Branch data Line data Source code
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 : :
15 : : /*
16 : : * bsearch - binary search an array of elements
17 : : * @key: pointer to item being searched for
18 : : * @base: pointer to first element to search
19 : : * @num: number of elements
20 : : * @size: size of each element
21 : : * @cmp: pointer to comparison function
22 : : *
23 : : * This function does a binary search on the given array. The
24 : : * contents of the array should already be in ascending sorted order
25 : : * under the provided comparison function.
26 : : *
27 : : * Note that the key need not have the same type as the elements in
28 : : * the array, e.g. key could be a string and the comparison function
29 : : * could compare the string with the struct's name field. However, if
30 : : * the key and elements in the array are of the same type, you can use
31 : : * the same comparison function for both sort() and bsearch().
32 : : */
33 : 0 : void *bsearch(const void *key, const void *base, size_t num, size_t size,
34 : : int (*cmp)(const void *key, const void *elt))
35 : : {
36 : : size_t start = 0, end = num;
37 : : int result;
38 : :
39 [ # # ]: 0 : while (start < end) {
40 : 0 : size_t mid = start + (end - start) / 2;
41 : :
42 : 0 : result = cmp(key, base + mid * size);
43 [ # # ]: 0 : if (result < 0)
44 : : end = mid;
45 [ # # ]: 0 : else if (result > 0)
46 : 0 : start = mid + 1;
47 : : else
48 : : return (void *)base + mid * size;
49 : : }
50 : :
51 : : return NULL;
52 : : }
53 : : EXPORT_SYMBOL(bsearch);
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