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 // LHAPowheg.h is a part of the PYTHIA event generator.
 // Copyright (C) 2024 Torbjorn Sjostrand.
 // PYTHIA is licenced under the GNU GPL v2 or later, see COPYING for details.
 // Please respect the MCnet Guidelines, see GUIDELINES for details.
 // Author: Philip Ilten, May 2015.
 
 #ifndef Pythia8_LHAPowheg_H
 #define Pythia8_LHAPowheg_H
 
 #include "Pythia8/Plugins.h"
 #include "Pythia8Plugins/LHAFortran.h"
 #include <sys/stat.h>
 #include <unistd.h>
 
 namespace Pythia8 {
 
 //==========================================================================
 
 // Give access to the POWHEG commonblocks and subroutines.
 
 extern "C" {
 
   // The random number common block.
   extern struct {
     int rnd_numseeds, rnd_initialseed, rnd_iwhichseed;
     char rnd_cwhichseed[4];
     int rnd_i1, rnd_i2;
   } pwhg_rnd_;
 
   // The RANMAR (R48 modification) common block.
   extern struct {
     double u[97];
     double c;
     int i97, j97;
   } r48st1_;
 
   // Initialize Powheg.
   void pwhginit_();
 
   // Reset the counters.
   void resetcnt_(const char *string, int length);
 
   // Generate an event.
   void pwhgevent_();
 
   // Access Powheg input data.
   double powheginput_(const char *string, int length);
 
 }
 
 //==========================================================================
 
 // A plugin class to generate events with hard processes from
 // POWHEGBOX matrix elements. See http://powhegbox.mib.infn.it/ for
 // further details on POWHEGBOX.
 
 // WARNING: If one wishes to use LHAPDF with both POWHEGBOX and
 // Pythia, only LHAPDF 6 should be used. If not, and differing PDF
 // sets are used between POWHEGBOX and Pythia, POWHEGBOX will not
 // re-initialize the PDF set and consequently will use the PDF set
 // last used by Pythia.
 
 class LHAupPowheg : public LHAupFortran {
 
 public:
 
   // Constructor.
   LHAupPowheg(Pythia* pythiaPtr, Settings* settingsPtr, Logger* loggerPtr);
 
   // Call pwhginit and fill the HEPRUP commonblock.
   bool fillHepRup();
 
   // Call pwhgevent and fill the HEEUP commonblock.
   bool fillHepEup();
 
 private:
 
   // Read a POWHEG settings string.
   bool readString(string line);
 
   // Read a POWHEG settings file.
   bool readFile(string name);
 
   // Write out the input for POWHEG.
   bool init();
 
   // The external random number generator.
   Rndm* rndmPtr{};
 
   // Logger.
   Logger* loggerPtr{};
 
   // The POWHEG run directory and PDF file (if not LHAPDF).
   string dir, pdf;
 
   // The map of POWHEG settings.
   map<string, string> settings;
 
   // The current working directory.
   char cwd[FILENAME_MAX];
 
 };
 
 //--------------------------------------------------------------------------
 
 // Constructor.
 
 LHAupPowheg::LHAupPowheg(Pythia *pythiaPtr, Settings *settingsPtr,
   Logger* loggerPtrIn) : loggerPtr(loggerPtrIn), dir("powhegrun"), pdf("") {
 
   // Load the settings.
   if (settingsPtr != nullptr) {
     dir = settingsPtr->word("POWHEG:dir");
     pdf = settingsPtr->word("POWHEG:pdf");
 
     // Read the command files and strings.
     for (string cmndFile : settingsPtr->wvec("POWHEG:cmndFiles"))
       readFile(cmndFile);
     for (string cmnd : settingsPtr->wvec("POWHEG:cmnds"))
       readString(cmnd);
   }
 
   // Set up the random number generator.
   if (pythiaPtr != nullptr) {
     if (settingsPtr->isFlag("POWHEG:pythiaRandom")) rndmPtr = &pythiaPtr->rndm;
   }
   mkdir(dir.c_str(), 0777);
   init();
 
 }
 
 //--------------------------------------------------------------------------
 
 // Call pwhginit and fill the HEPRUP commonblock.
 
 bool LHAupPowheg::fillHepRup() {
 
   // Set multiple random seeds to none.
   getcwd(cwd, sizeof(cwd));
   chdir(dir.c_str());
   strcpy(pwhg_rnd_.rnd_cwhichseed, "none");
 
   // Initialize Powheg.
   pwhginit_();
 
   // Reset all the counters.
   resetcnt_("upper bound failure in inclusive cross section", 46);
   resetcnt_("vetoed calls in inclusive cross section", 39);
   resetcnt_("upper bound failures in generation of radiation", 47);
   resetcnt_("vetoed radiation", 16);
   chdir(cwd);
   return fillHepEup();
 
 }
 
 //--------------------------------------------------------------------------
 
 // Set the random numbers, call pwhgevent, and fill the HEPEUP commonblock.
 
 bool LHAupPowheg::fillHepEup() {
 
   // Change directory.
   getcwd(cwd, sizeof(cwd));
   chdir(dir.c_str());
 
   // Reset the random block if requested.
   if (rndmPtr != nullptr) {
     r48st1_.i97 = 97;
     r48st1_.j97 = 33;
     r48st1_.c = rndmPtr->flat();
     for (int i = 0; i < 97; ++i) r48st1_.u[i] = rndmPtr->flat();
   }
 
   // Generate the event.
   pwhgevent_();
   chdir(cwd);
   return true;
 
 }
 
 //--------------------------------------------------------------------------
 
 // Read a POWHEG settings string. If a setting is repeated a warning
 // is printed but the most recent setting is used.
 
 bool LHAupPowheg::readString(string line) {
 
   // Copy string without initial and trailing blanks.
   if (line.find_first_not_of(" \n\t\v\b\r\f\a") == string::npos) return true;
   int firstChar = line.find_first_not_of(" \n\t\v\b\r\f\a");
   int lastChar  = line.find_last_not_of(" \n\t\v\b\r\f\a");
   line = line.substr(firstChar, lastChar + 1 - firstChar);
 
   // Find the key.
   firstChar = line.find_first_of("  \t\f\v\n\r");
   string key = toLower( line.substr(0, firstChar), false);
 
   // Add the setting.
   if (key.size() > 0
     && key.find_first_of("abcdedfghijklmnopqrtsuvwxyz") == 0) {
     map<string, string>::iterator setting = settings.find(key);
     if (setting != settings.end()) {
       if (loggerPtr) loggerPtr->WARNING_MSG(
         "replacing previous POWHEG setting for " + key);
       setting->second = line;
     } else settings[key] = line;
   }
   return true;
 
 }
 
 //--------------------------------------------------------------------------
 
 // Read a POWHEG settings file.
 
 bool LHAupPowheg::readFile(string name) {
 
   fstream config(name.c_str(), ios::in); string line;
   while (getline(config, line, '\n')) readString(line);
   config.close();
   return true;
 
 }
 
 //--------------------------------------------------------------------------
 
 // Write the input for POWHEG.
 
 bool LHAupPowheg::init() {
 
   // Copy over the PDF file if needed.
   if (pdf != "") {
     fstream pdfin(pdf.c_str(), ios::in | ios::binary);
     fstream pdfout((dir + "/" + pdf.substr(0, pdf.find_last_of("/"))).c_str(),
       ios::out | ios::binary);
     pdfout << pdfin.rdbuf();
     pdfin.close();
     pdfout.close();
   }
 
   // Copy the settings to the configuration file.
   fstream config((dir + "/" + "powheg.input").c_str(), ios::out);
   for (map<string, string>::iterator setting = settings.begin();
     setting != settings.end(); ++setting) config << setting->second << "\n";
   config.close();
   return true;
 
 }
 
 //--------------------------------------------------------------------------
 
 // Register POWHEG settings.
 
 void powhegSettings(Settings *settingsPtr) {
   settingsPtr->addWord("POWHEG:dir", "powhegrun");
   settingsPtr->addWord("POWHEG:pdf", "");
   settingsPtr->addWVec("POWHEG:cmnds", {});
   settingsPtr->addWVec("POWHEG:cmndFiles", {});
   settingsPtr->addFlag("POWHEG:pythiaRandom", true);
 }
 
 //--------------------------------------------------------------------------
 
 // Declare the plugin.
 
 PYTHIA8_PLUGIN_CLASS(LHAup, LHAupPowheg, true, true, true)
 PYTHIA8_PLUGIN_SETTINGS(powhegSettings)
 PYTHIA8_PLUGIN_VERSIONS(PYTHIA_VERSION_INTEGER)
 
 //==========================================================================
 
 } // end namespace Pythia8
 
 #endif // Pythia8_LHAPowheg_H

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