56 lines
1.5 KiB
C
56 lines
1.5 KiB
C
/*
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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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const char *pivot;
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int result;
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while (num > 0) {
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pivot = base + (num >> 1) * size;
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result = cmp(key, pivot);
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if (result == 0)
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return (void *)pivot;
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if (result > 0) {
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base = pivot + size;
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num--;
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}
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num >>= 1;
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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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