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53 lines
1.6 KiB
53 lines
1.6 KiB
/* |
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* A generic implementation of binary search for the Linux kernel |
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* |
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* Copyright (C) 2008-2009 Ksplice, Inc. |
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* Author: Tim Abbott <tabbott@ksplice.com> |
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* |
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* This program is free software; you can redistribute it and/or |
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* modify it under the terms of the GNU General Public License as |
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* published by the Free Software Foundation; version 2. |
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*/ |
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#include <linux/export.h> |
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#include <linux/bsearch.h> |
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/* |
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* bsearch - binary search an array of elements |
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* @key: pointer to item being searched for |
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* @base: pointer to first element to search |
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* @num: number of elements |
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* @size: size of each element |
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* @cmp: pointer to comparison function |
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* |
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* This function does a binary search on the given array. The |
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* contents of the array should already be in ascending sorted order |
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* under the provided comparison function. |
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* |
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* Note that the key need not have the same type as the elements in |
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* the array, e.g. key could be a string and the comparison function |
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* could compare the string with the struct's name field. However, if |
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* the key and elements in the array are of the same type, you can use |
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* the same comparison function for both sort() and bsearch(). |
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*/ |
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void *bsearch(const void *key, const void *base, size_t num, size_t size, |
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int (*cmp)(const void *key, const void *elt)) |
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{ |
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size_t start = 0, end = num; |
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int result; |
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while (start < end) { |
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size_t mid = start + (end - start) / 2; |
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result = cmp(key, base + mid * size); |
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if (result < 0) |
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end = mid; |
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else if (result > 0) |
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start = mid + 1; |
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else |
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return (void *)base + mid * size; |
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} |
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return NULL; |
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} |
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EXPORT_SYMBOL(bsearch);
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