moleculardna/src/DNAHashing.cc

0001 //
0002 // ********************************************************************
0003 // * License and Disclaimer                                           *
0004 // *                                                                  *
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0006 // * the Geant4 Collaboration.  It is provided  under  the terms  and *
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0010 // *                                                                  *
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0015 // * use.  Please see the license in the file  LICENSE  and URL above *
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0017 // *                                                                  *
0018 // * This  code  implementation is the result of  the  scientific and *
0019 // * technical work of the GEANT4 collaboration.                      *
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0022 // * use  in  resulting  scientific  publications,  and indicate your *
0023 // * acceptance of all terms of the Geant4 Software license.          *
0024 // ********************************************************************
0025 //
0026 //
0027 //  G4Hashing.cc
0028 //  Geant4
0029 //
0030 //  Created by Mathieu Karamitros
0031 //
0032 //
0033
0034 #include "DNAHashing.hh"
0035
0036 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
0037
0038 namespace G4::hashing
0039 {
0040 namespace crc32
0041 {
0042 uint32_t Hash(const char* str, size_t len)
0043 {
0044   uint32_t remainder = 0xFFFFFFFF;
0045   for (size_t idx = 0; idx < len; ++idx) {
0046     remainder = (remainder >> 8) ^ fCrc_table[(remainder ^ str[idx]) & 0x000000FF];
0047   }
0048   return remainder ^ 0xFFFFFFFF;
0049 }
0050
0051 uint32_t Hash(const std::string& str)
0052 {
0053   return Hash(str.c_str(), str.size());
0054 }
0055 }  // namespace crc32
0056
0057 namespace fnv
0058 {
0059 size_t Hash(const std::string& str)
0060 {
0061   size_t hash = fnv_offset_basis;
0062   for (size_t i = 0; i < str.length(); i++) {
0063     hash = hash ^ (str[i]);  // xor  the low 8 bits
0064     hash = hash * fnv_prime;  // multiply by the magic number
0065   }
0066   return hash;
0067 }
0068 }  // namespace fnv
0069
0070 namespace larson
0071 {
0072 size_t Hash(const char* str, unsigned int seed)
0073 {
0074   size_t hash = seed;
0075   while (*str != 0) {
0076     hash = hash * 101 + *str++;
0077   }
0078   return hash;
0079 }
0080
0081 size_t Hash(std::string str, unsigned int seed)
0082 {
0083   return Hash(str.c_str(), seed);
0084 }
0085 }  // namespace larson
0086 }  // namespace G4::hashing
0087
0088 //....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......