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 #include <linux/kernel.h>
31 #include <linux/string.h>
32
33 /*
34 * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function".
35 */
36 #define swapcode(TYPE, parmi, parmj, n) { \
37 long i = (n) / sizeof (TYPE); \
38 register TYPE *pi = (TYPE *) (parmi); \
39 register TYPE *pj = (TYPE *) (parmj); \
40 do { \
41 register TYPE t = *pi; \
42 *pi++ = *pj; \
43 *pj++ = t; \
44 } while (--i > 0); \
45 }
46
47 #define SWAPINIT(a, es) swaptype = ((char *)a - (char *)0) % sizeof(long) || \
48 es % sizeof(long) ? 2 : es == sizeof(long)? 0 : 1;
49
50 static __inline void
swapfunc(char * a,char * b,int n,int swaptype)51 swapfunc(char *a, char *b, int n, int swaptype)
52 {
53 if (swaptype <= 1)
54 swapcode(long, a, b, n)
55 else
56 swapcode(char, a, b, n)
57 }
58
59 #define swap(a, b) \
60 if (swaptype == 0) { \
61 long t = *(long *)(a); \
62 *(long *)(a) = *(long *)(b); \
63 *(long *)(b) = t; \
64 } else \
65 swapfunc(a, b, es, swaptype)
66
67 #define vecswap(a, b, n) if ((n) > 0) swapfunc(a, b, n, swaptype)
68
69 static __inline char *
med3(char * a,char * b,char * c,int (* cmp)(const void *,const void *))70 med3(char *a, char *b, char *c, int (*cmp)(const void *, const void *))
71 {
72 return cmp(a, b) < 0 ?
73 (cmp(b, c) < 0 ? b : (cmp(a, c) < 0 ? c : a ))
74 :(cmp(b, c) > 0 ? b : (cmp(a, c) < 0 ? a : c ));
75 }
76
77 void
qsort(void * aa,size_t n,size_t es,int (* cmp)(const void *,const void *))78 qsort(void *aa, size_t n, size_t es, int (*cmp)(const void *, const void *))
79 {
80 char *pa, *pb, *pc, *pd, *pl, *pm, *pn;
81 int d, r, swaptype, swap_cnt;
82 register char *a = aa;
83
84 loop: SWAPINIT(a, es);
85 swap_cnt = 0;
86 if (n < 7) {
87 for (pm = (char *)a + es; pm < (char *) a + n * es; pm += es)
88 for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0;
89 pl -= es)
90 swap(pl, pl - es);
91 return;
92 }
93 pm = (char *)a + (n / 2) * es;
94 if (n > 7) {
95 pl = (char *)a;
96 pn = (char *)a + (n - 1) * es;
97 if (n > 40) {
98 d = (n / 8) * es;
99 pl = med3(pl, pl + d, pl + 2 * d, cmp);
100 pm = med3(pm - d, pm, pm + d, cmp);
101 pn = med3(pn - 2 * d, pn - d, pn, cmp);
102 }
103 pm = med3(pl, pm, pn, cmp);
104 }
105 swap(a, pm);
106 pa = pb = (char *)a + es;
107
108 pc = pd = (char *)a + (n - 1) * es;
109 for (;;) {
110 while (pb <= pc && (r = cmp(pb, a)) <= 0) {
111 if (r == 0) {
112 swap_cnt = 1;
113 swap(pa, pb);
114 pa += es;
115 }
116 pb += es;
117 }
118 while (pb <= pc && (r = cmp(pc, a)) >= 0) {
119 if (r == 0) {
120 swap_cnt = 1;
121 swap(pc, pd);
122 pd -= es;
123 }
124 pc -= es;
125 }
126 if (pb > pc)
127 break;
128 swap(pb, pc);
129 swap_cnt = 1;
130 pb += es;
131 pc -= es;
132 }
133 if (swap_cnt == 0) { /* Switch to insertion sort */
134 for (pm = (char *) a + es; pm < (char *) a + n * es; pm += es)
135 for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0;
136 pl -= es)
137 swap(pl, pl - es);
138 return;
139 }
140
141 pn = (char *)a + n * es;
142 r = min(pa - (char *)a, pb - pa);
143 vecswap(a, pb - r, r);
144 r = min((long)(pd - pc), (long)(pn - pd - es));
145 vecswap(pb, pn - r, r);
146 if ((r = pb - pa) > es)
147 qsort(a, r / es, es, cmp);
148 if ((r = pd - pc) > es) {
149 /* Iterate rather than recurse to save stack space */
150 a = pn - r;
151 n = r / es;
152 goto loop;
153 }
154 /* qsort(pn - r, r / es, es, cmp);*/
155 }
156