1 /* 2 * mergesort() implementation for systems that don't have it. 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 #include "util.h" 35 36 #if defined(LIBC_SCCS) && !defined(lint) 37 static char sccsid[] = "@(#)merge.c 8.2 (Berkeley) 2/14/94"; 38 #endif /* LIBC_SCCS and not lint */ 39 40 #ifdef HAVE_MERGESORT 41 #undef yasm__mergesort 42 #endif 43 44 #ifndef HAVE_MERGESORT 45 /* 46 * Hybrid exponential search/linear search merge sort with hybrid 47 * natural/pairwise first pass. Requires about .3% more comparisons 48 * for random data than LSMS with pairwise first pass alone. 49 * It works for objects as small as two bytes. 50 */ 51 52 #define NATURAL 53 #define THRESHOLD 16 /* Best choice for natural merge cut-off. */ 54 55 /* #define NATURAL to get hybrid natural merge. 56 * (The default is pairwise merging.) 57 */ 58 59 #include <errno.h> 60 #include <string.h> 61 62 static void setup(unsigned char *, unsigned char *, size_t, size_t, 63 int (*)(const void *, const void *)); 64 static void insertionsort(unsigned char *, size_t, size_t, 65 int (*)(const void *, const void *)); 66 67 #define ISIZE sizeof(int) 68 #define PSIZE sizeof(unsigned char *) 69 #define ICOPY_LIST(src, dst, last) \ 70 do \ 71 *(int*)dst = *(int*)src, src += ISIZE, dst += ISIZE; \ 72 while(src < last) 73 #define ICOPY_ELT(src, dst, i) \ 74 do \ 75 *(int*) dst = *(int*) src, src += ISIZE, dst += ISIZE; \ 76 while (i -= ISIZE) 77 78 #define CCOPY_LIST(src, dst, last) \ 79 do \ 80 *dst++ = *src++; \ 81 while (src < last) 82 #define CCOPY_ELT(src, dst, i) \ 83 do \ 84 *dst++ = *src++; \ 85 while (i -= 1) 86 87 /* 88 * Find the next possible pointer head. (Trickery for forcing an array 89 * to do double duty as a linked list when objects do not align with word 90 * boundaries. 91 */ 92 /* Assumption: PSIZE is a power of 2. */ 93 #define EVAL(p) (unsigned char **) \ 94 ((unsigned char *)0 + \ 95 (((unsigned char *)p + PSIZE - 1 - (unsigned char *) 0) & ~(PSIZE - 1))) 96 #endif /*HAVE_MERGESORT*/ 97 98 /* 99 * Arguments are as for qsort. 100 */ 101 int 102 yasm__mergesort(void *base, size_t nmemb, size_t size, 103 int (*cmp)(const void *, const void *)) 104 { 105 #ifdef HAVE_MERGESORT 106 return mergesort(base, nmemb, size, cmp); 107 #else 108 size_t i; 109 int sense; 110 int big, iflag; 111 unsigned char *f1, *f2, *t, *b, *tp2, *q, *l1, *l2; 112 unsigned char *list2, *list1, *p2, *p, *last, **p1; 113 114 if (size < PSIZE / 2) { /* Pointers must fit into 2 * size. */ 115 #ifdef EINVAL 116 errno = EINVAL; 117 #endif 118 return (-1); 119 } 120 121 if (nmemb == 0) 122 return (0); 123 124 /* 125 * XXX 126 * Stupid subtraction for the Cray. 127 */ 128 iflag = 0; 129 if (!(size % ISIZE) && !(((char *)base - (char *)0) % ISIZE)) 130 iflag = 1; 131 132 if ((list2 = yasm_xmalloc(nmemb * size + PSIZE)) == NULL) 133 return (-1); 134 135 list1 = base; 136 setup(list1, list2, nmemb, size, cmp); 137 last = list2 + nmemb * size; 138 i = 0; 139 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 yasm_xfree(list2); 240 return (0); 241 #endif /*HAVE_MERGESORT*/ 242 } 243 244 #ifndef HAVE_MERGESORT 245 246 #define swap(a, b) { \ 247 s = b; \ 248 i = size; \ 249 do { \ 250 tmp = *a; *a++ = *s; *s++ = tmp; \ 251 } while (--i); \ 252 a -= size; \ 253 } 254 #define reverse(bot, top) { \ 255 s = top; \ 256 do { \ 257 i = size; \ 258 do { \ 259 tmp = *bot; *bot++ = *s; *s++ = tmp; \ 260 } while (--i); \ 261 s -= size2; \ 262 } while(bot < s); \ 263 } 264 265 /* 266 * Optional hybrid natural/pairwise first pass. Eats up list1 in runs of 267 * increasing order, list2 in a corresponding linked list. Checks for runs 268 * when THRESHOLD/2 pairs compare with same sense. (Only used when NATURAL 269 * is defined. Otherwise simple pairwise merging is used.) 270 */ 271 void 272 setup(unsigned char *list1, unsigned char *list2, size_t n, size_t size, 273 int (*cmp)(const void *, const void *)) 274 { 275 size_t i; 276 unsigned int tmp; 277 int length, sense; 278 size_t size2; 279 unsigned char *f1, *f2, *s, *l2, *last, *p2; 280 281 size2 = size*2; 282 if (n <= 5) { 283 insertionsort(list1, n, size, cmp); 284 *EVAL(list2) = (unsigned char*) list2 + n*size; 285 return; 286 } 287 /* 288 * Avoid running pointers out of bounds; limit n to evens 289 * for simplicity. 290 */ 291 i = 4 + (n & 1); 292 insertionsort(list1 + (n - i) * size, i, size, cmp); 293 last = list1 + size * (n - i); 294 *EVAL(list2 + (last - list1)) = list2 + n * size; 295 296 #ifdef NATURAL 297 p2 = list2; 298 f1 = list1; 299 sense = (cmp(f1, f1 + size) > 0); 300 for (; f1 < last; sense = !sense) { 301 length = 2; 302 /* Find pairs with same sense. */ 303 for (f2 = f1 + size2; f2 < last; f2 += size2) { 304 if ((cmp(f2, f2+ size) > 0) != sense) 305 break; 306 length += 2; 307 } 308 if (length < THRESHOLD) { /* Pairwise merge */ 309 do { 310 p2 = *EVAL(p2) = f1 + size2 - list1 + list2; 311 if (sense > 0) 312 swap (f1, f1 + size); 313 } while ((f1 += size2) < f2); 314 } else { /* Natural merge */ 315 l2 = f2; 316 for (f2 = f1 + size2; f2 < l2; f2 += size2) { 317 if ((cmp(f2-size, f2) > 0) != sense) { 318 p2 = *EVAL(p2) = f2 - list1 + list2; 319 if (sense > 0) 320 reverse(f1, f2-size); 321 f1 = f2; 322 } 323 } 324 if (sense > 0) 325 reverse (f1, f2-size); 326 f1 = f2; 327 if (f2 < last || cmp(f2 - size, f2) > 0) 328 p2 = *EVAL(p2) = f2 - list1 + list2; 329 else 330 p2 = *EVAL(p2) = list2 + n*size; 331 } 332 } 333 #else /* pairwise merge only. */ 334 for (f1 = list1, p2 = list2; f1 < last; f1 += size2) { 335 p2 = *EVAL(p2) = p2 + size2; 336 if (cmp (f1, f1 + size) > 0) 337 swap(f1, f1 + size); 338 } 339 #endif /* NATURAL */ 340 } 341 342 /* 343 * This is to avoid out-of-bounds addresses in sorting the 344 * last 4 elements. 345 */ 346 static void 347 insertionsort(unsigned char *a, size_t n, size_t size, 348 int (*cmp)(const void *, const void *)) 349 { 350 unsigned char *ai, *s, *t, *u, tmp; 351 size_t i; 352 353 for (ai = a+size; --n >= 1; ai += size) 354 for (t = ai; t > a; t -= size) { 355 u = t - size; 356 if (cmp(u, t) <= 0) 357 break; 358 swap(u, t); 359 } 360 } 361 #endif /*HAVE_MERGESORT*/ 362
