1 : /*-
2 : * Copyright (c) 1992, 1993
3 : * The Regents of the University of California. All rights reserved.
4 : *
5 : * This code is derived from software contributed to Berkeley by
6 : * Peter McIlroy.
7 : *
8 : * Redistribution and use in source and binary forms, with or without
9 : * modification, are permitted provided that the following conditions
10 : * are met:
11 : * 1. Redistributions of source code must retain the above copyright
12 : * notice, this list of conditions and the following disclaimer.
13 : * 2. Redistributions in binary form must reproduce the above copyright
14 : * notice, this list of conditions and the following disclaimer in the
15 : * documentation and/or other materials provided with the distribution.
16 : * 3. All advertising materials mentioning features or use of this software
17 : * must display the following acknowledgement:
18 : * This product includes software developed by the University of
19 : * California, Berkeley and its contributors.
20 : * 4. Neither the name of the University nor the names of its contributors
21 : * may be used to endorse or promote products derived from this software
22 : * without specific prior written permission.
23 : *
24 : * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25 : * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26 : * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27 : * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
28 : * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29 : * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30 : * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31 : * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32 : * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33 : * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34 : * SUCH DAMAGE.
35 : */
36 :
37 : /* $Id: mergesort.c,v 1.15 2004/09/23 15:57:30 hyanantha Exp $ */
38 :
39 : #if defined(LIBC_SCCS) && !defined(lint)
40 : static char sccsid[] = "@(#)merge.c 8.2 (Berkeley) 2/14/94";
41 : #endif /* LIBC_SCCS and not lint */
42 :
43 : /*
44 : * Hybrid exponential search/linear search merge sort with hybrid
45 : * natural/pairwise first pass. Requires about .3% more comparisons
46 : * for random data than LSMS with pairwise first pass alone.
47 : * It works for objects as small as two bytes.
48 : */
49 :
50 : #define NATURAL
51 : #define THRESHOLD 16 /* Best choice for natural merge cut-off. */
52 :
53 : /* #define NATURAL to get hybrid natural merge.
54 : * (The default is pairwise merging.)
55 : */
56 :
57 : #include <sys/types.h>
58 :
59 : #include <errno.h>
60 : #include <stdlib.h>
61 : #include <string.h>
62 :
63 : #include "php.h"
64 :
65 : #ifdef PHP_WIN32
66 : #include <winsock2.h> /* Includes definition for u_char */
67 : #endif
68 :
69 : static void setup(u_char *list1, u_char *list2, size_t n, size_t size, int (*cmp)(const void *, const void * TSRMLS_DC) TSRMLS_DC);
70 : static void insertionsort(u_char *a, size_t n, size_t size, int (*cmp)(const void *, const void * TSRMLS_DC) TSRMLS_DC);
71 :
72 : #define ISIZE sizeof(int)
73 : #define PSIZE sizeof(u_char *)
74 : #define ICOPY_LIST(src, dst, last) \
75 : do \
76 : *(int*)dst = *(int*)src, src += ISIZE, dst += ISIZE; \
77 : while(src < last)
78 : #define ICOPY_ELT(src, dst, i) \
79 : do \
80 : *(int*) dst = *(int*) src, src += ISIZE, dst += ISIZE; \
81 : while (i -= ISIZE)
82 :
83 : #define CCOPY_LIST(src, dst, last) \
84 : do \
85 : *dst++ = *src++; \
86 : while (src < last)
87 : #define CCOPY_ELT(src, dst, i) \
88 : do \
89 : *dst++ = *src++; \
90 : while (i -= 1)
91 :
92 : /*
93 : * Find the next possible pointer head. (Trickery for forcing an array
94 : * to do double duty as a linked list when objects do not align with word
95 : * boundaries.
96 : */
97 : /* Assumption: PSIZE is a power of 2. */
98 : #define EVAL(p) (u_char **) \
99 : ((u_char *)0 + \
100 : (((u_char *)p + PSIZE - 1 - (u_char *) 0) & ~(PSIZE - 1)))
101 :
102 : /* {{{ php_mergesort
103 : * Arguments are as for qsort.
104 : */
105 : int php_mergesort(void *base, size_t nmemb, size_t size, int (*cmp)(const void *, const void * TSRMLS_DC) TSRMLS_DC)
106 0 : {
107 : register unsigned int i;
108 : register int sense;
109 : int big, iflag;
110 : register u_char *f1, *f2, *t, *b, *tp2, *q, *l1, *l2;
111 : u_char *list2, *list1, *p2, *p, *last, **p1;
112 :
113 0 : if (size < PSIZE / 2) { /* Pointers must fit into 2 * size. */
114 0 : errno = EINVAL;
115 0 : return (-1);
116 : }
117 :
118 0 : if (nmemb == 0)
119 0 : return (0);
120 :
121 : /*
122 : * XXX
123 : * Stupid subtraction for the Cray.
124 : */
125 0 : iflag = 0;
126 0 : if (!(size % ISIZE) && !(((char *)base - (char *)0) % ISIZE))
127 0 : iflag = 1;
128 :
129 0 : if ((list2 = malloc(nmemb * size + PSIZE)) == NULL)
130 0 : return (-1);
131 :
132 0 : list1 = base;
133 0 : setup(list1, list2, nmemb, size, cmp TSRMLS_CC);
134 0 : last = list2 + nmemb * size;
135 0 : i = big = 0;
136 0 : while (*EVAL(list2) != last) {
137 0 : l2 = list1;
138 0 : p1 = EVAL(list1);
139 0 : for (tp2 = p2 = list2; p2 != last; p1 = EVAL(l2)) {
140 0 : p2 = *EVAL(p2);
141 0 : f1 = l2;
142 0 : f2 = l1 = list1 + (p2 - list2);
143 0 : if (p2 != last)
144 0 : p2 = *EVAL(p2);
145 0 : l2 = list1 + (p2 - list2);
146 0 : while (f1 < l1 && f2 < l2) {
147 0 : if ((*cmp)(f1, f2 TSRMLS_CC) <= 0) {
148 0 : q = f2;
149 0 : b = f1, t = l1;
150 0 : sense = -1;
151 : } else {
152 0 : q = f1;
153 0 : b = f2, t = l2;
154 0 : sense = 0;
155 : }
156 0 : if (!big) { /* here i = 0 */
157 0 : while ((b += size) < t && cmp(q, b TSRMLS_CC) >sense)
158 0 : if (++i == 6) {
159 0 : big = 1;
160 0 : goto EXPONENTIAL;
161 : }
162 : } else {
163 0 : EXPONENTIAL: for (i = size; ; i <<= 1)
164 0 : if ((p = (b + i)) >= t) {
165 0 : if ((p = t - size) > b &&
166 : (*cmp)(q, p TSRMLS_CC) <= sense)
167 0 : t = p;
168 : else
169 0 : b = p;
170 : break;
171 0 : } else if ((*cmp)(q, p TSRMLS_CC) <= sense) {
172 0 : t = p;
173 0 : if (i == size)
174 0 : big = 0;
175 0 : goto FASTCASE;
176 : } else
177 0 : b = p;
178 0 : while (t > b+size) {
179 0 : i = (((t - b) / size) >> 1) * size;
180 0 : if ((*cmp)(q, p = b + i TSRMLS_CC) <= sense)
181 0 : t = p;
182 : else
183 0 : b = p;
184 : }
185 0 : goto COPY;
186 0 : FASTCASE: while (i > size)
187 0 : if ((*cmp)(q,
188 : p = b + (i >>= 1) TSRMLS_CC) <= sense)
189 0 : t = p;
190 : else
191 0 : b = p;
192 0 : COPY: b = t;
193 : }
194 0 : i = size;
195 0 : if (q == f1) {
196 0 : if (iflag) {
197 0 : ICOPY_LIST(f2, tp2, b);
198 0 : ICOPY_ELT(f1, tp2, i);
199 : } else {
200 0 : CCOPY_LIST(f2, tp2, b);
201 0 : CCOPY_ELT(f1, tp2, i);
202 : }
203 : } else {
204 0 : if (iflag) {
205 0 : ICOPY_LIST(f1, tp2, b);
206 0 : ICOPY_ELT(f2, tp2, i);
207 : } else {
208 0 : CCOPY_LIST(f1, tp2, b);
209 0 : CCOPY_ELT(f2, tp2, i);
210 : }
211 : }
212 : }
213 0 : if (f2 < l2) {
214 0 : if (iflag)
215 0 : ICOPY_LIST(f2, tp2, l2);
216 : else
217 0 : CCOPY_LIST(f2, tp2, l2);
218 0 : } else if (f1 < l1) {
219 0 : if (iflag)
220 0 : ICOPY_LIST(f1, tp2, l1);
221 : else
222 0 : CCOPY_LIST(f1, tp2, l1);
223 : }
224 0 : *p1 = l2;
225 : }
226 0 : tp2 = list1; /* swap list1, list2 */
227 0 : list1 = list2;
228 0 : list2 = tp2;
229 0 : last = list2 + nmemb*size;
230 : }
231 0 : if (base == list2) {
232 0 : memmove(list2, list1, nmemb*size);
233 0 : list2 = list1;
234 : }
235 0 : free(list2);
236 0 : return (0);
237 : }
238 : /* }}} */
239 :
240 : #define swap(a, b) { \
241 : s = b; \
242 : i = size; \
243 : do { \
244 : tmp = *a; *a++ = *s; *s++ = tmp; \
245 : } while (--i); \
246 : a -= size; \
247 : }
248 : #define reverse(bot, top) { \
249 : s = top; \
250 : do { \
251 : i = size; \
252 : do { \
253 : tmp = *bot; *bot++ = *s; *s++ = tmp; \
254 : } while (--i); \
255 : s -= size2; \
256 : } while(bot < s); \
257 : }
258 :
259 : /* {{{ setup
260 : * Optional hybrid natural/pairwise first pass. Eats up list1 in runs of
261 : * increasing order, list2 in a corresponding linked list. Checks for runs
262 : * when THRESHOLD/2 pairs compare with same sense. (Only used when NATURAL
263 : * is defined. Otherwise simple pairwise merging is used.)
264 : */
265 : static void setup(u_char *list1, u_char *list2, size_t n, size_t size, int (*cmp)(const void *, const void * TSRMLS_DC) TSRMLS_DC)
266 0 : {
267 : int i, length, size2, tmp, sense;
268 : u_char *f1, *f2, *s, *l2, *last, *p2;
269 :
270 0 : size2 = size*2;
271 0 : if (n <= 5) {
272 0 : insertionsort(list1, n, size, cmp TSRMLS_CC);
273 0 : *EVAL(list2) = (u_char*) list2 + n*size;
274 0 : return;
275 : }
276 : /*
277 : * Avoid running pointers out of bounds; limit n to evens
278 : * for simplicity.
279 : */
280 0 : i = 4 + (n & 1);
281 0 : insertionsort(list1 + (n - i) * size, i, size, cmp TSRMLS_CC);
282 0 : last = list1 + size * (n - i);
283 0 : *EVAL(list2 + (last - list1)) = list2 + n * size;
284 :
285 : #ifdef NATURAL
286 0 : p2 = list2;
287 0 : f1 = list1;
288 0 : sense = (cmp(f1, f1 + size TSRMLS_CC) > 0);
289 0 : for (; f1 < last; sense = !sense) {
290 0 : length = 2;
291 : /* Find pairs with same sense. */
292 0 : for (f2 = f1 + size2; f2 < last; f2 += size2) {
293 0 : if ((cmp(f2, f2+ size TSRMLS_CC) > 0) != sense)
294 0 : break;
295 0 : length += 2;
296 : }
297 0 : if (length < THRESHOLD) { /* Pairwise merge */
298 : do {
299 0 : p2 = *EVAL(p2) = f1 + size2 - list1 + list2;
300 0 : if (sense > 0)
301 0 : swap (f1, f1 + size);
302 0 : } while ((f1 += size2) < f2);
303 : } else { /* Natural merge */
304 0 : l2 = f2;
305 0 : for (f2 = f1 + size2; f2 < l2; f2 += size2) {
306 0 : if ((cmp(f2-size, f2 TSRMLS_CC) > 0) != sense) {
307 0 : p2 = *EVAL(p2) = f2 - list1 + list2;
308 0 : if (sense > 0)
309 0 : reverse(f1, f2-size);
310 0 : f1 = f2;
311 : }
312 : }
313 0 : if (sense > 0)
314 0 : reverse (f1, f2-size);
315 0 : f1 = f2;
316 0 : if (f2 < last || cmp(f2 - size, f2 TSRMLS_CC) > 0)
317 0 : p2 = *EVAL(p2) = f2 - list1 + list2;
318 : else
319 0 : p2 = *EVAL(p2) = list2 + n*size;
320 : }
321 : }
322 : #else /* pairwise merge only. */
323 : for (f1 = list1, p2 = list2; f1 < last; f1 += size2) {
324 : p2 = *EVAL(p2) = p2 + size2;
325 : if (cmp (f1, f1 + size TSRMLS_CC) > 0)
326 : swap(f1, f1 + size);
327 : }
328 : #endif /* NATURAL */
329 : }
330 : /* }}} */
331 :
332 : /* {{{ insertionsort
333 : * This is to avoid out-of-bounds addresses in sorting the
334 : * last 4 elements.
335 : */
336 : static void insertionsort(u_char *a, size_t n, size_t size, int (*cmp)(const void *, const void * TSRMLS_DC) TSRMLS_DC)
337 0 : {
338 : u_char *ai, *s, *t, *u, tmp;
339 : int i;
340 :
341 0 : for (ai = a+size; --n >= 1; ai += size)
342 0 : for (t = ai; t > a; t -= size) {
343 0 : u = t - size;
344 0 : if (cmp(u, t TSRMLS_CC) <= 0)
345 0 : break;
346 0 : swap(u, t);
347 : }
348 0 : }
349 : /* }}} */
350 :
351 : /*
352 : * Local variables:
353 : * tab-width: 4
354 : * c-basic-offset: 4
355 : * End:
356 : * vim600: fdm=marker
357 : * vim: noet sw=4 ts=4
358 : */
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