mirror of
https://github.com/edk2-porting/linux-next.git
synced 2024-12-27 06:34:11 +08:00
1a94dc35bc
There a large number hand-coded binary searches in the kernel (run "git grep search | grep binary" to find many of them). Since in my experience, hand-coding binary searches can be error-prone, it seems worth cleaning this up by providing a generic binary search function. This generic binary search implementation comes from Ksplice. It has the same basic API as the C library bsearch() function. Ksplice uses it in half a dozen places with 4 different comparison functions, and I think our code is substantially cleaner because of this. Signed-off-by: Tim Abbott <tabbott@ksplice.com> Extra-bikeshedding-by: Alan Jenkins <alan-jenkins@tuffmail.co.uk> Extra-bikeshedding-by: André Goddard Rosa <andre.goddard@gmail.com> Extra-bikeshedding-by: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Alessio Igor Bogani <abogani@kernel.org> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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);
|