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/module.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 */
33void *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	while (start < end) {
40		size_t mid = start + (end - start) / 2;
 
41
42		result = cmp(key, base + mid * size);
43		if (result < 0)
44			end = mid;
45		else if (result > 0)
46			start = mid + 1;
47		else
48			return (void *)base + mid * size;
 
49	}
50
51	return NULL;
52}
53EXPORT_SYMBOL(bsearch);

 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 */
33void *bsearch(const void *key, const void *base, size_t num, size_t size,
34	      int (*cmp)(const void *key, const void *elt))
35{
36	const char *pivot;
37	int result;
38
39	while (num > 0) {
40		pivot = base + (num >> 1) * size;
41		result = cmp(key, pivot);
42
43		if (result == 0)
44			return (void *)pivot;
45
46		if (result > 0) {
47			base = pivot + size;
48			num--;
49		}
50		num >>= 1;
51	}
52
53	return NULL;
54}
55EXPORT_SYMBOL(bsearch);