Equalizer  1.2.1
rng.h
00001 
00002 /* Copyright (c) 2007-2012, Stefan Eilemann <eile@equalizergraphics.com> 
00003  *
00004  * This library is free software; you can redistribute it and/or modify it under
00005  * the terms of the GNU Lesser General Public License version 2.1 as published
00006  * by the Free Software Foundation.
00007  *  
00008  * This library is distributed in the hope that it will be useful, but WITHOUT
00009  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
00010  * FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more
00011  * details.
00012  * 
00013  * You should have received a copy of the GNU Lesser General Public License
00014  * along with this library; if not, write to the Free Software Foundation, Inc.,
00015  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
00016  */
00017 
00018 #ifndef COBASE_RNG_H
00019 #define COBASE_RNG_H
00020 
00021 #include <co/base/debug.h> // for EQASSERT
00022 #include <co/base/init.h>  // friend function
00023 #include <co/base/nonCopyable.h>
00024 #include <co/base/types.h>
00025 
00026 #pragma warning (push)
00027 #pragma warning (disable: 4985) // inconsistent decl of ceil
00028 
00029 #ifdef _WIN32
00030 #  ifndef NOMINMAX
00031 #    define NOMINMAX
00032 #  endif
00033 #  include <wtypes.h>
00034 #  include <wincrypt.h>
00035 #  pragma comment(lib, "advapi32.lib")
00036 #else
00037 #  include <unistd.h>
00038 #endif
00039 
00040 #include <fcntl.h>
00041 #include <limits>
00042 #include <stdio.h>
00043 #pragma warning (pop)
00044 
00045 namespace co
00046 {
00047 namespace base
00048 {
00055     class RNG : public NonCopyable
00056     {
00057     public:
00059         RNG() { _init(); }
00060 
00062         ~RNG() {}
00063 
00065         void reseed()
00066         {
00067 #ifdef Darwin
00068             srandomdev();
00069 #endif
00070         }
00071 
00080         template< typename T > T get()
00081         {
00082             T value;
00083 #ifdef Linux
00084             EQASSERTINFO( _fd >= 0, "init() not called?" );
00085             int read = ::read( _fd, &value, sizeof( T ));
00086             EQASSERTINFO( read == sizeof(T),
00087                           read << " != " << sizeof( T ) << ": " << sysError );
00088             if( read != sizeof( T ))
00089             {
00090                 EQERROR << "random number generator not working" << std::endl;
00091                 return 0;
00092             }
00093 
00094 #elif defined (_WIN32)
00095             EQASSERTINFO( _provider, "init() not called?" );
00096             if( !CryptGenRandom( _provider, sizeof( T ), (BYTE*)&value ))
00097             {
00098                 EQASSERTINFO( false, "random number generator not working: " <<
00099                                      sysError );
00100             }
00101 #else // Darwin
00102             uint8_t* bytes = reinterpret_cast< uint8_t* >( &value );
00103             for( size_t i=0; i<sizeof( T ); ++i )
00104                 bytes[i] = ( random() & 0xff );
00105 #endif
00106             return value;
00107         }
00108 
00109     private:
00110 #ifdef Linux
00111         static int _fd;
00112 #elif defined (_WIN32)
00113         static COBASE_API HCRYPTPROV _provider;
00114 #endif
00115         static COBASE_API bool _init();
00116         static void _exit();
00117         friend COBASE_API bool init( const int argc, char** argv );
00118     };
00119 
00120     template<> inline float RNG::get()
00121     {
00122         const float max_limits =
00123             static_cast< float >( std::numeric_limits< uint32_t >::max( ));
00124         return ( get< uint32_t >() / max_limits);
00125     }
00126     
00127     template<> inline double RNG::get()
00128     {
00129         const double max_limits =
00130             static_cast< double >( std::numeric_limits< uint64_t >::max( ));
00131         return ( get< uint64_t >() / max_limits);
00132     }
00133     
00134     template<> inline bool RNG::get()
00135     {
00136         return ( get< uint32_t >() & 1 );
00137     }
00138 }
00139 }
00140 #endif  // COBASE_RNG_H
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