[Boost-commit] svn:boost r68758 - in trunk/boost/random: . detail

Subject: [Boost-commit] svn:boost r68758 - in trunk/boost/random: . detail
From: steven_at_[hidden]
Date: 2011-02-09 20:27:13

Author: steven_watanabe
Date: 2011-02-09 20:27:11 EST (Wed, 09 Feb 2011)
New Revision: 68758
URL: http://svn.boost.org/trac/boost/changeset/68758

Log:
Factor out some common seeding code.
Added:
   trunk/boost/random/detail/seed_impl.hpp   (contents, props changed)
Text files modified: 
   trunk/boost/random/inversive_congruential.hpp |    16 ++--------------                        
   trunk/boost/random/linear_congruential.hpp    |    16 ++--------------                        
   trunk/boost/random/mersenne_twister.hpp       |    11 ++---------                             
   trunk/boost/random/subtract_with_carry.hpp    |    14 ++------------                          
   4 files changed, 8 insertions(+), 49 deletions(-)

Added: trunk/boost/random/detail/seed_impl.hpp
==============================================================================
--- (empty file)
+++ trunk/boost/random/detail/seed_impl.hpp	2011-02-09 20:27:11 EST (Wed, 09 Feb 2011)
@@ -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

Modified: trunk/boost/random/inversive_congruential.hpp
==============================================================================
--- trunk/boost/random/inversive_congruential.hpp	(original)
+++ trunk/boost/random/inversive_congruential.hpp	2011-02-09 20:27:11 EST (Wed, 09 Feb 2011)
@@ -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 @@
      * 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

Modified: trunk/boost/random/linear_congruential.hpp
==============================================================================
--- trunk/boost/random/linear_congruential.hpp	(original)
+++ trunk/boost/random/linear_congruential.hpp	2011-02-09 20:27:11 EST (Wed, 09 Feb 2011)
@@ -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 @@
      * 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

Modified: trunk/boost/random/mersenne_twister.hpp
==============================================================================
--- trunk/boost/random/mersenne_twister.hpp	(original)
+++ trunk/boost/random/mersenne_twister.hpp	2011-02-09 20:27:11 EST (Wed, 09 Feb 2011)
@@ -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 @@
      */
     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.

Modified: trunk/boost/random/subtract_with_carry.hpp
==============================================================================
--- trunk/boost/random/subtract_with_carry.hpp	(original)
+++ trunk/boost/random/subtract_with_carry.hpp	2011-02-09 20:27:11 EST (Wed, 09 Feb 2011)
@@ -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 @@
     /** 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;
     }