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);