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Diffstat (limited to 'src/third_party/boost-1.69.0/boost/random/random_device.hpp')
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diff --git a/src/third_party/boost-1.69.0/boost/random/random_device.hpp b/src/third_party/boost-1.69.0/boost/random/random_device.hpp new file mode 100644 index 00000000000..8f3903c953c --- /dev/null +++ b/src/third_party/boost-1.69.0/boost/random/random_device.hpp @@ -0,0 +1,143 @@ +/* boost random/random_device.hpp header file + * + * Copyright Jens Maurer 2000 + * Copyright Steven Watanabe 2010-2011 + * Distributed under the Boost Software License, Version 1.0. (See + * accompanying file LICENSE_1_0.txt or copy at + * http://www.boost.org/LICENSE_1_0.txt) + * + * $Id$ + * + * Revision history + * 2000-02-18 Portability fixes (thanks to Beman Dawes) + */ + +// See http://www.boost.org/libs/random for documentation. + + +#ifndef BOOST_RANDOM_RANDOM_DEVICE_HPP +#define BOOST_RANDOM_RANDOM_DEVICE_HPP + +#include <string> +#include <boost/config.hpp> +#include <boost/noncopyable.hpp> +#include <boost/random/detail/auto_link.hpp> +#include <boost/system/config.hpp> // force autolink to find Boost.System + +namespace boost { +namespace random { + +/** + * Class \random_device models a \nondeterministic_random_number_generator. + * It uses one or more implementation-defined stochastic processes to + * generate a sequence of uniformly distributed non-deterministic random + * numbers. For those environments where a non-deterministic random number + * generator is not available, class random_device must not be implemented. See + * + * @blockquote + * "Randomness Recommendations for Security", D. Eastlake, S. Crocker, + * J. Schiller, Network Working Group, RFC 1750, December 1994 + * @endblockquote + * + * for further discussions. + * + * @xmlnote + * Some operating systems abstract the computer hardware enough + * to make it difficult to non-intrusively monitor stochastic processes. + * However, several do provide a special device for exactly this purpose. + * It seems to be impossible to emulate the functionality using Standard + * C++ only, so users should be aware that this class may not be available + * on all platforms. + * @endxmlnote + * + * <b>Implementation Note for Linux</b> + * + * On the Linux operating system, token is interpreted as a filesystem + * path. It is assumed that this path denotes an operating system + * pseudo-device which generates a stream of non-deterministic random + * numbers. The pseudo-device should never signal an error or end-of-file. + * Otherwise, @c std::ios_base::failure is thrown. By default, + * \random_device uses the /dev/urandom pseudo-device to retrieve + * the random numbers. Another option would be to specify the /dev/random + * pseudo-device, which blocks on reads if the entropy pool has no more + * random bits available. + * + * <b>Implementation Note for Windows</b> + * + * On the Windows operating system, token is interpreted as the name + * of a cryptographic service provider. By default \random_device uses + * MS_DEF_PROV. + * + * <b>Performance</b> + * + * The test program <a href="\boost/libs/random/performance/nondet_random_speed.cpp"> + * nondet_random_speed.cpp</a> measures the execution times of the + * random_device.hpp implementation of the above algorithms in a tight + * loop. The performance has been evaluated on an + * Intel(R) Core(TM) i7 CPU Q 840 \@ 1.87GHz, 1867 Mhz with + * Visual C++ 2010, Microsoft Windows 7 Professional and with gcc 4.4.5, + * Ubuntu Linux 2.6.35-25-generic. + * + * <table cols="2"> + * <tr><th>Platform</th><th>time per invocation [microseconds]</th></tr> + * <tr><td> Windows </td><td>2.9</td></tr> + * <tr><td> Linux </td><td>1.7</td></tr> + * </table> + * + * The measurement error is estimated at +/- 1 usec. + */ +class random_device : private noncopyable +{ +public: + typedef unsigned int result_type; + BOOST_STATIC_CONSTANT(bool, has_fixed_range = false); + + /** Returns the smallest value that the \random_device can produce. */ + static result_type min BOOST_PREVENT_MACRO_SUBSTITUTION () { return 0; } + /** Returns the largest value that the \random_device can produce. */ + static result_type max BOOST_PREVENT_MACRO_SUBSTITUTION () { return ~0u; } + + /** Constructs a @c random_device, optionally using the default device. */ + BOOST_RANDOM_DECL random_device(); + /** + * Constructs a @c random_device, optionally using the given token as an + * access specification (for example, a URL) to some implementation-defined + * service for monitoring a stochastic process. + */ + BOOST_RANDOM_DECL explicit random_device(const std::string& token); + + BOOST_RANDOM_DECL ~random_device(); + + /** + * Returns: An entropy estimate for the random numbers returned by + * operator(), in the range min() to log2( max()+1). A deterministic + * random number generator (e.g. a pseudo-random number engine) + * has entropy 0. + * + * Throws: Nothing. + */ + BOOST_RANDOM_DECL double entropy() const; + /** Returns a random value in the range [min, max]. */ + BOOST_RANDOM_DECL unsigned int operator()(); + + /** Fills a range with random 32-bit values. */ + template<class Iter> + void generate(Iter begin, Iter end) + { + for(; begin != end; ++begin) { + *begin = (*this)(); + } + } + +private: + class impl; + impl * pimpl; +}; + +} // namespace random + +using random::random_device; + +} // namespace boost + +#endif /* BOOST_RANDOM_RANDOM_DEVICE_HPP */ |