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 <stdckdint.h> 53 #include <stdlib.h> 54 #include <string.h> 55 56 #ifdef I_AM_MERGESORT_B 57 #include "block_abi.h" 58 #define DECLARE_CMP DECLARE_BLOCK(int, cmp, const void *, const void *) 59 typedef DECLARE_BLOCK(int, cmp_t, const void *, const void *); 60 #define CMP(x, y) CALL_BLOCK(cmp, x, y) 61 #else 62 typedef int (*cmp_t)(const void *, const void *); 63 #define CMP(x, y) cmp(x, y) 64 #endif 65 66 static void setup(u_char *, u_char *, size_t, size_t, cmp_t); 67 static void insertionsort(u_char *, size_t, size_t, cmp_t); 68 69 #define PSIZE sizeof(u_char *) 70 #define COPY_LIST(src, dst, last) \ 71 do { \ 72 memcpy(dst, src, last - src); \ 73 dst += last - src; \ 74 src += last - src; \ 75 } while (0) 76 #define COPY_ELT(src, dst, i) \ 77 do { \ 78 memcpy(dst, src, i); \ 79 src += i; \ 80 dst += i; \ 81 } while (0) 82 83 /* 84 * Find the next possible pointer head. (Trickery for forcing an array 85 * to do double duty as a linked list when objects do not align with word 86 * boundaries. 87 */ 88 /* Assumption: PSIZE is a power of 2. */ 89 #define EVAL(p) (u_char **)roundup2((uintptr_t)p, PSIZE) 90 91 #ifdef I_AM_MERGESORT_B 92 int mergesort_b(void *, size_t, size_t, cmp_t); 93 #else 94 int mergesort(void *, size_t, size_t, cmp_t); 95 #endif 96 97 /* 98 * Arguments are as for qsort. 99 */ 100 int 101 #ifdef I_AM_MERGESORT_B 102 mergesort_b(void *base, size_t nmemb, size_t size, cmp_t cmp) 103 #else 104 mergesort(void *base, size_t nmemb, size_t size, cmp_t cmp) 105 #endif 106 { 107 size_t i, nbytes, asize; 108 int sense; 109 int big; 110 u_char *f1, *f2, *t, *b, *tp2, *q, *l1, *l2; 111 u_char *list2, *list1, *p2, *p, *last, **p1; 112 113 if (size < PSIZE / 2) { /* Pointers must fit into 2 * size. */ 114 errno = EINVAL; 115 return (-1); 116 } 117 118 if (nmemb == 0) 119 return (0); 120 121 if (ckd_mul(&nbytes, nmemb, size) || ckd_add(&asize, nbytes, PSIZE)) { 122 errno = EINVAL; 123 return (-1); 124 } 125 126 if ((list2 = malloc(asize)) == NULL) 127 return (-1); 128 129 list1 = base; 130 setup(list1, list2, nmemb, size, cmp); 131 last = list2 + nbytes; 132 i = big = 0; 133 while (*EVAL(list2) != last) { 134 l2 = list1; 135 p1 = EVAL(list1); 136 for (tp2 = p2 = list2; p2 != last; p1 = EVAL(l2)) { 137 p2 = *EVAL(p2); 138 f1 = l2; 139 f2 = l1 = list1 + (p2 - list2); 140 if (p2 != last) 141 p2 = *EVAL(p2); 142 l2 = list1 + (p2 - list2); 143 while (f1 < l1 && f2 < l2) { 144 if (CMP(f1, f2) <= 0) { 145 q = f2; 146 b = f1, t = l1; 147 sense = -1; 148 } else { 149 q = f1; 150 b = f2, t = l2; 151 sense = 0; 152 } 153 if (!big) { /* here i = 0 */ 154 while ((b += size) < t && CMP(q, b) >sense) 155 if (++i == 6) { 156 big = 1; 157 goto EXPONENTIAL; 158 } 159 } else { 160 EXPONENTIAL: for (i = size; ; i <<= 1) 161 if ((p = (b + i)) >= t) { 162 if ((p = t - size) > b && 163 CMP(q, p) <= sense) 164 t = p; 165 else 166 b = p; 167 break; 168 } else if (CMP(q, p) <= sense) { 169 t = p; 170 if (i == size) 171 big = 0; 172 goto FASTCASE; 173 } else 174 b = p; 175 while (t > b+size) { 176 i = (((t - b) / size) >> 1) * size; 177 if (CMP(q, p = b + i) <= sense) 178 t = p; 179 else 180 b = p; 181 } 182 goto COPY; 183 FASTCASE: while (i > size) 184 if (CMP(q, 185 p = b + (i >>= 1)) <= sense) 186 t = p; 187 else 188 b = p; 189 COPY: b = t; 190 } 191 i = size; 192 if (q == f1) { 193 COPY_LIST(f2, tp2, b); 194 COPY_ELT(f1, tp2, i); 195 } else { 196 COPY_LIST(f1, tp2, b); 197 COPY_ELT(f2, tp2, i); 198 } 199 } 200 if (f2 < l2) 201 COPY_LIST(f2, tp2, l2); 202 else if (f1 < l1) 203 COPY_LIST(f1, tp2, l1); 204 *p1 = l2; 205 } 206 tp2 = list1; /* swap list1, list2 */ 207 list1 = list2; 208 list2 = tp2; 209 last = list2 + nbytes; 210 } 211 if (base == list2) { 212 memmove(list2, list1, nbytes); 213 list2 = list1; 214 } 215 free(list2); 216 return (0); 217 } 218 219 #define swap(a, b) { \ 220 s = b; \ 221 i = size; \ 222 do { \ 223 tmp = *a; *a++ = *s; *s++ = tmp; \ 224 } while (--i); \ 225 a -= size; \ 226 } 227 #define reverse(bot, top) { \ 228 s = top; \ 229 do { \ 230 i = size; \ 231 do { \ 232 tmp = *bot; *bot++ = *s; *s++ = tmp; \ 233 } while (--i); \ 234 s -= size2; \ 235 } while(bot < s); \ 236 } 237 238 /* 239 * Optional hybrid natural/pairwise first pass. Eats up list1 in runs of 240 * increasing order, list2 in a corresponding linked list. Checks for runs 241 * when THRESHOLD/2 pairs compare with same sense. (Only used when NATURAL 242 * is defined. Otherwise simple pairwise merging is used.) 243 */ 244 void 245 setup(u_char *list1, u_char *list2, size_t n, size_t size, cmp_t cmp) 246 { 247 int i, length, size2, tmp, sense; 248 u_char *f1, *f2, *s, *l2, *last, *p2; 249 250 size2 = size*2; 251 if (n <= 5) { 252 insertionsort(list1, n, size, cmp); 253 *EVAL(list2) = (u_char*) list2 + n*size; 254 return; 255 } 256 /* 257 * Avoid running pointers out of bounds; limit n to evens 258 * for simplicity. 259 */ 260 i = 4 + (n & 1); 261 insertionsort(list1 + (n - i) * size, i, size, cmp); 262 last = list1 + size * (n - i); 263 *EVAL(list2 + (last - list1)) = list2 + n * size; 264 265 #ifdef NATURAL 266 p2 = list2; 267 f1 = list1; 268 sense = (CMP(f1, f1 + size) > 0); 269 for (; f1 < last; sense = !sense) { 270 length = 2; 271 /* Find pairs with same sense. */ 272 for (f2 = f1 + size2; f2 < last; f2 += size2) { 273 if ((CMP(f2, f2+ size) > 0) != sense) 274 break; 275 length += 2; 276 } 277 if (length < THRESHOLD) { /* Pairwise merge */ 278 do { 279 p2 = *EVAL(p2) = f1 + size2 - list1 + list2; 280 if (sense > 0) 281 swap (f1, f1 + size); 282 } while ((f1 += size2) < f2); 283 } else { /* Natural merge */ 284 l2 = f2; 285 for (f2 = f1 + size2; f2 < l2; f2 += size2) { 286 if ((CMP(f2-size, f2) > 0) != sense) { 287 p2 = *EVAL(p2) = f2 - list1 + list2; 288 if (sense > 0) 289 reverse(f1, f2-size); 290 f1 = f2; 291 } 292 } 293 if (sense > 0) 294 reverse (f1, f2-size); 295 f1 = f2; 296 if (f2 < last || CMP(f2 - size, f2) > 0) 297 p2 = *EVAL(p2) = f2 - list1 + list2; 298 else 299 p2 = *EVAL(p2) = list2 + n*size; 300 } 301 } 302 #else /* pairwise merge only. */ 303 for (f1 = list1, p2 = list2; f1 < last; f1 += size2) { 304 p2 = *EVAL(p2) = p2 + size2; 305 if (CMP (f1, f1 + size) > 0) 306 swap(f1, f1 + size); 307 } 308 #endif /* NATURAL */ 309 } 310 311 /* 312 * This is to avoid out-of-bounds addresses in sorting the 313 * last 4 elements. 314 */ 315 static void 316 insertionsort(u_char *a, size_t n, size_t size, cmp_t cmp) 317 { 318 u_char *ai, *s, *t, *u, tmp; 319 int i; 320 321 for (ai = a+size; --n >= 1; ai += size) 322 for (t = ai; t > a; t -= size) { 323 u = t - size; 324 if (CMP(u, t) <= 0) 325 break; 326 swap(u, t); 327 } 328 } 329