File: bsearch.c

package info (click to toggle)
linux 4.19.20-1
  • links: PTS, VCS
  • area: main
  • in suites: buster, sid
  • size: 954,852 kB
  • sloc: ansic: 16,749,828; asm: 271,286; makefile: 38,257; sh: 32,808; perl: 27,671; python: 21,022; cpp: 5,063; yacc: 4,648; lex: 2,585; awk: 1,385; ruby: 25; sed: 5
file content (55 lines) | stat: -rw-r--r-- 1,580 bytes parent folder | download | duplicates (7)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
/*
 * A generic implementation of binary search for the Linux kernel
 *
 * Copyright (C) 2008-2009 Ksplice, Inc.
 * Author: Tim Abbott <tabbott@ksplice.com>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; version 2.
 */

#include <linux/export.h>
#include <linux/bsearch.h>

/*
 * bsearch - binary search an array of elements
 * @key: pointer to item being searched for
 * @base: pointer to first element to search
 * @num: number of elements
 * @size: size of each element
 * @cmp: pointer to comparison function
 *
 * This function does a binary search on the given array.  The
 * contents of the array should already be in ascending sorted order
 * under the provided comparison function.
 *
 * Note that the key need not have the same type as the elements in
 * the array, e.g. key could be a string and the comparison function
 * could compare the string with the struct's name field.  However, if
 * the key and elements in the array are of the same type, you can use
 * the same comparison function for both sort() and bsearch().
 */
void *bsearch(const void *key, const void *base, size_t num, size_t size,
	      int (*cmp)(const void *key, const void *elt))
{
	const char *pivot;
	int result;

	while (num > 0) {
		pivot = base + (num >> 1) * size;
		result = cmp(key, pivot);

		if (result == 0)
			return (void *)pivot;

		if (result > 0) {
			base = pivot + size;
			num--;
		}
		num >>= 1;
	}

	return NULL;
}
EXPORT_SYMBOL(bsearch);