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. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by the University of 19 * California, Berkeley and its contributors. 20 * 4. Neither the name of the University nor the names of its contributors 21 * may be used to endorse or promote products derived from this software 22 * without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 * 36 * @(#)merge.c 8.2 (Berkeley) 2/14/94 37 * $DragonFly: src/lib/libc/stdlib/merge.c,v 1.5 2005/03/09 02:44:42 drhodus Exp $ 38 */ 39 40 /* 41 * Hybrid exponential search/linear search merge sort with hybrid 42 * natural/pairwise first pass. Requires about .3% more comparisons 43 * for random data than LSMS with pairwise first pass alone. 44 * It works for objects as small as two bytes. 45 */ 46 47 #define NATURAL 48 #define THRESHOLD 16 /* Best choice for natural merge cut-off. */ 49 50 /* #define NATURAL to get hybrid natural merge. 51 * (The default is pairwise merging.) 52 */ 53 54 #include <sys/types.h> 55 56 #include <errno.h> 57 #include <stdlib.h> 58 #include <string.h> 59 60 static void setup(u_char *, u_char *, size_t, size_t, 61 int (*)(const void *, const void *)); 62 static void insertionsort(u_char *, size_t, size_t, 63 int (*)(const void *, const void *)); 64 65 #define ISIZE sizeof(int) 66 #define PSIZE sizeof(u_char *) 67 #define ICOPY_LIST(src, dst, last) \ 68 do \ 69 *(int*)dst = *(int*)src, src += ISIZE, dst += ISIZE; \ 70 while(src < last) 71 #define ICOPY_ELT(src, dst, i) \ 72 do \ 73 *(int*) dst = *(int*) src, src += ISIZE, dst += ISIZE; \ 74 while (i -= ISIZE) 75 76 #define CCOPY_LIST(src, dst, last) \ 77 do \ 78 *dst++ = *src++; \ 79 while (src < last) 80 #define CCOPY_ELT(src, dst, i) \ 81 do \ 82 *dst++ = *src++; \ 83 while (i -= 1) 84 85 /* 86 * Find the next possible pointer head. (Trickery for forcing an array 87 * to do double duty as a linked list when objects do not align with word 88 * boundaries. 89 */ 90 /* Assumption: PSIZE is a power of 2. */ 91 #define EVAL(p) (u_char **) \ 92 ((u_char *)0 + \ 93 (((u_char *)p + PSIZE - 1 - (u_char *) 0) & ~(PSIZE - 1))) 94 95 /* 96 * Arguments are as for qsort. 97 */ 98 int 99 mergesort(base, nmemb, size, cmp) 100 void *base; 101 size_t nmemb; 102 size_t size; 103 int (*cmp) (const void *, const void *); 104 { 105 size_t i; 106 int sense; 107 int big, iflag; 108 u_char *f1, *f2, *t, *b, *tp2, *q, *l1, *l2; 109 u_char *list2, *list1, *p2, *p, *last, **p1; 110 111 if (size < PSIZE / 2) { /* Pointers must fit into 2 * size. */ 112 errno = EINVAL; 113 return (-1); 114 } 115 116 if (nmemb == 0) 117 return (0); 118 119 /* 120 * XXX 121 * Stupid subtraction for the Cray. 122 */ 123 iflag = 0; 124 if (!(size % ISIZE) && !(((char *)base - (char *)0) % ISIZE)) 125 iflag = 1; 126 127 if ((list2 = malloc(nmemb * size + PSIZE)) == NULL) 128 return (-1); 129 130 list1 = base; 131 setup(list1, list2, nmemb, size, cmp); 132 last = list2 + nmemb * size; 133 i = big = 0; 134 while (*EVAL(list2) != last) { 135 l2 = list1; 136 p1 = EVAL(list1); 137 for (tp2 = p2 = list2; p2 != last; p1 = EVAL(l2)) { 138 p2 = *EVAL(p2); 139 f1 = l2; 140 f2 = l1 = list1 + (p2 - list2); 141 if (p2 != last) 142 p2 = *EVAL(p2); 143 l2 = list1 + (p2 - list2); 144 while (f1 < l1 && f2 < l2) { 145 if ((*cmp)(f1, f2) <= 0) { 146 q = f2; 147 b = f1, t = l1; 148 sense = -1; 149 } else { 150 q = f1; 151 b = f2, t = l2; 152 sense = 0; 153 } 154 if (!big) { /* here i = 0 */ 155 while ((b += size) < t && cmp(q, b) >sense) 156 if (++i == 6) { 157 big = 1; 158 goto EXPONENTIAL; 159 } 160 } else { 161 EXPONENTIAL: for (i = size; ; i <<= 1) 162 if ((p = (b + i)) >= t) { 163 if ((p = t - size) > b && 164 (*cmp)(q, p) <= sense) 165 t = p; 166 else 167 b = p; 168 break; 169 } else if ((*cmp)(q, p) <= sense) { 170 t = p; 171 if (i == size) 172 big = 0; 173 goto FASTCASE; 174 } else 175 b = p; 176 while (t > b+size) { 177 i = (((t - b) / size) >> 1) * size; 178 if ((*cmp)(q, p = b + i) <= sense) 179 t = p; 180 else 181 b = p; 182 } 183 goto COPY; 184 FASTCASE: while (i > size) 185 if ((*cmp)(q, 186 p = b + (i >>= 1)) <= sense) 187 t = p; 188 else 189 b = p; 190 COPY: b = t; 191 } 192 i = size; 193 if (q == f1) { 194 if (iflag) { 195 ICOPY_LIST(f2, tp2, b); 196 ICOPY_ELT(f1, tp2, i); 197 } else { 198 CCOPY_LIST(f2, tp2, b); 199 CCOPY_ELT(f1, tp2, i); 200 } 201 } else { 202 if (iflag) { 203 ICOPY_LIST(f1, tp2, b); 204 ICOPY_ELT(f2, tp2, i); 205 } else { 206 CCOPY_LIST(f1, tp2, b); 207 CCOPY_ELT(f2, tp2, i); 208 } 209 } 210 } 211 if (f2 < l2) { 212 if (iflag) 213 ICOPY_LIST(f2, tp2, l2); 214 else 215 CCOPY_LIST(f2, tp2, l2); 216 } else if (f1 < l1) { 217 if (iflag) 218 ICOPY_LIST(f1, tp2, l1); 219 else 220 CCOPY_LIST(f1, tp2, l1); 221 } 222 *p1 = l2; 223 } 224 tp2 = list1; /* swap list1, list2 */ 225 list1 = list2; 226 list2 = tp2; 227 last = list2 + nmemb*size; 228 } 229 if (base == list2) { 230 memmove(list2, list1, nmemb*size); 231 list2 = list1; 232 } 233 free(list2); 234 return (0); 235 } 236 237 #define swap(a, b) { \ 238 s = b; \ 239 i = size; \ 240 do { \ 241 tmp = *a; *a++ = *s; *s++ = tmp; \ 242 } while (--i); \ 243 a -= size; \ 244 } 245 #define reverse(bot, top) { \ 246 s = top; \ 247 do { \ 248 i = size; \ 249 do { \ 250 tmp = *bot; *bot++ = *s; *s++ = tmp; \ 251 } while (--i); \ 252 s -= size2; \ 253 } while(bot < s); \ 254 } 255 256 /* 257 * Optional hybrid natural/pairwise first pass. Eats up list1 in runs of 258 * increasing order, list2 in a corresponding linked list. Checks for runs 259 * when THRESHOLD/2 pairs compare with same sense. (Only used when NATURAL 260 * is defined. Otherwise simple pairwise merging is used.) 261 */ 262 void 263 setup(list1, list2, n, size, cmp) 264 size_t n, size; 265 int (*cmp) (const void *, const void *); 266 u_char *list1, *list2; 267 { 268 int i, length, size2, tmp, sense; 269 u_char *f1, *f2, *s, *l2, *last, *p2; 270 271 size2 = size*2; 272 if (n <= 5) { 273 insertionsort(list1, n, size, cmp); 274 *EVAL(list2) = (u_char*) list2 + n*size; 275 return; 276 } 277 /* 278 * Avoid running pointers out of bounds; limit n to evens 279 * for simplicity. 280 */ 281 i = 4 + (n & 1); 282 insertionsort(list1 + (n - i) * size, i, size, cmp); 283 last = list1 + size * (n - i); 284 *EVAL(list2 + (last - list1)) = list2 + n * size; 285 286 #ifdef NATURAL 287 p2 = list2; 288 f1 = list1; 289 sense = (cmp(f1, f1 + size) > 0); 290 for (; f1 < last; sense = !sense) { 291 length = 2; 292 /* Find pairs with same sense. */ 293 for (f2 = f1 + size2; f2 < last; f2 += size2) { 294 if ((cmp(f2, f2+ size) > 0) != sense) 295 break; 296 length += 2; 297 } 298 if (length < THRESHOLD) { /* Pairwise merge */ 299 do { 300 p2 = *EVAL(p2) = f1 + size2 - list1 + list2; 301 if (sense > 0) 302 swap (f1, f1 + size); 303 } while ((f1 += size2) < f2); 304 } else { /* Natural merge */ 305 l2 = f2; 306 for (f2 = f1 + size2; f2 < l2; f2 += size2) { 307 if ((cmp(f2-size, f2) > 0) != sense) { 308 p2 = *EVAL(p2) = f2 - list1 + list2; 309 if (sense > 0) 310 reverse(f1, f2-size); 311 f1 = f2; 312 } 313 } 314 if (sense > 0) 315 reverse (f1, f2-size); 316 f1 = f2; 317 if (f2 < last || cmp(f2 - size, f2) > 0) 318 p2 = *EVAL(p2) = f2 - list1 + list2; 319 else 320 p2 = *EVAL(p2) = list2 + n*size; 321 } 322 } 323 #else /* pairwise merge only. */ 324 for (f1 = list1, p2 = list2; f1 < last; f1 += size2) { 325 p2 = *EVAL(p2) = p2 + size2; 326 if (cmp (f1, f1 + size) > 0) 327 swap(f1, f1 + size); 328 } 329 #endif /* NATURAL */ 330 } 331 332 /* 333 * This is to avoid out-of-bounds addresses in sorting the 334 * last 4 elements. 335 */ 336 static void 337 insertionsort(a, n, size, cmp) 338 u_char *a; 339 size_t n, size; 340 int (*cmp) (const void *, const void *); 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