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 #if defined(LIBC_SCCS) && !defined(lint)
38 static char sccsid[] = "@(#)merge.c 8.2 (Berkeley) 2/14/94";
39 #endif /* LIBC_SCCS and not lint */
40
41 /*
42 * Hybrid exponential search/linear search merge sort with hybrid
43 * natural/pairwise first pass. Requires about .3% more comparisons
44 * for random data than LSMS with pairwise first pass alone.
45 * It works for objects as small as two bytes.
46 */
47
48 #define NATURAL
49 #define THRESHOLD 16 /* Best choice for natural merge cut-off. */
50
51 /* #define NATURAL to get hybrid natural merge.
52 * (The default is pairwise merging.)
53 */
54
55 #include <sys/types.h>
56
57 #include <errno.h>
58 #include <stdlib.h>
59 #include <string.h>
60
61 #include "php.h"
62
63 #ifdef PHP_WIN32
64 #include <winsock2.h> /* Includes definition for u_char */
65 #endif
66
67 static void setup(u_char *list1, u_char *list2, size_t n, size_t size, int (*cmp)(const void *, const void *));
68 static void insertionsort(u_char *a, size_t n, size_t size, int (*cmp)(const void *, const void *));
69
70 #define ISIZE sizeof(int)
71 #define PSIZE sizeof(u_char *)
72 #define ICOPY_LIST(src, dst, last) \
73 do \
74 *(int*)dst = *(int*)src, src += ISIZE, dst += ISIZE; \
75 while(src < last)
76 #define ICOPY_ELT(src, dst, i) \
77 do \
78 *(int*) dst = *(int*) src, src += ISIZE, dst += ISIZE; \
79 while (i -= ISIZE)
80
81 #define CCOPY_LIST(src, dst, last) \
82 do \
83 *dst++ = *src++; \
84 while (src < last)
85 #define CCOPY_ELT(src, dst, i) \
86 do \
87 *dst++ = *src++; \
88 while (i -= 1)
89
90 /*
91 * Find the next possible pointer head. (Trickery for forcing an array
92 * to do double duty as a linked list when objects do not align with word
93 * boundaries.
94 */
95 /* Assumption: PSIZE is a power of 2. */
96 #define EVAL(p) (u_char **) \
97 ((u_char *)0 + \
98 (((u_char *)p + PSIZE - 1 - (u_char *) 0) & ~(PSIZE - 1)))
99
100 /* {{{ php_mergesort
101 * Arguments are as for qsort.
102 */
php_mergesort(void * base,size_t nmemb,size_t size,int (* cmp)(const void *,const void *))103 PHPAPI int php_mergesort(void *base, size_t nmemb, size_t size, int (*cmp)(const void *, const void *))
104 {
105 register size_t i;
106 register int sense;
107 int big, iflag;
108 register u_char *f1, *f2, *t, *b, *tp2, *q, *l1, *l2;
109 u_char *list2, *list1, *p2, *p, *last, **p1;
110
111 if (size < PSIZE / 2) { /* Pointers must fit into 2 * size. */
112 errno = EINVAL;
113 return (-1);
114 }
115
116 if (nmemb == 0)
117 return (0);
118
119 /*
120 * XXX
121 * Stupid subtraction for the Cray.
122 */
123 iflag = 0;
124 if (!(size % ISIZE) && !(((char *)base - (char *)0) % ISIZE))
125 iflag = 1;
126
127 if ((list2 = malloc(nmemb * size + PSIZE)) == NULL)
128 return (-1);
129
130 list1 = base;
131 setup(list1, list2, nmemb, size, cmp);
132 last = list2 + nmemb * size;
133 i = big = 0;
134 while (*EVAL(list2) != last) {
135 l2 = list1;
136 p1 = EVAL(list1);
137 for (tp2 = p2 = list2; p2 != last; p1 = EVAL(l2)) {
138 p2 = *EVAL(p2);
139 f1 = l2;
140 f2 = l1 = list1 + (p2 - list2);
141 if (p2 != last)
142 p2 = *EVAL(p2);
143 l2 = list1 + (p2 - list2);
144 while (f1 < l1 && f2 < l2) {
145 if ((*cmp)(f1, f2) <= 0) {
146 q = f2;
147 b = f1, t = l1;
148 sense = -1;
149 } else {
150 q = f1;
151 b = f2, t = l2;
152 sense = 0;
153 }
154 if (!big) { /* here i = 0 */
155 while ((b += size) < t && cmp(q, b) >sense)
156 if (++i == 6) {
157 big = 1;
158 goto EXPONENTIAL;
159 }
160 } else {
161 EXPONENTIAL: for (i = size; ; i <<= 1)
162 if ((p = (b + i)) >= t) {
163 if ((p = t - size) > b &&
164 (*cmp)(q, p) <= sense)
165 t = p;
166 else
167 b = p;
168 break;
169 } else if ((*cmp)(q, p) <= sense) {
170 t = p;
171 if (i == size)
172 big = 0;
173 goto FASTCASE;
174 } else
175 b = p;
176 while (t > b+size) {
177 i = (((t - b) / size) >> 1) * size;
178 if ((*cmp)(q, p = b + i) <= sense)
179 t = p;
180 else
181 b = p;
182 }
183 goto COPY;
184 FASTCASE: while (i > size)
185 if ((*cmp)(q,
186 p = b + (i >>= 1)) <= sense)
187 t = p;
188 else
189 b = p;
190 COPY: b = t;
191 }
192 i = size;
193 if (q == f1) {
194 if (iflag) {
195 ICOPY_LIST(f2, tp2, b);
196 ICOPY_ELT(f1, tp2, i);
197 } else {
198 CCOPY_LIST(f2, tp2, b);
199 CCOPY_ELT(f1, tp2, i);
200 }
201 } else {
202 if (iflag) {
203 ICOPY_LIST(f1, tp2, b);
204 ICOPY_ELT(f2, tp2, i);
205 } else {
206 CCOPY_LIST(f1, tp2, b);
207 CCOPY_ELT(f2, tp2, i);
208 }
209 }
210 }
211 if (f2 < l2) {
212 if (iflag)
213 ICOPY_LIST(f2, tp2, l2);
214 else
215 CCOPY_LIST(f2, tp2, l2);
216 } else if (f1 < l1) {
217 if (iflag)
218 ICOPY_LIST(f1, tp2, l1);
219 else
220 CCOPY_LIST(f1, tp2, l1);
221 }
222 *p1 = l2;
223 }
224 tp2 = list1; /* swap list1, list2 */
225 list1 = list2;
226 list2 = tp2;
227 last = list2 + nmemb*size;
228 }
229 if (base == list2) {
230 memmove(list2, list1, nmemb*size);
231 list2 = list1;
232 }
233 free(list2);
234 return (0);
235 }
236 /* }}} */
237
238 #define swap(a, b) { \
239 s = b; \
240 i = size; \
241 do { \
242 tmp = *a; *a++ = *s; *s++ = tmp; \
243 } while (--i); \
244 a -= size; \
245 }
246 #define reverse(bot, top) { \
247 s = top; \
248 do { \
249 i = size; \
250 do { \
251 tmp = *bot; *bot++ = *s; *s++ = tmp; \
252 } while (--i); \
253 s -= size2; \
254 } while(bot < s); \
255 }
256
257 /* {{{ setup
258 * Optional hybrid natural/pairwise first pass. Eats up list1 in runs of
259 * increasing order, list2 in a corresponding linked list. Checks for runs
260 * when THRESHOLD/2 pairs compare with same sense. (Only used when NATURAL
261 * is defined. Otherwise simple pairwise merging is used.)
262 */
setup(u_char * list1,u_char * list2,size_t n,size_t size,int (* cmp)(const void *,const void *))263 static void setup(u_char *list1, u_char *list2, size_t n, size_t size, int (*cmp)(const void *, const void *))
264 {
265 size_t i, length, size2, sense;
266 u_char *f1, *f2, *s, *l2, *last, *p2, tmp;
267
268 size2 = size*2;
269 if (n <= 5) {
270 insertionsort(list1, n, size, cmp);
271 *EVAL(list2) = (u_char*) list2 + n*size;
272 return;
273 }
274 /*
275 * Avoid running pointers out of bounds; limit n to evens
276 * for simplicity.
277 */
278 i = 4 + (n & 1);
279 insertionsort(list1 + (n - i) * size, i, size, cmp);
280 last = list1 + size * (n - i);
281 *EVAL(list2 + (last - list1)) = list2 + n * size;
282
283 #ifdef NATURAL
284 p2 = list2;
285 f1 = list1;
286 sense = (cmp(f1, f1 + size) > 0);
287 for (; f1 < last; sense = !sense) {
288 length = 2;
289 /* Find pairs with same sense. */
290 for (f2 = f1 + size2; f2 < last; f2 += size2) {
291 if ((cmp(f2, f2+ size) > 0) != sense)
292 break;
293 length += 2;
294 }
295 if (length < THRESHOLD) { /* Pairwise merge */
296 do {
297 p2 = *EVAL(p2) = f1 + size2 - list1 + list2;
298 if (sense > 0)
299 swap (f1, f1 + size);
300 } while ((f1 += size2) < f2);
301 } else { /* Natural merge */
302 l2 = f2;
303 for (f2 = f1 + size2; f2 < l2; f2 += size2) {
304 if ((cmp(f2-size, f2) > 0) != sense) {
305 p2 = *EVAL(p2) = f2 - list1 + list2;
306 if (sense > 0)
307 reverse(f1, f2-size);
308 f1 = f2;
309 }
310 }
311 if (sense > 0)
312 reverse (f1, f2-size);
313 f1 = f2;
314 if (f2 < last || cmp(f2 - size, f2) > 0)
315 p2 = *EVAL(p2) = f2 - list1 + list2;
316 else
317 p2 = *EVAL(p2) = list2 + n*size;
318 }
319 }
320 #else /* pairwise merge only. */
321 for (f1 = list1, p2 = list2; f1 < last; f1 += size2) {
322 p2 = *EVAL(p2) = p2 + size2;
323 if (cmp (f1, f1 + size) > 0)
324 swap(f1, f1 + size);
325 }
326 #endif /* NATURAL */
327 }
328 /* }}} */
329
330 /* {{{ insertionsort
331 * This is to avoid out-of-bounds addresses in sorting the
332 * last 4 elements.
333 */
insertionsort(u_char * a,size_t n,size_t size,int (* cmp)(const void *,const void *))334 static void insertionsort(u_char *a, size_t n, size_t size, int (*cmp)(const void *, const void *))
335 {
336 u_char *ai, *s, *t, *u, tmp;
337 size_t i;
338
339 for (ai = a+size; --n >= 1; ai += size)
340 for (t = ai; t > a; t -= size) {
341 u = t - size;
342 if (cmp(u, t) <= 0)
343 break;
344 swap(u, t);
345 }
346 }
347 /* }}} */
348
349 /*
350 * Local variables:
351 * tab-width: 4
352 * c-basic-offset: 4
353 * End:
354 * vim600: fdm=marker
355 * vim: noet sw=4 ts=4
356 */
357
