blob: e33c179089dbff6bf97752284ad705a543328fb5 [file] [log] [blame]
* A generic implementation of binary search for the Linux kernel
* Copyright (C) 2008-2009 Ksplice, Inc.
* Author: Tim Abbott <>
* 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))
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;
return (void *)base + mid * size;
return NULL;