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vn-verdnaturachat/ios/Pods/boost-for-react-native/boost/random/detail/seed_impl.hpp

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