11573Srgrimes/*- 21573Srgrimes * Copyright (c) 1991, 1993 31573Srgrimes * The Regents of the University of California. All rights reserved. 4264042Stheraven * Copyright (c) 2014 David T. Chisnall 5264042Stheraven * All rights reserved. 61573Srgrimes * 71573Srgrimes * This code is derived from software contributed to Berkeley by 81573Srgrimes * Ronnie Kon at Mindcraft Inc., Kevin Lew and Elmer Yglesias. 91573Srgrimes * 101573Srgrimes * Redistribution and use in source and binary forms, with or without 111573Srgrimes * modification, are permitted provided that the following conditions 121573Srgrimes * are met: 131573Srgrimes * 1. Redistributions of source code must retain the above copyright 141573Srgrimes * notice, this list of conditions and the following disclaimer. 151573Srgrimes * 2. Redistributions in binary form must reproduce the above copyright 161573Srgrimes * notice, this list of conditions and the following disclaimer in the 171573Srgrimes * documentation and/or other materials provided with the distribution. 18251069Semaste * 3. Neither the name of the University nor the names of its contributors 191573Srgrimes * may be used to endorse or promote products derived from this software 201573Srgrimes * without specific prior written permission. 211573Srgrimes * 221573Srgrimes * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 231573Srgrimes * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 241573Srgrimes * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 251573Srgrimes * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 261573Srgrimes * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 271573Srgrimes * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 281573Srgrimes * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 291573Srgrimes * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 301573Srgrimes * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 311573Srgrimes * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 321573Srgrimes * SUCH DAMAGE. 331573Srgrimes */ 341573Srgrimes 351573Srgrimes#if defined(LIBC_SCCS) && !defined(lint) 361573Srgrimesstatic char sccsid[] = "@(#)heapsort.c 8.1 (Berkeley) 6/4/93"; 371573Srgrimes#endif /* LIBC_SCCS and not lint */ 3892889Sobrien#include <sys/cdefs.h> 3992889Sobrien__FBSDID("$FreeBSD$"); 401573Srgrimes 411573Srgrimes#include <errno.h> 4215312Sbde#include <stddef.h> 431573Srgrimes#include <stdlib.h> 441573Srgrimes 45264042Stheraven#ifdef I_AM_HEAPSORT_B 46264042Stheraven#include "block_abi.h" 47264042Stheraven#define COMPAR(x, y) CALL_BLOCK(compar, x, y) 48264143Stheraventypedef DECLARE_BLOCK(int, heapsort_block, const void *, const void *); 49264042Stheraven#else 50264042Stheraven#define COMPAR(x, y) compar(x, y) 51264042Stheraven#endif 52264042Stheraven 531573Srgrimes/* 541573Srgrimes * Swap two areas of size number of bytes. Although qsort(3) permits random 551573Srgrimes * blocks of memory to be sorted, sorting pointers is almost certainly the 561573Srgrimes * common case (and, were it not, could easily be made so). Regardless, it 571573Srgrimes * isn't worth optimizing; the SWAP's get sped up by the cache, and pointer 581573Srgrimes * arithmetic gets lost in the time required for comparison function calls. 591573Srgrimes */ 601573Srgrimes#define SWAP(a, b, count, size, tmp) { \ 611573Srgrimes count = size; \ 621573Srgrimes do { \ 631573Srgrimes tmp = *a; \ 641573Srgrimes *a++ = *b; \ 651573Srgrimes *b++ = tmp; \ 661573Srgrimes } while (--count); \ 671573Srgrimes} 681573Srgrimes 691573Srgrimes/* Copy one block of size size to another. */ 701573Srgrimes#define COPY(a, b, count, size, tmp1, tmp2) { \ 711573Srgrimes count = size; \ 721573Srgrimes tmp1 = a; \ 731573Srgrimes tmp2 = b; \ 741573Srgrimes do { \ 751573Srgrimes *tmp1++ = *tmp2++; \ 761573Srgrimes } while (--count); \ 771573Srgrimes} 781573Srgrimes 791573Srgrimes/* 801573Srgrimes * Build the list into a heap, where a heap is defined such that for 811573Srgrimes * the records K1 ... KN, Kj/2 >= Kj for 1 <= j/2 <= j <= N. 821573Srgrimes * 831573Srgrimes * There two cases. If j == nmemb, select largest of Ki and Kj. If 841573Srgrimes * j < nmemb, select largest of Ki, Kj and Kj+1. 851573Srgrimes */ 861573Srgrimes#define CREATE(initval, nmemb, par_i, child_i, par, child, size, count, tmp) { \ 871573Srgrimes for (par_i = initval; (child_i = par_i * 2) <= nmemb; \ 881573Srgrimes par_i = child_i) { \ 891573Srgrimes child = base + child_i * size; \ 90264042Stheraven if (child_i < nmemb && COMPAR(child, child + size) < 0) { \ 911573Srgrimes child += size; \ 921573Srgrimes ++child_i; \ 931573Srgrimes } \ 941573Srgrimes par = base + par_i * size; \ 95264042Stheraven if (COMPAR(child, par) <= 0) \ 961573Srgrimes break; \ 971573Srgrimes SWAP(par, child, count, size, tmp); \ 981573Srgrimes } \ 991573Srgrimes} 1001573Srgrimes 1011573Srgrimes/* 1021573Srgrimes * Select the top of the heap and 'heapify'. Since by far the most expensive 1031573Srgrimes * action is the call to the compar function, a considerable optimization 1041573Srgrimes * in the average case can be achieved due to the fact that k, the displaced 105298830Spfg * elememt, is usually quite small, so it would be preferable to first 1061573Srgrimes * heapify, always maintaining the invariant that the larger child is copied 1071573Srgrimes * over its parent's record. 1081573Srgrimes * 1091573Srgrimes * Then, starting from the *bottom* of the heap, finding k's correct place, 1101573Srgrimes * again maintianing the invariant. As a result of the invariant no element 1111573Srgrimes * is 'lost' when k is assigned its correct place in the heap. 1121573Srgrimes * 1131573Srgrimes * The time savings from this optimization are on the order of 15-20% for the 1141573Srgrimes * average case. See Knuth, Vol. 3, page 158, problem 18. 1151573Srgrimes * 1161573Srgrimes * XXX Don't break the #define SELECT line, below. Reiser cpp gets upset. 1171573Srgrimes */ 1181573Srgrimes#define SELECT(par_i, child_i, nmemb, par, child, size, k, count, tmp1, tmp2) { \ 1191573Srgrimes for (par_i = 1; (child_i = par_i * 2) <= nmemb; par_i = child_i) { \ 1201573Srgrimes child = base + child_i * size; \ 121264042Stheraven if (child_i < nmemb && COMPAR(child, child + size) < 0) { \ 1221573Srgrimes child += size; \ 1231573Srgrimes ++child_i; \ 1241573Srgrimes } \ 1251573Srgrimes par = base + par_i * size; \ 1261573Srgrimes COPY(par, child, count, size, tmp1, tmp2); \ 1271573Srgrimes } \ 1281573Srgrimes for (;;) { \ 1291573Srgrimes child_i = par_i; \ 1301573Srgrimes par_i = child_i / 2; \ 1311573Srgrimes child = base + child_i * size; \ 1321573Srgrimes par = base + par_i * size; \ 133264042Stheraven if (child_i == 1 || COMPAR(k, par) < 0) { \ 1341573Srgrimes COPY(child, k, count, size, tmp1, tmp2); \ 1351573Srgrimes break; \ 1361573Srgrimes } \ 1371573Srgrimes COPY(child, par, count, size, tmp1, tmp2); \ 1381573Srgrimes } \ 1391573Srgrimes} 1401573Srgrimes 141288005Srodrigc#ifdef I_AM_HEAPSORT_B 142288026Srodrigcint heapsort_b(void *, size_t, size_t, heapsort_block); 143288005Srodrigc#else 144288026Srodrigcint heapsort(void *, size_t, size_t, 145288026Srodrigc int (*)(const void *, const void *)); 146288005Srodrigc#endif 1471573Srgrimes/* 1481573Srgrimes * Heapsort -- Knuth, Vol. 3, page 145. Runs in O (N lg N), both average 1491573Srgrimes * and worst. While heapsort is faster than the worst case of quicksort, 1501573Srgrimes * the BSD quicksort does median selection so that the chance of finding 1511573Srgrimes * a data set that will trigger the worst case is nonexistent. Heapsort's 1521573Srgrimes * only advantage over quicksort is that it requires little additional memory. 1531573Srgrimes */ 154264042Stheraven#ifdef I_AM_HEAPSORT_B 1551573Srgrimesint 156287793Srodrigcheapsort_b(void *vbase, size_t nmemb, size_t size, heapsort_block compar) 157264042Stheraven#else 158264042Stheravenint 159287793Srodrigcheapsort(void *vbase, size_t nmemb, size_t size, 160287793Srodrigc int (*compar)(const void *, const void *)) 161264042Stheraven#endif 1621573Srgrimes{ 163175259Sdas size_t cnt, i, j, l; 16492889Sobrien char tmp, *tmp1, *tmp2; 1651573Srgrimes char *base, *k, *p, *t; 1661573Srgrimes 1671573Srgrimes if (nmemb <= 1) 1681573Srgrimes return (0); 1691573Srgrimes 1701573Srgrimes if (!size) { 1711573Srgrimes errno = EINVAL; 1721573Srgrimes return (-1); 1731573Srgrimes } 1741573Srgrimes 1751573Srgrimes if ((k = malloc(size)) == NULL) 1761573Srgrimes return (-1); 1771573Srgrimes 1781573Srgrimes /* 1791573Srgrimes * Items are numbered from 1 to nmemb, so offset from size bytes 1801573Srgrimes * below the starting address. 1811573Srgrimes */ 1821573Srgrimes base = (char *)vbase - size; 1831573Srgrimes 1841573Srgrimes for (l = nmemb / 2 + 1; --l;) 1851573Srgrimes CREATE(l, nmemb, i, j, t, p, size, cnt, tmp); 1861573Srgrimes 1871573Srgrimes /* 1881573Srgrimes * For each element of the heap, save the largest element into its 1891573Srgrimes * final slot, save the displaced element (k), then recreate the 1901573Srgrimes * heap. 1911573Srgrimes */ 1921573Srgrimes while (nmemb > 1) { 1931573Srgrimes COPY(k, base + nmemb * size, cnt, size, tmp1, tmp2); 1941573Srgrimes COPY(base + nmemb * size, base + size, cnt, size, tmp1, tmp2); 1951573Srgrimes --nmemb; 1961573Srgrimes SELECT(i, j, nmemb, t, p, size, k, cnt, tmp1, tmp2); 1971573Srgrimes } 1981573Srgrimes free(k); 1991573Srgrimes return (0); 2001573Srgrimes} 201