blob: d50048446b77dcb782ce9b223c0472e92ac1e44b
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 | size_t start = 0, end = num; |
38 | int result; |
39 | |
40 | while (start < end) { |
41 | size_t mid = start + (end - start) / 2; |
42 | |
43 | result = cmp(key, base + mid * size); |
44 | if (result < 0) |
45 | end = mid; |
46 | else if (result > 0) |
47 | start = mid + 1; |
48 | else |
49 | return (void *)base + mid * size; |
50 | } |
51 | |
52 | return NULL; |
53 | } |
54 | EXPORT_SYMBOL(bsearch); |
55 | NOKPROBE_SYMBOL(bsearch); |
56 |