Annotation of embedaddon/php/main/mergesort.c, revision 1.1
1.1 ! misho 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: /* $Id: mergesort.c 265279 2008-08-22 12:59:46Z helly $ */
! 38:
! 39: #if defined(LIBC_SCCS) && !defined(lint)
! 40: static char sccsid[] = "@(#)merge.c 8.2 (Berkeley) 2/14/94";
! 41: #endif /* LIBC_SCCS and not lint */
! 42:
! 43: /*
! 44: * Hybrid exponential search/linear search merge sort with hybrid
! 45: * natural/pairwise first pass. Requires about .3% more comparisons
! 46: * for random data than LSMS with pairwise first pass alone.
! 47: * It works for objects as small as two bytes.
! 48: */
! 49:
! 50: #define NATURAL
! 51: #define THRESHOLD 16 /* Best choice for natural merge cut-off. */
! 52:
! 53: /* #define NATURAL to get hybrid natural merge.
! 54: * (The default is pairwise merging.)
! 55: */
! 56:
! 57: #include <sys/types.h>
! 58:
! 59: #include <errno.h>
! 60: #include <stdlib.h>
! 61: #include <string.h>
! 62:
! 63: #include "php.h"
! 64:
! 65: #ifdef PHP_WIN32
! 66: #include <winsock2.h> /* Includes definition for u_char */
! 67: #endif
! 68:
! 69: static void setup(u_char *list1, u_char *list2, size_t n, size_t size, int (*cmp)(const void *, const void * TSRMLS_DC) TSRMLS_DC);
! 70: static void insertionsort(u_char *a, size_t n, size_t size, int (*cmp)(const void *, const void * TSRMLS_DC) TSRMLS_DC);
! 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: /* {{{ php_mergesort
! 103: * Arguments are as for qsort.
! 104: */
! 105: PHPAPI int php_mergesort(void *base, size_t nmemb, size_t size, int (*cmp)(const void *, const void * TSRMLS_DC) TSRMLS_DC)
! 106: {
! 107: register unsigned int i;
! 108: register int sense;
! 109: int big, iflag;
! 110: register u_char *f1, *f2, *t, *b, *tp2, *q, *l1, *l2;
! 111: u_char *list2, *list1, *p2, *p, *last, **p1;
! 112:
! 113: if (size < PSIZE / 2) { /* Pointers must fit into 2 * size. */
! 114: errno = EINVAL;
! 115: return (-1);
! 116: }
! 117:
! 118: if (nmemb == 0)
! 119: return (0);
! 120:
! 121: /*
! 122: * XXX
! 123: * Stupid subtraction for the Cray.
! 124: */
! 125: iflag = 0;
! 126: if (!(size % ISIZE) && !(((char *)base - (char *)0) % ISIZE))
! 127: iflag = 1;
! 128:
! 129: if ((list2 = malloc(nmemb * size + PSIZE)) == NULL)
! 130: return (-1);
! 131:
! 132: list1 = base;
! 133: setup(list1, list2, nmemb, size, cmp TSRMLS_CC);
! 134: last = list2 + nmemb * size;
! 135: i = big = 0;
! 136: while (*EVAL(list2) != last) {
! 137: l2 = list1;
! 138: p1 = EVAL(list1);
! 139: for (tp2 = p2 = list2; p2 != last; p1 = EVAL(l2)) {
! 140: p2 = *EVAL(p2);
! 141: f1 = l2;
! 142: f2 = l1 = list1 + (p2 - list2);
! 143: if (p2 != last)
! 144: p2 = *EVAL(p2);
! 145: l2 = list1 + (p2 - list2);
! 146: while (f1 < l1 && f2 < l2) {
! 147: if ((*cmp)(f1, f2 TSRMLS_CC) <= 0) {
! 148: q = f2;
! 149: b = f1, t = l1;
! 150: sense = -1;
! 151: } else {
! 152: q = f1;
! 153: b = f2, t = l2;
! 154: sense = 0;
! 155: }
! 156: if (!big) { /* here i = 0 */
! 157: while ((b += size) < t && cmp(q, b TSRMLS_CC) >sense)
! 158: if (++i == 6) {
! 159: big = 1;
! 160: goto EXPONENTIAL;
! 161: }
! 162: } else {
! 163: EXPONENTIAL: for (i = size; ; i <<= 1)
! 164: if ((p = (b + i)) >= t) {
! 165: if ((p = t - size) > b &&
! 166: (*cmp)(q, p TSRMLS_CC) <= sense)
! 167: t = p;
! 168: else
! 169: b = p;
! 170: break;
! 171: } else if ((*cmp)(q, p TSRMLS_CC) <= sense) {
! 172: t = p;
! 173: if (i == size)
! 174: big = 0;
! 175: goto FASTCASE;
! 176: } else
! 177: b = p;
! 178: while (t > b+size) {
! 179: i = (((t - b) / size) >> 1) * size;
! 180: if ((*cmp)(q, p = b + i TSRMLS_CC) <= sense)
! 181: t = p;
! 182: else
! 183: b = p;
! 184: }
! 185: goto COPY;
! 186: FASTCASE: while (i > size)
! 187: if ((*cmp)(q,
! 188: p = b + (i >>= 1) TSRMLS_CC) <= sense)
! 189: t = p;
! 190: else
! 191: b = p;
! 192: COPY: b = t;
! 193: }
! 194: i = size;
! 195: if (q == f1) {
! 196: if (iflag) {
! 197: ICOPY_LIST(f2, tp2, b);
! 198: ICOPY_ELT(f1, tp2, i);
! 199: } else {
! 200: CCOPY_LIST(f2, tp2, b);
! 201: CCOPY_ELT(f1, tp2, i);
! 202: }
! 203: } else {
! 204: if (iflag) {
! 205: ICOPY_LIST(f1, tp2, b);
! 206: ICOPY_ELT(f2, tp2, i);
! 207: } else {
! 208: CCOPY_LIST(f1, tp2, b);
! 209: CCOPY_ELT(f2, tp2, i);
! 210: }
! 211: }
! 212: }
! 213: if (f2 < l2) {
! 214: if (iflag)
! 215: ICOPY_LIST(f2, tp2, l2);
! 216: else
! 217: CCOPY_LIST(f2, tp2, l2);
! 218: } else if (f1 < l1) {
! 219: if (iflag)
! 220: ICOPY_LIST(f1, tp2, l1);
! 221: else
! 222: CCOPY_LIST(f1, tp2, l1);
! 223: }
! 224: *p1 = l2;
! 225: }
! 226: tp2 = list1; /* swap list1, list2 */
! 227: list1 = list2;
! 228: list2 = tp2;
! 229: last = list2 + nmemb*size;
! 230: }
! 231: if (base == list2) {
! 232: memmove(list2, list1, nmemb*size);
! 233: list2 = list1;
! 234: }
! 235: free(list2);
! 236: return (0);
! 237: }
! 238: /* }}} */
! 239:
! 240: #define swap(a, b) { \
! 241: s = b; \
! 242: i = size; \
! 243: do { \
! 244: tmp = *a; *a++ = *s; *s++ = tmp; \
! 245: } while (--i); \
! 246: a -= size; \
! 247: }
! 248: #define reverse(bot, top) { \
! 249: s = top; \
! 250: do { \
! 251: i = size; \
! 252: do { \
! 253: tmp = *bot; *bot++ = *s; *s++ = tmp; \
! 254: } while (--i); \
! 255: s -= size2; \
! 256: } while(bot < s); \
! 257: }
! 258:
! 259: /* {{{ setup
! 260: * Optional hybrid natural/pairwise first pass. Eats up list1 in runs of
! 261: * increasing order, list2 in a corresponding linked list. Checks for runs
! 262: * when THRESHOLD/2 pairs compare with same sense. (Only used when NATURAL
! 263: * is defined. Otherwise simple pairwise merging is used.)
! 264: */
! 265: static void setup(u_char *list1, u_char *list2, size_t n, size_t size, int (*cmp)(const void *, const void * TSRMLS_DC) TSRMLS_DC)
! 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 TSRMLS_CC);
! 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 TSRMLS_CC);
! 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 TSRMLS_CC) > 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 TSRMLS_CC) > 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 TSRMLS_CC) > 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 TSRMLS_CC) > 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 TSRMLS_CC) > 0)
! 326: swap(f1, f1 + size);
! 327: }
! 328: #endif /* NATURAL */
! 329: }
! 330: /* }}} */
! 331:
! 332: /* {{{ insertionsort
! 333: * This is to avoid out-of-bounds addresses in sorting the
! 334: * last 4 elements.
! 335: */
! 336: static void insertionsort(u_char *a, size_t n, size_t size, int (*cmp)(const void *, const void * TSRMLS_DC) TSRMLS_DC)
! 337: {
! 338: u_char *ai, *s, *t, *u, tmp;
! 339: int i;
! 340:
! 341: for (ai = a+size; --n >= 1; ai += size)
! 342: for (t = ai; t > a; t -= size) {
! 343: u = t - size;
! 344: if (cmp(u, t TSRMLS_CC) <= 0)
! 345: break;
! 346: swap(u, t);
! 347: }
! 348: }
! 349: /* }}} */
! 350:
! 351: /*
! 352: * Local variables:
! 353: * tab-width: 4
! 354: * c-basic-offset: 4
! 355: * End:
! 356: * vim600: fdm=marker
! 357: * vim: noet sw=4 ts=4
! 358: */
FreeBSD-CVSweb <freebsd-cvsweb@FreeBSD.org>
![[BACK]](/icons/cvsweb/back.gif){kind=icon}
Return to mergesort.c CVS log ![[TXT]](/icons/cvsweb/text.gif){kind=icon}
![[DIR]](/icons/cvsweb/dir.gif){kind=icon}
Up to [ELWIX - Embedded LightWeight unIX -] / embedaddon / php / main