1 /*- 2 * Copyright (c) 1992, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * This code is derived from software contributed to Berkeley by 6 * Peter McIlroy. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. Neither the name of the University nor the names of its contributors 17 * may be used to endorse or promote products derived from this software 18 * without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 */ 32 33 #if defined(LIBC_SCCS) && !defined(lint) 34 static char sccsid[] = "@(#)merge.c 8.2 (Berkeley) 2/14/94"; 35 #endif /* LIBC_SCCS and not lint */ 36 #include <sys/cdefs.h> 37 __FBSDID("$FreeBSD$"); 38 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/types.h> 54 55 #include <errno.h> 56 #include <stdlib.h> 57 #include <string.h> 58 59 static void setup(u_char *, u_char *, size_t, size_t, 60 int (*)(const void *, const void *)); 61 static void insertionsort(u_char *, size_t, size_t, 62 int (*)(const void *, const void *)); 63 64 #define ISIZE sizeof(int) 65 #define PSIZE sizeof(u_char *) 66 #define ICOPY_LIST(src, dst, last) \ 67 do \ 68 *(int*)dst = *(int*)src, src += ISIZE, dst += ISIZE; \ 69 while(src < last) 70 #define ICOPY_ELT(src, dst, i) \ 71 do \ 72 *(int*) dst = *(int*) src, src += ISIZE, dst += ISIZE; \ 73 while (i -= ISIZE) 74 75 #define CCOPY_LIST(src, dst, last) \ 76 do \ 77 *dst++ = *src++; \ 78 while (src < last) 79 #define CCOPY_ELT(src, dst, i) \ 80 do \ 81 *dst++ = *src++; \ 82 while (i -= 1) 83 84 /* 85 * Find the next possible pointer head. (Trickery for forcing an array 86 * to do double duty as a linked list when objects do not align with word 87 * boundaries. 88 */ 89 /* Assumption: PSIZE is a power of 2. */ 90 #define EVAL(p) (u_char **) \ 91 ((u_char *)0 + \ 92 (((u_char *)p + PSIZE - 1 - (u_char *) 0) & ~(PSIZE - 1))) 93 94 /* 95 * Arguments are as for qsort. 96 */ 97 int 98 mergesort(base, nmemb, size, cmp) 99 void *base; 100 size_t nmemb; 101 size_t size; 102 int (*cmp)(const void *, const void *); 103 { 104 size_t i; 105 int sense; 106 int big, iflag; 107 u_char *f1, *f2, *t, *b, *tp2, *q, *l1, *l2; 108 u_char *list2, *list1, *p2, *p, *last, **p1; 109 110 if (size < PSIZE / 2) { /* Pointers must fit into 2 * size. */ 111 errno = EINVAL; 112 return (-1); 113 } 114 115 if (nmemb == 0) 116 return (0); 117 118 /* 119 * XXX 120 * Stupid subtraction for the Cray. 121 */ 122 iflag = 0; 123 if (!(size % ISIZE) && !(((char *)base - (char *)0) % ISIZE)) 124 iflag = 1; 125 126 if ((list2 = malloc(nmemb * size + PSIZE)) == NULL) 127 return (-1); 128 129 list1 = base; 130 setup(list1, list2, nmemb, size, cmp); 131 last = list2 + nmemb * size; 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 if (iflag) { 194 ICOPY_LIST(f2, tp2, b); 195 ICOPY_ELT(f1, tp2, i); 196 } else { 197 CCOPY_LIST(f2, tp2, b); 198 CCOPY_ELT(f1, tp2, i); 199 } 200 } else { 201 if (iflag) { 202 ICOPY_LIST(f1, tp2, b); 203 ICOPY_ELT(f2, tp2, i); 204 } else { 205 CCOPY_LIST(f1, tp2, b); 206 CCOPY_ELT(f2, tp2, i); 207 } 208 } 209 } 210 if (f2 < l2) { 211 if (iflag) 212 ICOPY_LIST(f2, tp2, l2); 213 else 214 CCOPY_LIST(f2, tp2, l2); 215 } else if (f1 < l1) { 216 if (iflag) 217 ICOPY_LIST(f1, tp2, l1); 218 else 219 CCOPY_LIST(f1, tp2, l1); 220 } 221 *p1 = l2; 222 } 223 tp2 = list1; /* swap list1, list2 */ 224 list1 = list2; 225 list2 = tp2; 226 last = list2 + nmemb*size; 227 } 228 if (base == list2) { 229 memmove(list2, list1, nmemb*size); 230 list2 = list1; 231 } 232 free(list2); 233 return (0); 234 } 235 236 #define swap(a, b) { \ 237 s = b; \ 238 i = size; \ 239 do { \ 240 tmp = *a; *a++ = *s; *s++ = tmp; \ 241 } while (--i); \ 242 a -= size; \ 243 } 244 #define reverse(bot, top) { \ 245 s = top; \ 246 do { \ 247 i = size; \ 248 do { \ 249 tmp = *bot; *bot++ = *s; *s++ = tmp; \ 250 } while (--i); \ 251 s -= size2; \ 252 } while(bot < s); \ 253 } 254 255 /* 256 * Optional hybrid natural/pairwise first pass. Eats up list1 in runs of 257 * increasing order, list2 in a corresponding linked list. Checks for runs 258 * when THRESHOLD/2 pairs compare with same sense. (Only used when NATURAL 259 * is defined. Otherwise simple pairwise merging is used.) 260 */ 261 void 262 setup(list1, list2, n, size, cmp) 263 size_t n, size; 264 int (*cmp)(const void *, const void *); 265 u_char *list1, *list2; 266 { 267 int i, length, size2, tmp, sense; 268 u_char *f1, *f2, *s, *l2, *last, *p2; 269 270 size2 = size*2; 271 if (n <= 5) { 272 insertionsort(list1, n, size, cmp); 273 *EVAL(list2) = (u_char*) list2 + n*size; 274 return; 275 } 276 /* 277 * Avoid running pointers out of bounds; limit n to evens 278 * for simplicity. 279 */ 280 i = 4 + (n & 1); 281 insertionsort(list1 + (n - i) * size, i, size, cmp); 282 last = list1 + size * (n - i); 283 *EVAL(list2 + (last - list1)) = list2 + n * size; 284 285 #ifdef NATURAL 286 p2 = list2; 287 f1 = list1; 288 sense = (cmp(f1, f1 + size) > 0); 289 for (; f1 < last; sense = !sense) { 290 length = 2; 291 /* Find pairs with same sense. */ 292 for (f2 = f1 + size2; f2 < last; f2 += size2) { 293 if ((cmp(f2, f2+ size) > 0) != sense) 294 break; 295 length += 2; 296 } 297 if (length < THRESHOLD) { /* Pairwise merge */ 298 do { 299 p2 = *EVAL(p2) = f1 + size2 - list1 + list2; 300 if (sense > 0) 301 swap (f1, f1 + size); 302 } while ((f1 += size2) < f2); 303 } else { /* Natural merge */ 304 l2 = f2; 305 for (f2 = f1 + size2; f2 < l2; f2 += size2) { 306 if ((cmp(f2-size, f2) > 0) != sense) { 307 p2 = *EVAL(p2) = f2 - list1 + list2; 308 if (sense > 0) 309 reverse(f1, f2-size); 310 f1 = f2; 311 } 312 } 313 if (sense > 0) 314 reverse (f1, f2-size); 315 f1 = f2; 316 if (f2 < last || cmp(f2 - size, f2) > 0) 317 p2 = *EVAL(p2) = f2 - list1 + list2; 318 else 319 p2 = *EVAL(p2) = list2 + n*size; 320 } 321 } 322 #else /* pairwise merge only. */ 323 for (f1 = list1, p2 = list2; f1 < last; f1 += size2) { 324 p2 = *EVAL(p2) = p2 + size2; 325 if (cmp (f1, f1 + size) > 0) 326 swap(f1, f1 + size); 327 } 328 #endif /* NATURAL */ 329 } 330 331 /* 332 * This is to avoid out-of-bounds addresses in sorting the 333 * last 4 elements. 334 */ 335 static void 336 insertionsort(a, n, size, cmp) 337 u_char *a; 338 size_t n, size; 339 int (*cmp)(const void *, const void *); 340 { 341 u_char *ai, *s, *t, *u, tmp; 342 int i; 343 344 for (ai = a+size; --n >= 1; ai += size) 345 for (t = ai; t > a; t -= size) { 346 u = t - size; 347 if (cmp(u, t) <= 0) 348 break; 349 swap(u, t); 350 } 351 } 352