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 * $FreeBSD: src/sys/libkern/qsort.c,v 1.15 2004/07/15 23:58:23 glebius Exp $
30 */
31
32 #include <sys/param.h>
33 #include <sys/libkern.h>
34
35 #ifdef I_AM_KQSORT_R
36 typedef int cmp_t(void *, const void *, const void *);
37 #else
38 typedef int cmp_t(const void *, const void *);
39 #endif
40 static __inline char *med3(char *, char *, char *, cmp_t *, void *);
41 static __inline void swapfunc(char *, char *, int, int);
42
43 #define min(a, b) (a) < (b) ? (a) : (b)
44
45 /*
46 * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function".
47 */
48 #define swapcode(TYPE, parmi, parmj, n) { \
49 long i = (n) / sizeof (TYPE); \
50 TYPE *pi = (TYPE *) (parmi); \
51 TYPE *pj = (TYPE *) (parmj); \
52 do { \
53 TYPE t = *pi; \
54 *pi++ = *pj; \
55 *pj++ = t; \
56 } while (--i > 0); \
57 }
58
59 #define SWAPINIT(a, es) swaptype = ((char *)a - (char *)0) % sizeof(long) || \
60 es % sizeof(long) ? 2 : es == sizeof(long)? 0 : 1;
61
62 static __inline void
swapfunc(char * a,char * b,int n,int swaptype)63 swapfunc(char *a, char *b, int n, int swaptype)
64 {
65 if(swaptype <= 1)
66 swapcode(long, a, b, n)
67 else
68 swapcode(char, a, b, n)
69 }
70
71 #define swap(a, b) \
72 if (swaptype == 0) { \
73 long t = *(long *)(a); \
74 *(long *)(a) = *(long *)(b); \
75 *(long *)(b) = t; \
76 } else \
77 swapfunc(a, b, es, swaptype)
78
79 #define vecswap(a, b, n) if ((n) > 0) swapfunc(a, b, n, swaptype)
80
81 #ifdef I_AM_KQSORT_R
82 #define CMP(t, x, y) (cmp((t), (x), (y)))
83 #else
84 #define CMP(t, x, y) (cmp((x), (y)))
85 #endif
86
87 static __inline char *
med3(char * a,char * b,char * c,cmp_t * cmp,void * thunk __unused)88 med3(char *a, char *b, char *c, cmp_t *cmp, void *thunk
89 #ifndef I_AM_KQSORT_R
90 __unused
91 #endif
92 )
93 {
94 return CMP(thunk, a, b) < 0 ?
95 (CMP(thunk, b, c) < 0 ? b : (CMP(thunk, a, c) < 0 ? c : a ))
96 :(CMP(thunk, b, c) > 0 ? b : (CMP(thunk, a, c) < 0 ? a : c ));
97 }
98
99 #ifdef I_AM_KQSORT_R
100 void
kqsort_r(void * a,size_t n,size_t es,void * thunk,cmp_t * cmp)101 kqsort_r(void *a, size_t n, size_t es, void *thunk, cmp_t *cmp)
102 #else
103 #define thunk NULL
104 void
105 kqsort(void *a, size_t n, size_t es, cmp_t *cmp)
106 #endif
107 {
108 char *pa, *pb, *pc, *pd, *pl, *pm, *pn;
109 int d, r, swaptype, swap_cnt;
110
111 loop: SWAPINIT(a, es);
112 swap_cnt = 0;
113 if (n < 7) {
114 for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es)
115 for (pl = pm; pl > (char *)a && CMP(thunk, pl - es, pl) > 0;
116 pl -= es)
117 swap(pl, pl - es);
118 return;
119 }
120 pm = (char *)a + (n / 2) * es;
121 if (n > 7) {
122 pl = a;
123 pn = (char *)a + (n - 1) * es;
124 if (n > 40) {
125 d = (n / 8) * es;
126 pl = med3(pl, pl + d, pl + 2 * d, cmp, thunk);
127 pm = med3(pm - d, pm, pm + d, cmp, thunk);
128 pn = med3(pn - 2 * d, pn - d, pn, cmp, thunk);
129 }
130 pm = med3(pl, pm, pn, cmp, thunk);
131 }
132 swap(a, pm);
133 pa = pb = (char *)a + es;
134
135 pc = pd = (char *)a + (n - 1) * es;
136 for (;;) {
137 while (pb <= pc && (r = CMP(thunk, pb, a)) <= 0) {
138 if (r == 0) {
139 swap_cnt = 1;
140 swap(pa, pb);
141 pa += es;
142 }
143 pb += es;
144 }
145 while (pb <= pc && (r = CMP(thunk, pc, a)) >= 0) {
146 if (r == 0) {
147 swap_cnt = 1;
148 swap(pc, pd);
149 pd -= es;
150 }
151 pc -= es;
152 }
153 if (pb > pc)
154 break;
155 swap(pb, pc);
156 swap_cnt = 1;
157 pb += es;
158 pc -= es;
159 }
160 if (swap_cnt == 0) { /* Switch to insertion sort */
161 for (pm = (char *)a + es; pm < (char *)a + n * es; pm += es)
162 for (pl = pm; pl > (char *)a && CMP(thunk, pl - es, pl) > 0;
163 pl -= es)
164 swap(pl, pl - es);
165 return;
166 }
167
168 pn = (char *)a + n * es;
169 r = min(pa - (char *)a, pb - pa);
170 vecswap(a, pb - r, r);
171 r = min(pd - pc, pn - pd - es);
172 vecswap(pb, pn - r, r);
173 if ((r = pb - pa) > es)
174 #ifdef I_AM_KQSORT_R
175 kqsort_r(a, r / es, es, thunk, cmp);
176 #else
177 kqsort(a, r / es, es, cmp);
178 #endif
179 if ((r = pd - pc) > es) {
180 /* Iterate rather than recurse to save stack space */
181 a = pn - r;
182 n = r / es;
183 goto loop;
184 }
185 }
186