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mergesort.c
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1.1.1.2 (vendor branch):
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Tue May 29 12:34:35 2012 UTC (12 years, 1 month ago) by
misho
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MAIN
CVS tags:
v5_4_3elwix,
v5_4_29p0,
v5_4_29,
v5_4_20p0,
v5_4_20,
v5_4_17p0,
v5_4_17,
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php 5.4.3+patches
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 1.1.1.2 2012/05/29 12:34:35 misho 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: PHPAPI int php_mergesort(void *base, size_t nmemb, size_t size, int (*cmp)(const void *, const void * TSRMLS_DC) TSRMLS_DC)
106: {
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: if (size < PSIZE / 2) { /* Pointers must fit into 2 * size. */
114: errno = EINVAL;
115: return (-1);
116: }
117:
118: if (nmemb == 0)
119: return (0);
120:
121: /*
122: * XXX
123: * Stupid subtraction for the Cray.
124: */
125: iflag = 0;
126: if (!(size % ISIZE) && !(((char *)base - (char *)0) % ISIZE))
127: iflag = 1;
128:
129: if ((list2 = malloc(nmemb * size + PSIZE)) == NULL)
130: return (-1);
131:
132: list1 = base;
133: setup(list1, list2, nmemb, size, cmp TSRMLS_CC);
134: last = list2 + nmemb * size;
135: i = big = 0;
136: while (*EVAL(list2) != last) {
137: l2 = list1;
138: p1 = EVAL(list1);
139: for (tp2 = p2 = list2; p2 != last; p1 = EVAL(l2)) {
140: p2 = *EVAL(p2);
141: f1 = l2;
142: f2 = l1 = list1 + (p2 - list2);
143: if (p2 != last)
144: p2 = *EVAL(p2);
145: l2 = list1 + (p2 - list2);
146: while (f1 < l1 && f2 < l2) {
147: if ((*cmp)(f1, f2 TSRMLS_CC) <= 0) {
148: q = f2;
149: b = f1, t = l1;
150: sense = -1;
151: } else {
152: q = f1;
153: b = f2, t = l2;
154: sense = 0;
155: }
156: if (!big) { /* here i = 0 */
157: while ((b += size) < t && cmp(q, b TSRMLS_CC) >sense)
158: if (++i == 6) {
159: big = 1;
160: goto EXPONENTIAL;
161: }
162: } else {
163: EXPONENTIAL: for (i = size; ; i <<= 1)
164: if ((p = (b + i)) >= t) {
165: if ((p = t - size) > b &&
166: (*cmp)(q, p TSRMLS_CC) <= sense)
167: t = p;
168: else
169: b = p;
170: break;
171: } else if ((*cmp)(q, p TSRMLS_CC) <= sense) {
172: t = p;
173: if (i == size)
174: big = 0;
175: goto FASTCASE;
176: } else
177: b = p;
178: while (t > b+size) {
179: i = (((t - b) / size) >> 1) * size;
180: if ((*cmp)(q, p = b + i TSRMLS_CC) <= sense)
181: t = p;
182: else
183: b = p;
184: }
185: goto COPY;
186: FASTCASE: while (i > size)
187: if ((*cmp)(q,
188: p = b + (i >>= 1) TSRMLS_CC) <= sense)
189: t = p;
190: else
191: b = p;
192: COPY: b = t;
193: }
194: i = size;
195: if (q == f1) {
196: if (iflag) {
197: ICOPY_LIST(f2, tp2, b);
198: ICOPY_ELT(f1, tp2, i);
199: } else {
200: CCOPY_LIST(f2, tp2, b);
201: CCOPY_ELT(f1, tp2, i);
202: }
203: } else {
204: if (iflag) {
205: ICOPY_LIST(f1, tp2, b);
206: ICOPY_ELT(f2, tp2, i);
207: } else {
208: CCOPY_LIST(f1, tp2, b);
209: CCOPY_ELT(f2, tp2, i);
210: }
211: }
212: }
213: if (f2 < l2) {
214: if (iflag)
215: ICOPY_LIST(f2, tp2, l2);
216: else
217: CCOPY_LIST(f2, tp2, l2);
218: } else if (f1 < l1) {
219: if (iflag)
220: ICOPY_LIST(f1, tp2, l1);
221: else
222: CCOPY_LIST(f1, tp2, l1);
223: }
224: *p1 = l2;
225: }
226: tp2 = list1; /* swap list1, list2 */
227: list1 = list2;
228: list2 = tp2;
229: last = list2 + nmemb*size;
230: }
231: if (base == list2) {
232: memmove(list2, list1, nmemb*size);
233: list2 = list1;
234: }
235: free(list2);
236: 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: {
267: int i, length, size2, tmp, sense;
268: u_char *f1, *f2, *s, *l2, *last, *p2;
269:
270: size2 = size*2;
271: if (n <= 5) {
272: insertionsort(list1, n, size, cmp TSRMLS_CC);
273: *EVAL(list2) = (u_char*) list2 + n*size;
274: return;
275: }
276: /*
277: * Avoid running pointers out of bounds; limit n to evens
278: * for simplicity.
279: */
280: i = 4 + (n & 1);
281: insertionsort(list1 + (n - i) * size, i, size, cmp TSRMLS_CC);
282: last = list1 + size * (n - i);
283: *EVAL(list2 + (last - list1)) = list2 + n * size;
284:
285: #ifdef NATURAL
286: p2 = list2;
287: f1 = list1;
288: sense = (cmp(f1, f1 + size TSRMLS_CC) > 0);
289: for (; f1 < last; sense = !sense) {
290: length = 2;
291: /* Find pairs with same sense. */
292: for (f2 = f1 + size2; f2 < last; f2 += size2) {
293: if ((cmp(f2, f2+ size TSRMLS_CC) > 0) != sense)
294: break;
295: length += 2;
296: }
297: if (length < THRESHOLD) { /* Pairwise merge */
298: do {
299: p2 = *EVAL(p2) = f1 + size2 - list1 + list2;
300: if (sense > 0)
301: swap (f1, f1 + size);
302: } while ((f1 += size2) < f2);
303: } else { /* Natural merge */
304: l2 = f2;
305: for (f2 = f1 + size2; f2 < l2; f2 += size2) {
306: if ((cmp(f2-size, f2 TSRMLS_CC) > 0) != sense) {
307: p2 = *EVAL(p2) = f2 - list1 + list2;
308: if (sense > 0)
309: reverse(f1, f2-size);
310: f1 = f2;
311: }
312: }
313: if (sense > 0)
314: reverse (f1, f2-size);
315: f1 = f2;
316: if (f2 < last || cmp(f2 - size, f2 TSRMLS_CC) > 0)
317: p2 = *EVAL(p2) = f2 - list1 + list2;
318: else
319: 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: {
338: u_char *ai, *s, *t, *u, tmp;
339: int i;
340:
341: for (ai = a+size; --n >= 1; ai += size)
342: for (t = ai; t > a; t -= size) {
343: u = t - size;
344: if (cmp(u, t TSRMLS_CC) <= 0)
345: break;
346: swap(u, t);
347: }
348: }
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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