Teuchos Package Browser (Single Doxygen Collection) Version of the Day
Loading...
Searching...
No Matches
Teuchos_HashUtils.cpp
Go to the documentation of this file.
1// @HEADER
2// ***********************************************************************
3//
4// Teuchos: Common Tools Package
5// Copyright (2004) Sandia Corporation
6//
7// Under terms of Contract DE-AC04-94AL85000, there is a non-exclusive
8// license for use of this work by or on behalf of the U.S. Government.
9//
10// Redistribution and use in source and binary forms, with or without
11// modification, are permitted provided that the following conditions are
12// met:
13//
14// 1. Redistributions of source code must retain the above copyright
15// notice, this list of conditions and the following disclaimer.
16//
17// 2. Redistributions in binary form must reproduce the above copyright
18// notice, this list of conditions and the following disclaimer in the
19// documentation and/or other materials provided with the distribution.
20//
21// 3. Neither the name of the Corporation nor the names of the
22// contributors may be used to endorse or promote products derived from
23// this software without specific prior written permission.
24//
25// THIS SOFTWARE IS PROVIDED BY SANDIA CORPORATION "AS IS" AND ANY
26// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
27// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
28// PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL SANDIA CORPORATION OR THE
29// CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
30// EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
31// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
32// PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
33// LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
34// NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
35// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
36//
37// Questions? Contact Michael A. Heroux (maherou@sandia.gov)
38//
39// ***********************************************************************
40// @HEADER
41
42#include "Teuchos_HashUtils.hpp"
43#include "Teuchos_Assert.hpp"
45
46using namespace Teuchos;
47
48
49const int HashUtils::primeCount_ = 33;
50const int HashUtils::primes_[]
51= {11, 19, 37, 59, 101, 163, 271, 443, 733, 1187, 1907, 3061,
52 4919, 7759, 12379, 19543, 30841, 48487, 75989,
53 119089, 185971, 290347, 452027, 703657, 1093237,
54 1695781, 2627993, 4067599, 6290467, 9718019,
55 15000607, 23133937, 35650091};
56
57
58int HashUtils::nextPrime(int newCapacity)
59{
61 std::logic_error,
62 "HashUtils::nextPrime() overflow");
63
64 for (int i=0; i<primeCount_; i++)
65 {
66 if (newCapacity <= primes_[i])
67 {
68 return primes_[i];
69 }
70 }
71
73 std::logic_error,
74 "unexpected case in HashUtils::nextPrime()");
76}
77
84int HashUtils::getHashCode(const unsigned char *a, size_t len)
85{
86 int total=0;
87 unsigned char *to = reinterpret_cast<unsigned char *>(&total);
88 int c=0;
89 for (size_t i=0; i < len; i++){
90 to[c++] += a[i];
91 if (c == sizeof(int))
92 c = 0;
93 }
94 if (total < 0)
95 {
96 /* Convert the largest -ve int to zero and -1 to
97 * std::numeric_limits<int>::max()
98 * */
99 size_t maxIntBeforeWrap = std::numeric_limits<int>::max();
100 maxIntBeforeWrap ++;
101 total += maxIntBeforeWrap;
102 }
103 return total;
104}
#define TEUCHOS_UNREACHABLE_RETURN(dummyReturnVal)
Avoid warning about unreachable or missing return from function.
Utilities for generating hashcodes.
static int getHashCode(const unsigned char *a, size_t len)
static int nextPrime(int newCapacity)
static const int primeCount_
static const int primes_[]
#define TEUCHOS_TEST_FOR_EXCEPTION(throw_exception_test, Exception, msg)
Macro for throwing an exception with breakpointing to ease debugging.