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 /* 39 * Hybrid exponential search/linear search merge sort with hybrid 40 * natural/pairwise first pass. Requires about .3% more comparisons 41 * for random data than LSMS with pairwise first pass alone. 42 * It works for objects as small as two bytes. 43 */ 44 45 #define NATURAL 46 #define THRESHOLD 16 /* Best choice for natural merge cut-off. */ 47 48 /* #define NATURAL to get hybrid natural merge. 49 * (The default is pairwise merging.) 50 */ 51 52 #include <sys/param.h> 53 54 #include <errno.h> 55 #include <stdlib.h> 56 #include <string.h> 57 58 #ifdef I_AM_MERGESORT_B 59 #include "block_abi.h" 60 #define DECLARE_CMP DECLARE_BLOCK(int, cmp, const void *, const void *) 61 typedef DECLARE_BLOCK(int, cmp_t, const void *, const void *); 62 #define CMP(x, y) CALL_BLOCK(cmp, x, y) 63 #else 64 typedef int (*cmp_t)(const void *, const void *); 65 #define CMP(x, y) cmp(x, y) 66 #endif 67 68 static void setup(u_char *, u_char *, size_t, size_t, cmp_t); 69 static void insertionsort(u_char *, size_t, size_t, cmp_t); 70 71 #define ISIZE sizeof(int) 72 #define PSIZE sizeof(u_char *) 73 #define ICOPY_LIST(src, dst, last) \ 74 do \ 75 *(int*)dst = *(int*)src, src += ISIZE, dst += ISIZE; \ 76 while(src < last) 77 #define ICOPY_ELT(src, dst, i) \ 78 do \ 79 *(int*) dst = *(int*) src, src += ISIZE, dst += ISIZE; \ 80 while (i -= ISIZE) 81 82 #define CCOPY_LIST(src, dst, last) \ 83 do \ 84 *dst++ = *src++; \ 85 while (src < last) 86 #define CCOPY_ELT(src, dst, i) \ 87 do \ 88 *dst++ = *src++; \ 89 while (i -= 1) 90 91 /* 92 * Find the next possible pointer head. (Trickery for forcing an array 93 * to do double duty as a linked list when objects do not align with word 94 * boundaries. 95 */ 96 /* Assumption: PSIZE is a power of 2. */ 97 #define EVAL(p) (u_char **)roundup2((uintptr_t)p, PSIZE) 98 99 #ifdef I_AM_MERGESORT_B 100 int mergesort_b(void *, size_t, size_t, cmp_t); 101 #else 102 int mergesort(void *, size_t, size_t, cmp_t); 103 #endif 104 105 /* 106 * Arguments are as for qsort. 107 */ 108 int 109 #ifdef I_AM_MERGESORT_B 110 mergesort_b(void *base, size_t nmemb, size_t size, cmp_t cmp) 111 #else 112 mergesort(void *base, size_t nmemb, size_t size, cmp_t cmp) 113 #endif 114 { 115 size_t i; 116 int sense; 117 int big, iflag; 118 u_char *f1, *f2, *t, *b, *tp2, *q, *l1, *l2; 119 u_char *list2, *list1, *p2, *p, *last, **p1; 120 121 if (size < PSIZE / 2) { /* Pointers must fit into 2 * size. */ 122 errno = EINVAL; 123 return (-1); 124 } 125 126 if (nmemb == 0) 127 return (0); 128 129 iflag = 0; 130 if (__is_aligned(size, ISIZE) && __is_aligned(base, ISIZE)) 131 iflag = 1; 132 133 if ((list2 = malloc(nmemb * size + PSIZE)) == NULL) 134 return (-1); 135 136 list1 = base; 137 setup(list1, list2, nmemb, size, cmp); 138 last = list2 + nmemb * size; 139 i = big = 0; 140 while (*EVAL(list2) != last) { 141 l2 = list1; 142 p1 = EVAL(list1); 143 for (tp2 = p2 = list2; p2 != last; p1 = EVAL(l2)) { 144 p2 = *EVAL(p2); 145 f1 = l2; 146 f2 = l1 = list1 + (p2 - list2); 147 if (p2 != last) 148 p2 = *EVAL(p2); 149 l2 = list1 + (p2 - list2); 150 while (f1 < l1 && f2 < l2) { 151 if (CMP(f1, f2) <= 0) { 152 q = f2; 153 b = f1, t = l1; 154 sense = -1; 155 } else { 156 q = f1; 157 b = f2, t = l2; 158 sense = 0; 159 } 160 if (!big) { /* here i = 0 */ 161 while ((b += size) < t && CMP(q, b) >sense) 162 if (++i == 6) { 163 big = 1; 164 goto EXPONENTIAL; 165 } 166 } else { 167 EXPONENTIAL: for (i = size; ; i <<= 1) 168 if ((p = (b + i)) >= t) { 169 if ((p = t - size) > b && 170 CMP(q, p) <= sense) 171 t = p; 172 else 173 b = p; 174 break; 175 } else if (CMP(q, p) <= sense) { 176 t = p; 177 if (i == size) 178 big = 0; 179 goto FASTCASE; 180 } else 181 b = p; 182 while (t > b+size) { 183 i = (((t - b) / size) >> 1) * size; 184 if (CMP(q, p = b + i) <= sense) 185 t = p; 186 else 187 b = p; 188 } 189 goto COPY; 190 FASTCASE: while (i > size) 191 if (CMP(q, 192 p = b + (i >>= 1)) <= sense) 193 t = p; 194 else 195 b = p; 196 COPY: b = t; 197 } 198 i = size; 199 if (q == f1) { 200 if (iflag) { 201 ICOPY_LIST(f2, tp2, b); 202 ICOPY_ELT(f1, tp2, i); 203 } else { 204 CCOPY_LIST(f2, tp2, b); 205 CCOPY_ELT(f1, tp2, i); 206 } 207 } else { 208 if (iflag) { 209 ICOPY_LIST(f1, tp2, b); 210 ICOPY_ELT(f2, tp2, i); 211 } else { 212 CCOPY_LIST(f1, tp2, b); 213 CCOPY_ELT(f2, tp2, i); 214 } 215 } 216 } 217 if (f2 < l2) { 218 if (iflag) 219 ICOPY_LIST(f2, tp2, l2); 220 else 221 CCOPY_LIST(f2, tp2, l2); 222 } else if (f1 < l1) { 223 if (iflag) 224 ICOPY_LIST(f1, tp2, l1); 225 else 226 CCOPY_LIST(f1, tp2, l1); 227 } 228 *p1 = l2; 229 } 230 tp2 = list1; /* swap list1, list2 */ 231 list1 = list2; 232 list2 = tp2; 233 last = list2 + nmemb*size; 234 } 235 if (base == list2) { 236 memmove(list2, list1, nmemb*size); 237 list2 = list1; 238 } 239 free(list2); 240 return (0); 241 } 242 243 #define swap(a, b) { \ 244 s = b; \ 245 i = size; \ 246 do { \ 247 tmp = *a; *a++ = *s; *s++ = tmp; \ 248 } while (--i); \ 249 a -= size; \ 250 } 251 #define reverse(bot, top) { \ 252 s = top; \ 253 do { \ 254 i = size; \ 255 do { \ 256 tmp = *bot; *bot++ = *s; *s++ = tmp; \ 257 } while (--i); \ 258 s -= size2; \ 259 } while(bot < s); \ 260 } 261 262 /* 263 * Optional hybrid natural/pairwise first pass. Eats up list1 in runs of 264 * increasing order, list2 in a corresponding linked list. Checks for runs 265 * when THRESHOLD/2 pairs compare with same sense. (Only used when NATURAL 266 * is defined. Otherwise simple pairwise merging is used.) 267 */ 268 void 269 setup(u_char *list1, u_char *list2, size_t n, size_t size, cmp_t cmp) 270 { 271 int i, length, size2, tmp, sense; 272 u_char *f1, *f2, *s, *l2, *last, *p2; 273 274 size2 = size*2; 275 if (n <= 5) { 276 insertionsort(list1, n, size, cmp); 277 *EVAL(list2) = (u_char*) list2 + n*size; 278 return; 279 } 280 /* 281 * Avoid running pointers out of bounds; limit n to evens 282 * for simplicity. 283 */ 284 i = 4 + (n & 1); 285 insertionsort(list1 + (n - i) * size, i, size, cmp); 286 last = list1 + size * (n - i); 287 *EVAL(list2 + (last - list1)) = list2 + n * size; 288 289 #ifdef NATURAL 290 p2 = list2; 291 f1 = list1; 292 sense = (CMP(f1, f1 + size) > 0); 293 for (; f1 < last; sense = !sense) { 294 length = 2; 295 /* Find pairs with same sense. */ 296 for (f2 = f1 + size2; f2 < last; f2 += size2) { 297 if ((CMP(f2, f2+ size) > 0) != sense) 298 break; 299 length += 2; 300 } 301 if (length < THRESHOLD) { /* Pairwise merge */ 302 do { 303 p2 = *EVAL(p2) = f1 + size2 - list1 + list2; 304 if (sense > 0) 305 swap (f1, f1 + size); 306 } while ((f1 += size2) < f2); 307 } else { /* Natural merge */ 308 l2 = f2; 309 for (f2 = f1 + size2; f2 < l2; f2 += size2) { 310 if ((CMP(f2-size, f2) > 0) != sense) { 311 p2 = *EVAL(p2) = f2 - list1 + list2; 312 if (sense > 0) 313 reverse(f1, f2-size); 314 f1 = f2; 315 } 316 } 317 if (sense > 0) 318 reverse (f1, f2-size); 319 f1 = f2; 320 if (f2 < last || CMP(f2 - size, f2) > 0) 321 p2 = *EVAL(p2) = f2 - list1 + list2; 322 else 323 p2 = *EVAL(p2) = list2 + n*size; 324 } 325 } 326 #else /* pairwise merge only. */ 327 for (f1 = list1, p2 = list2; f1 < last; f1 += size2) { 328 p2 = *EVAL(p2) = p2 + size2; 329 if (CMP (f1, f1 + size) > 0) 330 swap(f1, f1 + size); 331 } 332 #endif /* NATURAL */ 333 } 334 335 /* 336 * This is to avoid out-of-bounds addresses in sorting the 337 * last 4 elements. 338 */ 339 static void 340 insertionsort(u_char *a, size_t n, size_t size, cmp_t cmp) 341 { 342 u_char *ai, *s, *t, *u, tmp; 343 int i; 344 345 for (ai = a+size; --n >= 1; ai += size) 346 for (t = ai; t > a; t -= size) { 347 u = t - size; 348 if (CMP(u, t) <= 0) 349 break; 350 swap(u, t); 351 } 352 } 353