1 /*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1992, 1993
5 * The Regents of the University of California. All rights reserved.
6 *
7 * This code is derived from software contributed to Berkeley by
8 * Peter McIlroy.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 * 3. Neither the name of the University nor the names of its contributors
19 * may be used to endorse or promote products derived from this software
20 * without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 */
34
35 #if defined(LIBC_SCCS) && !defined(lint)
36 static char sccsid[] = "@(#)merge.c 8.2 (Berkeley) 2/14/94";
37 #endif /* LIBC_SCCS and not lint */
38 #include <sys/cdefs.h>
39 __FBSDID("$FreeBSD$");
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/param.h>
56
57 #include <errno.h>
58 #include <stdlib.h>
59 #include <string.h>
60
61 #ifdef I_AM_MERGESORT_B
62 #include "block_abi.h"
63 #define DECLARE_CMP DECLARE_BLOCK(int, cmp, const void *, const void *)
64 typedef DECLARE_BLOCK(int, cmp_t, const void *, const void *);
65 #define CMP(x, y) CALL_BLOCK(cmp, x, y)
66 #else
67 typedef int (*cmp_t)(const void *, const void *);
68 #define CMP(x, y) cmp(x, y)
69 #endif
70
71 static void setup(u_char *, u_char *, size_t, size_t, cmp_t);
72 static void insertionsort(u_char *, size_t, size_t, cmp_t);
73
74 #define ISIZE sizeof(int)
75 #define PSIZE sizeof(u_char *)
76 #define ICOPY_LIST(src, dst, last) \
77 do \
78 *(int*)dst = *(int*)src, src += ISIZE, dst += ISIZE; \
79 while(src < last)
80 #define ICOPY_ELT(src, dst, i) \
81 do \
82 *(int*) dst = *(int*) src, src += ISIZE, dst += ISIZE; \
83 while (i -= ISIZE)
84
85 #define CCOPY_LIST(src, dst, last) \
86 do \
87 *dst++ = *src++; \
88 while (src < last)
89 #define CCOPY_ELT(src, dst, i) \
90 do \
91 *dst++ = *src++; \
92 while (i -= 1)
93
94 /*
95 * Find the next possible pointer head. (Trickery for forcing an array
96 * to do double duty as a linked list when objects do not align with word
97 * boundaries.
98 */
99 /* Assumption: PSIZE is a power of 2. */
100 #define EVAL(p) (u_char **)roundup2((uintptr_t)p, PSIZE)
101
102 #ifdef I_AM_MERGESORT_B
103 int mergesort_b(void *, size_t, size_t, cmp_t);
104 #else
105 int mergesort(void *, size_t, size_t, cmp_t);
106 #endif
107
108 /*
109 * Arguments are as for qsort.
110 */
111 int
112 #ifdef I_AM_MERGESORT_B
mergesort_b(void * base,size_t nmemb,size_t size,cmp_t cmp)113 mergesort_b(void *base, size_t nmemb, size_t size, cmp_t cmp)
114 #else
115 mergesort(void *base, size_t nmemb, size_t size, cmp_t cmp)
116 #endif
117 {
118 size_t i;
119 int sense;
120 int big, iflag;
121 u_char *f1, *f2, *t, *b, *tp2, *q, *l1, *l2;
122 u_char *list2, *list1, *p2, *p, *last, **p1;
123
124 if (size < PSIZE / 2) { /* Pointers must fit into 2 * size. */
125 errno = EINVAL;
126 return (-1);
127 }
128
129 if (nmemb == 0)
130 return (0);
131
132 iflag = 0;
133 if (__is_aligned(size, ISIZE) && __is_aligned(base, ISIZE))
134 iflag = 1;
135
136 if ((list2 = malloc(nmemb * size + PSIZE)) == NULL)
137 return (-1);
138
139 list1 = base;
140 setup(list1, list2, nmemb, size, cmp);
141 last = list2 + nmemb * size;
142 i = big = 0;
143 while (*EVAL(list2) != last) {
144 l2 = list1;
145 p1 = EVAL(list1);
146 for (tp2 = p2 = list2; p2 != last; p1 = EVAL(l2)) {
147 p2 = *EVAL(p2);
148 f1 = l2;
149 f2 = l1 = list1 + (p2 - list2);
150 if (p2 != last)
151 p2 = *EVAL(p2);
152 l2 = list1 + (p2 - list2);
153 while (f1 < l1 && f2 < l2) {
154 if (CMP(f1, f2) <= 0) {
155 q = f2;
156 b = f1, t = l1;
157 sense = -1;
158 } else {
159 q = f1;
160 b = f2, t = l2;
161 sense = 0;
162 }
163 if (!big) { /* here i = 0 */
164 while ((b += size) < t && CMP(q, b) >sense)
165 if (++i == 6) {
166 big = 1;
167 goto EXPONENTIAL;
168 }
169 } else {
170 EXPONENTIAL: for (i = size; ; i <<= 1)
171 if ((p = (b + i)) >= t) {
172 if ((p = t - size) > b &&
173 CMP(q, p) <= sense)
174 t = p;
175 else
176 b = p;
177 break;
178 } else if (CMP(q, p) <= sense) {
179 t = p;
180 if (i == size)
181 big = 0;
182 goto FASTCASE;
183 } else
184 b = p;
185 while (t > b+size) {
186 i = (((t - b) / size) >> 1) * size;
187 if (CMP(q, p = b + i) <= sense)
188 t = p;
189 else
190 b = p;
191 }
192 goto COPY;
193 FASTCASE: while (i > size)
194 if (CMP(q,
195 p = b + (i >>= 1)) <= sense)
196 t = p;
197 else
198 b = p;
199 COPY: b = t;
200 }
201 i = size;
202 if (q == f1) {
203 if (iflag) {
204 ICOPY_LIST(f2, tp2, b);
205 ICOPY_ELT(f1, tp2, i);
206 } else {
207 CCOPY_LIST(f2, tp2, b);
208 CCOPY_ELT(f1, tp2, i);
209 }
210 } else {
211 if (iflag) {
212 ICOPY_LIST(f1, tp2, b);
213 ICOPY_ELT(f2, tp2, i);
214 } else {
215 CCOPY_LIST(f1, tp2, b);
216 CCOPY_ELT(f2, tp2, i);
217 }
218 }
219 }
220 if (f2 < l2) {
221 if (iflag)
222 ICOPY_LIST(f2, tp2, l2);
223 else
224 CCOPY_LIST(f2, tp2, l2);
225 } else if (f1 < l1) {
226 if (iflag)
227 ICOPY_LIST(f1, tp2, l1);
228 else
229 CCOPY_LIST(f1, tp2, l1);
230 }
231 *p1 = l2;
232 }
233 tp2 = list1; /* swap list1, list2 */
234 list1 = list2;
235 list2 = tp2;
236 last = list2 + nmemb*size;
237 }
238 if (base == list2) {
239 memmove(list2, list1, nmemb*size);
240 list2 = list1;
241 }
242 free(list2);
243 return (0);
244 }
245
246 #define swap(a, b) { \
247 s = b; \
248 i = size; \
249 do { \
250 tmp = *a; *a++ = *s; *s++ = tmp; \
251 } while (--i); \
252 a -= size; \
253 }
254 #define reverse(bot, top) { \
255 s = top; \
256 do { \
257 i = size; \
258 do { \
259 tmp = *bot; *bot++ = *s; *s++ = tmp; \
260 } while (--i); \
261 s -= size2; \
262 } while(bot < s); \
263 }
264
265 /*
266 * Optional hybrid natural/pairwise first pass. Eats up list1 in runs of
267 * increasing order, list2 in a corresponding linked list. Checks for runs
268 * when THRESHOLD/2 pairs compare with same sense. (Only used when NATURAL
269 * is defined. Otherwise simple pairwise merging is used.)
270 */
271 void
setup(u_char * list1,u_char * list2,size_t n,size_t size,cmp_t cmp)272 setup(u_char *list1, u_char *list2, size_t n, size_t size, cmp_t cmp)
273 {
274 int i, length, size2, tmp, sense;
275 u_char *f1, *f2, *s, *l2, *last, *p2;
276
277 size2 = size*2;
278 if (n <= 5) {
279 insertionsort(list1, n, size, cmp);
280 *EVAL(list2) = (u_char*) list2 + n*size;
281 return;
282 }
283 /*
284 * Avoid running pointers out of bounds; limit n to evens
285 * for simplicity.
286 */
287 i = 4 + (n & 1);
288 insertionsort(list1 + (n - i) * size, i, size, cmp);
289 last = list1 + size * (n - i);
290 *EVAL(list2 + (last - list1)) = list2 + n * size;
291
292 #ifdef NATURAL
293 p2 = list2;
294 f1 = list1;
295 sense = (CMP(f1, f1 + size) > 0);
296 for (; f1 < last; sense = !sense) {
297 length = 2;
298 /* Find pairs with same sense. */
299 for (f2 = f1 + size2; f2 < last; f2 += size2) {
300 if ((CMP(f2, f2+ size) > 0) != sense)
301 break;
302 length += 2;
303 }
304 if (length < THRESHOLD) { /* Pairwise merge */
305 do {
306 p2 = *EVAL(p2) = f1 + size2 - list1 + list2;
307 if (sense > 0)
308 swap (f1, f1 + size);
309 } while ((f1 += size2) < f2);
310 } else { /* Natural merge */
311 l2 = f2;
312 for (f2 = f1 + size2; f2 < l2; f2 += size2) {
313 if ((CMP(f2-size, f2) > 0) != sense) {
314 p2 = *EVAL(p2) = f2 - list1 + list2;
315 if (sense > 0)
316 reverse(f1, f2-size);
317 f1 = f2;
318 }
319 }
320 if (sense > 0)
321 reverse (f1, f2-size);
322 f1 = f2;
323 if (f2 < last || CMP(f2 - size, f2) > 0)
324 p2 = *EVAL(p2) = f2 - list1 + list2;
325 else
326 p2 = *EVAL(p2) = list2 + n*size;
327 }
328 }
329 #else /* pairwise merge only. */
330 for (f1 = list1, p2 = list2; f1 < last; f1 += size2) {
331 p2 = *EVAL(p2) = p2 + size2;
332 if (CMP (f1, f1 + size) > 0)
333 swap(f1, f1 + size);
334 }
335 #endif /* NATURAL */
336 }
337
338 /*
339 * This is to avoid out-of-bounds addresses in sorting the
340 * last 4 elements.
341 */
342 static void
insertionsort(u_char * a,size_t n,size_t size,cmp_t cmp)343 insertionsort(u_char *a, size_t n, size_t size, cmp_t cmp)
344 {
345 u_char *ai, *s, *t, *u, tmp;
346 int i;
347
348 for (ai = a+size; --n >= 1; ai += size)
349 for (t = ai; t > a; t -= size) {
350 u = t - size;
351 if (CMP(u, t) <= 0)
352 break;
353 swap(u, t);
354 }
355 }
356