From 009e1548d538cc85dbcfec497cde139d02261052 Mon Sep 17 00:00:00 2001
From: Sterling Harper <smharper@mit.edu>
Date: Wed, 31 Oct 2018 10:20:29 -0400
Subject: [PATCH] Make energy_bins/rev_energy_bins match F90 impl.

---
 src/mgxs_interface.cpp        | 8 ++++----
 src/source.cpp                | 9 ++-------
 src/tallies/filter_energy.cpp | 6 ++----
 3 files changed, 8 insertions(+), 15 deletions(-)

diff --git a/src/mgxs_interface.cpp b/src/mgxs_interface.cpp
index 5cec8811f..0729e466c 100644
--- a/src/mgxs_interface.cpp
+++ b/src/mgxs_interface.cpp
@@ -99,11 +99,11 @@ void read_mg_cross_sections_header_c(hid_t file_id)
   read_attribute(file_id, "energy_groups", num_energy_groups);
 
   ensure_exists(file_id, "group structure", true);
-  read_attribute(file_id, "group structure", energy_bins);
+  read_attribute(file_id, "group structure", rev_energy_bins);
 
-  // Create reverse energy bins
-  std::copy(energy_bins.crbegin(), energy_bins.crend(),
-    std::back_inserter(rev_energy_bins));
+  // Reverse energy bins
+  std::copy(rev_energy_bins.crbegin(), rev_energy_bins.crend(),
+    std::back_inserter(energy_bins));
 
   // Create average energies
   for (int i = 0; i < energy_bins.size() - 1; ++i) {
diff --git a/src/source.cpp b/src/source.cpp
index bfed41b6a..315ff2cdd 100644
--- a/src/source.cpp
+++ b/src/source.cpp
@@ -292,8 +292,6 @@ void initialize_source()
   }
 }
 
-extern "C" double* rev_energy_bins_ptr();
-
 Bank sample_external_source()
 {
   // Set the random number generator to the source stream.
@@ -320,11 +318,8 @@ Bank sample_external_source()
 
   // If running in MG, convert site % E to group
   if (!settings::run_CE) {
-    // Get pointer to rev_energy_bins array on Fortran side
-    double* rev_energy_bins = rev_energy_bins_ptr();
-
-    int n = num_energy_groups + 1;
-    site.E = lower_bound_index(rev_energy_bins, rev_energy_bins + n, site.E);
+    site.E = lower_bound_index(rev_energy_bins.begin(), rev_energy_bins.end(),
+                               site.E);
     site.E = num_energy_groups - site.E;
   }
 
diff --git a/src/tallies/filter_energy.cpp b/src/tallies/filter_energy.cpp
index 779681b84..d6dd8b9ac 100644
--- a/src/tallies/filter_energy.cpp
+++ b/src/tallies/filter_energy.cpp
@@ -13,9 +13,6 @@ namespace openmc {
 // EnergyFilter implementation
 //==============================================================================
 
-// Used to grab the rev_energy_bins array defined in Fortran.
-extern "C" double* rev_energy_bins_ptr();
-
 void
 EnergyFilter::from_xml(pugi::xml_node node)
 {
@@ -30,7 +27,6 @@ EnergyFilter::from_xml(pugi::xml_node node)
   if (!settings::run_CE) {
     if (n_bins_ == num_energy_groups) {
       matches_transport_groups_ = true;
-      double* rev_energy_bins = rev_energy_bins_ptr();
       for (auto i = 0; i < n_bins_ + 1; i++) {
         if (rev_energy_bins[i] != bins_[i]) {
           matches_transport_groups_ = false;
@@ -80,6 +76,7 @@ std::string
 EnergyFilter::text_label(int bin) const
 {
   std::stringstream out;
+  //TODO: off-by-one
   out << "Incoming Energy [" << bins_[bin-1] << ", " << bins_[bin] << ")";
   return out.str();
 }
@@ -110,6 +107,7 @@ std::string
 EnergyoutFilter::text_label(int bin) const
 {
   std::stringstream out;
+  //TODO: off-by-one
   out << "Outgoing Energy [" << bins_[bin-1] << ", " << bins_[bin] << ")";
   return out.str();
 }