1 /* 2 * A generic implementation of binary search for the Linux kernel 3 * 4 * Copyright (C) 2008-2009 Ksplice, Inc. 5 * Author: Tim Abbott <tabbott@ksplice.com> 6 * 7 * This program is free software; you can redistribute it and/or 8 * modify it under the terms of the GNU General Public License as 9 * published by the Free Software Foundation; version 2. 10 */ 11 12 #include <linux/export.h> 13 #include <linux/bsearch.h> 14 #include <linux/kprobes.h> 15 16 /* 17 * bsearch - binary search an array of elements 18 * @key: pointer to item being searched for 19 * @base: pointer to first element to search 20 * @num: number of elements 21 * @size: size of each element 22 * @cmp: pointer to comparison function 23 * 24 * This function does a binary search on the given array. The 25 * contents of the array should already be in ascending sorted order 26 * under the provided comparison function. 27 * 28 * Note that the key need not have the same type as the elements in 29 * the array, e.g. key could be a string and the comparison function 30 * could compare the string with the struct's name field. However, if 31 * the key and elements in the array are of the same type, you can use 32 * the same comparison function for both sort() and bsearch(). 33 */ 34 void *bsearch(const void *key, const void *base, size_t num, size_t size, 35 int (*cmp)(const void *key, const void *elt)) 36 { 37 const char *pivot; 38 int result; 39 40 while (num > 0) { 41 pivot = base + (num >> 1) * size; 42 result = cmp(key, pivot); 43 44 if (result == 0) 45 return (void *)pivot; 46 47 if (result > 0) { 48 base = pivot + size; 49 num--; 50 } 51 num >>= 1; 52 } 53 54 return NULL; 55 } 56 EXPORT_SYMBOL(bsearch); 57 NOKPROBE_SYMBOL(bsearch); 58