/*
 * 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 "bsearch.h"

/*
 * bsearch - binary search an array of elements
 * @key: pointer to item being searched for
 * @base: pointer to data to sort
 * @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))
{
  int start = 0, end = num - 1, mid, result;

  if (num == 0) {
    return NULL;
  }

  while (start <= end) {
    mid = (start + end) / 2;
    result = cmp(key, base + mid * size);

    if (result < 0) {
      end = mid - 1;
    } else if (result > 0) {
      start = mid + 1;
    } else {
      return (void *)base + mid * size;
    }
  }

  return NULL;
}
//EXPORT_SYMBOL(bsearch);