/*

 * 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 <xen/lib.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;

}