > es) {
203 /* Iterate rather than recurse to save stack space */
204 /* qsort(pn - d2, d2 / es, es, cmp); */
205 a = pn - d2;
206 n = d2 / es;
207 goto loop;
208 }
209 } else {
210 /* Recurse on right partition, then iterate on left partition */
211 if (d2 > es) {
212 #ifdef I_AM_QSORT_R
213 qsort_r(pn - d2, d2 / es, es, thunk, cmp);
214 #else
215 qsort(pn - d2, d2 / es, es, cmp);
216 #endif
217 }
218 if (d1 > es) {
219 /* Iterate rather than recurse to save stack space */
220 /* qsort(a, d1 / es, es, cmp); */
221 n = d1 / es;
222 goto loop;
223 }
224 }
225 }
226