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 /* 40 * Hybrid exponential search/linear search merge sort with hybrid 41 * natural/pairwise first pass. Requires about .3% more comparisons 42 * for random data than LSMS with pairwise first pass alone. 43 * It works for objects as small as two bytes. 44 */ 45 46 #define NATURAL 47 #define THRESHOLD 16 /* Best choice for natural merge cut-off. */ 48 49 /* #define NATURAL to get hybrid natural merge. 50 * (The default is pairwise merging.) 51 */ 52 53 #include <sys/param.h> 54 55 #include <errno.h> 56 #include <stdlib.h> 57 #include <string.h> 58 59 #ifdef I_AM_MERGESORT_B 60 #include "block_abi.h" 61 #define DECLARE_CMP DECLARE_BLOCK(int, cmp, const void *, const void *) 62 typedef DECLARE_BLOCK(int, cmp_t, const void *, const void *); 63 #define CMP(x, y) CALL_BLOCK(cmp, x, y) 64 #else 65 typedef int (*cmp_t)(const void *, const void *); 66 #define CMP(x, y) cmp(x, y) 67 #endif 68 69 static void setup(u_char *, u_char *, size_t, size_t, cmp_t); 70 static void insertionsort(u_char *, size_t, size_t, cmp_t); 71 72 #define ISIZE sizeof(int) 73 #define PSIZE sizeof(u_char *) 74 #define ICOPY_LIST(src, dst, last) \ 75 do \ 76 *(int*)dst = *(int*)src, src += ISIZE, dst += ISIZE; \ 77 while(src < last) 78 #define ICOPY_ELT(src, dst, i) \ 79 do \ 80 *(int*) dst = *(int*) src, src += ISIZE, dst += ISIZE; \ 81 while (i -= ISIZE) 82 83 #define CCOPY_LIST(src, dst, last) \ 84 do \ 85 *dst++ = *src++; \ 86 while (src < last) 87 #define CCOPY_ELT(src, dst, i) \ 88 do \ 89 *dst++ = *src++; \ 90 while (i -= 1) 91 92 /* 93 * Find the next possible pointer head. (Trickery for forcing an array 94 * to do double duty as a linked list when objects do not align with word 95 * boundaries. 96 */ 97 /* Assumption: PSIZE is a power of 2. */ 98 #define EVAL(p) (u_char **)roundup2((uintptr_t)p, PSIZE) 99 100 #ifdef I_AM_MERGESORT_B 101 int mergesort_b(void *, size_t, size_t, cmp_t); 102 #else 103 int mergesort(void *, size_t, size_t, cmp_t); 104 #endif 105 106 /* 107 * Arguments are as for qsort. 108 */ 109 int 110 #ifdef I_AM_MERGESORT_B 111 mergesort_b(void *base, size_t nmemb, size_t size, cmp_t cmp) 112 #else 113 mergesort(void *base, size_t nmemb, size_t size, cmp_t cmp) 114 #endif 115 { 116 size_t i; 117 int sense; 118 int big, iflag; 119 u_char *f1, *f2, *t, *b, *tp2, *q, *l1, *l2; 120 u_char *list2, *list1, *p2, *p, *last, **p1; 121 122 if (size < PSIZE / 2) { /* Pointers must fit into 2 * size. */ 123 errno = EINVAL; 124 return (-1); 125 } 126 127 if (nmemb == 0) 128 return (0); 129 130 iflag = 0; 131 if (__is_aligned(size, ISIZE) && __is_aligned(base, ISIZE)) 132 iflag = 1; 133 134 if ((list2 = malloc(nmemb * size + PSIZE)) == NULL) 135 return (-1); 136 137 list1 = base; 138 setup(list1, list2, nmemb, size, cmp); 139 last = list2 + nmemb * size; 140 i = big = 0; 141 while (*EVAL(list2) != last) { 142 l2 = list1; 143 p1 = EVAL(list1); 144 for (tp2 = p2 = list2; p2 != last; p1 = EVAL(l2)) { 145 p2 = *EVAL(p2); 146 f1 = l2; 147 f2 = l1 = list1 + (p2 - list2); 148 if (p2 != last) 149 p2 = *EVAL(p2); 150 l2 = list1 + (p2 - list2); 151 while (f1 < l1 && f2 < l2) { 152 if (CMP(f1, f2) <= 0) { 153 q = f2; 154 b = f1, t = l1; 155 sense = -1; 156 } else { 157 q = f1; 158 b = f2, t = l2; 159 sense = 0; 160 } 161 if (!big) { /* here i = 0 */ 162 while ((b += size) < t && CMP(q, b) >sense) 163 if (++i == 6) { 164 big = 1; 165 goto EXPONENTIAL; 166 } 167 } else { 168 EXPONENTIAL: for (i = size; ; i <<= 1) 169 if ((p = (b + i)) >= t) { 170 if ((p = t - size) > b && 171 CMP(q, p) <= sense) 172 t = p; 173 else 174 b = p; 175 break; 176 } else if (CMP(q, p) <= sense) { 177 t = p; 178 if (i == size) 179 big = 0; 180 goto FASTCASE; 181 } else 182 b = p; 183 while (t > b+size) { 184 i = (((t - b) / size) >> 1) * size; 185 if (CMP(q, p = b + i) <= sense) 186 t = p; 187 else 188 b = p; 189 } 190 goto COPY; 191 FASTCASE: while (i > size) 192 if (CMP(q, 193 p = b + (i >>= 1)) <= sense) 194 t = p; 195 else 196 b = p; 197 COPY: b = t; 198 } 199 i = size; 200 if (q == f1) { 201 if (iflag) { 202 ICOPY_LIST(f2, tp2, b); 203 ICOPY_ELT(f1, tp2, i); 204 } else { 205 CCOPY_LIST(f2, tp2, b); 206 CCOPY_ELT(f1, tp2, i); 207 } 208 } else { 209 if (iflag) { 210 ICOPY_LIST(f1, tp2, b); 211 ICOPY_ELT(f2, tp2, i); 212 } else { 213 CCOPY_LIST(f1, tp2, b); 214 CCOPY_ELT(f2, tp2, i); 215 } 216 } 217 } 218 if (f2 < l2) { 219 if (iflag) 220 ICOPY_LIST(f2, tp2, l2); 221 else 222 CCOPY_LIST(f2, tp2, l2); 223 } else if (f1 < l1) { 224 if (iflag) 225 ICOPY_LIST(f1, tp2, l1); 226 else 227 CCOPY_LIST(f1, tp2, l1); 228 } 229 *p1 = l2; 230 } 231 tp2 = list1; /* swap list1, list2 */ 232 list1 = list2; 233 list2 = tp2; 234 last = list2 + nmemb*size; 235 } 236 if (base == list2) { 237 memmove(list2, list1, nmemb*size); 238 list2 = list1; 239 } 240 free(list2); 241 return (0); 242 } 243 244 #define swap(a, b) { \ 245 s = b; \ 246 i = size; \ 247 do { \ 248 tmp = *a; *a++ = *s; *s++ = tmp; \ 249 } while (--i); \ 250 a -= size; \ 251 } 252 #define reverse(bot, top) { \ 253 s = top; \ 254 do { \ 255 i = size; \ 256 do { \ 257 tmp = *bot; *bot++ = *s; *s++ = tmp; \ 258 } while (--i); \ 259 s -= size2; \ 260 } while(bot < s); \ 261 } 262 263 /* 264 * Optional hybrid natural/pairwise first pass. Eats up list1 in runs of 265 * increasing order, list2 in a corresponding linked list. Checks for runs 266 * when THRESHOLD/2 pairs compare with same sense. (Only used when NATURAL 267 * is defined. Otherwise simple pairwise merging is used.) 268 */ 269 void 270 setup(u_char *list1, u_char *list2, size_t n, size_t size, cmp_t cmp) 271 { 272 int i, length, size2, tmp, sense; 273 u_char *f1, *f2, *s, *l2, *last, *p2; 274 275 size2 = size*2; 276 if (n <= 5) { 277 insertionsort(list1, n, size, cmp); 278 *EVAL(list2) = (u_char*) list2 + n*size; 279 return; 280 } 281 /* 282 * Avoid running pointers out of bounds; limit n to evens 283 * for simplicity. 284 */ 285 i = 4 + (n & 1); 286 insertionsort(list1 + (n - i) * size, i, size, cmp); 287 last = list1 + size * (n - i); 288 *EVAL(list2 + (last - list1)) = list2 + n * size; 289 290 #ifdef NATURAL 291 p2 = list2; 292 f1 = list1; 293 sense = (CMP(f1, f1 + size) > 0); 294 for (; f1 < last; sense = !sense) { 295 length = 2; 296 /* Find pairs with same sense. */ 297 for (f2 = f1 + size2; f2 < last; f2 += size2) { 298 if ((CMP(f2, f2+ size) > 0) != sense) 299 break; 300 length += 2; 301 } 302 if (length < THRESHOLD) { /* Pairwise merge */ 303 do { 304 p2 = *EVAL(p2) = f1 + size2 - list1 + list2; 305 if (sense > 0) 306 swap (f1, f1 + size); 307 } while ((f1 += size2) < f2); 308 } else { /* Natural merge */ 309 l2 = f2; 310 for (f2 = f1 + size2; f2 < l2; f2 += size2) { 311 if ((CMP(f2-size, f2) > 0) != sense) { 312 p2 = *EVAL(p2) = f2 - list1 + list2; 313 if (sense > 0) 314 reverse(f1, f2-size); 315 f1 = f2; 316 } 317 } 318 if (sense > 0) 319 reverse (f1, f2-size); 320 f1 = f2; 321 if (f2 < last || CMP(f2 - size, f2) > 0) 322 p2 = *EVAL(p2) = f2 - list1 + list2; 323 else 324 p2 = *EVAL(p2) = list2 + n*size; 325 } 326 } 327 #else /* pairwise merge only. */ 328 for (f1 = list1, p2 = list2; f1 < last; f1 += size2) { 329 p2 = *EVAL(p2) = p2 + size2; 330 if (CMP (f1, f1 + size) > 0) 331 swap(f1, f1 + size); 332 } 333 #endif /* NATURAL */ 334 } 335 336 /* 337 * This is to avoid out-of-bounds addresses in sorting the 338 * last 4 elements. 339 */ 340 static void 341 insertionsort(u_char *a, size_t n, size_t size, cmp_t cmp) 342 { 343 u_char *ai, *s, *t, *u, tmp; 344 int i; 345 346 for (ai = a+size; --n >= 1; ai += size) 347 for (t = ai; t > a; t -= size) { 348 u = t - size; 349 if (CMP(u, t) <= 0) 350 break; 351 swap(u, t); 352 } 353 } 354