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//
// Qss_misc
//
// Auxiliary namespace for QSS data.
//
// Authors: Lucio Santi, Rodrigo Castro (Univ. Buenos Aires), 2018-2021 
// --------------------------------------------------------------------
#ifndef _QSS_MISC_H_
#define _QSS_MISC_H_ 1

#include "G4Types.hh"

using QSS_simulator = struct QSS_simulator_*;
using QSSSubstep = struct QSSSubstep_*;

/**
 * @brief Qss_misc defines an auxiliary namespace for QSS drivers data.
 */

namespace Qss_misc
{ 
  // Convention of Geant4 notation of indices
  constexpr unsigned int PXidx= 0;
  constexpr unsigned int PYidx= 1;
  constexpr unsigned int PZidx= 2;

  constexpr unsigned int VXidx= 3;
  constexpr unsigned int VYidx= 4;
  constexpr unsigned int VZidx= 5;

  // Method parameters & constants
  constexpr unsigned int MAX_QSS_STEPPER_ORDER= 3;
  constexpr unsigned int VAR_IDX_END= 6;
  constexpr unsigned int MIN_SUBSTEPS= 20;

  constexpr G4double INF= 1.0e20;
}

#if defined(WIN32) || defined(__MINGW32__)
#define unlikely(x)   (x)  // Until C++20 can be assumed
#define   likely(x)   (x)  //    >> ditto >>
#else
#define unlikely(x)   __builtin_expect((x),0)   // gcc/clang extension - not portable
#define   likely(x)   __builtin_expect((x),1)
#endif

// #define likely(x)   (x)  // [[likely]]     // The C++20 portable way
// #define likely(x)   (x)  // [[unlikely]]   //     >>    >> 
// This syntax appears to be part of C++20
// See
// - https://en.cppreference.com/w/cpp/language/attributes/likely
// - https://stackoverflow.com/questions/51797959/how-to-use-c20s-likely-unlikely-attribute-in-if-else-statement
// - https://usingstdcpp.org/2018/03/18/jacksonville18-iso-cpp-report/

#define SUBSTEP_STRUCT(sim, i)     (sim->substeps[i])
#define SUBSTEP_START(sim, i)      (sim->substeps[(i)].start_time)
#define SUBSTEP_X(sim, i)          (sim->substeps[(i)].x)
#define SUBSTEP_TX(sim, i)         (sim->substeps[(i)].tx)
#define SUBSTEP_LEN(sim, i)        (sim->substeps[(i)].len)

#define LAST_SUBSTEP_STRUCT(sim)     (SUBSTEP_STRUCT(sim, sim->cur_substep_idx-1))

#define CUR_SUBSTEP_START(sim)      (SUBSTEP_START(sim, sim->cur_substep_idx))
#define CUR_SUBSTEP_X(sim)          (SUBSTEP_X(sim, sim->cur_substep_idx))
#define CUR_SUBSTEP_TX(sim)         (SUBSTEP_TX(sim, sim->cur_substep_idx))
#define CUR_SUBSTEP_LEN(sim)        (SUBSTEP_LEN(sim, sim->cur_substep_idx))

#define CUR_SUBSTEP(sim)            (sim->cur_substep_idx)
#define LAST_SUBSTEP(sim)           (sim->cur_substep_idx-1)
#define MAX_SUBSTEP(sim)            (sim->max_substep_idx)
#define SUBSTEPS(sim)               (sim->substeps)

struct QSSSubstep_
{
  G4double x[Qss_misc::VAR_IDX_END*(Qss_misc::MAX_QSS_STEPPER_ORDER+1)];
  G4double tx[Qss_misc::VAR_IDX_END];

  G4double start_time;
  G4double len;
};

struct QSS_simulator_
{
  G4double x[Qss_misc::VAR_IDX_END*(Qss_misc::MAX_QSS_STEPPER_ORDER+1)];
  G4double tx[Qss_misc::VAR_IDX_END];

  G4double q[Qss_misc::VAR_IDX_END*(Qss_misc::MAX_QSS_STEPPER_ORDER+1)];
  G4double tq[Qss_misc::VAR_IDX_END];

  G4double nextStateTime[Qss_misc::VAR_IDX_END];
  G4double time;
  G4int minIndex;

  G4double dQMin[Qss_misc::VAR_IDX_END];
  G4double dQRel[Qss_misc::VAR_IDX_END];
  G4double lqu[Qss_misc::VAR_IDX_END];

  G4double alg[Qss_misc::VAR_IDX_END];
  G4double it;

  G4int *SD[Qss_misc::VAR_IDX_END];
  G4int states;

  QSSSubstep substeps;
  G4int cur_substep_idx;
  G4int max_substep_idx;
};

#endif