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 /*
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 */
41
42 #define NATURAL
43 #define THRESHOLD 16 /* Best choice for natural merge cut-off. */
44
45 /* #define NATURAL to get hybrid natural merge.
46 * (The default is pairwise merging.)
47 */
48
49 #include <sys/param.h>
50
51 #include <errno.h>
52 #include <stdlib.h>
53 #include <string.h>
54
55 #ifdef I_AM_MERGESORT_B
56 #include "block_abi.h"
57 #define DECLARE_CMP DECLARE_BLOCK(int, cmp, const void *, const void *)
58 typedef DECLARE_BLOCK(int, cmp_t, const void *, const void *);
59 #define CMP(x, y) CALL_BLOCK(cmp, x, y)
60 #else
61 typedef int (*cmp_t)(const void *, const void *);
62 #define CMP(x, y) cmp(x, y)
63 #endif
64
65 static void setup(u_char *, u_char *, size_t, size_t, cmp_t);
66 static void insertionsort(u_char *, size_t, size_t, cmp_t);
67
68 #define ISIZE sizeof(int)
69 #define PSIZE sizeof(u_char *)
70 #define ICOPY_LIST(src, dst, last) \
71 do \
72 *(int*)dst = *(int*)src, src += ISIZE, dst += ISIZE; \
73 while(src < last)
74 #define ICOPY_ELT(src, dst, i) \
75 do \
76 *(int*) dst = *(int*) src, src += ISIZE, dst += ISIZE; \
77 while (i -= ISIZE)
78
79 #define CCOPY_LIST(src, dst, last) \
80 do \
81 *dst++ = *src++; \
82 while (src < last)
83 #define CCOPY_ELT(src, dst, i) \
84 do \
85 *dst++ = *src++; \
86 while (i -= 1)
87
88 /*
89 * Find the next possible pointer head. (Trickery for forcing an array
90 * to do double duty as a linked list when objects do not align with word
91 * boundaries.
92 */
93 /* Assumption: PSIZE is a power of 2. */
94 #define EVAL(p) (u_char **)roundup2((uintptr_t)p, PSIZE)
95
96 #ifdef I_AM_MERGESORT_B
97 int mergesort_b(void *, size_t, size_t, cmp_t);
98 #else
99 int mergesort(void *, size_t, size_t, cmp_t);
100 #endif
101
102 /*
103 * Arguments are as for qsort.
104 */
105 int
106 #ifdef I_AM_MERGESORT_B
mergesort_b(void * base,size_t nmemb,size_t size,cmp_t cmp)107 mergesort_b(void *base, size_t nmemb, size_t size, cmp_t cmp)
108 #else
109 mergesort(void *base, size_t nmemb, size_t size, cmp_t cmp)
110 #endif
111 {
112 size_t i;
113 int sense;
114 int big, iflag;
115 u_char *f1, *f2, *t, *b, *tp2, *q, *l1, *l2;
116 u_char *list2, *list1, *p2, *p, *last, **p1;
117
118 if (size < PSIZE / 2) { /* Pointers must fit into 2 * size. */
119 errno = EINVAL;
120 return (-1);
121 }
122
123 if (nmemb == 0)
124 return (0);
125
126 iflag = 0;
127 if (__is_aligned(size, ISIZE) && __is_aligned(base, ISIZE))
128 iflag = 1;
129
130 if ((list2 = malloc(nmemb * size + PSIZE)) == NULL)
131 return (-1);
132
133 list1 = base;
134 setup(list1, list2, nmemb, size, cmp);
135 last = list2 + nmemb * size;
136 i = big = 0;
137 while (*EVAL(list2) != last) {
138 l2 = list1;
139 p1 = EVAL(list1);
140 for (tp2 = p2 = list2; p2 != last; p1 = EVAL(l2)) {
141 p2 = *EVAL(p2);
142 f1 = l2;
143 f2 = l1 = list1 + (p2 - list2);
144 if (p2 != last)
145 p2 = *EVAL(p2);
146 l2 = list1 + (p2 - list2);
147 while (f1 < l1 && f2 < l2) {
148 if (CMP(f1, f2) <= 0) {
149 q = f2;
150 b = f1, t = l1;
151 sense = -1;
152 } else {
153 q = f1;
154 b = f2, t = l2;
155 sense = 0;
156 }
157 if (!big) { /* here i = 0 */
158 while ((b += size) < t && CMP(q, b) >sense)
159 if (++i == 6) {
160 big = 1;
161 goto EXPONENTIAL;
162 }
163 } else {
164 EXPONENTIAL: for (i = size; ; i <<= 1)
165 if ((p = (b + i)) >= t) {
166 if ((p = t - size) > b &&
167 CMP(q, p) <= sense)
168 t = p;
169 else
170 b = p;
171 break;
172 } else if (CMP(q, p) <= sense) {
173 t = p;
174 if (i == size)
175 big = 0;
176 goto FASTCASE;
177 } else
178 b = p;
179 while (t > b+size) {
180 i = (((t - b) / size) >> 1) * size;
181 if (CMP(q, p = b + i) <= sense)
182 t = p;
183 else
184 b = p;
185 }
186 goto COPY;
187 FASTCASE: while (i > size)
188 if (CMP(q,
189 p = b + (i >>= 1)) <= sense)
190 t = p;
191 else
192 b = p;
193 COPY: b = t;
194 }
195 i = size;
196 if (q == f1) {
197 if (iflag) {
198 ICOPY_LIST(f2, tp2, b);
199 ICOPY_ELT(f1, tp2, i);
200 } else {
201 CCOPY_LIST(f2, tp2, b);
202 CCOPY_ELT(f1, tp2, i);
203 }
204 } else {
205 if (iflag) {
206 ICOPY_LIST(f1, tp2, b);
207 ICOPY_ELT(f2, tp2, i);
208 } else {
209 CCOPY_LIST(f1, tp2, b);
210 CCOPY_ELT(f2, tp2, i);
211 }
212 }
213 }
214 if (f2 < l2) {
215 if (iflag)
216 ICOPY_LIST(f2, tp2, l2);
217 else
218 CCOPY_LIST(f2, tp2, l2);
219 } else if (f1 < l1) {
220 if (iflag)
221 ICOPY_LIST(f1, tp2, l1);
222 else
223 CCOPY_LIST(f1, tp2, l1);
224 }
225 *p1 = l2;
226 }
227 tp2 = list1; /* swap list1, list2 */
228 list1 = list2;
229 list2 = tp2;
230 last = list2 + nmemb*size;
231 }
232 if (base == list2) {
233 memmove(list2, list1, nmemb*size);
234 list2 = list1;
235 }
236 free(list2);
237 return (0);
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 /*
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 void
setup(u_char * list1,u_char * list2,size_t n,size_t size,cmp_t cmp)266 setup(u_char *list1, u_char *list2, size_t n, size_t size, cmp_t cmp)
267 {
268 int i, length, size2, tmp, sense;
269 u_char *f1, *f2, *s, *l2, *last, *p2;
270
271 size2 = size*2;
272 if (n <= 5) {
273 insertionsort(list1, n, size, cmp);
274 *EVAL(list2) = (u_char*) list2 + n*size;
275 return;
276 }
277 /*
278 * Avoid running pointers out of bounds; limit n to evens
279 * for simplicity.
280 */
281 i = 4 + (n & 1);
282 insertionsort(list1 + (n - i) * size, i, size, cmp);
283 last = list1 + size * (n - i);
284 *EVAL(list2 + (last - list1)) = list2 + n * size;
285
286 #ifdef NATURAL
287 p2 = list2;
288 f1 = list1;
289 sense = (CMP(f1, f1 + size) > 0);
290 for (; f1 < last; sense = !sense) {
291 length = 2;
292 /* Find pairs with same sense. */
293 for (f2 = f1 + size2; f2 < last; f2 += size2) {
294 if ((CMP(f2, f2+ size) > 0) != sense)
295 break;
296 length += 2;
297 }
298 if (length < THRESHOLD) { /* Pairwise merge */
299 do {
300 p2 = *EVAL(p2) = f1 + size2 - list1 + list2;
301 if (sense > 0)
302 swap (f1, f1 + size);
303 } while ((f1 += size2) < f2);
304 } else { /* Natural merge */
305 l2 = f2;
306 for (f2 = f1 + size2; f2 < l2; f2 += size2) {
307 if ((CMP(f2-size, f2) > 0) != sense) {
308 p2 = *EVAL(p2) = f2 - list1 + list2;
309 if (sense > 0)
310 reverse(f1, f2-size);
311 f1 = f2;
312 }
313 }
314 if (sense > 0)
315 reverse (f1, f2-size);
316 f1 = f2;
317 if (f2 < last || CMP(f2 - size, f2) > 0)
318 p2 = *EVAL(p2) = f2 - list1 + list2;
319 else
320 p2 = *EVAL(p2) = list2 + n*size;
321 }
322 }
323 #else /* pairwise merge only. */
324 for (f1 = list1, p2 = list2; f1 < last; f1 += size2) {
325 p2 = *EVAL(p2) = p2 + size2;
326 if (CMP (f1, f1 + size) > 0)
327 swap(f1, f1 + size);
328 }
329 #endif /* NATURAL */
330 }
331
332 /*
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,cmp_t cmp)337 insertionsort(u_char *a, size_t n, size_t size, cmp_t cmp)
338 {
339 u_char *ai, *s, *t, *u, tmp;
340 int i;
341
342 for (ai = a+size; --n >= 1; ai += size)
343 for (t = ai; t > a; t -= size) {
344 u = t - size;
345 if (CMP(u, t) <= 0)
346 break;
347 swap(u, t);
348 }
349 }
350