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 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 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 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