Blob


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 * 4. Neither the name of the University nor the names of its contributors
17 * may be used to endorse or promote products derived from this software
18 * without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 */
33 #include <sys/cdefs.h>
35 /*
36 * Hybrid exponential search/linear search merge sort with hybrid
37 * natural/pairwise first pass. Requires about .3% more comparisons
38 * for random data than LSMS with pairwise first pass alone.
39 * It works for objects as small as two bytes.
40 */
42 #define NATURAL
43 #define THRESHOLD 16 /* Best choice for natural merge cut-off. */
45 /* #define NATURAL to get hybrid natural merge.
46 * (The default is pairwise merging.)
47 */
49 #include <sys/types.h>
51 #include <errno.h>
52 #include <stdlib.h>
53 #include <string.h>
55 #include "got_compat.h"
57 static void setup(unsigned char *, unsigned char *, size_t, size_t,
58 int (*)(const void *, const void *));
59 static void insertionsort(unsigned char *, size_t, size_t,
60 int (*)(const void *, const void *));
62 #define ISIZE sizeof(int)
63 #define PSIZE sizeof(unsigned char *)
64 #define ICOPY_LIST(src, dst, last) \
65 do \
66 *(int*)dst = *(int*)src, src += ISIZE, dst += ISIZE; \
67 while(src < last)
68 #define ICOPY_ELT(src, dst, i) \
69 do \
70 *(int*) dst = *(int*) src, src += ISIZE, dst += ISIZE; \
71 while (i -= ISIZE)
73 #define CCOPY_LIST(src, dst, last) \
74 do \
75 *dst++ = *src++; \
76 while (src < last)
77 #define CCOPY_ELT(src, dst, i) \
78 do \
79 *dst++ = *src++; \
80 while (i -= 1)
82 /*
83 * Find the next possible pointer head. (Trickery for forcing an array
84 * to do double duty as a linked list when objects do not align with word
85 * boundaries.
86 */
87 /* Assumption: PSIZE is a power of 2. */
88 #define EVAL(p) (unsigned char **) \
89 ((unsigned char *)0 + \
90 (((unsigned char *)p + PSIZE - 1 - \
91 (unsigned char *)0) & ~(PSIZE - 1)))
93 /*
94 * Arguments are as for qsort.
95 */
96 int
97 mergesort(void *base, size_t nmemb, size_t size,
98 int (*cmp)(const void *, const void *))
99 {
100 size_t i;
101 int sense;
102 int big, iflag;
103 unsigned char *f1, *f2, *t, *b, *tp2, *q, *l1, *l2;
104 unsigned char *list2, *list1, *p2, *p, *last, **p1;
106 if (size < PSIZE / 2) { /* Pointers must fit into 2 * size. */
107 errno = EINVAL;
108 return (-1);
111 if (nmemb == 0)
112 return (0);
114 /*
115 * XXX
116 * Stupid subtraction for the Cray.
117 */
118 iflag = 0;
119 if (!(size % ISIZE) && !(((char *)base - (char *)0) % ISIZE))
120 iflag = 1;
122 if ((list2 = malloc(nmemb * size + PSIZE)) == NULL)
123 return (-1);
125 list1 = base;
126 setup(list1, list2, nmemb, size, cmp);
127 last = list2 + nmemb * size;
128 i = big = 0;
129 while (*EVAL(list2) != last) {
130 l2 = list1;
131 p1 = EVAL(list1);
132 for (tp2 = p2 = list2; p2 != last; p1 = EVAL(l2)) {
133 p2 = *EVAL(p2);
134 f1 = l2;
135 f2 = l1 = list1 + (p2 - list2);
136 if (p2 != last)
137 p2 = *EVAL(p2);
138 l2 = list1 + (p2 - list2);
139 while (f1 < l1 && f2 < l2) {
140 if ((*cmp)(f1, f2) <= 0) {
141 q = f2;
142 b = f1, t = l1;
143 sense = -1;
144 } else {
145 q = f1;
146 b = f2, t = l2;
147 sense = 0;
149 if (!big) { /* here i = 0 */
150 while ((b += size) < t && cmp(q, b) >sense)
151 if (++i == 6) {
152 big = 1;
153 goto EXPONENTIAL;
155 } else {
156 EXPONENTIAL: for (i = size; ; i <<= 1)
157 if ((p = (b + i)) >= t) {
158 if ((p = t - size) > b &&
159 (*cmp)(q, p) <= sense)
160 t = p;
161 else
162 b = p;
163 break;
164 } else if ((*cmp)(q, p) <= sense) {
165 t = p;
166 if (i == size)
167 big = 0;
168 goto FASTCASE;
169 } else
170 b = p;
171 while (t > b+size) {
172 i = (((t - b) / size) >> 1) * size;
173 if ((*cmp)(q, p = b + i) <= sense)
174 t = p;
175 else
176 b = p;
178 goto COPY;
179 FASTCASE: while (i > size)
180 if ((*cmp)(q,
181 p = b + (i >>= 1)) <= sense)
182 t = p;
183 else
184 b = p;
185 COPY: b = t;
187 i = size;
188 if (q == f1) {
189 if (iflag) {
190 ICOPY_LIST(f2, tp2, b);
191 ICOPY_ELT(f1, tp2, i);
192 } else {
193 CCOPY_LIST(f2, tp2, b);
194 CCOPY_ELT(f1, tp2, i);
196 } else {
197 if (iflag) {
198 ICOPY_LIST(f1, tp2, b);
199 ICOPY_ELT(f2, tp2, i);
200 } else {
201 CCOPY_LIST(f1, tp2, b);
202 CCOPY_ELT(f2, tp2, i);
206 if (f2 < l2) {
207 if (iflag)
208 ICOPY_LIST(f2, tp2, l2);
209 else
210 CCOPY_LIST(f2, tp2, l2);
211 } else if (f1 < l1) {
212 if (iflag)
213 ICOPY_LIST(f1, tp2, l1);
214 else
215 CCOPY_LIST(f1, tp2, l1);
217 *p1 = l2;
219 tp2 = list1; /* swap list1, list2 */
220 list1 = list2;
221 list2 = tp2;
222 last = list2 + nmemb*size;
224 if (base == list2) {
225 memmove(list2, list1, nmemb*size);
226 list2 = list1;
228 free(list2);
229 return (0);
232 #define swap(a, b) { \
233 s = b; \
234 i = size; \
235 do { \
236 tmp = *a; *a++ = *s; *s++ = tmp; \
237 } while (--i); \
238 a -= size; \
240 #define reverse(bot, top) { \
241 s = top; \
242 do { \
243 i = size; \
244 do { \
245 tmp = *bot; *bot++ = *s; *s++ = tmp; \
246 } while (--i); \
247 s -= size2; \
248 } while(bot < s); \
251 /*
252 * Optional hybrid natural/pairwise first pass. Eats up list1 in runs of
253 * increasing order, list2 in a corresponding linked list. Checks for runs
254 * when THRESHOLD/2 pairs compare with same sense. (Only used when NATURAL
255 * is defined. Otherwise simple pairwise merging is used.)
256 */
257 static void
258 setup(unsigned char *list1, unsigned char *list2, size_t n, size_t size,
259 int (*cmp)(const void *, const void *))
261 int i, length, size2, tmp, sense;
262 unsigned char *f1, *f2, *s, *l2, *last, *p2;
264 size2 = size*2;
265 if (n <= 5) {
266 insertionsort(list1, n, size, cmp);
267 *EVAL(list2) = (unsigned char*) list2 + n*size;
268 return;
270 /*
271 * Avoid running pointers out of bounds; limit n to evens
272 * for simplicity.
273 */
274 i = 4 + (n & 1);
275 insertionsort(list1 + (n - i) * size, i, size, cmp);
276 last = list1 + size * (n - i);
277 *EVAL(list2 + (last - list1)) = list2 + n * size;
279 #ifdef NATURAL
280 p2 = list2;
281 f1 = list1;
282 sense = (cmp(f1, f1 + size) > 0);
283 for (; f1 < last; sense = !sense) {
284 length = 2;
285 /* Find pairs with same sense. */
286 for (f2 = f1 + size2; f2 < last; f2 += size2) {
287 if ((cmp(f2, f2+ size) > 0) != sense)
288 break;
289 length += 2;
291 if (length < THRESHOLD) { /* Pairwise merge */
292 do {
293 p2 = *EVAL(p2) = f1 + size2 - list1 + list2;
294 if (sense > 0)
295 swap (f1, f1 + size);
296 } while ((f1 += size2) < f2);
297 } else { /* Natural merge */
298 l2 = f2;
299 for (f2 = f1 + size2; f2 < l2; f2 += size2) {
300 if ((cmp(f2-size, f2) > 0) != sense) {
301 p2 = *EVAL(p2) = f2 - list1 + list2;
302 if (sense > 0)
303 reverse(f1, f2-size);
304 f1 = f2;
307 if (sense > 0)
308 reverse (f1, f2-size);
309 f1 = f2;
310 if (f2 < last || cmp(f2 - size, f2) > 0)
311 p2 = *EVAL(p2) = f2 - list1 + list2;
312 else
313 p2 = *EVAL(p2) = list2 + n*size;
316 #else /* pairwise merge only. */
317 for (f1 = list1, p2 = list2; f1 < last; f1 += size2) {
318 p2 = *EVAL(p2) = p2 + size2;
319 if (cmp (f1, f1 + size) > 0)
320 swap(f1, f1 + size);
322 #endif /* NATURAL */
325 /*
326 * This is to avoid out-of-bounds addresses in sorting the
327 * last 4 elements.
328 */
329 static void
330 insertionsort(unsigned char *a, size_t n, size_t size,
331 int (*cmp)(const void *, const void *))
333 unsigned char *ai, *s, *t, *u, tmp;
334 int i;
336 for (ai = a+size; --n >= 1; ai += size)
337 for (t = ai; t > a; t -= size) {
338 u = t - size;
339 if (cmp(u, t) <= 0)
340 break;
341 swap(u, t);