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 #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 **) \ 99 ((u_char *)0 + \ 100 (((u_char *)p + PSIZE - 1 - (u_char *) 0) & ~(PSIZE - 1))) 101 102 /* 103 * Arguments are as for qsort. 104 */ 105 int 106 #ifdef I_AM_MERGESORT_B 107 mergesort_b(base, nmemb, size, cmp) 108 #else 109 mergesort(base, nmemb, size, cmp) 110 #endif 111 void *base; 112 size_t nmemb; 113 size_t size; 114 cmp_t cmp; 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 /* 131 * XXX 132 * Stupid subtraction for the Cray. 133 */ 134 iflag = 0; 135 if (!(size % ISIZE) && !(((char *)base - (char *)0) % ISIZE)) 136 iflag = 1; 137 138 if ((list2 = malloc(nmemb * size + PSIZE)) == NULL) 139 return (-1); 140 141 list1 = base; 142 setup(list1, list2, nmemb, size, cmp); 143 last = list2 + nmemb * size; 144 i = big = 0; 145 while (*EVAL(list2) != last) { 146 l2 = list1; 147 p1 = EVAL(list1); 148 for (tp2 = p2 = list2; p2 != last; p1 = EVAL(l2)) { 149 p2 = *EVAL(p2); 150 f1 = l2; 151 f2 = l1 = list1 + (p2 - list2); 152 if (p2 != last) 153 p2 = *EVAL(p2); 154 l2 = list1 + (p2 - list2); 155 while (f1 < l1 && f2 < l2) { 156 if (CMP(f1, f2) <= 0) { 157 q = f2; 158 b = f1, t = l1; 159 sense = -1; 160 } else { 161 q = f1; 162 b = f2, t = l2; 163 sense = 0; 164 } 165 if (!big) { /* here i = 0 */ 166 while ((b += size) < t && CMP(q, b) >sense) 167 if (++i == 6) { 168 big = 1; 169 goto EXPONENTIAL; 170 } 171 } else { 172 EXPONENTIAL: for (i = size; ; i <<= 1) 173 if ((p = (b + i)) >= t) { 174 if ((p = t - size) > b && 175 CMP(q, p) <= sense) 176 t = p; 177 else 178 b = p; 179 break; 180 } else if (CMP(q, p) <= sense) { 181 t = p; 182 if (i == size) 183 big = 0; 184 goto FASTCASE; 185 } else 186 b = p; 187 while (t > b+size) { 188 i = (((t - b) / size) >> 1) * size; 189 if (CMP(q, p = b + i) <= sense) 190 t = p; 191 else 192 b = p; 193 } 194 goto COPY; 195 FASTCASE: while (i > size) 196 if (CMP(q, 197 p = b + (i >>= 1)) <= sense) 198 t = p; 199 else 200 b = p; 201 COPY: b = t; 202 } 203 i = size; 204 if (q == f1) { 205 if (iflag) { 206 ICOPY_LIST(f2, tp2, b); 207 ICOPY_ELT(f1, tp2, i); 208 } else { 209 CCOPY_LIST(f2, tp2, b); 210 CCOPY_ELT(f1, tp2, i); 211 } 212 } else { 213 if (iflag) { 214 ICOPY_LIST(f1, tp2, b); 215 ICOPY_ELT(f2, tp2, i); 216 } else { 217 CCOPY_LIST(f1, tp2, b); 218 CCOPY_ELT(f2, tp2, i); 219 } 220 } 221 } 222 if (f2 < l2) { 223 if (iflag) 224 ICOPY_LIST(f2, tp2, l2); 225 else 226 CCOPY_LIST(f2, tp2, l2); 227 } else if (f1 < l1) { 228 if (iflag) 229 ICOPY_LIST(f1, tp2, l1); 230 else 231 CCOPY_LIST(f1, tp2, l1); 232 } 233 *p1 = l2; 234 } 235 tp2 = list1; /* swap list1, list2 */ 236 list1 = list2; 237 list2 = tp2; 238 last = list2 + nmemb*size; 239 } 240 if (base == list2) { 241 memmove(list2, list1, nmemb*size); 242 list2 = list1; 243 } 244 free(list2); 245 return (0); 246 } 247 248 #define swap(a, b) { \ 249 s = b; \ 250 i = size; \ 251 do { \ 252 tmp = *a; *a++ = *s; *s++ = tmp; \ 253 } while (--i); \ 254 a -= size; \ 255 } 256 #define reverse(bot, top) { \ 257 s = top; \ 258 do { \ 259 i = size; \ 260 do { \ 261 tmp = *bot; *bot++ = *s; *s++ = tmp; \ 262 } while (--i); \ 263 s -= size2; \ 264 } while(bot < s); \ 265 } 266 267 /* 268 * Optional hybrid natural/pairwise first pass. Eats up list1 in runs of 269 * increasing order, list2 in a corresponding linked list. Checks for runs 270 * when THRESHOLD/2 pairs compare with same sense. (Only used when NATURAL 271 * is defined. Otherwise simple pairwise merging is used.) 272 */ 273 void 274 setup(list1, list2, n, size, cmp) 275 size_t n, size; 276 u_char *list1, *list2; 277 cmp_t cmp; 278 { 279 int i, length, size2, tmp, sense; 280 u_char *f1, *f2, *s, *l2, *last, *p2; 281 282 size2 = size*2; 283 if (n <= 5) { 284 insertionsort(list1, n, size, cmp); 285 *EVAL(list2) = (u_char*) list2 + n*size; 286 return; 287 } 288 /* 289 * Avoid running pointers out of bounds; limit n to evens 290 * for simplicity. 291 */ 292 i = 4 + (n & 1); 293 insertionsort(list1 + (n - i) * size, i, size, cmp); 294 last = list1 + size * (n - i); 295 *EVAL(list2 + (last - list1)) = list2 + n * size; 296 297 #ifdef NATURAL 298 p2 = list2; 299 f1 = list1; 300 sense = (CMP(f1, f1 + size) > 0); 301 for (; f1 < last; sense = !sense) { 302 length = 2; 303 /* Find pairs with same sense. */ 304 for (f2 = f1 + size2; f2 < last; f2 += size2) { 305 if ((CMP(f2, f2+ size) > 0) != sense) 306 break; 307 length += 2; 308 } 309 if (length < THRESHOLD) { /* Pairwise merge */ 310 do { 311 p2 = *EVAL(p2) = f1 + size2 - list1 + list2; 312 if (sense > 0) 313 swap (f1, f1 + size); 314 } while ((f1 += size2) < f2); 315 } else { /* Natural merge */ 316 l2 = f2; 317 for (f2 = f1 + size2; f2 < l2; f2 += size2) { 318 if ((CMP(f2-size, f2) > 0) != sense) { 319 p2 = *EVAL(p2) = f2 - list1 + list2; 320 if (sense > 0) 321 reverse(f1, f2-size); 322 f1 = f2; 323 } 324 } 325 if (sense > 0) 326 reverse (f1, f2-size); 327 f1 = f2; 328 if (f2 < last || CMP(f2 - size, f2) > 0) 329 p2 = *EVAL(p2) = f2 - list1 + list2; 330 else 331 p2 = *EVAL(p2) = list2 + n*size; 332 } 333 } 334 #else /* pairwise merge only. */ 335 for (f1 = list1, p2 = list2; f1 < last; f1 += size2) { 336 p2 = *EVAL(p2) = p2 + size2; 337 if (CMP (f1, f1 + size) > 0) 338 swap(f1, f1 + size); 339 } 340 #endif /* NATURAL */ 341 } 342 343 /* 344 * This is to avoid out-of-bounds addresses in sorting the 345 * last 4 elements. 346 */ 347 static void 348 insertionsort(a, n, size, cmp) 349 u_char *a; 350 size_t n, size; 351 cmp_t cmp; 352 { 353 u_char *ai, *s, *t, *u, tmp; 354 int i; 355 356 for (ai = a+size; --n >= 1; ai += size) 357 for (t = ai; t > a; t -= size) { 358 u = t - size; 359 if (CMP(u, t) <= 0) 360 break; 361 swap(u, t); 362 } 363 } 364