From 3cac2a6702c12755eb10fa741c8bd1013500985b Mon Sep 17 00:00:00 2001
From: Paul Romano <paul.k.romano@gmail.com>
Date: Thu, 21 Feb 2019 16:04:21 -0600
Subject: [PATCH] Remove Fortan compatibility functions

---
 include/openmc/material.h                     |   9 +-
 include/openmc/nuclide.h                      |  10 +-
 include/openmc/output.h                       |   2 +
 include/openmc/particle.h                     | 222 ++++++++----------
 include/openmc/reaction.h                     |  22 --
 include/openmc/tallies/filter.h               |   2 +-
 include/openmc/tallies/filter_sph_harm.h      |   3 +-
 include/openmc/tallies/filter_sptl_legendre.h |   3 +-
 src/bank.cpp                                  |  38 ---
 src/bremsstrahlung.cpp                        |   9 -
 src/cell.cpp                                  |   4 -
 src/eigenvalue.cpp                            |  16 --
 src/material.cpp                              |  30 +--
 src/mesh.cpp                                  |  46 +---
 src/nuclide.cpp                               |   6 +-
 src/output.cpp                                |   2 +-
 src/particle.cpp                              |  17 --
 src/reaction.cpp                              |  79 +------
 src/settings.cpp                              |  14 --
 src/simulation.cpp                            |  25 +-
 src/source.cpp                                |   4 -
 src/tallies/derivative.cpp                    |  12 -
 src/tallies/filter.cpp                        |  44 ----
 src/tallies/filter_particle.cpp               |   7 -
 src/tallies/tally.cpp                         |  82 -------
 src/thermal.cpp                               |  26 --
 src/timer.cpp                                 |  16 --
 27 files changed, 115 insertions(+), 635 deletions(-)

diff --git a/include/openmc/material.h b/include/openmc/material.h
index 28d48aa4a..f43db5928 100644
--- a/include/openmc/material.h
+++ b/include/openmc/material.h
@@ -106,7 +106,7 @@ private:
 };
 
 //==============================================================================
-// Fortran compatibility
+// Non-member functions
 //==============================================================================
 
 //! Read material data from materials.xml
@@ -114,12 +114,5 @@ void read_materials_xml();
 
 void free_memory_material();
 
-//==============================================================================
-// Fortran compatibility
-//==============================================================================
-
-extern "C" int* material_element(int i_material);
-extern "C" bool material_isotropic(int i_material, int i_nuc_mat);
-
 } // namespace openmc
 #endif // OPENMC_MATERIAL_H
diff --git a/include/openmc/nuclide.h b/include/openmc/nuclide.h
index 72c8c72c3..c8b34d08e 100644
--- a/include/openmc/nuclide.h
+++ b/include/openmc/nuclide.h
@@ -176,7 +176,7 @@ private:
 //! Checks for the right version of nuclear data within HDF5 files
 void check_data_version(hid_t file_id);
 
-extern "C" bool multipole_in_range(const Nuclide* nuc, double E);
+bool multipole_in_range(const Nuclide* nuc, double E);
 
 //==============================================================================
 // Global variables
@@ -209,14 +209,6 @@ extern MaterialMacroXS material_xs;
 
 void nuclides_clear();
 
-//==============================================================================
-// Fortran compatibility
-//==============================================================================
-
-extern "C" void set_micro_xs();
-extern "C" void nuclide_calculate_urr_xs(bool use_mp, int i_nuclide,
-                                         int i_temp, double E);
-
 } // namespace openmc
 
 #endif // OPENMC_NUCLIDE_H
diff --git a/include/openmc/output.h b/include/openmc/output.h
index e2387dd27..117f75148 100644
--- a/include/openmc/output.h
+++ b/include/openmc/output.h
@@ -56,5 +56,7 @@ void print_runtime();
 //! Display results for global tallies including k-effective estimators
 void print_results();
 
+void write_tallies();
+
 } // namespace openmc
 #endif // OPENMC_OUTPUT_H
diff --git a/include/openmc/particle.h b/include/openmc/particle.h
index 01c7eaefc..32d6c843b 100644
--- a/include/openmc/particle.h
+++ b/include/openmc/particle.h
@@ -38,151 +38,133 @@ enum class ParticleType {
   neutron, photon, electron, positron
 };
 
-extern "C" {
+struct LocalCoord {
+  int cell {-1};
+  int universe {-1};
+  int lattice {-1};
+  int lattice_x {-1};
+  int lattice_y {-1};
+  int lattice_z {-1};
+  double xyz[3]; //!< particle position
+  double uvw[3]; //!< particle direction
+  bool rotated {false};  //!< Is the level rotated?
 
-  struct LocalCoord {
-    int cell {-1};
-    int universe {-1};
-    int lattice {-1};
-    int lattice_x {-1};
-    int lattice_y {-1};
-    int lattice_z {-1};
-    double xyz[3]; //!< particle position
-    double uvw[3]; //!< particle direction
-    bool rotated {false};  //!< Is the level rotated?
+  //! clear data from a single coordinate level
+  void reset();
+};
 
-    //! clear data from a single coordinate level
-    void reset();
-  };
+//============================================================================
+//! State of a particle being transported through geometry
+//============================================================================
 
-  //============================================================================
-  //! State of a particle being transported through geometry
-  //============================================================================
+struct Particle {
+  int64_t id;  //!< Unique ID
+  int type;    //!< Particle type (n, p, e, etc.)
 
-  struct Particle {
-    int64_t id;  //!< Unique ID
-    int type;    //!< Particle type (n, p, e, etc.)
+  int n_coord;                  //!< number of current coordinate levels
+  int cell_instance;            //!< offset for distributed properties
+  LocalCoord coord[MAX_COORD];  //!< coordinates for all levels
 
-    int n_coord;                  //!< number of current coordinate levels
-    int cell_instance;            //!< offset for distributed properties
-    LocalCoord coord[MAX_COORD];  //!< coordinates for all levels
+  // Particle coordinates before crossing a surface
+  int last_n_coord;          //!< number of current coordinates
+  int last_cell[MAX_COORD];  //!< coordinates for all levels
 
-    // Particle coordinates before crossing a surface
-    int last_n_coord;          //!< number of current coordinates
-    int last_cell[MAX_COORD];  //!< coordinates for all levels
+  // Energy data
+  double E;       //!< post-collision energy in eV
+  double last_E;  //!< pre-collision energy in eV
+  int g;          //!< post-collision energy group (MG only)
+  int last_g;     //!< pre-collision energy group (MG only)
 
-    // Energy data
-    double E;       //!< post-collision energy in eV
-    double last_E;  //!< pre-collision energy in eV
-    int g;          //!< post-collision energy group (MG only)
-    int last_g;     //!< pre-collision energy group (MG only)
+  // Other physical data
+  double wgt;     //!< particle weight
+  double mu;      //!< angle of scatter
+  bool alive;     //!< is particle alive?
 
-    // Other physical data
-    double wgt;     //!< particle weight
-    double mu;      //!< angle of scatter
-    bool alive;     //!< is particle alive?
+  // Other physical data
+  double last_xyz_current[3];  //!< coordinates of the last collision or
+                                //!< reflective/periodic surface crossing for
+                                //!< current tallies
+  double last_xyz[3];          //!< previous coordinates
+  double last_uvw[3];          //!< previous direction coordinates
+  double last_wgt;             //!< pre-collision particle weight
+  double absorb_wgt;           //!< weight absorbed for survival biasing
 
-    // Other physical data
-    double last_xyz_current[3];  //!< coordinates of the last collision or
-                                 //!< reflective/periodic surface crossing for
-                                 //!< current tallies
-    double last_xyz[3];          //!< previous coordinates
-    double last_uvw[3];          //!< previous direction coordinates
-    double last_wgt;             //!< pre-collision particle weight
-    double absorb_wgt;           //!< weight absorbed for survival biasing
+  // What event took place
+  bool fission;       //!< did particle cause implicit fission
+  int event;          //!< scatter, absorption
+  int event_nuclide;  //!< index in nuclides array
+  int event_MT;       //!< reaction MT
+  int delayed_group;  //!< delayed group
 
-    // What event took place
-    bool fission;       //!< did particle cause implicit fission
-    int event;          //!< scatter, absorption
-    int event_nuclide;  //!< index in nuclides array
-    int event_MT;       //!< reaction MT
-    int delayed_group;  //!< delayed group
+  // Post-collision physical data
+  int n_bank;        //!< number of fission sites banked
+  double wgt_bank;   //!< weight of fission sites banked
+  int n_delayed_bank[MAX_DELAYED_GROUPS];  //!< number of delayed fission
+                                            //!< sites banked
 
-    // Post-collision physical data
-    int n_bank;        //!< number of fission sites banked
-    double wgt_bank;   //!< weight of fission sites banked
-    int n_delayed_bank[MAX_DELAYED_GROUPS];  //!< number of delayed fission
-                                             //!< sites banked
+  // Indices for various arrays
+  int surface;        //!< index for surface particle is on
+  int cell_born;      //!< index for cell particle was born in
+  int material;       //!< index for current material
+  int last_material;  //!< index for last material
 
-    // Indices for various arrays
-    int surface;        //!< index for surface particle is on
-    int cell_born;      //!< index for cell particle was born in
-    int material;       //!< index for current material
-    int last_material;  //!< index for last material
+  // Temperature of current cell
+  double sqrtkT;       //!< sqrt(k_Boltzmann * temperature) in eV
+  double last_sqrtkT;  //!< last temperature
 
-    // Temperature of current cell
-    double sqrtkT;       //!< sqrt(k_Boltzmann * temperature) in eV
-    double last_sqrtkT;  //!< last temperature
+  // Statistical data
+  int n_collision;  //!< number of collisions
 
-    // Statistical data
-    int n_collision;  //!< number of collisions
+  // Track output
+  bool write_track {false};
 
-    // Track output
-    bool write_track {false};
+  // Secondary particles created
+  int64_t n_secondary {};
+  Bank secondary_bank[MAX_SECONDARY];
 
-    // Secondary particles created
-    int64_t n_secondary {};
-    Bank secondary_bank[MAX_SECONDARY];
+  //! resets all coordinate levels for the particle
+  void clear();
 
-    //! resets all coordinate levels for the particle
-    void clear();
+  //! create a secondary particle
+  //
+  //! stores the current phase space attributes of the particle in the
+  //! secondary bank and increments the number of sites in the secondary bank.
+  //! \param uvw Direction of the secondary particle
+  //! \param E Energy of the secondary particle in [eV]
+  //! \param type Particle type
+  //! \param run_CE Whether continuous-energy data is being used
+  void create_secondary(const double* uvw, double E, int type, bool run_CE);
 
-    //! create a secondary particle
-    //
-    //! stores the current phase space attributes of the particle in the
-    //! secondary bank and increments the number of sites in the secondary bank.
-    //! \param uvw Direction of the secondary particle
-    //! \param E Energy of the secondary particle in [eV]
-    //! \param type Particle type
-    //! \param run_CE Whether continuous-energy data is being used
-    void create_secondary(const double* uvw, double E, int type, bool run_CE);
+  //! sets default attributes for a particle
+  void initialize();
 
-    //! sets default attributes for a particle
-    void initialize();
+  //! initialize from a source site
+  //
+  //! initializes a particle from data stored in a source site. The source
+  //! site may have been produced from an external source, from fission, or
+  //! simply as a secondary particle.
+  //! \param src Source site data
+  void from_source(const Bank* src);
 
-    //! initialize from a source site
-    //
-    //! initializes a particle from data stored in a source site. The source
-    //! site may have been produced from an external source, from fission, or
-    //! simply as a secondary particle.
-    //! \param src Source site data
-    void from_source(const Bank* src);
+  //! Transport a particle from birth to death
+  void transport();
 
-    //! Transport a particle from birth to death
-    void transport();
+  //! Cross a surface and handle boundary conditions
+  void cross_surface();
 
-    //! Cross a surface and handle boundary conditions
-    void cross_surface();
+  //! mark a particle as lost and create a particle restart file
+  //! \param message A warning message to display
+  void mark_as_lost(const char* message);
 
-    //! mark a particle as lost and create a particle restart file
-    //! \param message A warning message to display
-    void mark_as_lost(const char* message);
+  void mark_as_lost(const std::string& message)
+  {mark_as_lost(message.c_str());}
 
-    void mark_as_lost(const std::string& message)
-    {mark_as_lost(message.c_str());}
+  void mark_as_lost(const std::stringstream& message)
+  {mark_as_lost(message.str());}
 
-    void mark_as_lost(const std::stringstream& message)
-    {mark_as_lost(message.str());}
-
-    //! create a particle restart HDF5 file
-    void write_restart() const;
-  };
-
-
-  //============================================================================
-  // Fortran compatibility functions
-  //============================================================================
-
-  void reset_coord(LocalCoord* c);
-  void particle_clear(Particle* p);
-  void particle_create_secondary(Particle* p, const double* uvw, double E,
-                                 int type, bool run_CE);
-  void particle_initialize(Particle* p);
-  void particle_from_source(Particle* p, const Bank* src);
-  void particle_mark_as_lost(Particle* p, const char* message);
-  void particle_write_restart(Particle* p);
-
-} // extern "C"
+  //! create a particle restart HDF5 file
+  void write_restart() const;
+};
 
 } // namespace openmc
 
diff --git a/include/openmc/reaction.h b/include/openmc/reaction.h
index 7f20e7a95..dd6de245f 100644
--- a/include/openmc/reaction.h
+++ b/include/openmc/reaction.h
@@ -46,28 +46,6 @@ public:
 
 std::string reaction_name(int mt);
 
-//==============================================================================
-// Fortran compatibility functions
-//==============================================================================
-
-extern "C" {
-  int reaction_mt(Reaction* rx);
-  double reaction_q_value(Reaction* rx);
-  bool reaction_scatter_in_cm(Reaction* rx);
-  bool reaction_redundant(Reaction* rx);
-  double reaction_product_decay_rate(Reaction* rx, int product);
-  int reaction_product_emission_mode(Reaction* rx, int product);
-  int reaction_product_particle(Reaction* rx, int product);
-  void reaction_product_sample(Reaction* rx, int product, double E_in,
-                               double* E_out, double* mu);
-  int reaction_products_size(Reaction* rx);
-  double reaction_product_yield(Reaction* rx, int product, double E);
-  double reaction_sample_elastic_mu(Reaction* rx, double E);
-  double reaction_xs(Reaction* xs, int temperature, int energy);
-  int reaction_xs_size(Reaction* xs, int temperature);
-  int reaction_xs_threshold(Reaction* xs, int temperature);
-}
-
 } // namespace openmc
 
 #endif // OPENMC_REACTION_H
diff --git a/include/openmc/tallies/filter.h b/include/openmc/tallies/filter.h
index cf4176e06..c2fd4dfb3 100644
--- a/include/openmc/tallies/filter.h
+++ b/include/openmc/tallies/filter.h
@@ -101,7 +101,7 @@ namespace model {
 
 Filter* allocate_filter(const std::string& type);
 
-// Filter-related Fortran functions that will be called from C++
+//! Make sure index corresponds to a valid filter
 int verify_filter(int32_t index);
 
 } // namespace openmc
diff --git a/include/openmc/tallies/filter_sph_harm.h b/include/openmc/tallies/filter_sph_harm.h
index 786ef1a58..b53b62441 100644
--- a/include/openmc/tallies/filter_sph_harm.h
+++ b/include/openmc/tallies/filter_sph_harm.h
@@ -7,9 +7,8 @@
 
 namespace openmc {
 
-//TODO: those integer values are not needed when Fortran interop is removed
 enum class SphericalHarmonicsCosine {
-  scatter = 1, particle = 2
+  scatter, particle
 };
 
 //==============================================================================
diff --git a/include/openmc/tallies/filter_sptl_legendre.h b/include/openmc/tallies/filter_sptl_legendre.h
index 1b94ecf3d..995bc7360 100644
--- a/include/openmc/tallies/filter_sptl_legendre.h
+++ b/include/openmc/tallies/filter_sptl_legendre.h
@@ -7,9 +7,8 @@
 
 namespace openmc {
 
-//TODO: those integer values are not needed when Fortran interop is removed
 enum class LegendreAxis {
-  x = 1, y = 2, z = 3
+  x, y, z
 };
 
 //==============================================================================
diff --git a/src/bank.cpp b/src/bank.cpp
index 02cf587eb..5f2f9cec5 100644
--- a/src/bank.cpp
+++ b/src/bank.cpp
@@ -70,42 +70,4 @@ extern "C" int openmc_fission_bank(Bank** ptr, int64_t* n)
   }
 }
 
-//==============================================================================
-// Fortran compatibility
-//==============================================================================
-
-extern "C" int fission_bank_delayed_group(int64_t i) {
-  return simulation::fission_bank[i-1].delayed_group;
-}
-
-extern "C" double fission_bank_E(int64_t i) {
-  return simulation::fission_bank[i-1].E;
-}
-
-extern "C" double fission_bank_wgt(int64_t i) {
-  return simulation::fission_bank[i-1].wgt;
-}
-
-extern "C" void source_bank_xyz(int64_t i, double* xyz)
-{
-  xyz[0] = simulation::source_bank[i-1].xyz[0];
-  xyz[1] = simulation::source_bank[i-1].xyz[1];
-  xyz[2] = simulation::source_bank[i-1].xyz[2];
-}
-
-extern "C" double source_bank_E(int64_t i)
-{
-  return simulation::source_bank[i-1].E;
-}
-
-extern "C" double source_bank_wgt(int64_t i)
-{
-  return simulation::source_bank[i-1].wgt;
-}
-
-extern "C" void source_bank_set_wgt(int64_t i, double wgt)
-{
-  simulation::source_bank[i-1].wgt = wgt;
-}
-
 } // namespace openmc
diff --git a/src/bremsstrahlung.cpp b/src/bremsstrahlung.cpp
index ce699a3f4..f0ece1a53 100644
--- a/src/bremsstrahlung.cpp
+++ b/src/bremsstrahlung.cpp
@@ -115,13 +115,4 @@ void thick_target_bremsstrahlung(Particle& p, double* E_lost)
   }
 }
 
-//==============================================================================
-// Fortran compatibility
-//==============================================================================
-
-extern "C" void set_log_ttb_e_grid()
-{
-  data::ttb_e_grid = xt::log(data::ttb_e_grid);
-}
-
 } // namespace openmc
diff --git a/src/cell.cpp b/src/cell.cpp
index 6a962eced..435b155b7 100644
--- a/src/cell.cpp
+++ b/src/cell.cpp
@@ -844,10 +844,6 @@ int32_t next_cell(DAGCell* cur_cell, DAGSurface* surf_xed)
 }
 #endif
 
-//==============================================================================
-// Fortran compatibility functions
-//==============================================================================
-
 extern "C" int cells_size() { return model::cells.size(); }
 
 } // namespace openmc
diff --git a/src/eigenvalue.cpp b/src/eigenvalue.cpp
index b3678a021..d0e493608 100644
--- a/src/eigenvalue.cpp
+++ b/src/eigenvalue.cpp
@@ -652,20 +652,4 @@ void read_eigenvalue_hdf5(hid_t group)
   read_dataset(group, "k_abs_tra", simulation::k_abs_tra);
 }
 
-//==============================================================================
-// Fortran compatibility
-//==============================================================================
-
-extern "C" double entropy_c(int i)
-{
-  return simulation::entropy.at(i - 1);
-}
-
-extern "C" void entropy_clear()
-{
-  simulation::entropy.clear();
-}
-
-extern "C" void k_sum_reset() { simulation::k_sum.fill(0.0); }
-
 } // namespace openmc
diff --git a/src/material.cpp b/src/material.cpp
index 3fa648c42..3153d585a 100644
--- a/src/material.cpp
+++ b/src/material.cpp
@@ -1139,34 +1139,6 @@ openmc_extend_materials(int32_t n, int32_t* index_start, int32_t* index_end)
   return 0;
 }
 
-//==============================================================================
-// Fortran compatibility functions
-//==============================================================================
-
-extern "C" {
-  size_t n_materials() { return model::materials.size(); }
-
-  int32_t material_id(int32_t i_mat) {return model::materials[i_mat - 1]->id_;}
-
-  int material_nuclide(int32_t i_mat, int idx)
-  {
-    return model::materials[i_mat - 1]->nuclide_[idx - 1] + 1;
-  }
-
-  int material_nuclide_size(int32_t i_mat)
-  {
-    return model::materials[i_mat - 1]->nuclide_.size();
-  }
-
-  double material_atom_density(int32_t i_mat, int idx)
-  {
-    return model::materials[i_mat - 1]->atom_density_(idx - 1);
-  }
-
-  double material_density_gpcc(int32_t i_mat)
-  {
-    return model::materials[i_mat - 1]->density_gpcc_;
-  }
-}
+extern "C" size_t n_materials() { return model::materials.size(); }
 
 } // namespace openmc
diff --git a/src/mesh.cpp b/src/mesh.cpp
index 85c0b5432..b02a49ff4 100644
--- a/src/mesh.cpp
+++ b/src/mesh.cpp
@@ -900,50 +900,6 @@ void free_memory_mesh()
   model::mesh_map.clear();
 }
 
-//==============================================================================
-// Fortran compatibility
-//==============================================================================
-
-extern "C" {
-  int n_meshes() { return model::meshes.size(); }
-
-  RegularMesh* mesh_ptr(int i) { return model::meshes.at(i).get(); }
-
-  int32_t mesh_id(RegularMesh* m) { return m->id_; }
-
-  double mesh_volume_frac(RegularMesh* m) { return m->volume_frac_; }
-
-  int mesh_n_dimension(RegularMesh* m) { return m->n_dimension_; }
-
-  int mesh_dimension(RegularMesh* m, int i) { return m->shape_(i - 1); }
-
-  double mesh_lower_left(RegularMesh* m, int i) { return m->lower_left_(i - 1); }
-
-  double mesh_upper_right(RegularMesh* m, int i) { return m->upper_right_(i - 1); }
-
-  double mesh_width(RegularMesh* m, int i) { return m->width_(i - 1); }
-
-  int mesh_get_bin(RegularMesh* m, const double* xyz)
-  {
-    return m->get_bin({xyz});
-  }
-
-  int mesh_get_bin_from_indices(RegularMesh* m, const int* ijk)
-  {
-    return m->get_bin_from_indices(ijk);
-  }
-
-  void mesh_get_indices(RegularMesh* m, const double* xyz, int* ijk, bool* in_mesh)
-  {
-    m->get_indices({xyz}, ijk, in_mesh);
-  }
-
-  void mesh_get_indices_from_bin(RegularMesh* m, int bin, int* ijk)
-  {
-    m->get_indices_from_bin(bin, ijk);
-  }
-
-}
-
+extern "C" int n_meshes() { return model::meshes.size(); }
 
 } // namespace openmc
diff --git a/src/nuclide.cpp b/src/nuclide.cpp
index b58ca2c49..592bcceb5 100644
--- a/src/nuclide.cpp
+++ b/src/nuclide.cpp
@@ -968,11 +968,7 @@ void nuclides_clear()
   data::nuclide_map.clear();
 }
 
-//==============================================================================
-// Fortran compatibility functions
-//==============================================================================
-
-extern "C" bool multipole_in_range(const Nuclide* nuc, double E)
+bool multipole_in_range(const Nuclide* nuc, double E)
 {
   return nuc->multipole_ && E >= nuc->multipole_->E_min_&&
     E <= nuc->multipole_->E_max_;
diff --git a/src/output.cpp b/src/output.cpp
index 29d873173..35cd9f9aa 100644
--- a/src/output.cpp
+++ b/src/output.cpp
@@ -620,7 +620,7 @@ const std::unordered_map<int, const char*> score_names = {
 
 //! Create an ASCII output file showing all tally results.
 
-extern "C" void
+void
 write_tallies()
 {
   if (model::tallies.empty()) return;
diff --git a/src/particle.cpp b/src/particle.cpp
index 90d3d2835..bcd981b26 100644
--- a/src/particle.cpp
+++ b/src/particle.cpp
@@ -703,21 +703,4 @@ Particle::write_restart() const
   } // #pragma omp critical
 }
 
-//==============================================================================
-// Fortran compatibility functions
-//==============================================================================
-
-void reset_coord(LocalCoord* c) { c->reset(); }
-void particle_clear(Particle* p) { p->clear(); }
-void particle_initialize(Particle* p) { p->initialize(); }
-void particle_from_source(Particle* p, const Bank* src)
-{
-  p->from_source(src);
-}
-void particle_mark_as_lost(Particle* p, const char* message)
-{
-  p->mark_as_lost(message);
-}
-void particle_write_restart(Particle* p) { p->write_restart(); }
-
 } // namespace openmc
diff --git a/src/reaction.cpp b/src/reaction.cpp
index 4e418e7fe..66b841ef4 100644
--- a/src/reaction.cpp
+++ b/src/reaction.cpp
@@ -270,81 +270,4 @@ std::string reaction_name(int mt)
   }
 }
 
-
-//==============================================================================
-// Fortran compatibility functions
-//==============================================================================
-
-int reaction_mt(Reaction* rx) { return rx->mt_; }
-
-double reaction_q_value(Reaction* rx) { return rx->q_value_; }
-
-bool reaction_scatter_in_cm(Reaction* rx) { return rx->scatter_in_cm_; }
-
-bool reaction_redundant(Reaction* rx) { return rx->redundant_; }
-
-double reaction_product_decay_rate(Reaction* rx, int product)
-{
-  return rx->products_[product - 1].decay_rate_;
-}
-
-int reaction_product_emission_mode(Reaction* rx, int product)
-{
-  switch (rx->products_[product - 1].emission_mode_) {
-  case ReactionProduct::EmissionMode::prompt:
-    return 1;
-  case ReactionProduct::EmissionMode::delayed:
-    return 2;
-  case ReactionProduct::EmissionMode::total:
-    return 3;
-  }
-}
-
-int reaction_product_particle(Reaction* rx, int product)
-{
-  return static_cast<int>(rx->products_[product - 1].particle_);
-}
-
-void reaction_product_sample(Reaction* rx, int product, double E_in, double* E_out, double* mu)
-{
-  rx->products_[product - 1].sample(E_in, *E_out, *mu);
-}
-
-double reaction_product_yield(Reaction* rx, int product, double E)
-{
-  return (*rx->products_[product - 1].yield_)(E);
-}
-
-int reaction_products_size(Reaction* rx) { return rx->products_.size(); }
-
-double reaction_xs(Reaction* rx, int temperature, int energy)
-{
-  return rx->xs_[temperature - 1].value[energy - 1];
-}
-
-double reaction_sample_elastic_mu(Reaction* rx, double E)
-{
-  // Get elastic scattering distribution
-  auto& d = rx->products_[0].distribution_[0];
-
-  // Check if it is an uncorrelated angle-energy distribution
-  auto d_ = dynamic_cast<UncorrelatedAngleEnergy*>(d.get());
-  if (d_) {
-    return d_->angle().sample(E);
-  } else {
-    return 2.0*prn() - 1.0;
-  }
-
-}
-
-int reaction_xs_size(Reaction* rx, int temperature)
-{
-  return rx->xs_[temperature - 1].value.size();
-}
-
-int reaction_xs_threshold(Reaction* rx, int temperature)
-{
-  return rx->xs_[temperature - 1].threshold;
-}
-
-}
+} // namespace openmc
diff --git a/src/settings.cpp b/src/settings.cpp
index fff0baa38..92e85ab17 100644
--- a/src/settings.cpp
+++ b/src/settings.cpp
@@ -788,18 +788,4 @@ void free_memory_settings() {
   settings::res_scat_nuclides.clear();
 }
 
-//==============================================================================
-// Fortran compatibility functions
-//==============================================================================
-
-extern "C" {
-  const char* path_cross_sections_c() {
-    return settings::path_cross_sections.c_str();
-  }
-  const char* path_input_c() {
-    return settings::path_input.c_str();
-  }
-
-}
-
 } // namespace openmc
diff --git a/src/simulation.cpp b/src/simulation.cpp
index 4f496e5ec..50ce1b5c0 100644
--- a/src/simulation.cpp
+++ b/src/simulation.cpp
@@ -26,13 +26,6 @@
 #include <algorithm>
 #include <string>
 
-namespace openmc {
-
-// data/functions from Fortran side
-extern "C" void write_tallies();
-
-} // namespace openmc
-
 //==============================================================================
 // C API functions
 //==============================================================================
@@ -135,7 +128,7 @@ int openmc_simulation_finalize()
   simulation::time_active.stop();
   simulation::time_finalize.start();
 
-  // Deallocate Fortran variables, set tallies to inactive
+  // Clear material nuclide mapping
   for (auto& mat : model::materials) {
     mat->mat_nuclide_index_.clear();
   }
@@ -580,20 +573,4 @@ void free_memory_simulation()
   simulation::entropy.clear();
 }
 
-//==============================================================================
-// Fortran compatibility
-//==============================================================================
-
-extern "C" double k_generation(int i) { return simulation::k_generation.at(i - 1); }
-extern "C" int k_generation_size() { return simulation::k_generation.size(); }
-extern "C" void k_generation_clear() { simulation::k_generation.clear(); }
-extern "C" void k_generation_reserve(int i) { simulation::k_generation.reserve(i); }
-extern "C" int64_t work_index(int rank) { return simulation::work_index[rank]; }
-
-// This function was moved here to get around a bug on macOS whereby an invalid
-// pointer is returned for the threadprivate filter_matches
-extern "C" FilterMatch* filter_match_pointer(int indx) {
-  return &simulation::filter_matches[indx];
-}
-
 } // namespace openmc
diff --git a/src/source.cpp b/src/source.cpp
index 6fbb9c72d..1ebdc235b 100644
--- a/src/source.cpp
+++ b/src/source.cpp
@@ -332,10 +332,6 @@ void free_memory_source()
   model::external_sources.clear();
 }
 
-//==============================================================================
-// Fortran compatibility functions
-//==============================================================================
-
 void fill_source_bank_fixedsource()
 {
   if (settings::path_source.empty()) {
diff --git a/src/tallies/derivative.cpp b/src/tallies/derivative.cpp
index e51033534..b5b85fd6f 100644
--- a/src/tallies/derivative.cpp
+++ b/src/tallies/derivative.cpp
@@ -693,16 +693,4 @@ void zero_flux_derivs()
   for (auto& deriv : model::tally_derivs) deriv.flux_deriv = 0.;
 }
 
-//==============================================================================
-// Fortran interop
-//==============================================================================
-
-extern "C" int n_tally_derivs() {return model::tally_derivs.size();}
-
-extern "C" TallyDerivative*
-tally_deriv_c(int i)
-{
-  return &model::tally_derivs[i];
-}
-
 }// namespace openmc
diff --git a/src/tallies/filter.cpp b/src/tallies/filter.cpp
index 629f38714..db90f9c49 100644
--- a/src/tallies/filter.cpp
+++ b/src/tallies/filter.cpp
@@ -193,48 +193,4 @@ openmc_new_filter(const char* type, int32_t* index)
   return 0;
 }
 
-//==============================================================================
-// Fortran compatibility functions
-//==============================================================================
-
-extern "C" {
-  // filter_match_point moved to simulation.cpp
-
-
-  int32_t filter_get_id(Filter* filt) {return filt->id_;}
-
-  void filter_set_id(Filter* filt, int32_t id) {filt->id_ = id;}
-
-  void filter_from_xml(Filter* filt, pugi::xml_node* node)
-  {filt->from_xml(*node);}
-
-  void
-  filter_get_all_bins(Filter* filt, Particle* p, int estimator,
-                      FilterMatch* match)
-  {
-    filt->get_all_bins(p, estimator, *match);
-  }
-
-  void filter_to_statepoint(Filter* filt, hid_t group)
-  {filt->to_statepoint(group);}
-
-  void filter_text_label(Filter* filt, int bin, char* label)
-  {
-    std::string label_str = filt->text_label(bin);
-    int i = 0;
-    for (; i < label_str.size() && i < MAX_LINE_LEN; i++)
-      label[i] = label_str[i];
-    label[i] = '\0';
-  }
-
-  void filter_initialize(Filter* filt) {filt->initialize();}
-
-  int filter_n_bins(Filter* filt) {return filt->n_bins_;}
-
-  int mesh_filter_get_mesh(MeshFilter* filt) {return filt->mesh();}
-
-  int sphharm_filter_get_cosine(SphericalHarmonicsFilter* filt)
-  {return static_cast<int>(filt->cosine_);}
-}
-
 } // namespace openmc
diff --git a/src/tallies/filter_particle.cpp b/src/tallies/filter_particle.cpp
index b8bc32286..403ef9500 100644
--- a/src/tallies/filter_particle.cpp
+++ b/src/tallies/filter_particle.cpp
@@ -38,11 +38,4 @@ ParticleFilter::text_label(int bin) const
   return "Particle " + std::to_string(particles_[bin]);
 }
 
-//==============================================================================
-// Fortran interoperability
-//==============================================================================
-
-extern "C" int particle_filter_particles(ParticleFilter* filt, int i)
-{return filt->particles_[i];}
-
 } // namespace openmc
diff --git a/src/tallies/tally.cpp b/src/tallies/tally.cpp
index dbd7ddd47..b98f4ad7e 100644
--- a/src/tallies/tally.cpp
+++ b/src/tallies/tally.cpp
@@ -1396,86 +1396,4 @@ openmc_global_tallies(double** ptr)
 
 extern "C" size_t tallies_size() { return model::tallies.size(); }
 
-//==============================================================================
-// Fortran compatibility functions
-//==============================================================================
-
-extern "C" {
-  Tally* tally_pointer(int indx) {return model::tallies[indx].get();}
-
-  int active_tallies_data(int i)
-  {return model::active_tallies[i-1];}
-
-  int active_tallies_size()
-  {return model::active_tallies.size();}
-
-  int active_analog_tallies_size()
-  {return model::active_analog_tallies.size();}
-
-  int active_tracklength_tallies_size()
-  {return model::active_tracklength_tallies.size();}
-
-  int active_collision_tallies_size()
-  {return model::active_collision_tallies.size();}
-
-  int active_meshsurf_tallies_size()
-  {return model::active_meshsurf_tallies.size();}
-
-  int active_surface_tallies_size()
-  {return model::active_surface_tallies.size();}
-
-  void tally_init_from_xml(Tally* tally, pugi::xml_node* node)
-  {tally->init_from_xml(*node);}
-
-  int tally_get_id_c(Tally* tally) {return tally->id_;}
-
-  void tally_set_id_c(Tally* tally, int id) {tally->id_ = id;}
-
-  int tally_get_type_c(Tally* tally) {return tally->type_;}
-
-  void tally_set_type_c(Tally* tally, int type) {tally->type_ = type;}
-
-  int tally_get_estimator_c(Tally* tally) {return tally->estimator_;}
-
-  void tally_set_estimator_c(Tally* tally, int e) {tally->estimator_ = e;}
-
-  bool tally_get_depletion_rx_c(Tally* tally) {return tally->depletion_rx_;}
-
-  int tally_get_n_scores_c(Tally* tally) {return tally->scores_.size();}
-
-  int tally_get_score_c(Tally* tally, int i) {return tally->scores_[i];}
-
-  void tally_set_filters_c(Tally* tally, int n, int32_t filter_indices[])
-  {tally->set_filters(filter_indices, n);}
-
-  int tally_get_n_filters_c(Tally* tally) {return tally->filters().size();}
-
-  int32_t tally_get_filter_c(Tally* tally, int i) {return tally->filters(i);}
-
-  int32_t tally_get_n_filter_bins_c(Tally* tally)
-  {return tally->n_filter_bins();}
-
-  int tally_get_n_nuclide_bins_c(Tally* tally)
-  {return tally->nuclides_.size();}
-
-  int tally_get_nuclide_bins_c(Tally* tally, int i)
-  {return tally->nuclides_[i-1];}
-
-  int tally_get_energyout_filter_c(Tally* tally)
-  {return tally->energyout_filter_;}
-
-  void tally_set_scores(Tally* tally, pugi::xml_node* node)
-  {tally->set_scores(*node);}
-
-  void tally_set_nuclides(Tally* tally, pugi::xml_node* node)
-  {tally->set_nuclides(*node);}
-
-  // void tally_init_triggers(Tally* tally, int i_tally, pugi::xml_node* node)
-  // {tally->init_triggers(*node, i_tally);}
-
-  int tally_get_deriv_c(Tally* tally) {return tally->deriv_;}
-
-  int tally_set_deriv_c(Tally* tally, int deriv) {tally->deriv_ = deriv;}
-}
-
 } // namespace openmc
diff --git a/src/thermal.cpp b/src/thermal.cpp
index 40fc6f075..3c2d9ba43 100644
--- a/src/thermal.cpp
+++ b/src/thermal.cpp
@@ -593,30 +593,4 @@ void free_memory_thermal()
   data::thermal_scatt_map.clear();
 }
 
-//==============================================================================
-// Fortran compatibility functions
-//==============================================================================
-
-extern "C" ThermalScattering*
-sab_from_hdf5(hid_t group, const double* temperature, int n)
-{
-  // Convert temperatures to a vector
-  std::vector<double> T {temperature, temperature + n};
-
-  // Create new object and return it
-  data::thermal_scatt.push_back(std::make_unique<ThermalScattering>(group, T));
-
-  return data::thermal_scatt.back().get();
-}
-
-extern "C" bool sab_has_nuclide(int i_sab, const char* name)
-{
-  return data::thermal_scatt[i_sab - 1]->has_nuclide(name);
-}
-
-extern "C" double sab_threshold(int i_sab)
-{
-  return data::thermal_scatt[i_sab - 1]->threshold();
-}
-
 } // namespace openmc
diff --git a/src/timer.cpp b/src/timer.cpp
index 8e5d5d481..2303c6090 100644
--- a/src/timer.cpp
+++ b/src/timer.cpp
@@ -54,22 +54,6 @@ double Timer::elapsed()
   }
 }
 
-//==============================================================================
-// Fortran compatibility
-//==============================================================================
-
-extern "C" double time_active_elapsed() { return simulation::time_active.elapsed(); }
-extern "C" double time_bank_elapsed() { return simulation::time_bank.elapsed(); }
-extern "C" double time_bank_sample_elapsed() { return simulation::time_bank_sample.elapsed(); }
-extern "C" double time_bank_sendrecv_elapsed() { return simulation::time_bank_sendrecv.elapsed(); }
-extern "C" double time_finalize_elapsed() { return simulation::time_finalize.elapsed(); }
-extern "C" double time_inactive_elapsed() { return simulation::time_inactive.elapsed(); }
-extern "C" double time_initialize_elapsed() { return simulation::time_initialize.elapsed(); }
-extern "C" double time_read_xs_elapsed() { return simulation::time_read_xs.elapsed(); }
-extern "C" double time_tallies_elapsed() { return simulation::time_tallies.elapsed(); }
-extern "C" double time_total_elapsed() { return simulation::time_total.elapsed(); }
-extern "C" double time_transport_elapsed() { return simulation::time_transport.elapsed(); }
-
 //==============================================================================
 // Non-member functions
 //==============================================================================