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MicroURNG.hpp
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1/*
2Copyright 2010-2011, D. E. Shaw Research.
3All rights reserved.
4
5Redistribution and use in source and binary forms, with or without
6modification, are permitted provided that the following conditions are
7met:
8
9* Redistributions of source code must retain the above copyright
10 notice, this list of conditions, and the following disclaimer.
11
12* Redistributions in binary form must reproduce the above copyright
13 notice, this list of conditions, and the following disclaimer in the
14 documentation and/or other materials provided with the distribution.
15
16* Neither the name of D. E. Shaw Research nor the names of its
17 contributors may be used to endorse or promote products derived from
18 this software without specific prior written permission.
19
20THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
21"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
22LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
23A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
24OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
25SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
26LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
27DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
28THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
29(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
30OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
31*/
32#ifndef __MicroURNG_dot_hpp__
33#define __MicroURNG_dot_hpp__
34
35#include <stdexcept>
36#include <limits>
37
38namespace r123{
78template<typename CBRNG>
80 // According to C++11, a URNG requires only a result_type,
81 // operator()(), min() and max() methods. Everything else
82 // (ctr_type, key_type, reset() method, etc.) is "value added"
83 // for the benefit of users that "know" that they're dealing with
84 // a MicroURNG.
85public:
86 typedef CBRNG cbrng_type;
87 static const int BITS = 32;
88 typedef typename cbrng_type::ctr_type ctr_type;
89 typedef typename cbrng_type::key_type key_type;
90 typedef typename cbrng_type::ukey_type ukey_type;
91 typedef typename ctr_type::value_type result_type;
92
93 R123_STATIC_ASSERT( std::numeric_limits<result_type>::digits >= BITS, "The result_type must have at least 32 bits" );
94
96 if(last_elem == 0){
97 // jam n into the high bits of c
98 const size_t W = std::numeric_limits<result_type>::digits;
99 ctr_type c = c0;
100 c[c0.size()-1] |= n<<(W-BITS);
101 rdata = b(c,k);
102 n++;
103 last_elem = rdata.size();
104 }
105 return rdata[--last_elem];
106 }
107 MicroURNG(cbrng_type _b, ctr_type _c0, ukey_type _uk) : b(_b), c0(_c0), k(_uk), n(0), last_elem(0) {
108 chkhighbits();
109 }
110 MicroURNG(ctr_type _c0, ukey_type _uk) : b(), c0(_c0), k(_uk), n(0), last_elem(0) {
111 chkhighbits();
112 }
113
114 // _Min and _Max work around a bug in the library shipped with MacOS Xcode 4.5.2.
115 // See the commment in conventional/Engine.hpp.
116 const static result_type _Min = 0;
117 const static result_type _Max = ~((result_type)0);
118
121 // extra methods:
122 const ctr_type& counter() const{ return c0; }
124 c0 = _c0;
125 chkhighbits();
126 k = _uk;
127 n = 0;
128 last_elem = 0;
129 }
130
131private:
132 cbrng_type b;
133 ctr_type c0;
134 key_type k;
136 size_t last_elem;
137 ctr_type rdata;
138 void chkhighbits(){
139 result_type r = c0[c0.size()-1];
140 result_type mask = ((uint64_t)std::numeric_limits<result_type>::max R123_NO_MACRO_SUBST ())>>BITS;
141 if((r&mask) != r)
142 throw std::runtime_error("MicroURNG: c0, does not have high bits clear");
143 }
144};
145} // namespace r123
146#endif
Definition MicroURNG.hpp:79
const ctr_type & counter() const
Definition MicroURNG.hpp:122
MicroURNG(cbrng_type _b, ctr_type _c0, ukey_type _uk)
Definition MicroURNG.hpp:107
static const result_type _Min
Definition MicroURNG.hpp:116
static R123_CONSTEXPR result_type max R123_NO_MACRO_SUBST()
Definition MicroURNG.hpp:120
static const result_type _Max
Definition MicroURNG.hpp:117
ctr_type::value_type result_type
Definition MicroURNG.hpp:91
cbrng_type::ctr_type ctr_type
Definition MicroURNG.hpp:88
result_type operator()()
Definition MicroURNG.hpp:95
cbrng_type::ukey_type ukey_type
Definition MicroURNG.hpp:90
MicroURNG(ctr_type _c0, ukey_type _uk)
Definition MicroURNG.hpp:110
static R123_CONSTEXPR result_type min R123_NO_MACRO_SUBST()
Definition MicroURNG.hpp:119
CBRNG cbrng_type
Definition MicroURNG.hpp:86
static const int BITS
Definition MicroURNG.hpp:87
void reset(ctr_type _c0, ukey_type _uk)
Definition MicroURNG.hpp:123
cbrng_type::key_type key_type
Definition MicroURNG.hpp:89
static Ftype uneg11(Itype in)
Return a signed value in [-1,1].
Definition uniform.hpp:206
Definition aes.h:242