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/types.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 **) \ 101 ((u_char *)0 + \ 102 (((u_char *)p + PSIZE - 1 - (u_char *) 0) & ~(PSIZE - 1))) 103 104 #ifdef I_AM_MERGESORT_B 105 int mergesort_b(void *, size_t, size_t, cmp_t); 106 #else 107 int mergesort(void *, size_t, size_t, cmp_t); 108 #endif 109 110 /* 111 * Arguments are as for qsort. 112 */ 113 int 114 #ifdef I_AM_MERGESORT_B 115 mergesort_b(void *base, size_t nmemb, size_t size, cmp_t cmp) 116 #else 117 mergesort(void *base, size_t nmemb, size_t size, cmp_t cmp) 118 #endif 119 { 120 size_t i; 121 int sense; 122 int big, iflag; 123 u_char *f1, *f2, *t, *b, *tp2, *q, *l1, *l2; 124 u_char *list2, *list1, *p2, *p, *last, **p1; 125 126 if (size < PSIZE / 2) { /* Pointers must fit into 2 * size. */ 127 errno = EINVAL; 128 return (-1); 129 } 130 131 if (nmemb == 0) 132 return (0); 133 134 /* 135 * XXX 136 * Stupid subtraction for the Cray. 137 */ 138 iflag = 0; 139 if (!(size % ISIZE) && !(((char *)base - (char *)0) % ISIZE)) 140 iflag = 1; 141 142 if ((list2 = malloc(nmemb * size + PSIZE)) == NULL) 143 return (-1); 144 145 list1 = base; 146 setup(list1, list2, nmemb, size, cmp); 147 last = list2 + nmemb * size; 148 i = big = 0; 149 while (*EVAL(list2) != last) { 150 l2 = list1; 151 p1 = EVAL(list1); 152 for (tp2 = p2 = list2; p2 != last; p1 = EVAL(l2)) { 153 p2 = *EVAL(p2); 154 f1 = l2; 155 f2 = l1 = list1 + (p2 - list2); 156 if (p2 != last) 157 p2 = *EVAL(p2); 158 l2 = list1 + (p2 - list2); 159 while (f1 < l1 && f2 < l2) { 160 if (CMP(f1, f2) <= 0) { 161 q = f2; 162 b = f1, t = l1; 163 sense = -1; 164 } else { 165 q = f1; 166 b = f2, t = l2; 167 sense = 0; 168 } 169 if (!big) { /* here i = 0 */ 170 while ((b += size) < t && CMP(q, b) >sense) 171 if (++i == 6) { 172 big = 1; 173 goto EXPONENTIAL; 174 } 175 } else { 176 EXPONENTIAL: for (i = size; ; i <<= 1) 177 if ((p = (b + i)) >= t) { 178 if ((p = t - size) > b && 179 CMP(q, p) <= sense) 180 t = p; 181 else 182 b = p; 183 break; 184 } else if (CMP(q, p) <= sense) { 185 t = p; 186 if (i == size) 187 big = 0; 188 goto FASTCASE; 189 } else 190 b = p; 191 while (t > b+size) { 192 i = (((t - b) / size) >> 1) * size; 193 if (CMP(q, p = b + i) <= sense) 194 t = p; 195 else 196 b = p; 197 } 198 goto COPY; 199 FASTCASE: while (i > size) 200 if (CMP(q, 201 p = b + (i >>= 1)) <= sense) 202 t = p; 203 else 204 b = p; 205 COPY: b = t; 206 } 207 i = size; 208 if (q == f1) { 209 if (iflag) { 210 ICOPY_LIST(f2, tp2, b); 211 ICOPY_ELT(f1, tp2, i); 212 } else { 213 CCOPY_LIST(f2, tp2, b); 214 CCOPY_ELT(f1, tp2, i); 215 } 216 } else { 217 if (iflag) { 218 ICOPY_LIST(f1, tp2, b); 219 ICOPY_ELT(f2, tp2, i); 220 } else { 221 CCOPY_LIST(f1, tp2, b); 222 CCOPY_ELT(f2, tp2, i); 223 } 224 } 225 } 226 if (f2 < l2) { 227 if (iflag) 228 ICOPY_LIST(f2, tp2, l2); 229 else 230 CCOPY_LIST(f2, tp2, l2); 231 } else if (f1 < l1) { 232 if (iflag) 233 ICOPY_LIST(f1, tp2, l1); 234 else 235 CCOPY_LIST(f1, tp2, l1); 236 } 237 *p1 = l2; 238 } 239 tp2 = list1; /* swap list1, list2 */ 240 list1 = list2; 241 list2 = tp2; 242 last = list2 + nmemb*size; 243 } 244 if (base == list2) { 245 memmove(list2, list1, nmemb*size); 246 list2 = list1; 247 } 248 free(list2); 249 return (0); 250 } 251 252 #define swap(a, b) { \ 253 s = b; \ 254 i = size; \ 255 do { \ 256 tmp = *a; *a++ = *s; *s++ = tmp; \ 257 } while (--i); \ 258 a -= size; \ 259 } 260 #define reverse(bot, top) { \ 261 s = top; \ 262 do { \ 263 i = size; \ 264 do { \ 265 tmp = *bot; *bot++ = *s; *s++ = tmp; \ 266 } while (--i); \ 267 s -= size2; \ 268 } while(bot < s); \ 269 } 270 271 /* 272 * Optional hybrid natural/pairwise first pass. Eats up list1 in runs of 273 * increasing order, list2 in a corresponding linked list. Checks for runs 274 * when THRESHOLD/2 pairs compare with same sense. (Only used when NATURAL 275 * is defined. Otherwise simple pairwise merging is used.) 276 */ 277 void 278 setup(u_char *list1, u_char *list2, size_t n, size_t size, cmp_t cmp) 279 { 280 int i, length, size2, tmp, sense; 281 u_char *f1, *f2, *s, *l2, *last, *p2; 282 283 size2 = size*2; 284 if (n <= 5) { 285 insertionsort(list1, n, size, cmp); 286 *EVAL(list2) = (u_char*) list2 + n*size; 287 return; 288 } 289 /* 290 * Avoid running pointers out of bounds; limit n to evens 291 * for simplicity. 292 */ 293 i = 4 + (n & 1); 294 insertionsort(list1 + (n - i) * size, i, size, cmp); 295 last = list1 + size * (n - i); 296 *EVAL(list2 + (last - list1)) = list2 + n * size; 297 298 #ifdef NATURAL 299 p2 = list2; 300 f1 = list1; 301 sense = (CMP(f1, f1 + size) > 0); 302 for (; f1 < last; sense = !sense) { 303 length = 2; 304 /* Find pairs with same sense. */ 305 for (f2 = f1 + size2; f2 < last; f2 += size2) { 306 if ((CMP(f2, f2+ size) > 0) != sense) 307 break; 308 length += 2; 309 } 310 if (length < THRESHOLD) { /* Pairwise merge */ 311 do { 312 p2 = *EVAL(p2) = f1 + size2 - list1 + list2; 313 if (sense > 0) 314 swap (f1, f1 + size); 315 } while ((f1 += size2) < f2); 316 } else { /* Natural merge */ 317 l2 = f2; 318 for (f2 = f1 + size2; f2 < l2; f2 += size2) { 319 if ((CMP(f2-size, f2) > 0) != sense) { 320 p2 = *EVAL(p2) = f2 - list1 + list2; 321 if (sense > 0) 322 reverse(f1, f2-size); 323 f1 = f2; 324 } 325 } 326 if (sense > 0) 327 reverse (f1, f2-size); 328 f1 = f2; 329 if (f2 < last || CMP(f2 - size, f2) > 0) 330 p2 = *EVAL(p2) = f2 - list1 + list2; 331 else 332 p2 = *EVAL(p2) = list2 + n*size; 333 } 334 } 335 #else /* pairwise merge only. */ 336 for (f1 = list1, p2 = list2; f1 < last; f1 += size2) { 337 p2 = *EVAL(p2) = p2 + size2; 338 if (CMP (f1, f1 + size) > 0) 339 swap(f1, f1 + size); 340 } 341 #endif /* NATURAL */ 342 } 343 344 /* 345 * This is to avoid out-of-bounds addresses in sorting the 346 * last 4 elements. 347 */ 348 static void 349 insertionsort(u_char *a, size_t n, size_t size, cmp_t cmp) 350 { 351 u_char *ai, *s, *t, *u, tmp; 352 int i; 353 354 for (ai = a+size; --n >= 1; ai += size) 355 for (t = ai; t > a; t -= size) { 356 u = t - size; 357 if (CMP(u, t) <= 0) 358 break; 359 swap(u, t); 360 } 361 } 362