1 /* The following is the NetBSD libc qsort implementation modified in order to
2 * support partial sorting of ranges for Redis.
3 *
4 * Copyright(C) 2009-2012 Salvatore Sanfilippo. All rights reserved.
5 *
6 * The original copyright notice follows. */
7
8
9 /* $NetBSD: qsort.c,v 1.19 2009/01/30 23:38:44 lukem Exp $ */
10
11 /*-
12 * Copyright (c) 1992, 1993
13 * The Regents of the University of California. All rights reserved.
14 *
15 * Redistribution and use in source and binary forms, with or without
16 * modification, are permitted provided that the following conditions
17 * are met:
18 * 1. Redistributions of source code must retain the above copyright
19 * notice, this list of conditions and the following disclaimer.
20 * 2. Redistributions in binary form must reproduce the above copyright
21 * notice, this list of conditions and the following disclaimer in the
22 * documentation and/or other materials provided with the distribution.
23 * 3. Neither the name of the University nor the names of its contributors
24 * may be used to endorse or promote products derived from this software
25 * without specific prior written permission.
26 *
27 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
28 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
29 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
30 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
31 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
32 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
33 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
34 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
35 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
36 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
37 * SUCH DAMAGE.
38 */
39
40 #include <sys/types.h>
41
42 #include <errno.h>
43 #include <stdlib.h>
44
45 static inline char *med3 (char *, char *, char *,
46 int (*)(const void *, const void *));
47 static inline void swapfunc (char *, char *, size_t, int);
48
49 #define min(a, b) (a) < (b) ? a : b
50
51 /*
52 * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function".
53 */
54 #define swapcode(TYPE, parmi, parmj, n) { \
55 size_t i = (n) / sizeof (TYPE); \
56 TYPE *pi = (TYPE *)(void *)(parmi); \
57 TYPE *pj = (TYPE *)(void *)(parmj); \
58 do { \
59 TYPE t = *pi; \
60 *pi++ = *pj; \
61 *pj++ = t; \
62 } while (--i > 0); \
63 }
64
65 #define SWAPINIT(a, es) swaptype = ((char *)a - (char *)0) % sizeof(long) || \
66 es % sizeof(long) ? 2 : es == sizeof(long)? 0 : 1;
67
68 static inline void
swapfunc(char * a,char * b,size_t n,int swaptype)69 swapfunc(char *a, char *b, size_t n, int swaptype)
70 {
71
72 if (swaptype <= 1)
73 swapcode(long, a, b, n)
74 else
75 swapcode(char, a, b, n)
76 }
77
78 #define swap(a, b) \
79 if (swaptype == 0) { \
80 long t = *(long *)(void *)(a); \
81 *(long *)(void *)(a) = *(long *)(void *)(b); \
82 *(long *)(void *)(b) = t; \
83 } else \
84 swapfunc(a, b, es, swaptype)
85
86 #define vecswap(a, b, n) if ((n) > 0) swapfunc((a), (b), (size_t)(n), swaptype)
87
88 static inline char *
med3(char * a,char * b,char * c,int (* cmp)(const void *,const void *))89 med3(char *a, char *b, char *c,
90 int (*cmp) (const void *, const void *))
91 {
92
93 return cmp(a, b) < 0 ?
94 (cmp(b, c) < 0 ? b : (cmp(a, c) < 0 ? c : a ))
95 :(cmp(b, c) > 0 ? b : (cmp(a, c) < 0 ? a : c ));
96 }
97
98 static void
_pqsort(void * a,size_t n,size_t es,int (* cmp)(const void *,const void *),void * lrange,void * rrange)99 _pqsort(void *a, size_t n, size_t es,
100 int (*cmp) (const void *, const void *), void *lrange, void *rrange)
101 {
102 char *pa, *pb, *pc, *pd, *pl, *pm, *pn;
103 size_t d, r;
104 int swaptype, cmp_result;
105
106 loop: SWAPINIT(a, es);
107 if (n < 7) {
108 for (pm = (char *) a + es; pm < (char *) a + n * es; pm += es)
109 for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0;
110 pl -= es)
111 swap(pl, pl - es);
112 return;
113 }
114 pm = (char *) a + (n / 2) * es;
115 if (n > 7) {
116 pl = (char *) a;
117 pn = (char *) a + (n - 1) * es;
118 if (n > 40) {
119 d = (n / 8) * es;
120 pl = med3(pl, pl + d, pl + 2 * d, cmp);
121 pm = med3(pm - d, pm, pm + d, cmp);
122 pn = med3(pn - 2 * d, pn - d, pn, cmp);
123 }
124 pm = med3(pl, pm, pn, cmp);
125 }
126 swap(a, pm);
127 pa = pb = (char *) a + es;
128
129 pc = pd = (char *) a + (n - 1) * es;
130 for (;;) {
131 while (pb <= pc && (cmp_result = cmp(pb, a)) <= 0) {
132 if (cmp_result == 0) {
133 swap(pa, pb);
134 pa += es;
135 }
136 pb += es;
137 }
138 while (pb <= pc && (cmp_result = cmp(pc, a)) >= 0) {
139 if (cmp_result == 0) {
140 swap(pc, pd);
141 pd -= es;
142 }
143 pc -= es;
144 }
145 if (pb > pc)
146 break;
147 swap(pb, pc);
148 pb += es;
149 pc -= es;
150 }
151
152 pn = (char *) a + n * es;
153 r = min(pa - (char *) a, pb - pa);
154 vecswap(a, pb - r, r);
155 r = min((size_t)(pd - pc), pn - pd - es);
156 vecswap(pb, pn - r, r);
157 if ((r = pb - pa) > es) {
158 void *_l = a, *_r = ((unsigned char*)a)+r-1;
159 if (!((lrange < _l && rrange < _l) ||
160 (lrange > _r && rrange > _r)))
161 _pqsort(a, r / es, es, cmp, lrange, rrange);
162 }
163 if ((r = pd - pc) > es) {
164 void *_l, *_r;
165
166 /* Iterate rather than recurse to save stack space */
167 a = pn - r;
168 n = r / es;
169
170 _l = a;
171 _r = ((unsigned char*)a)+r-1;
172 if (!((lrange < _l && rrange < _l) ||
173 (lrange > _r && rrange > _r)))
174 goto loop;
175 }
176 /* qsort(pn - r, r / es, es, cmp);*/
177 }
178
179 void
pqsort(void * a,size_t n,size_t es,int (* cmp)(const void *,const void *),size_t lrange,size_t rrange)180 pqsort(void *a, size_t n, size_t es,
181 int (*cmp) (const void *, const void *), size_t lrange, size_t rrange)
182 {
183 _pqsort(a,n,es,cmp,((unsigned char*)a)+(lrange*es),
184 ((unsigned char*)a)+((rrange+1)*es)-1);
185 }
186