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Teuchos_HashUtils.cpp
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41 
42 #include "Teuchos_HashUtils.hpp"
43 #include "Teuchos_Assert.hpp"
44 
45 using namespace Teuchos;
46 
47 
48 const int HashUtils::primeCount_ = 33;
49 const int HashUtils::primes_[]
50 = {11, 19, 37, 59, 101, 163, 271, 443, 733, 1187, 1907, 3061,
51  4919, 7759, 12379, 19543, 30841, 48487, 75989,
52  119089, 185971, 290347, 452027, 703657, 1093237,
53  1695781, 2627993, 4067599, 6290467, 9718019,
54  15000607, 23133937, 35650091};
55 
56 
57 int HashUtils::nextPrime(int newCapacity)
58 {
60  std::logic_error,
61  "HashUtils::nextPrime() overflow");
62 
63  for (int i=0; i<primeCount_; i++)
64  {
65  if (newCapacity <= primes_[i])
66  {
67  return primes_[i];
68  }
69  }
70 
72  std::logic_error,
73  "unexpected case in HashUtils::nextPrime()");
74  return 0;
75 }
76 
83 int HashUtils::getHashCode(const unsigned char *a, size_t len)
84 {
85  int total=0;
86  unsigned char *to = reinterpret_cast<unsigned char *>(&total);
87  int c=0;
88  for (size_t i=0; i < len; i++){
89  to[c++] += a[i];
90  if (c == sizeof(int))
91  c = 0;
92  }
93  if (total < 0)
94  {
95  /* Convert the largest -ve int to zero and -1 to
96  * std::numeric_limits<int>::max()
97  * */
98  size_t maxIntBeforeWrap = std::numeric_limits<int>::max();
99  maxIntBeforeWrap ++;
100  total += maxIntBeforeWrap;
101  }
102  return total;
103 }
#define TEUCHOS_TEST_FOR_EXCEPTION(throw_exception_test, Exception, msg)
Macro for throwing an exception with breakpointing to ease debugging.
static int getHashCode(const unsigned char *a, size_t len)
static int nextPrime(int newCapacity)
static const int primes_[]
static const int primeCount_
Utilities for generating hashcodes.