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1 | /* The following is the NetBSD libc qsort implementation modified in order to |
2 | * support partial sorting of ranges for Redis. |
3 | * |
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4 | * Copyright(C) 2009-2010 Salvatore Sanfilippo. All rights reserved. |
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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 | |
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40 | #include <sys/types.h> |
41 | |
42 | #include <assert.h> |
43 | #include <errno.h> |
44 | #include <stdlib.h> |
45 | |
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46 | static inline char *med3 (char *, char *, char *, |
47 | int (*)(const void *, const void *)); |
48 | static inline void swapfunc (char *, char *, size_t, int); |
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49 | |
50 | #define min(a, b) (a) < (b) ? a : b |
51 | |
52 | /* |
53 | * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function". |
54 | */ |
55 | #define swapcode(TYPE, parmi, parmj, n) { \ |
56 | size_t i = (n) / sizeof (TYPE); \ |
57 | TYPE *pi = (TYPE *)(void *)(parmi); \ |
58 | TYPE *pj = (TYPE *)(void *)(parmj); \ |
59 | do { \ |
60 | TYPE t = *pi; \ |
61 | *pi++ = *pj; \ |
62 | *pj++ = t; \ |
63 | } while (--i > 0); \ |
64 | } |
65 | |
66 | #define SWAPINIT(a, es) swaptype = ((char *)a - (char *)0) % sizeof(long) || \ |
67 | es % sizeof(long) ? 2 : es == sizeof(long)? 0 : 1; |
68 | |
69 | static inline void |
70 | swapfunc(char *a, char *b, size_t n, int swaptype) |
71 | { |
72 | |
73 | if (swaptype <= 1) |
74 | swapcode(long, a, b, n) |
75 | else |
76 | swapcode(char, a, b, n) |
77 | } |
78 | |
79 | #define swap(a, b) \ |
80 | if (swaptype == 0) { \ |
81 | long t = *(long *)(void *)(a); \ |
82 | *(long *)(void *)(a) = *(long *)(void *)(b); \ |
83 | *(long *)(void *)(b) = t; \ |
84 | } else \ |
85 | swapfunc(a, b, es, swaptype) |
86 | |
87 | #define vecswap(a, b, n) if ((n) > 0) swapfunc((a), (b), (size_t)(n), swaptype) |
88 | |
89 | static inline char * |
90 | med3(char *a, char *b, char *c, |
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91 | int (*cmp) (const void *, const void *)) |
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92 | { |
93 | |
94 | return cmp(a, b) < 0 ? |
95 | (cmp(b, c) < 0 ? b : (cmp(a, c) < 0 ? c : a )) |
96 | :(cmp(b, c) > 0 ? b : (cmp(a, c) < 0 ? a : c )); |
97 | } |
98 | |
99 | static void |
100 | _pqsort(void *a, size_t n, size_t es, |
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101 | int (*cmp) (const void *, const void *), void *lrange, void *rrange) |
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102 | { |
103 | char *pa, *pb, *pc, *pd, *pl, *pm, *pn; |
104 | size_t d, r; |
105 | int swaptype, swap_cnt, cmp_result; |
106 | |
107 | loop: SWAPINIT(a, es); |
108 | swap_cnt = 0; |
109 | if (n < 7) { |
110 | for (pm = (char *) a + es; pm < (char *) a + n * es; pm += es) |
111 | for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0; |
112 | pl -= es) |
113 | swap(pl, pl - es); |
114 | return; |
115 | } |
116 | pm = (char *) a + (n / 2) * es; |
117 | if (n > 7) { |
118 | pl = (char *) a; |
119 | pn = (char *) a + (n - 1) * es; |
120 | if (n > 40) { |
121 | d = (n / 8) * es; |
122 | pl = med3(pl, pl + d, pl + 2 * d, cmp); |
123 | pm = med3(pm - d, pm, pm + d, cmp); |
124 | pn = med3(pn - 2 * d, pn - d, pn, cmp); |
125 | } |
126 | pm = med3(pl, pm, pn, cmp); |
127 | } |
128 | swap(a, pm); |
129 | pa = pb = (char *) a + es; |
130 | |
131 | pc = pd = (char *) a + (n - 1) * es; |
132 | for (;;) { |
133 | while (pb <= pc && (cmp_result = cmp(pb, a)) <= 0) { |
134 | if (cmp_result == 0) { |
135 | swap_cnt = 1; |
136 | swap(pa, pb); |
137 | pa += es; |
138 | } |
139 | pb += es; |
140 | } |
141 | while (pb <= pc && (cmp_result = cmp(pc, a)) >= 0) { |
142 | if (cmp_result == 0) { |
143 | swap_cnt = 1; |
144 | swap(pc, pd); |
145 | pd -= es; |
146 | } |
147 | pc -= es; |
148 | } |
149 | if (pb > pc) |
150 | break; |
151 | swap(pb, pc); |
152 | swap_cnt = 1; |
153 | pb += es; |
154 | pc -= es; |
155 | } |
156 | if (swap_cnt == 0) { /* Switch to insertion sort */ |
157 | for (pm = (char *) a + es; pm < (char *) a + n * es; pm += es) |
158 | for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0; |
159 | pl -= es) |
160 | swap(pl, pl - es); |
161 | return; |
162 | } |
163 | |
164 | pn = (char *) a + n * es; |
165 | r = min(pa - (char *) a, pb - pa); |
166 | vecswap(a, pb - r, r); |
167 | r = min((size_t)(pd - pc), pn - pd - es); |
168 | vecswap(pb, pn - r, r); |
169 | if ((r = pb - pa) > es) { |
170 | void *_l = a, *_r = ((unsigned char*)a)+r-1; |
171 | if (!((lrange < _l && rrange < _l) || |
172 | (lrange > _r && rrange > _r))) |
173 | _pqsort(a, r / es, es, cmp, lrange, rrange); |
174 | } |
175 | if ((r = pd - pc) > es) { |
176 | void *_l, *_r; |
177 | |
178 | /* Iterate rather than recurse to save stack space */ |
179 | a = pn - r; |
180 | n = r / es; |
181 | |
182 | _l = a; |
183 | _r = ((unsigned char*)a)+r-1; |
184 | if (!((lrange < _l && rrange < _l) || |
185 | (lrange > _r && rrange > _r))) |
186 | goto loop; |
187 | } |
188 | /* qsort(pn - r, r / es, es, cmp);*/ |
189 | } |
190 | |
191 | void |
192 | pqsort(void *a, size_t n, size_t es, |
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193 | int (*cmp) (const void *, const void *), size_t lrange, size_t rrange) |
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194 | { |
195 | _pqsort(a,n,es,cmp,((unsigned char*)a)+(lrange*es), |
196 | ((unsigned char*)a)+((rrange+1)*es)-1); |
197 | } |