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 37 #if defined(LIBC_SCCS) && !defined(lint) 38 static char sccsid[] = "@(#)merge.c 8.2 (Berkeley) 2/14/94"; 39 #endif /* LIBC_SCCS and not lint */ 40 41 /* 42 * Hybrid exponential search/linear search merge sort with hybrid 43 * natural/pairwise first pass. Requires about .3% more comparisons 44 * for random data than LSMS with pairwise first pass alone. 45 * It works for objects as small as two bytes. 46 */ 47 48 #define NATURAL 49 #define THRESHOLD 16 /* Best choice for natural merge cut-off. */ 50 51 /* #define NATURAL to get hybrid natural merge. 52 * (The default is pairwise merging.) 53 */ 54 55 #include <sys/types.h> 56 57 #include <errno.h> 58 #include <stdlib.h> 59 #include <string.h> 60 61 static void setup __P((u_char *, u_char *, size_t, size_t, int (*)())); 62 static void insertionsort __P((u_char *, size_t, size_t, int (*)())); 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 register size_t size; 102 int (*cmp) __P((const void *, const void *)); 103 { 104 register int i, sense; 105 int big, iflag; 106 register u_char *f1, *f2, *t, *b, *tp2, *q, *l1, *l2; 107 u_char *list2, *list1, *p2, *p, *last, **p1; 108 109 if (size < PSIZE / 2) { /* Pointers must fit into 2 * size. */ 110 errno = EINVAL; 111 return (-1); 112 } 113 114 if (nmemb == 0) 115 return (0); 116 117 /* 118 * XXX 119 * Stupid subtraction for the Cray. 120 */ 121 iflag = 0; 122 if (!(size % ISIZE) && !(((char *)base - (char *)0) % ISIZE)) 123 iflag = 1; 124 125 if ((list2 = malloc(nmemb * size + PSIZE)) == NULL) 126 return (-1); 127 128 list1 = base; 129 setup(list1, list2, nmemb, size, cmp); 130 last = list2 + nmemb * size; 131 i = big = 0; 132 while (*EVAL(list2) != last) { 133 l2 = list1; 134 p1 = EVAL(list1); 135 for (tp2 = p2 = list2; p2 != last; p1 = EVAL(l2)) { 136 p2 = *EVAL(p2); 137 f1 = l2; 138 f2 = l1 = list1 + (p2 - list2); 139 if (p2 != last) 140 p2 = *EVAL(p2); 141 l2 = list1 + (p2 - list2); 142 while (f1 < l1 && f2 < l2) { 143 if ((*cmp)(f1, f2) <= 0) { 144 q = f2; 145 b = f1, t = l1; 146 sense = -1; 147 } else { 148 q = f1; 149 b = f2, t = l2; 150 sense = 0; 151 } 152 if (!big) { /* here i = 0 */ 153 while ((b += size) < t && cmp(q, b) >sense) 154 if (++i == 6) { 155 big = 1; 156 goto EXPONENTIAL; 157 } 158 } else { 159 EXPONENTIAL: for (i = size; ; i <<= 1) 160 if ((p = (b + i)) >= t) { 161 if ((p = t - size) > b && 162 (*cmp)(q, p) <= sense) 163 t = p; 164 else 165 b = p; 166 break; 167 } else if ((*cmp)(q, p) <= sense) { 168 t = p; 169 if (i == size) 170 big = 0; 171 goto FASTCASE; 172 } else 173 b = p; 174 while (t > b+size) { 175 i = (((t - b) / size) >> 1) * size; 176 if ((*cmp)(q, p = b + i) <= sense) 177 t = p; 178 else 179 b = p; 180 } 181 goto COPY; 182 FASTCASE: while (i > size) 183 if ((*cmp)(q, 184 p = b + (i >>= 1)) <= sense) 185 t = p; 186 else 187 b = p; 188 COPY: b = t; 189 } 190 i = size; 191 if (q == f1) { 192 if (iflag) { 193 ICOPY_LIST(f2, tp2, b); 194 ICOPY_ELT(f1, tp2, i); 195 } else { 196 CCOPY_LIST(f2, tp2, b); 197 CCOPY_ELT(f1, tp2, i); 198 } 199 } else { 200 if (iflag) { 201 ICOPY_LIST(f1, tp2, b); 202 ICOPY_ELT(f2, tp2, i); 203 } else { 204 CCOPY_LIST(f1, tp2, b); 205 CCOPY_ELT(f2, tp2, i); 206 } 207 } 208 } 209 if (f2 < l2) { 210 if (iflag) 211 ICOPY_LIST(f2, tp2, l2); 212 else 213 CCOPY_LIST(f2, tp2, l2); 214 } else if (f1 < l1) { 215 if (iflag) 216 ICOPY_LIST(f1, tp2, l1); 217 else 218 CCOPY_LIST(f1, tp2, l1); 219 } 220 *p1 = l2; 221 } 222 tp2 = list1; /* swap list1, list2 */ 223 list1 = list2; 224 list2 = tp2; 225 last = list2 + nmemb*size; 226 } 227 if (base == list2) { 228 memmove(list2, list1, nmemb*size); 229 list2 = list1; 230 } 231 free(list2); 232 return (0); 233 } 234 235 #define swap(a, b) { \ 236 s = b; \ 237 i = size; \ 238 do { \ 239 tmp = *a; *a++ = *s; *s++ = tmp; \ 240 } while (--i); \ 241 a -= size; \ 242 } 243 #define reverse(bot, top) { \ 244 s = top; \ 245 do { \ 246 i = size; \ 247 do { \ 248 tmp = *bot; *bot++ = *s; *s++ = tmp; \ 249 } while (--i); \ 250 s -= size2; \ 251 } while(bot < s); \ 252 } 253 254 /* 255 * Optional hybrid natural/pairwise first pass. Eats up list1 in runs of 256 * increasing order, list2 in a corresponding linked list. Checks for runs 257 * when THRESHOLD/2 pairs compare with same sense. (Only used when NATURAL 258 * is defined. Otherwise simple pairwise merging is used.) 259 */ 260 void 261 setup(list1, list2, n, size, cmp) 262 size_t n, size; 263 int (*cmp) __P((const void *, const void *)); 264 u_char *list1, *list2; 265 { 266 int i, length, size2, tmp, sense; 267 u_char *f1, *f2, *s, *l2, *last, *p2; 268 269 size2 = size*2; 270 if (n <= 5) { 271 insertionsort(list1, n, size, cmp); 272 *EVAL(list2) = (u_char*) list2 + n*size; 273 return; 274 } 275 /* 276 * Avoid running pointers out of bounds; limit n to evens 277 * for simplicity. 278 */ 279 i = 4 + (n & 1); 280 insertionsort(list1 + (n - i) * size, i, size, cmp); 281 last = list1 + size * (n - i); 282 *EVAL(list2 + (last - list1)) = list2 + n * size; 283 284 #ifdef NATURAL 285 p2 = list2; 286 f1 = list1; 287 sense = (cmp(f1, f1 + size) > 0); 288 for (; f1 < last; sense = !sense) { 289 length = 2; 290 /* Find pairs with same sense. */ 291 for (f2 = f1 + size2; f2 < last; f2 += size2) { 292 if ((cmp(f2, f2+ size) > 0) != sense) 293 break; 294 length += 2; 295 } 296 if (length < THRESHOLD) { /* Pairwise merge */ 297 do { 298 p2 = *EVAL(p2) = f1 + size2 - list1 + list2; 299 if (sense > 0) 300 swap (f1, f1 + size); 301 } while ((f1 += size2) < f2); 302 } else { /* Natural merge */ 303 l2 = f2; 304 for (f2 = f1 + size2; f2 < l2; f2 += size2) { 305 if ((cmp(f2-size, f2) > 0) != sense) { 306 p2 = *EVAL(p2) = f2 - list1 + list2; 307 if (sense > 0) 308 reverse(f1, f2-size); 309 f1 = f2; 310 } 311 } 312 if (sense > 0) 313 reverse (f1, f2-size); 314 f1 = f2; 315 if (f2 < last || cmp(f2 - size, f2) > 0) 316 p2 = *EVAL(p2) = f2 - list1 + list2; 317 else 318 p2 = *EVAL(p2) = list2 + n*size; 319 } 320 } 321 #else /* pairwise merge only. */ 322 for (f1 = list1, p2 = list2; f1 < last; f1 += size2) { 323 p2 = *EVAL(p2) = p2 + size2; 324 if (cmp (f1, f1 + size) > 0) 325 swap(f1, f1 + size); 326 } 327 #endif /* NATURAL */ 328 } 329 330 /* 331 * This is to avoid out-of-bounds addresses in sorting the 332 * last 4 elements. 333 */ 334 static void 335 insertionsort(a, n, size, cmp) 336 u_char *a; 337 size_t n, size; 338 int (*cmp) __P((const void *, const void *)); 339 { 340 u_char *ai, *s, *t, *u, tmp; 341 int i; 342 343 for (ai = a+size; --n >= 1; ai += size) 344 for (t = ai; t > a; t -= size) { 345 u = t - size; 346 if (cmp(u, t) <= 0) 347 break; 348 swap(u, t); 349 } 350 } 351