RanshiEngine.cc

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// $Id:$
// -*- C++ -*-
//
// -----------------------------------------------------------------------
//                           HEP Random
//                      --- RanshiEngine ---
//                    class implementation file
// -----------------------------------------------------------------------
//
// This algorithm implements the random number generator as proposed by 
// "F. Gutbrod, Comp. Phys. Comm. 87 (1995) 291-306". 
//
// =======================================================================
// Ken Smith      - Created:                                 9th June 1998
//                - Removed pow() from flat method:          21st Jul 1998
//                - Added conversion operators:               6th Aug 1998
// J. Marraffino  - Added some explicit casts to deal with
//                  machines where sizeof(int) != sizeof(long) 22 Aug 1998
// M. Fischler    - Modified constructors taking seeds to not
//                  depend on numEngines (same seeds should
//                  produce same sequences).  Default still
//                  depends on numEngines.                      16 Sep 1998
//                - Modified use of the various exponents of 2
//                  to avoid per-instance space overhead and
//                  correct the rounding procedure              16 Sep 1998
// J. Marraffino  - Remove dependence on hepString class        13 May 1999
// M. Fischler    - In restore, checkFile for file not found    03 Dec 2004
// M. Fischler    - Methods for instance save/restore            12/8/04    
// M. Fischler    - split get() into tag validation and 
//                  getState() for anonymous restores           12/27/04    
// M. Fischler    - State-saving using only ints, for portability 4/12/05
//
// =======================================================================

#include "CLHEP/Random/RanshiEngine.h"
#include "CLHEP/Random/engineIDulong.h"
#include <string.h>     // for strcmp

namespace CLHEP {

static const int MarkerLen = 64; // Enough room to hold a begin or end marker. 

std::string RanshiEngine::name() const {return "RanshiEngine";}

// Number of instances with automatic seed selection
int RanshiEngine::numEngines = 0;

RanshiEngine::RanshiEngine()
: HepRandomEngine(),
  halfBuff(0), numFlats(0) 
{
  int i = 0;
  while (i < numBuff) {    
    buffer[i] = (unsigned int)(numEngines+19780503L*(i+1));
    ++i;
  }
  theSeed = numEngines+19780503L*++i;
  redSpin = (unsigned int)(theSeed & 0xffffffff);
  ++numEngines;
  for( i = 0; i < 10000; ++i) flat();  // Warm-up by running thorugh 10000 nums
}

RanshiEngine::RanshiEngine(std::istream& is)
: HepRandomEngine(),
  halfBuff(0), numFlats(0) 
{
  is >> *this;
}

RanshiEngine::RanshiEngine(long seed)
: HepRandomEngine(),
  halfBuff(0), numFlats(0) 
{
  for (int i = 0; i < numBuff; ++i) {
    buffer[i] = (unsigned int)seed&0xffffffff;
  }
  theSeed = seed;
  redSpin = (unsigned int)(theSeed & 0xffffffff);
  int j;
  for (j = 0; j < numBuff*20; ++j) {      // "warm-up" for engine to hit
    flat();                               //  every ball on average 20X.
  }
}

RanshiEngine::RanshiEngine(int rowIndex, int colIndex)
: HepRandomEngine(),
  halfBuff(0), numFlats(0) 
{
  int i = 0;
  while( i < numBuff ) {
    buffer[i] = (unsigned int)((rowIndex + (i+1)*(colIndex+8))&0xffffffff);
    ++i;
  }
  theSeed = rowIndex;
  redSpin = colIndex & 0xffffffff;
  for( i = 0; i < 100; ++i) flat();    // Warm-up by running thorugh 100 nums
}

RanshiEngine::~RanshiEngine() { }

double RanshiEngine::flat() {
  unsigned int redAngle = (((numBuff/2) - 1) & redSpin) + halfBuff;
  unsigned int blkSpin     = buffer[redAngle] & 0xffffffff;
  unsigned int boostResult = blkSpin ^ redSpin;

  buffer[redAngle] = ((blkSpin << 17) | (blkSpin >> (32-17))) ^ redSpin;
  
  redSpin  = (blkSpin + numFlats++) & 0xffffffff;
  halfBuff = numBuff/2 - halfBuff;
  
  return ( blkSpin * twoToMinus_32() +            // most significant part
           (boostResult>>11) * twoToMinus_53() +  // fill in remaining bits
           nearlyTwoToMinus_54());              // non-zero
}

void RanshiEngine::flatArray(const int size, double* vect) {
  for (int i = 0; i < size; ++i) {
    vect[i] = flat();
  }
}

void RanshiEngine::setSeed(long seed, int) {
  *this = RanshiEngine(seed); 
}

void RanshiEngine::setSeeds(const long* seeds, int) {
  if (*seeds) {
    int i = 0;
    while (seeds[i] && i < numBuff) {
      buffer[i] = (unsigned int)seeds[i];
      ++i;
    }
    while (i < numBuff) {
      buffer[i] = buffer[i-1];
      ++i;
    }
    theSeed = seeds[0];
    redSpin = (unsigned int)theSeed;
  }
  theSeeds = seeds;
}
     
void RanshiEngine::saveStatus(const char filename[]) const {
  std::ofstream outFile(filename, std::ios::out);
  if (!outFile.bad()) {
    outFile << "Uvec\n";
    std::vector<unsigned long> v = put();
    for (unsigned int i=0; i<v.size(); ++i) {
      outFile << v[i] << "\n";
    }
  }
}

void RanshiEngine::restoreStatus(const char filename[]) {
  std::ifstream inFile(filename, std::ios::in);
  if (!checkFile ( inFile, filename, engineName(), "restoreStatus" )) {
    std::cerr << "  -- Engine state remains unchanged\n";
    return;
  }
  if ( possibleKeywordInput ( inFile, "Uvec", theSeed ) ) {
    std::vector<unsigned long> v;
    unsigned long xin;
    for (unsigned int ivec=0; ivec < VECTOR_STATE_SIZE; ++ivec) {
      inFile >> xin;
      if (!inFile) {
        inFile.clear(std::ios::badbit | inFile.rdstate());
        std::cerr << "\nRanshiEngine state (vector) description improper."
               << "\nrestoreStatus has failed."
               << "\nInput stream is probably mispositioned now." << std::endl;
        return;
      }
      v.push_back(xin);
    }
    getState(v);
    return;
  }

  if (!inFile.bad()) {
//     inFile >> theSeed;  removed -- encompased by possibleKeywordInput
    for (int i = 0; i < numBuff; ++i) {
      inFile >> buffer[i];
    }
    inFile >> redSpin >> numFlats >> halfBuff;
  }
}

void RanshiEngine::showStatus() const {
  std::cout << std::setprecision(20) << std::endl;
  std::cout << "----------- Ranshi engine status ----------" << std::endl;
  std::cout << "Initial seed      = " << theSeed << std::endl;
  std::cout << "Current red spin  = " << redSpin << std::endl;
  std::cout << "Values produced   = " << numFlats << std::endl;
  std::cout << "Side of buffer    = " << (halfBuff ? "upper" : "lower")
            << std::endl;
  std::cout << "Current buffer    = " << std::endl;
  for (int i = 0; i < numBuff; i+=4) {
    std::cout << std::setw(10) << std::setiosflags(std::ios::right)
              << buffer[i]     << std::setw(11) << buffer[i+1] << std::setw(11)
              << buffer[i+2]   << std::setw(11) << buffer[i+3] << std::endl;
  }
  std::cout << "-------------------------------------------" << std::endl;
}

RanshiEngine::operator float() {
  unsigned int redAngle = (((numBuff/2) - 1) & redSpin) + halfBuff;
  unsigned int blkSpin  = buffer[redAngle] & 0xffffffff;
  
  buffer[redAngle] = ((blkSpin << 17) | (blkSpin >> (32-17))) ^ redSpin;
  
  redSpin  = (blkSpin + numFlats++) & 0xffffffff;
  halfBuff = numBuff/2 - halfBuff;
  
  return float(blkSpin * twoToMinus_32());
}

RanshiEngine::operator unsigned int() {
  unsigned int redAngle = (((numBuff/2) - 1) & redSpin) + halfBuff;
  unsigned int blkSpin  = buffer[redAngle] & 0xffffffff;
  
  buffer[redAngle] = ((blkSpin << 17) | (blkSpin >> (32-17))) ^ redSpin;
  
  redSpin  = (blkSpin + numFlats++) & 0xffffffff;
  halfBuff = numBuff/2 - halfBuff;
  
  return blkSpin;
}

std::ostream& RanshiEngine::put (std::ostream& os ) const {
  char beginMarker[] = "RanshiEngine-begin";
  os << beginMarker << "\nUvec\n";
  std::vector<unsigned long> v = put();
  for (unsigned int i=0; i<v.size(); ++i) {
     os <<  v[i] <<  "\n";
  }
  return os;  
}

std::vector<unsigned long> RanshiEngine::put () const {
  std::vector<unsigned long> v;
  v.push_back (engineIDulong<RanshiEngine>());
  for (int i = 0; i < numBuff; ++i) {
    v.push_back(static_cast<unsigned long>(buffer[i]));
  }
  v.push_back(static_cast<unsigned long>(redSpin));
  v.push_back(static_cast<unsigned long>(numFlats));
  v.push_back(static_cast<unsigned long>(halfBuff));  
  return v;
}

std::istream& RanshiEngine::get (std::istream& is) {
  char beginMarker [MarkerLen];
  is >> std::ws;
  is.width(MarkerLen);  // causes the next read to the char* to be <=
                        // that many bytes, INCLUDING A TERMINATION \0 
                        // (Stroustrup, section 21.3.2)
  is >> beginMarker;
  if (strcmp(beginMarker,"RanshiEngine-begin")) {
    is.clear(std::ios::badbit | is.rdstate());
    std::cerr << "\nInput mispositioned or"
              << "\nRanshiEngine state description missing or"
              << "\nwrong engine type found." << std::endl;
    return is;
  }
  return getState(is);
}

std::string RanshiEngine::beginTag ( )  { 
  return "RanshiEngine-begin"; 
}
  
std::istream& RanshiEngine::getState (std::istream& is) {
  if ( possibleKeywordInput ( is, "Uvec", theSeed ) ) {
    std::vector<unsigned long> v;
    unsigned long uu;
    for (unsigned int ivec=0; ivec < VECTOR_STATE_SIZE; ++ivec) {
      is >> uu;
      if (!is) {
        is.clear(std::ios::badbit | is.rdstate());
        std::cerr << "\nRanshiEngine state (vector) description improper."
                << "\ngetState() has failed."
               << "\nInput stream is probably mispositioned now." << std::endl;
        return is;
      }
      v.push_back(uu);
    }
    getState(v);
    return (is);
  }

//  is >> theSeed;  Removed, encompassed by possibleKeywordInput()

  char endMarker   [MarkerLen];
  for (int i = 0; i < numBuff; ++i) {
    is >> buffer[i];
  }
  is >> redSpin >> numFlats >> halfBuff;
  is >> std::ws;
  is.width(MarkerLen);  
  is >> endMarker;
  if (strcmp(endMarker,"RanshiEngine-end")) {
    is.clear(std::ios::badbit | is.rdstate());
    std::cerr << "\nRanshiEngine state description incomplete."
              << "\nInput stream is probably mispositioned now." << std::endl;
    return is;
  }
  return is;
}

bool RanshiEngine::get (const std::vector<unsigned long> & v) {
  if ((v[0] & 0xffffffffUL) != engineIDulong<RanshiEngine>()) {
    std::cerr << 
        "\nRanshiEngine get:state vector has wrong ID word - state unchanged\n";
    return false;
  }
  return getState(v);
}

bool RanshiEngine::getState (const std::vector<unsigned long> & v) {
  if (v.size() != VECTOR_STATE_SIZE ) {
    std::cerr << 
        "\nRanshiEngine get:state vector has wrong length - state unchanged\n";
    return false;
  }
  for (int i = 0; i < numBuff; ++i) {
    buffer[i] = v[i+1];
  }
  redSpin  = v[numBuff+1];
  numFlats = v[numBuff+2]; 
  halfBuff = v[numBuff+3];
  return true;
}

}  // namespace CLHEP