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