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Grid/lib/sitmo_rng/sitmo_prng_engine.hpp
Guido Cossu 70ed9fc40c Updating the engine to the last version
2017-01-25 18:10:41 +00:00

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// Copyright (c) 2012-2016 M.A. (Thijs) van den Berg, http://sitmo.com/
//
// Use, modification and distribution are subject to the MIT Software License.
//
// The MIT License (MIT)
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
// version history:
// version 1, 6 Sep 2012
// version 2, 10 Dec 2013
// bug fix in the discard() routine, it was discarding to many elements
// added the version() method
// version 3...5, 13 Dec 2013
// fixed type-conversion earning
// fixed potential issues with constructor template matching
// version 6, 4 March 2016
// made min() max() constexpr for C+11 compiler (thanks to James Joseph Balamuta)
#ifndef SITMO_PRNG_ENGINE_HPP
#define SITMO_PRNG_ENGINE_HPP
#include <iostream>
#ifdef __GNUC__
#include <stdint.h> // respecting the C99 standard.
#endif
#ifdef _MSC_VER
typedef unsigned __int64 uint64_t; // Visual Studio 6.0(VC6) and newer..
typedef unsigned __int32 uint32_t;
#endif
// Double mixing function
#define MIX2(x0,x1,rx,z0,z1,rz) \
x0 += x1; \
z0 += z1; \
x1 = (x1 << rx) | (x1 >> (64-rx)); \
z1 = (z1 << rz) | (z1 >> (64-rz)); \
x1 ^= x0; \
z1 ^= z0;
// Double mixing function with key adition
#define MIXK(x0,x1,rx,z0,z1,rz,k0,k1,l0,l1) \
x1 += k1; \
z1 += l1; \
x0 += x1+k0; \
z0 += z1+l0; \
x1 = (x1 << rx) | (x1 >> (64-rx)); \
z1 = (z1 << rz) | (z1 >> (64-rz)); \
x1 ^= x0; \
z1 ^= z0; \
namespace sitmo {
// enable_if for C__98 compilers
template<bool C, typename T = void>
struct sitmo_enable_if { typedef T type; };
template<typename T>
struct sitmo_enable_if<false, T> { };
// SFINAE check for the existence of a "void generate(int*,int*)"member function
template<typename T>
struct has_generate_template
{
typedef char (&Two)[2];;
template<typename F, void (F::*)(int *, int *)> struct helper {};
template<typename C> static char test(helper<C, &C::template generate<int*> >*);
template<typename C> static Two test(...);
static bool const value = sizeof(test<T>(0)) == sizeof(char);
};
class prng_engine
{
public:
// "req" are requirements as stated in the C++ 11 draft n3242=11-0012
//
// req: 26.5.1.3 Uniform random number generator requirements, p.906, table 116, row 1
typedef uint32_t result_type;
// req: 26.5.1.3 Uniform random number generator requirements, p.906, table 116, row 3 & 4
#if __cplusplus <= 199711L
static result_type (min)() { return 0; }
static result_type (max)() { return 0xFFFFFFFF; }
#else
static constexpr result_type (min)() { return 0; }
static constexpr result_type (max)() { return 0xFFFFFFFF; }
#endif
// -------------------------------------------------
// Constructors
// -------------------------------------------------
// req: 26.5.1.4 Random number engine requirements, p.907 table 117, row 1
// Creates an engine with the same initial state as all other
// default-constructed engines of type E.
prng_engine()
{
seed();
}
// req: 26.5.1.4 Random number engine requirements, p.907 table 117, row 2
// Creates an engine that compares equal to x.
prng_engine(const prng_engine& x)
{
for (unsigned short i=0; i<4; ++i) {
_s[i] = x._s[i];
_k[i] = x._k[i];
_o[i] = x._o[i];
}
_o_counter = x._o_counter;
}
// req: 26.5.1.4 Random number engine requirements, p.907 table 117, row 3
// Creates an engine with initial O(size of state) state determined by s.
prng_engine(uint32_t s)
{
seed(s);
}
// req: 26.5.1.4 Random number engine requirements, p.908 table 117, row 4
// Creates an engine with an initial state that depends on a sequence
// produced by one call to q.generate.
template<class Seq>
prng_engine(Seq& q, typename sitmo_enable_if< has_generate_template<Seq>::value >::type* = 0 )
{
seed(q);
}
// -------------------------------------------------
// Seeding
// -------------------------------------------------
// req: 26.5.1.4 Random number engine requirements, p.908 table 117, row 5
void seed()
{
for (unsigned short i=0; i<4; ++i) {
_k[i] = 0;
_s[i] = 0;
}
_o_counter = 0;
_o[0] = 0x09218ebde6c85537;
_o[1] = 0x55941f5266d86105;
_o[2] = 0x4bd25e16282434dc;
_o[3] = 0xee29ec846bd2e40b;
}
// req: 26.5.1.4 Random number engine requirements, p.908 table 117, row 6
// s needs to be of return_type, which is uint32_t
void seed(uint32_t s)
{
for (unsigned short i=0; i<4; ++i) {
_k[i] = 0;
_s[i] = 0;
}
_k[0] = s;
_o_counter = 0;
encrypt_counter();
}
// req: 26.5.1.4 Random number engine requirements, p.908 table 117, row 7
template<class Seq>
void seed(Seq& q, typename sitmo_enable_if< has_generate_template<Seq>::value >::type* = 0 )
{
typename Seq::result_type w[8];
q.generate(&w[0], &w[8]);
for (unsigned short i=0; i<4; ++i) {
_k[i] = ( static_cast<uint64_t>(w[2*i]) << 32) | w[2*i+1];
_s[i] = 0;
}
_o_counter = 0;
encrypt_counter();
}
// req: 26.5.1.4 Random number engine requirements, p.908 table 117, row 8
// Advances e’s state ei to ei+1 = TA(ei) and returns GA(ei).
uint32_t operator()()
{
// can we return a value from the current block?
if (_o_counter < 8) {
unsigned short _o_index = _o_counter >> 1;
_o_counter++;
if (_o_counter&1)
return _o[_o_index] & 0xFFFFFFFF;
else
return _o[_o_index] >> 32;
}
// generate a new block and return the first 32 bits
inc_counter();
encrypt_counter();
_o_counter = 1; // the next call
return _o[0] & 0xFFFFFFFF; // this call
}
// -------------------------------------------------
// misc
// -------------------------------------------------
// req: 26.5.1.4 Random number engine requirements, p.908 table 117, row 9
// Advances e’s state ei to ei+z by any means equivalent to z
// consecutive calls e().
void discard(uint64_t z)
{
// check if we stay in the current block
if (z < 8 - _o_counter) {
_o_counter += static_cast<unsigned short>(z);
return;
}
// we will have to generate a new block...
z -= (8 - _o_counter); // discard the remainder of the current blok
_o_counter = z % 8; // set the pointer in the correct element in the new block
z -= _o_counter; // update z
z >>= 3; // the number of buffers is elements/8
++z; // and one more because we crossed the buffer line
inc_counter(z);
encrypt_counter();
}
// -------------------------------------------------
// IO
// -------------------------------------------------
template<class CharT, class Traits>
friend std::basic_ostream<CharT,Traits>&
operator<<(std::basic_ostream<CharT,Traits>& os, const prng_engine& s) {
for (unsigned short i=0; i<4; ++i)
os << s._k[i] << ' ' << s._s[i] << ' ' << s._o[i] << ' ';
os << s._o_counter;
return os;
}
template<class CharT, class Traits>
friend std::basic_istream<CharT,Traits>&
operator>>(std::basic_istream<CharT,Traits>& is, prng_engine& s) {
for (unsigned short i=0; i<4; ++i)
is >> s._k[i] >> s._s[i] >> s._o[i];
is >> s._o_counter;
return is;
}
// req: 26.5.1.4 Random number engine requirements, p.908 table 117, row 10
// This operator is an equivalence relation. With Sx and Sy as the infinite
// sequences of values that would be generated by repeated future calls to
// x() and y(), respectively, returns true if Sx = Sy; else returns false.
bool operator==(const prng_engine& y)
{
if (_o_counter != y._o_counter) return false;
for (unsigned short i=0; i<4; ++i) {
if (_s[i] != y._s[i]) return false;
if (_k[i] != y._k[i]) return false;
if (_o[i] != y._o[i]) return false;
}
return true;
}
// req: 26.5.1.4 Random number engine requirements, p.908 table 117, row 11
bool operator!=(const prng_engine& y)
{
return !(*this == y);
}
// Extra function to set the key
void set_key(uint64_t k0=0, uint64_t k1=0, uint64_t k2=0, uint64_t k3=0)
{
_k[0] = k0; _k[1] = k1; _k[2] = k2; _k[3] = k3;
encrypt_counter();
}
// set the counter
void set_counter(uint64_t s0=0, uint64_t s1=0, uint64_t s2=0, uint64_t s3=0, unsigned short o_counter=0)
{
_s[0] = s0;
_s[1] = s1;
_s[2] = s2;
_s[3] = s3;
_o_counter = o_counter % 8;
encrypt_counter();
}
// versioning
uint32_t version()
{
return 5;
}
private:
void encrypt_counter()
{
uint64_t b[4];
uint64_t k[5];
for (unsigned short i=0; i<4; ++i) b[i] = _s[i];
for (unsigned short i=0; i<4; ++i) k[i] = _k[i];
k[4] = 0x1BD11BDAA9FC1A22 ^ k[0] ^ k[1] ^ k[2] ^ k[3];
MIXK(b[0], b[1], 14, b[2], b[3], 16, k[0], k[1], k[2], k[3]);
MIX2(b[0], b[3], 52, b[2], b[1], 57);
MIX2(b[0], b[1], 23, b[2], b[3], 40);
MIX2(b[0], b[3], 5, b[2], b[1], 37);
MIXK(b[0], b[1], 25, b[2], b[3], 33, k[1], k[2], k[3], k[4]+1);
MIX2(b[0], b[3], 46, b[2], b[1], 12);
MIX2(b[0], b[1], 58, b[2], b[3], 22);
MIX2(b[0], b[3], 32, b[2], b[1], 32);
MIXK(b[0], b[1], 14, b[2], b[3], 16, k[2], k[3], k[4], k[0]+2);
MIX2(b[0], b[3], 52, b[2], b[1], 57);
MIX2(b[0], b[1], 23, b[2], b[3], 40);
MIX2(b[0], b[3], 5, b[2], b[1], 37);
MIXK(b[0], b[1], 25, b[2], b[3], 33, k[3], k[4], k[0], k[1]+3);
MIX2(b[0], b[3], 46, b[2], b[1], 12);
MIX2(b[0], b[1], 58, b[2], b[3], 22);
MIX2(b[0], b[3], 32, b[2], b[1], 32);
MIXK(b[0], b[1], 14, b[2], b[3], 16, k[4], k[0], k[1], k[2]+4);
MIX2(b[0], b[3], 52, b[2], b[1], 57);
MIX2(b[0], b[1], 23, b[2], b[3], 40);
MIX2(b[0], b[3], 5, b[2], b[1], 37);
for (unsigned int i=0; i<4; ++i) _o[i] = b[i] + k[i];
_o[3] += 5;
}
void inc_counter()
{
++_s[0];
if (_s[0] != 0) return;
++_s[1];
if (_s[1] != 0) return;
++_s[2];
if (_s[2] != 0) return;
++_s[3];
}
void inc_counter(uint64_t z)
{
if (z > 0xFFFFFFFFFFFFFFFF - _s[0]) { // check if we will overflow the first 64 bit int
++_s[1];
if (_s[1] == 0) {
++_s[2];
if (_s[2] == 0) {
++_s[3];
}
}
}
_s[0] += z;
}
private:
uint64_t _k[4]; // key
uint64_t _s[4]; // state (counter)
uint64_t _o[4]; // cipher output 4 * 64 bit = 256 bit output
unsigned short _o_counter; // output chunk counter, the 256 random bits in _o
// are returned in eight 32 bit chunks
};
} // namespace sitmo
#undef MIXK
#undef MIX2
#endif
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