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 */
bsearch(const void * key,const void * base,size_t num,size_t size,int (* cmp)(const void * key,const void * elt))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