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merge.c
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1 /*@-mustmod -sizeoftype @*/
2 /*-
3 * Copyright (c) 1992, 1993
4 * The Regents of the University of California. All rights reserved.
5 *
6 * This code is derived from software contributed to Berkeley by
7 * Peter McIlroy.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 * notice, this list of conditions and the following disclaimer in the
16 * documentation and/or other materials provided with the distribution.
17 * 3. All advertising materials mentioning features or use of this software
18 * must display the following acknowledgement:
19 * This product includes software developed by the University of
20 * California, Berkeley and its contributors.
21 * 4. Neither the name of the University nor the names of its contributors
22 * may be used to endorse or promote products derived from this software
23 * without specific prior written permission.
24 *
25 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
26 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
27 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
28 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
29 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
30 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
31 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
32 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
33 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
34 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
35 * SUCH DAMAGE.
36 */
37
38 #if defined(LIBC_SCCS) && !defined(lint)
39 static char sccsid[] = "@(#)merge.c 8.2 (Berkeley) 2/14/94";
40 #endif /* LIBC_SCCS and not lint */
41
42 /*
43 * Hybrid exponential search/linear search merge sort with hybrid
44 * natural/pairwise first pass. Requires about .3% more comparisons
45 * for random data than LSMS with pairwise first pass alone.
46 * It works for objects as small as two bytes.
47 */
48
49 #define NATURAL
50 #define THRESHOLD 16 /* Best choice for natural merge cut-off. */
51
52 /* #define NATURAL to get hybrid natural merge.
53 * (The default is pairwise merging.)
54 */
55
56 #include "system.h"
57
58 #include <rpmiotypes.h>
59 #include <rpmtag.h>
60 #include <rpmdb.h>
61
62 #include "debug.h"
63
64 #define ISIZE sizeof(int)
65 #define PSIZE sizeof(unsigned char *)
66 #define ICOPY_LIST(src, dst, last) \
67 do \
68 *(int*)dst = *(int*)src, src += ISIZE, dst += ISIZE; \
69 while(src < last)
70 #define ICOPY_ELT(src, dst, i) \
71 do \
72 *(int*) dst = *(int*) src, src += ISIZE, dst += ISIZE; \
73 while (i -= ISIZE)
74
75 #define CCOPY_LIST(src, dst, last) \
76 do \
77 *dst++ = *src++; \
78 while (src < last)
79 #define CCOPY_ELT(src, dst, i) \
80 do \
81 *dst++ = *src++; \
82 while (i -= 1)
83
84 /*
85 * Find the next possible pointer head. (Trickery for forcing an array
86 * to do double duty as a linked list when objects do not align with word
87 * boundaries.
88 */
89 /* Assumption: PSIZE is a power of 2. */
90 #define EVAL(p) (unsigned char **) \
91 ((unsigned char *)0 + \
92 (((unsigned char *)p + PSIZE - 1 - (unsigned char *) 0) & ~(PSIZE - 1)))
93
94 #define swap(a, b) { \
95 s = b; \
96 i = (int) size; \
97 do { \
98 tmp = *a; *a++ = *s; *s++ = tmp; \
99 } while (--i); \
100 a -= size; \
101 }
102 #define reverse(bot, top) { \
103 s = top; \
104 do { \
105 i = (int) size; \
106 do { \
107 tmp = *bot; *bot++ = *s; *s++ = tmp; \
108 } while (--i); \
109 s -= size2; \
110 } while(bot < s); \
111 }
112
113 /*
114 * This is to avoid out-of-bounds addresses in sorting the
115 * last 4 elements.
116 */
117 static void
118 insertionsort(unsigned char *a, size_t n, size_t size,
119 int (*cmp) (const void *, const void *))
120 /*@modifies *a @*/
121 {
122 u_char *ai, *s, *t, *u, tmp;
123 int i;
124
125 for (ai = a+size; --n >= 1; ai += size)
126 for (t = ai; t > a; t -= size) {
127 u = t - size;
128 if (cmp(u, t) <= 0)
129 /*@innerbreak@*/ break;
130 swap(u, t);
131 }
132 }
133
134 /*
135 * Optional hybrid natural/pairwise first pass. Eats up list1 in runs of
136 * increasing order, list2 in a corresponding linked list. Checks for runs
137 * when THRESHOLD/2 pairs compare with same sense. (Only used when NATURAL
138 * is defined. Otherwise simple pairwise merging is used.)
139 */
140 static void
141 setup(unsigned char *list1, /*@out@*/ unsigned char *list2,
142 size_t n, size_t size, int (*cmp) (const void *, const void *))
143 /*@modifies list1, list2 @*/
144 {
145 int i, length, size2, sense;
146 unsigned char *f1, *f2, *s, *l2, *last, *p2, tmp;
147
148 size2 = size*2;
149 if (n <= 5) {
150 insertionsort(list1, n, size, cmp);
151 *EVAL(list2) = (unsigned char*) list2 + n*size;
152 return;
153 }
154 /*
155 * Avoid running pointers out of bounds; limit n to evens
156 * for simplicity.
157 */
158 i = (int)(4 + (n & 1));
159 insertionsort(list1 + (n - i) * size, i, size, cmp);
160 last = list1 + size * (n - i);
161 *EVAL(list2 + (last - list1)) = list2 + n * size;
162
163 #ifdef NATURAL
164 p2 = list2;
165 f1 = list1;
166 sense = (cmp(f1, f1 + size) > 0);
167 for (; f1 < last; sense = !sense) {
168 length = 2;
169 /* Find pairs with same sense. */
170 for (f2 = f1 + size2; f2 < last; f2 += size2) {
171 if ((cmp(f2, f2+ size) > 0) != sense)
172 /*@innerbreak@*/ break;
173 length += 2;
174 }
175 if (length < THRESHOLD) { /* Pairwise merge */
176 do {
177 p2 = *EVAL(p2) = f1 + size2 - list1 + list2;
178 if (sense > 0)
179 swap (f1, f1 + size);
180 } while ((f1 += size2) < f2);
181 } else { /* Natural merge */
182 l2 = f2;
183 for (f2 = f1 + size2; f2 < l2; f2 += size2) {
184 if ((cmp(f2-size, f2) > 0) != sense) {
185 p2 = *EVAL(p2) = f2 - list1 + list2;
186 if (sense > 0)
187 reverse(f1, f2-size);
188 f1 = f2;
189 }
190 }
191 if (sense > 0)
192 reverse (f1, f2-size);
193 f1 = f2;
194 if (f2 < last || cmp(f2 - size, f2) > 0)
195 p2 = *EVAL(p2) = f2 - list1 + list2;
196 else
197 p2 = *EVAL(p2) = list2 + n*size;
198 }
199 }
200 #else /* pairwise merge only. */
201 for (f1 = list1, p2 = list2; f1 < last; f1 += size2) {
202 p2 = *EVAL(p2) = p2 + size2;
203 if (cmp (f1, f1 + size) > 0)
204 swap(f1, f1 + size);
205 }
206 #endif /* NATURAL */
207 }
208
209 /*
210 * Arguments are as for qsort.
211 */
212 int
213 rpm_mergesort(void *base, size_t nmemb, size_t size,
214 int (*cmp) (const void *, const void *))
215 {
216 register int i, sense;
217 int big, iflag;
218 register unsigned char *f1, *f2, *t, *b, *q, *l1, *l2;
219 /*@dependent@*/
220 register unsigned char *tp2;
221 /*@owned@*/
222 unsigned char *list2;
223 /*@dependent@*/
224 unsigned char *list1;
225 unsigned char *p2, *p, *last, **p1;
226
227 if (size < PSIZE / 2) { /* Pointers must fit into 2 * size. */
228 errno = EINVAL;
229 return (-1);
230 }
231
232 if (nmemb == 0)
233 return (0);
234
235 /*
236 * XXX
237 * Stupid subtraction for the Cray.
238 */
239 iflag = 0;
240 if (!(size % ISIZE) && !(((char *)base - (char *)0) % ISIZE))
241 iflag = 1;
242
243 if ((list2 = malloc(nmemb * size + PSIZE)) == NULL)
244 return (-1);
245
246 list1 = base;
247 setup(list1, list2, nmemb, size, cmp);
248 last = list2 + nmemb * size;
249 i = big = 0;
250 while (*EVAL(list2) != last) {
251 l2 = list1;
252 p1 = EVAL(list1);
253 for (tp2 = p2 = list2; p2 != last; p1 = EVAL(l2)) {
254 p2 = *EVAL(p2);
255 f1 = l2;
256 f2 = l1 = list1 + (p2 - list2);
257 if (p2 != last)
258 p2 = *EVAL(p2);
259 l2 = list1 + (p2 - list2);
260 while (f1 < l1 && f2 < l2) {
261 if ((*cmp)(f1, f2) <= 0) {
262 q = f2;
263 b = f1, t = l1;
264 sense = -1;
265 } else {
266 q = f1;
267 b = f2, t = l2;
268 sense = 0;
269 }
270 if (!big) { /* here i = 0 */
271 while ((b += size) < t && cmp(q, b) >sense)
272 if (++i == 6) {
273 big = 1;
274 goto EXPONENTIAL;
275 }
276 } else {
277 /*@-shiftimplementation@*/
278 EXPONENTIAL: for (i = (int) size; ; i <<= 1)
279 if ((p = (b + i)) >= t) {
280 if ((p = t - size) > b &&
281 (*cmp)(q, p) <= sense)
282 t = p;
283 else
284 b = p;
285 /*@innerbreak@*/ break;
286 } else if ((*cmp)(q, p) <= sense) {
287 t = p;
288 if (i == (int) size)
289 big = 0;
290 goto FASTCASE;
291 } else
292 b = p;
293 /*@-infloopsuncon@*/
294 while (t > b+size) {
295 i = (int) ((((t - b) / size) >> 1) * size);
296 if ((*cmp)(q, p = b + i) <= sense)
297 t = p;
298 else
299 b = p;
300 }
301 goto COPY;
302 FASTCASE: while (i > (int) size)
303 if ((*cmp)(q,
304 p = b + (i >>= 1)) <= sense)
305 t = p;
306 else
307 b = p;
308 /*@=infloopsuncon@*/
309 /*@=shiftimplementation@*/
310 COPY: b = t;
311 }
312 i = (int) size;
313 if (q == f1) {
314 if (iflag) {
315 ICOPY_LIST(f2, tp2, b);
316 ICOPY_ELT(f1, tp2, i);
317 } else {
318 CCOPY_LIST(f2, tp2, b);
319 CCOPY_ELT(f1, tp2, i);
320 }
321 } else {
322 if (iflag) {
323 ICOPY_LIST(f1, tp2, b);
324 ICOPY_ELT(f2, tp2, i);
325 } else {
326 CCOPY_LIST(f1, tp2, b);
327 CCOPY_ELT(f2, tp2, i);
328 }
329 }
330 }
331 if (f2 < l2) {
332 if (iflag)
333 ICOPY_LIST(f2, tp2, l2);
334 else
335 CCOPY_LIST(f2, tp2, l2);
336 } else if (f1 < l1) {
337 if (iflag)
338 ICOPY_LIST(f1, tp2, l1);
339 else
340 CCOPY_LIST(f1, tp2, l1);
341 }
342 *p1 = l2;
343 }
344 /*@-dependenttrans@*/
345 tp2 = list1; /* swap list1, list2 */
346 list1 = list2;
347 list2 = tp2;
348 /*@=dependenttrans@*/
349 last = list2 + nmemb*size;
350 }
351 if (base == list2) {
352 memmove(list2, list1, nmemb*size);
353 list2 = list1;
354 }
355 /*@-usereleased@*/
356 free(list2);
357 /*@=usereleased@*/
358 return (0);
359 }
360 /*@=mustmod =sizeoftype @*/