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Factor out some common seeding code.

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[SVN r68758]
This commit is contained in:
Steven Watanabe 2011-02-10 01:27:11 +00:00
parent 0908708463
commit b5be1f6d9e
5 changed files with 176 additions and 49 deletions
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168
include/boost/random/detail/seed_impl.hpp Normal file
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@ -0,0 +1,168 @@
/* 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 <boost/cstdint.hpp>
#include <boost/integer/integer_mask.hpp>
#include <boost/integer/static_log2.hpp>
#include <boost/type_traits/is_signed.hpp>
#include <boost/type_traits/make_unsigned.hpp>
#include <boost/random/detail/const_mod.hpp>
#include <boost/random/detail/signed_unsigned_tools.hpp>
namespace boost {
namespace random {
namespace detail {
template<class Engine, int Bits, class Iter>
void generate_from_real(Engine& eng, Iter begin, Iter end)
{
typedef typename Engine::result_type RealType;
int remaining_bits = 0;
boost::uint32_t saved_bits;
RealType mult32 = 4294967296.0; // 2^32
for(; begin != end; ++begin) {
RealType val = eng();
int available_bits = Bits;
if(available_bits < 32 - remaining_bits) {
saved_bits |= boost::uint32_t(val * mult32) >> remaining_bits;
remaining_bits += available_bits;
} else {
if(remaining_bits != 0) {
val *= boost::uint32_t(1) << (32 - remaining_bits);
boost::uint32_t extra_bits = boost::uint32_t(val);
val -= extra_bits;
*begin++ = saved_bits | extra_bits;
if(begin == end) break;
available_bits -= 32 - remaining_bits;
remaining_bits = 0;
}
for(; available_bits >= 32; available_bits -= 32) {
val *= mult32;
boost::uint32_t word = boost::uint32_t(val);
val -= word;
*begin++ = word;
if(begin == end) break;
}
remaining_bits = available_bits;
saved_bits = boost::uint32_t(val * mult32);
}
}
}
template<class Engine, class Iter>
void generate_from_int(Engine& eng, Iter begin, Iter end)
{
typedef typename Engine::result_type IntType;
typedef typename boost::make_unsigned<IntType>::type unsigned_type;
int remaining_bits = 0;
boost::uint32_t saved_bits;
unsigned_type range = boost::random::detail::subtract<IntType>()((eng.max)(), (eng.min)());
int bits = 0;
unsigned_type mask = 0;
for(; bits < std::numeric_limits<unsigned_type>::digits; ++bits)
{
unsigned_type test = mask | (unsigned_type(1) << bits);
if(test <= range) {
mask = test;
} else {
break;
}
}
for(; begin != end; ++begin) {
unsigned_type val;
do {
val = boost::random::detail::subtract<IntType>()(eng(), (eng.min)());
} while(val > mask);
int available_bits = bits;
if(available_bits < 32 - remaining_bits) {
saved_bits |= boost::uint32_t(val) << remaining_bits;
remaining_bits += bits;
} else {
if(remaining_bits != 0) {
boost::uint32_t extra_bits = boost::uint32_t(val) & ((boost::uint32_t(1) << (32 - remaining_bits)) - 1);
val >>= 32 - remaining_bits;
*begin++ = saved_bits | (extra_bits << remaining_bits);
if(begin == end) break;
available_bits -= 32 - remaining_bits;
remaining_bits = 0;
}
for(; available_bits >= 32; available_bits -= 32) {
boost::uint32_t word = boost::uint32_t(val);
val >>= 32;
*begin++ = word;
if(begin == end) break;
}
remaining_bits = available_bits;
saved_bits = val;
}
}
}
template<class IntType, IntType m, class SeedSeq>
IntType seed_one_int(SeedSeq& seq)
{
static const int log = ::boost::static_log2<m>::value;
static const int k =
(log + ((~(static_cast<IntType>(1) << log) & m)? 32 : 31)) / 32;
boost::uint_least32_t array[k + 3];
seq.generate(&array[0], &array[0] + k + 3);
IntType s = 0;
for(int j = 0; j < k; ++j) {
IntType digit = IntType(array[j+3]) % m;
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_)
{
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::is_signed<IntType>());
}
}
}
}
#endif

16
include/boost/random/inversive_congruential.hpp
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@ -25,6 +25,7 @@
#include <boost/random/detail/const_mod.hpp>
#include <boost/random/detail/seed.hpp>
#include <boost/random/detail/operators.hpp>
#include <boost/random/detail/seed_impl.hpp>
namespace boost {
namespace random {
@ -141,20 +142,7 @@ public:
* Seeds an @c inversive_congruential_engine using values from a SeedSeq.
*/
BOOST_RANDOM_DETAIL_SEED_SEQ_SEED(inversive_congruential_engine, SeedSeq, seq)
{
static const int log = ::boost::static_log2<modulus>::value;
static const int k =
(log + ((~(static_cast<IntType>(1) << log) & modulus)? 32 : 31)) / 32;
boost::uint32_t array[k + 3];
seq.generate(&array[0], &array[0] + k + 3);
IntType s = 0;
IntType mul = 1;
for(int j = 0; j < k; ++j) {
s = const_mod<IntType, modulus>::mult_add(array[j + 3], mul, s);
mul <<= 32;
}
seed(s);
}
{ seed(detail::seed_one_int<IntType, modulus>(seq)); }
/**
* seeds an @c inversive_congruential_engine with values taken

16
include/boost/random/linear_congruential.hpp
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@ -28,6 +28,7 @@
#include <boost/random/detail/config.hpp>
#include <boost/random/detail/const_mod.hpp>
#include <boost/random/detail/seed.hpp>
#include <boost/random/detail/seed_impl.hpp>
#include <boost/detail/workaround.hpp>
#include <boost/random/detail/disable_warnings.hpp>
@ -146,20 +147,7 @@ public:
* Seeds a @c linear_congruential_engine using values from a SeedSeq.
*/
BOOST_RANDOM_DETAIL_SEED_SEQ_SEED(linear_congruential_engine, SeedSeq, seq)
{
static const int log = ::boost::static_log2<m>::value;
static const int k =
(log + ((~(static_cast<IntType>(1) << log) & m)? 32 : 31)) / 32;
boost::uint32_t array[k + 3];
seq.generate(&array[0], &array[0] + k + 3);
IntType s = 0;
IntType mul = 1;
for(int j = 0; j < k; ++j) {
s = const_mod<IntType, m>::mult_add(array[j + 3], mul, s);
mul <<= 32;
}
seed(s);
}
{ seed(detail::seed_one_int<IntType, m>(seq)); }
/**
* seeds a @c linear_congruential_engine with values taken

11
include/boost/random/mersenne_twister.hpp
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@ -25,6 +25,7 @@
#include <boost/random/detail/config.hpp>
#include <boost/random/detail/ptr_helper.hpp>
#include <boost/random/detail/seed.hpp>
#include <boost/random/detail/seed_impl.hpp>
#include <boost/random/detail/generator_seed_seq.hpp>
namespace boost {
@ -152,15 +153,7 @@ public:
*/
BOOST_RANDOM_DETAIL_SEED_SEQ_SEED(mersenne_twister_engine, SeeqSeq, seq)
{
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 += storage[(w+31)/32*j + k] << 32*k;
}
x[j] = val;
}
detail::seed_array_int<w>(seq, x);
i = n;
// fix up the state if it's all zeroes.

14
include/boost/random/subtract_with_carry.hpp
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@ -29,7 +29,7 @@
#include <boost/random/detail/config.hpp>
#include <boost/random/detail/seed.hpp>
#include <boost/random/detail/operators.hpp>
#include <boost/random/detail/generator_seed_seq.hpp>
#include <boost/random/detail/seed_impl.hpp>
#include <boost/random/linear_congruential.hpp>
@ -107,17 +107,7 @@ public:
/** Seeds the generator with values produced by @c seq.generate(). */
BOOST_RANDOM_DETAIL_SEED_SEQ_SEED(subtract_with_carry, SeedSeq, seq)
{
uint32_t storage[((w+31)/32) * long_lag];
seq.generate(&storage[0], &storage[0] + ((w+31)/32) * long_lag);
for(std::size_t j = 0; j < long_lag; j++) {
IntType val = 0;
for(std::size_t k = 0; k < (w+31)/32; ++k) {
result_type inc =
static_cast<result_type>(storage[(w+31)/32*j + k]);
val += inc << 32*k;
}
x[j] = val % modulus;
}
detail::seed_array_int<w>(seq, x);
carry = (x[long_lag-1] == 0);
k = 0;
}