mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-27 03:10:12 +00:00
54 lines
1.6 KiB
C
54 lines
1.6 KiB
C
![]() |
/*
|
||
|
* 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/module.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))
|
||
|
{
|
||
|
size_t start = 0, end = num;
|
||
|
int result;
|
||
|
|
||
|
while (start < end) {
|
||
|
size_t mid = start + (end - start) / 2;
|
||
|
|
||
|
result = cmp(key, base + mid * size);
|
||
|
if (result < 0)
|
||
|
end = mid;
|
||
|
else if (result > 0)
|
||
|
start = mid + 1;
|
||
|
else
|
||
|
return (void *)base + mid * size;
|
||
|
}
|
||
|
|
||
|
return NULL;
|
||
|
}
|
||
|
EXPORT_SYMBOL(bsearch);
|