1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * A generic implementation of binary search for the Linux kernel 4 * 5 * Copyright (C) 2008-2009 Ksplice, Inc. 6 * Author: Tim Abbott <tabbott@ksplice.com> 7 */ 8 9 #include <linux/export.h> 10 #include <linux/bsearch.h> 11 #include <linux/kprobes.h> 12 13 /* 14 * bsearch - binary search an array of elements 15 * @key: pointer to item being searched for 16 * @base: pointer to first element to search 17 * @num: number of elements 18 * @size: size of each element 19 * @cmp: pointer to comparison function 20 * 21 * This function does a binary search on the given array. The 22 * contents of the array should already be in ascending sorted order 23 * under the provided comparison function. 24 * 25 * Note that the key need not have the same type as the elements in 26 * the array, e.g. key could be a string and the comparison function 27 * could compare the string with the struct's name field. However, if 28 * the key and elements in the array are of the same type, you can use 29 * the same comparison function for both sort() and bsearch(). 30 */ 31 void *bsearch(const void *key, const void *base, size_t num, size_t size, 32 int (*cmp)(const void *key, const void *elt)) 33 { 34 const char *pivot; 35 int result; 36 37 while (num > 0) { 38 pivot = base + (num >> 1) * size; 39 result = cmp(key, pivot); 40 41 if (result == 0) 42 return (void *)pivot; 43 44 if (result > 0) { 45 base = pivot + size; 46 num--; 47 } 48 num >>= 1; 49 } 50 51 return NULL; 52 } 53 EXPORT_SYMBOL(bsearch); 54 NOKPROBE_SYMBOL(bsearch); 55