| 1 | // SPDX-License-Identifier: GPL-2.0-only |
| 2 | /* |
| 3 | * A generic implementation of binary search for the Linux kernel |
| 4 | * |
| 5 | * Copyright (C) 2008-2009 Ksplice, Inc. |
| 6 | * Author: Tim Abbott <tabbott@ksplice.com> |
| 7 | */ |
| 8 | |
| 9 | #include <linux/export.h> |
| 10 | #include <linux/bsearch.h> |
| 11 | #include <linux/kprobes.h> |
| 12 | |
| 13 | /* |
| 14 | * bsearch - binary search an array of elements |
| 15 | * @key: pointer to item being searched for |
| 16 | * @base: pointer to first element to search |
| 17 | * @num: number of elements |
| 18 | * @size: size of each element |
| 19 | * @cmp: pointer to comparison function |
| 20 | * |
| 21 | * This function does a binary search on the given array. The |
| 22 | * contents of the array should already be in ascending sorted order |
| 23 | * under the provided comparison function. |
| 24 | * |
| 25 | * Note that the key need not have the same type as the elements in |
| 26 | * the array, e.g. key could be a string and the comparison function |
| 27 | * could compare the string with the struct's name field. However, if |
| 28 | * the key and elements in the array are of the same type, you can use |
| 29 | * the same comparison function for both sort() and bsearch(). |
| 30 | */ |
| 31 | void *bsearch(const void *key, const void *base, size_t num, size_t size, |
| 32 | int (*cmp)(const void *key, const void *elt)) |
| 33 | { |
| 34 | const char *pivot; |
| 35 | int result; |
| 36 | |
| 37 | while (num > 0) { |
| 38 | pivot = base + (num >> 1) * size; |
| 39 | result = cmp(key, pivot); |
| 40 | |
| 41 | if (result == 0) |
| 42 | return (void *)pivot; |
| 43 | |
| 44 | if (result > 0) { |
| 45 | base = pivot + size; |
| 46 | num--; |
| 47 | } |
| 48 | num >>= 1; |
| 49 | } |
| 50 | |
| 51 | return NULL; |
| 52 | } |
| 53 | EXPORT_SYMBOL(bsearch); |
| 54 | NOKPROBE_SYMBOL(bsearch); |