399 lines
14 KiB
C++
399 lines
14 KiB
C++
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/* boost random/detail/seed.hpp header file
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*
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* Copyright Steven Watanabe 2009
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* Distributed under the Boost Software License, Version 1.0. (See
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* accompanying file LICENSE_1_0.txt or copy at
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* http://www.boost.org/LICENSE_1_0.txt)
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*
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* See http://www.boost.org for most recent version including documentation.
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*
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* $Id$
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*/
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#ifndef BOOST_RANDOM_DETAIL_SEED_IMPL_HPP
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#define BOOST_RANDOM_DETAIL_SEED_IMPL_HPP
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#include <stdexcept>
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#include <boost/cstdint.hpp>
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#include <boost/throw_exception.hpp>
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#include <boost/config/no_tr1/cmath.hpp>
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#include <boost/integer/integer_mask.hpp>
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#include <boost/integer/static_log2.hpp>
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#include <boost/random/traits.hpp>
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#include <boost/mpl/bool.hpp>
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#include <boost/mpl/if.hpp>
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#include <boost/mpl/int.hpp>
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#include <boost/random/detail/const_mod.hpp>
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#include <boost/random/detail/integer_log2.hpp>
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#include <boost/random/detail/signed_unsigned_tools.hpp>
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#include <boost/random/detail/generator_bits.hpp>
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#include <boost/random/detail/disable_warnings.hpp>
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namespace boost {
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namespace random {
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namespace detail {
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// finds the seed type of an engine, given its
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// result_type. If the result_type is integral
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// the seed type is the same. If the result_type
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// is floating point, the seed type is uint32_t
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template<class T>
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struct seed_type
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{
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typedef typename boost::mpl::if_<boost::is_integral<T>,
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T,
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boost::uint32_t
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>::type type;
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};
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template<int N>
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struct const_pow_impl
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{
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template<class T>
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static T call(T arg, int n, T result)
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{
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return const_pow_impl<N / 2>::call(T(arg * arg), n / 2,
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n%2 == 0? result : T(result * arg));
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}
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};
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template<>
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struct const_pow_impl<0>
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{
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template<class T>
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static T call(T, int, T result)
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{
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return result;
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}
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};
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// requires N is an upper bound on n
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template<int N, class T>
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inline T const_pow(T arg, int n) { return const_pow_impl<N>::call(arg, n, T(1)); }
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template<class T>
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inline T pow2(int n)
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{
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typedef unsigned int_type;
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const int max_bits = std::numeric_limits<int_type>::digits;
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T multiplier = T(int_type(1) << (max_bits - 1)) * 2;
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return (int_type(1) << (n % max_bits)) *
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const_pow<std::numeric_limits<T>::digits / max_bits>(multiplier, n / max_bits);
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}
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template<class Engine, class Iter>
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void generate_from_real(Engine& eng, Iter begin, Iter end)
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{
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using std::fmod;
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typedef typename Engine::result_type RealType;
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const int Bits = detail::generator_bits<Engine>::value();
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int remaining_bits = 0;
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boost::uint_least32_t saved_bits = 0;
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RealType multiplier = pow2<RealType>( Bits);
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RealType mult32 = RealType(4294967296.0); // 2^32
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while(true) {
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RealType val = eng() * multiplier;
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int available_bits = Bits;
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// Make sure the compiler can optimize this out
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// if it isn't possible.
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if(Bits < 32 && available_bits < 32 - remaining_bits) {
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saved_bits |= boost::uint_least32_t(val) << remaining_bits;
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remaining_bits += Bits;
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} else {
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// If Bits < 32, then remaining_bits != 0, since
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// if remaining_bits == 0, available_bits < 32 - 0,
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// and we won't get here to begin with.
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if(Bits < 32 || remaining_bits != 0) {
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boost::uint_least32_t divisor =
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(boost::uint_least32_t(1) << (32 - remaining_bits));
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boost::uint_least32_t extra_bits = boost::uint_least32_t(fmod(val, mult32)) & (divisor - 1);
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val = val / divisor;
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*begin++ = saved_bits | (extra_bits << remaining_bits);
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if(begin == end) return;
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available_bits -= 32 - remaining_bits;
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remaining_bits = 0;
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}
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// If Bits < 32 we should never enter this loop
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if(Bits >= 32) {
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for(; available_bits >= 32; available_bits -= 32) {
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boost::uint_least32_t word = boost::uint_least32_t(fmod(val, mult32));
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val /= mult32;
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*begin++ = word;
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if(begin == end) return;
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}
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}
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remaining_bits = available_bits;
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saved_bits = static_cast<boost::uint_least32_t>(val);
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}
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}
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}
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template<class Engine, class Iter>
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void generate_from_int(Engine& eng, Iter begin, Iter end)
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{
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typedef typename Engine::result_type IntType;
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typedef typename boost::random::traits::make_unsigned<IntType>::type unsigned_type;
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int remaining_bits = 0;
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boost::uint_least32_t saved_bits = 0;
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unsigned_type range = boost::random::detail::subtract<IntType>()((eng.max)(), (eng.min)());
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int bits =
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(range == (std::numeric_limits<unsigned_type>::max)()) ?
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std::numeric_limits<unsigned_type>::digits :
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detail::integer_log2(range + 1);
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{
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int discarded_bits = detail::integer_log2(bits);
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unsigned_type excess = (range + 1) >> (bits - discarded_bits);
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if(excess != 0) {
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int extra_bits = detail::integer_log2((excess - 1) ^ excess);
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bits = bits - discarded_bits + extra_bits;
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}
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}
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unsigned_type mask = (static_cast<unsigned_type>(2) << (bits - 1)) - 1;
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unsigned_type limit = ((range + 1) & ~mask) - 1;
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while(true) {
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unsigned_type val;
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do {
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val = boost::random::detail::subtract<IntType>()(eng(), (eng.min)());
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} while(limit != range && val > limit);
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val &= mask;
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int available_bits = bits;
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if(available_bits == 32) {
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*begin++ = static_cast<boost::uint_least32_t>(val) & 0xFFFFFFFFu;
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if(begin == end) return;
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} else if(available_bits % 32 == 0) {
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for(int i = 0; i < available_bits / 32; ++i) {
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boost::uint_least32_t word = boost::uint_least32_t(val) & 0xFFFFFFFFu;
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int suppress_warning = (bits >= 32);
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BOOST_ASSERT(suppress_warning == 1);
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val >>= (32 * suppress_warning);
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*begin++ = word;
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if(begin == end) return;
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}
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} else if(bits < 32 && available_bits < 32 - remaining_bits) {
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saved_bits |= boost::uint_least32_t(val) << remaining_bits;
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remaining_bits += bits;
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} else {
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if(bits < 32 || remaining_bits != 0) {
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boost::uint_least32_t extra_bits = boost::uint_least32_t(val) & ((boost::uint_least32_t(1) << (32 - remaining_bits)) - 1);
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val >>= 32 - remaining_bits;
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*begin++ = saved_bits | (extra_bits << remaining_bits);
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if(begin == end) return;
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available_bits -= 32 - remaining_bits;
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remaining_bits = 0;
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}
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if(bits >= 32) {
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for(; available_bits >= 32; available_bits -= 32) {
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boost::uint_least32_t word = boost::uint_least32_t(val) & 0xFFFFFFFFu;
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int suppress_warning = (bits >= 32);
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BOOST_ASSERT(suppress_warning == 1);
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val >>= (32 * suppress_warning);
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*begin++ = word;
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if(begin == end) return;
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}
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}
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remaining_bits = available_bits;
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saved_bits = static_cast<boost::uint_least32_t>(val);
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}
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}
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}
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template<class Engine, class Iter>
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void generate_impl(Engine& eng, Iter first, Iter last, boost::mpl::true_)
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{
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return detail::generate_from_int(eng, first, last);
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}
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template<class Engine, class Iter>
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void generate_impl(Engine& eng, Iter first, Iter last, boost::mpl::false_)
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{
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return detail::generate_from_real(eng, first, last);
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}
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template<class Engine, class Iter>
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void generate(Engine& eng, Iter first, Iter last)
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{
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return detail::generate_impl(eng, first, last, boost::random::traits::is_integral<typename Engine::result_type>());
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}
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template<class IntType, IntType m, class SeedSeq>
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IntType seed_one_int(SeedSeq& seq)
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{
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static const int log = ::boost::mpl::if_c<(m == 0),
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::boost::mpl::int_<(::std::numeric_limits<IntType>::digits)>,
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::boost::static_log2<m> >::type::value;
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static const int k =
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(log + ((~(static_cast<IntType>(2) << (log - 1)) & m)? 32 : 31)) / 32;
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::boost::uint_least32_t array[log / 32 + 4];
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seq.generate(&array[0], &array[0] + k + 3);
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IntType s = 0;
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for(int j = 0; j < k; ++j) {
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IntType digit = const_mod<IntType, m>::apply(IntType(array[j+3]));
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IntType mult = IntType(1) << 32*j;
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s = const_mod<IntType, m>::mult_add(mult, digit, s);
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}
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return s;
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}
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template<class IntType, IntType m, class Iter>
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IntType get_one_int(Iter& first, Iter last)
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{
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static const int log = ::boost::mpl::if_c<(m == 0),
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::boost::mpl::int_<(::std::numeric_limits<IntType>::digits)>,
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::boost::static_log2<m> >::type::value;
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static const int k =
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(log + ((~(static_cast<IntType>(2) << (log - 1)) & m)? 32 : 31)) / 32;
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IntType s = 0;
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for(int j = 0; j < k; ++j) {
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if(first == last) {
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boost::throw_exception(::std::invalid_argument("Not enough elements in call to seed."));
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}
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IntType digit = const_mod<IntType, m>::apply(IntType(*first++));
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IntType mult = IntType(1) << 32*j;
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s = const_mod<IntType, m>::mult_add(mult, digit, s);
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}
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return s;
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}
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// TODO: work in-place whenever possible
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template<int w, std::size_t n, class SeedSeq, class UIntType>
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void seed_array_int_impl(SeedSeq& seq, UIntType (&x)[n])
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{
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boost::uint_least32_t storage[((w+31)/32) * n];
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seq.generate(&storage[0], &storage[0] + ((w+31)/32) * n);
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for(std::size_t j = 0; j < n; j++) {
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UIntType val = 0;
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for(std::size_t k = 0; k < (w+31)/32; ++k) {
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val += static_cast<UIntType>(storage[(w+31)/32*j + k]) << 32*k;
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}
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x[j] = val & ::boost::low_bits_mask_t<w>::sig_bits;
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}
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}
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template<int w, std::size_t n, class SeedSeq, class IntType>
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inline void seed_array_int_impl(SeedSeq& seq, IntType (&x)[n], boost::mpl::true_)
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{
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BOOST_STATIC_ASSERT_MSG(boost::is_integral<IntType>::value, "Sorry but this routine has not been ported to non built-in integers as it relies on a reinterpret_cast.");
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typedef typename boost::make_unsigned<IntType>::type unsigned_array[n];
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seed_array_int_impl<w>(seq, reinterpret_cast<unsigned_array&>(x));
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}
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template<int w, std::size_t n, class SeedSeq, class IntType>
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inline void seed_array_int_impl(SeedSeq& seq, IntType (&x)[n], boost::mpl::false_)
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{
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seed_array_int_impl<w>(seq, x);
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}
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template<int w, std::size_t n, class SeedSeq, class IntType>
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inline void seed_array_int(SeedSeq& seq, IntType (&x)[n])
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{
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seed_array_int_impl<w>(seq, x, boost::random::traits::is_signed<IntType>());
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}
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template<int w, std::size_t n, class Iter, class UIntType>
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void fill_array_int_impl(Iter& first, Iter last, UIntType (&x)[n])
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{
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for(std::size_t j = 0; j < n; j++) {
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UIntType val = 0;
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for(std::size_t k = 0; k < (w+31)/32; ++k) {
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if(first == last) {
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boost::throw_exception(std::invalid_argument("Not enough elements in call to seed."));
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}
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val += static_cast<UIntType>(*first++) << 32*k;
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}
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x[j] = val & ::boost::low_bits_mask_t<w>::sig_bits;
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}
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}
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template<int w, std::size_t n, class Iter, class IntType>
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inline void fill_array_int_impl(Iter& first, Iter last, IntType (&x)[n], boost::mpl::true_)
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{
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BOOST_STATIC_ASSERT_MSG(boost::is_integral<IntType>::value, "Sorry but this routine has not been ported to non built-in integers as it relies on a reinterpret_cast.");
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typedef typename boost::make_unsigned<IntType>::type unsigned_array[n];
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fill_array_int_impl<w>(first, last, reinterpret_cast<unsigned_array&>(x));
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}
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template<int w, std::size_t n, class Iter, class IntType>
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inline void fill_array_int_impl(Iter& first, Iter last, IntType (&x)[n], boost::mpl::false_)
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{
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fill_array_int_impl<w>(first, last, x);
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}
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template<int w, std::size_t n, class Iter, class IntType>
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inline void fill_array_int(Iter& first, Iter last, IntType (&x)[n])
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{
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fill_array_int_impl<w>(first, last, x, boost::random::traits::is_signed<IntType>());
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}
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template<int w, std::size_t n, class RealType>
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void seed_array_real_impl(const boost::uint_least32_t* storage, RealType (&x)[n])
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{
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boost::uint_least32_t mask = ~((~boost::uint_least32_t(0)) << (w%32));
|
||
|
|
RealType two32 = 4294967296.0;
|
||
|
|
const RealType divisor = RealType(1)/detail::pow2<RealType>(w);
|
||
|
|
unsigned int j;
|
||
|
|
for(j = 0; j < n; ++j) {
|
||
|
|
RealType val = RealType(0);
|
||
|
|
RealType mult = divisor;
|
||
|
|
for(int k = 0; k < w/32; ++k) {
|
||
|
|
val += *storage++ * mult;
|
||
|
|
mult *= two32;
|
||
|
|
}
|
||
|
|
if(mask != 0) {
|
||
|
|
val += (*storage++ & mask) * mult;
|
||
|
|
}
|
||
|
|
BOOST_ASSERT(val >= 0);
|
||
|
|
BOOST_ASSERT(val < 1);
|
||
|
|
x[j] = val;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
template<int w, std::size_t n, class SeedSeq, class RealType>
|
||
|
|
void seed_array_real(SeedSeq& seq, RealType (&x)[n])
|
||
|
|
{
|
||
|
|
using std::pow;
|
||
|
|
boost::uint_least32_t storage[((w+31)/32) * n];
|
||
|
|
seq.generate(&storage[0], &storage[0] + ((w+31)/32) * n);
|
||
|
|
seed_array_real_impl<w>(storage, x);
|
||
|
|
}
|
||
|
|
|
||
|
|
template<int w, std::size_t n, class Iter, class RealType>
|
||
|
|
void fill_array_real(Iter& first, Iter last, RealType (&x)[n])
|
||
|
|
{
|
||
|
|
boost::uint_least32_t mask = ~((~boost::uint_least32_t(0)) << (w%32));
|
||
|
|
RealType two32 = 4294967296.0;
|
||
|
|
const RealType divisor = RealType(1)/detail::pow2<RealType>(w);
|
||
|
|
unsigned int j;
|
||
|
|
for(j = 0; j < n; ++j) {
|
||
|
|
RealType val = RealType(0);
|
||
|
|
RealType mult = divisor;
|
||
|
|
for(int k = 0; k < w/32; ++k, ++first) {
|
||
|
|
if(first == last) boost::throw_exception(std::invalid_argument("Not enough elements in call to seed."));
|
||
|
|
val += *first * mult;
|
||
|
|
mult *= two32;
|
||
|
|
}
|
||
|
|
if(mask != 0) {
|
||
|
|
if(first == last) boost::throw_exception(std::invalid_argument("Not enough elements in call to seed."));
|
||
|
|
val += (*first & mask) * mult;
|
||
|
|
++first;
|
||
|
|
}
|
||
|
|
BOOST_ASSERT(val >= 0);
|
||
|
|
BOOST_ASSERT(val < 1);
|
||
|
|
x[j] = val;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
#include <boost/random/detail/enable_warnings.hpp>
|
||
|
|
|
||
|
|
#endif
|