11dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project/* 21dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * Copyright (c) 1990 Regents of the University of California. 31dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * All rights reserved. 41dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * 51dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * Redistribution and use in source and binary forms, with or without 61dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * modification, are permitted provided that the following conditions 71dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * are met: 81dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * 1. Redistributions of source code must retain the above copyright 91dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * notice, this list of conditions and the following disclaimer. 101dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * 2. Redistributions in binary form must reproduce the above copyright 111dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * notice, this list of conditions and the following disclaimer in the 121dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * documentation and/or other materials provided with the distribution. 131dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * 3. Neither the name of the University nor the names of its contributors 141dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * may be used to endorse or promote products derived from this software 151dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * without specific prior written permission. 161dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * 171dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 181dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 191dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 201dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 211dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 221dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 231dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 241dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 251dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 261dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 271dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * SUCH DAMAGE. 281dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project */ 291dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project 301dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project#include <stdlib.h> 311dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project 321dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project/* 331dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * Perform a binary search. 341dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * 351dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * The code below is a bit sneaky. After a comparison fails, we 361dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * divide the work in half by moving either left or right. If lim 371dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * is odd, moving left simply involves halving lim: e.g., when lim 381dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * is 5 we look at item 2, so we change lim to 2 so that we will 391dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * look at items 0 & 1. If lim is even, the same applies. If lim 401dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * is odd, moving right again involes halving lim, this time moving 411dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * the base up one item past p: e.g., when lim is 5 we change base 421dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * to item 3 and make lim 2 so that we will look at items 3 and 4. 431dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * If lim is even, however, we have to shrink it by one before 441dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * halving: e.g., when lim is 4, we still looked at item 2, so we 451dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * have to make lim 3, then halve, obtaining 1, so that we will only 461dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project * look at item 3. 471dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project */ 481dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Projectvoid * 491dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Projectbsearch(const void *key, const void *base0, size_t nmemb, size_t size, 501dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project int (*compar)(const void *, const void *)) 511dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project{ 521dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project const char *base = base0; 531dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project int lim, cmp; 541dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project const void *p; 551dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project 561dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project for (lim = nmemb; lim != 0; lim >>= 1) { 571dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project p = base + (lim >> 1) * size; 581dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project cmp = (*compar)(key, p); 591dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project if (cmp > 0) { /* key > p: move right */ 601dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project base = (char *)p + size; 611dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project lim--; 62acdb052030d6e537e51d8b42e07b2a9e71e6ee42André Goddard Rosa } else if (cmp == 0) { 63acdb052030d6e537e51d8b42e07b2a9e71e6ee42André Goddard Rosa return ((void *)p); 641dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project } /* else move left */ 651dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project } 661dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project return (NULL); 671dc9e472e19acfe6dc7f41e429236e7eef7ceda1The Android Open Source Project} 68