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1 | 1 | /* |
2 | 2 | * qsort.c: standard quicksort algorithm |
3 | | - * |
4 | | - * Modifications from vanilla NetBSD source: |
5 | | - * Add do ... while() macro fix |
6 | | - * Remove __inline, _DIAGASSERTs, __P |
7 | | - * Remove ill-considered "swap_cnt" switch to insertion sort, |
8 | | - * in favor of a simple check for presorted input. |
9 | | - * Take care to recurse on the smaller partition, to bound stack usage. |
10 | | - * |
11 | | - * CAUTION: if you change this file, see also qsort_arg.c, gen_qsort_tuple.pl |
12 | | - * |
13 | | - * src/port/qsort.c |
14 | | - */ |
15 | | - |
16 | | -/* $NetBSD: qsort.c,v 1.13 2003/08/07 16:43:42 agc Exp $ */ |
17 | | - |
18 | | -/*- |
19 | | - * Copyright (c) 1992, 1993 |
20 | | - * The Regents of the University of California. All rights reserved. |
21 | | - * |
22 | | - * Redistribution and use in source and binary forms, with or without |
23 | | - * modification, are permitted provided that the following conditions |
24 | | - * are met: |
25 | | - * 1. Redistributions of source code must retain the above copyright |
26 | | - * notice, this list of conditions and the following disclaimer. |
27 | | - * 2. Redistributions in binary form must reproduce the above copyright |
28 | | - * notice, this list of conditions and the following disclaimer in the |
29 | | - * documentation and/or other materials provided with the distribution. |
30 | | - * 3. Neither the name of the University nor the names of its contributors |
31 | | - * may be used to endorse or promote products derived from this software |
32 | | - * without specific prior written permission. |
33 | | - * |
34 | | - * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND |
35 | | - * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
36 | | - * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
37 | | - * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE |
38 | | - * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
39 | | - * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
40 | | - * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
41 | | - * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
42 | | - * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
43 | | - * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
44 | | - * SUCH DAMAGE. |
45 | 3 | */ |
46 | 4 |
|
47 | 5 | #include "c.h" |
48 | 6 |
|
49 | | - |
50 | | -static char *med3(char *a, char *b, char *c, |
51 | | - int (*cmp) (const void *, const void *)); |
52 | | -static void swapfunc(char *, char *, size_t, int); |
53 | | - |
54 | | -/* |
55 | | - * Qsort routine based on J. L. Bentley and M. D. McIlroy, |
56 | | - * "Engineering a sort function", |
57 | | - * Software--Practice and Experience 23 (1993) 1249-1265. |
58 | | - * |
59 | | - * We have modified their original by adding a check for already-sorted input, |
60 | | - * which seems to be a win per discussions on pgsql-hackers around 2006-03-21. |
61 | | - * |
62 | | - * Also, we recurse on the smaller partition and iterate on the larger one, |
63 | | - * which ensures we cannot recurse more than log(N) levels (since the |
64 | | - * partition recursed to is surely no more than half of the input). Bentley |
65 | | - * and McIlroy explicitly rejected doing this on the grounds that it's "not |
66 | | - * worth the effort", but we have seen crashes in the field due to stack |
67 | | - * overrun, so that judgment seems wrong. |
68 | | - */ |
69 | | - |
70 | | -#define swapcode(TYPE, parmi, parmj, n) \ |
71 | | -do { \ |
72 | | - size_t i = (n) / sizeof (TYPE); \ |
73 | | - TYPE *pi = (TYPE *)(void *)(parmi); \ |
74 | | - TYPE *pj = (TYPE *)(void *)(parmj); \ |
75 | | - do { \ |
76 | | - TYPE t = *pi; \ |
77 | | - *pi++ = *pj; \ |
78 | | - *pj++ = t; \ |
79 | | - } while (--i > 0); \ |
80 | | -} while (0) |
81 | | - |
82 | | -#define SWAPINIT(a, es) swaptype = ((char *)(a) - (char *)0) % sizeof(long) || \ |
83 | | - (es) % sizeof(long) ? 2 : (es) == sizeof(long)? 0 : 1 |
84 | | - |
85 | | -static void |
86 | | -swapfunc(char *a, char *b, size_t n, int swaptype) |
87 | | -{ |
88 | | - if (swaptype <= 1) |
89 | | - swapcode(long, a, b, n); |
90 | | - else |
91 | | - swapcode(char, a, b, n); |
92 | | -} |
93 | | - |
94 | | -#define swap(a, b) \ |
95 | | - if (swaptype == 0) { \ |
96 | | - long t = *(long *)(void *)(a); \ |
97 | | - *(long *)(void *)(a) = *(long *)(void *)(b); \ |
98 | | - *(long *)(void *)(b) = t; \ |
99 | | - } else \ |
100 | | - swapfunc(a, b, es, swaptype) |
101 | | - |
102 | | -#define vecswap(a, b, n) if ((n) > 0) swapfunc(a, b, n, swaptype) |
103 | | - |
104 | | -static char * |
105 | | -med3(char *a, char *b, char *c, int (*cmp) (const void *, const void *)) |
106 | | -{ |
107 | | - return cmp(a, b) < 0 ? |
108 | | - (cmp(b, c) < 0 ? b : (cmp(a, c) < 0 ? c : a)) |
109 | | - : (cmp(b, c) > 0 ? b : (cmp(a, c) < 0 ? a : c)); |
110 | | -} |
111 | | - |
112 | | -void |
113 | | -pg_qsort(void *a, size_t n, size_t es, int (*cmp) (const void *, const void *)) |
114 | | -{ |
115 | | - char *pa, |
116 | | - *pb, |
117 | | - *pc, |
118 | | - *pd, |
119 | | - *pl, |
120 | | - *pm, |
121 | | - *pn; |
122 | | - size_t d1, |
123 | | - d2; |
124 | | - int r, |
125 | | - swaptype, |
126 | | - presorted; |
127 | | - |
128 | | -loop:SWAPINIT(a, es); |
129 | | - if (n < 7) |
130 | | - { |
131 | | - for (pm = (char *) a + es; pm < (char *) a + n * es; pm += es) |
132 | | - for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0; |
133 | | - pl -= es) |
134 | | - swap(pl, pl - es); |
135 | | - return; |
136 | | - } |
137 | | - presorted = 1; |
138 | | - for (pm = (char *) a + es; pm < (char *) a + n * es; pm += es) |
139 | | - { |
140 | | - if (cmp(pm - es, pm) > 0) |
141 | | - { |
142 | | - presorted = 0; |
143 | | - break; |
144 | | - } |
145 | | - } |
146 | | - if (presorted) |
147 | | - return; |
148 | | - pm = (char *) a + (n / 2) * es; |
149 | | - if (n > 7) |
150 | | - { |
151 | | - pl = (char *) a; |
152 | | - pn = (char *) a + (n - 1) * es; |
153 | | - if (n > 40) |
154 | | - { |
155 | | - size_t d = (n / 8) * es; |
156 | | - |
157 | | - pl = med3(pl, pl + d, pl + 2 * d, cmp); |
158 | | - pm = med3(pm - d, pm, pm + d, cmp); |
159 | | - pn = med3(pn - 2 * d, pn - d, pn, cmp); |
160 | | - } |
161 | | - pm = med3(pl, pm, pn, cmp); |
162 | | - } |
163 | | - swap(a, pm); |
164 | | - pa = pb = (char *) a + es; |
165 | | - pc = pd = (char *) a + (n - 1) * es; |
166 | | - for (;;) |
167 | | - { |
168 | | - while (pb <= pc && (r = cmp(pb, a)) <= 0) |
169 | | - { |
170 | | - if (r == 0) |
171 | | - { |
172 | | - swap(pa, pb); |
173 | | - pa += es; |
174 | | - } |
175 | | - pb += es; |
176 | | - } |
177 | | - while (pb <= pc && (r = cmp(pc, a)) >= 0) |
178 | | - { |
179 | | - if (r == 0) |
180 | | - { |
181 | | - swap(pc, pd); |
182 | | - pd -= es; |
183 | | - } |
184 | | - pc -= es; |
185 | | - } |
186 | | - if (pb > pc) |
187 | | - break; |
188 | | - swap(pb, pc); |
189 | | - pb += es; |
190 | | - pc -= es; |
191 | | - } |
192 | | - pn = (char *) a + n * es; |
193 | | - d1 = Min(pa - (char *) a, pb - pa); |
194 | | - vecswap(a, pb - d1, d1); |
195 | | - d1 = Min(pd - pc, pn - pd - es); |
196 | | - vecswap(pb, pn - d1, d1); |
197 | | - d1 = pb - pa; |
198 | | - d2 = pd - pc; |
199 | | - if (d1 <= d2) |
200 | | - { |
201 | | - /* Recurse on left partition, then iterate on right partition */ |
202 | | - if (d1 > es) |
203 | | - pg_qsort(a, d1 / es, es, cmp); |
204 | | - if (d2 > es) |
205 | | - { |
206 | | - /* Iterate rather than recurse to save stack space */ |
207 | | - /* pg_qsort(pn - d2, d2 / es, es, cmp); */ |
208 | | - a = pn - d2; |
209 | | - n = d2 / es; |
210 | | - goto loop; |
211 | | - } |
212 | | - } |
213 | | - else |
214 | | - { |
215 | | - /* Recurse on right partition, then iterate on left partition */ |
216 | | - if (d2 > es) |
217 | | - pg_qsort(pn - d2, d2 / es, es, cmp); |
218 | | - if (d1 > es) |
219 | | - { |
220 | | - /* Iterate rather than recurse to save stack space */ |
221 | | - /* pg_qsort(a, d1 / es, es, cmp); */ |
222 | | - n = d1 / es; |
223 | | - goto loop; |
224 | | - } |
225 | | - } |
226 | | -} |
| 7 | +#define ST_SORT pg_qsort |
| 8 | +#define ST_ELEMENT_TYPE_VOID |
| 9 | +#define ST_COMPARE_RUNTIME_POINTER |
| 10 | +#define ST_SCOPE |
| 11 | +#define ST_DECLARE |
| 12 | +#define ST_DEFINE |
| 13 | +#include "lib/sort_template.h" |
227 | 14 |
|
228 | 15 | /* |
229 | 16 | * qsort comparator wrapper for strcmp. |
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