move and comment GetLevelsAndLogicalLocationsFlat

src/mesh/mesh.cpp

@@ -1347,4 +1347,24 @@ void Mesh::SetupMPIComms() {
 #endif
 }
 
+// Return list of locations and levels for the legacy tree
+// TODO(LFR): It doesn't make sense to offset the level by the
+//   legacy tree root level since the location indices are defined
+//   for loc.level(). It seems this level offset is required for
+//   the output to agree with the legacy output though.
+std::pair<std::vector<std::int64_t>, std::vector<std::int64_t>>
+Mesh::GetLevelsAndLogicalLocationsFlat() const noexcept {
+  std::vector<std::int64_t> levels, logicalLocations;
+  levels.reserve(nbtotal);
+  logicalLocations.reserve(nbtotal * 3);
+  for (auto loc : loclist) {
+    loc = forest.GetLegacyTreeLocation(loc);
+    levels.push_back(loc.level() - GetLegacyTreeRootLevel());
+    logicalLocations.push_back(loc.lx1());
+    logicalLocations.push_back(loc.lx2());
+    logicalLocations.push_back(loc.lx3());
+  }
+  return std::make_pair(levels, logicalLocations);
+}
+
 } // namespace parthenon

src/mesh/mesh.hpp

@@ -205,20 +205,8 @@ class Mesh {
   std::vector<int> GetNbList() const noexcept { return nblist; }
   std::vector<LogicalLocation> GetLocList() const noexcept { return loclist; }
 
-  // TODO(JMM): Put in implementation file?
-  auto GetLevelsAndLogicalLocationsFlat() const noexcept {
-    std::vector<std::int64_t> levels, logicalLocations;
-    levels.reserve(nbtotal);
-    logicalLocations.reserve(nbtotal * 3);
-    for (auto loc : loclist) {
-      loc = forest.GetLegacyTreeLocation(loc);
-      levels.push_back(loc.level());
-      logicalLocations.push_back(loc.lx1());
-      logicalLocations.push_back(loc.lx2());
-      logicalLocations.push_back(loc.lx3());
-    }
-    return std::make_pair(levels, logicalLocations);
-  }
+  std::pair<std::vector<std::int64_t>, std::vector<std::int64_t>>
+  GetLevelsAndLogicalLocationsFlat() const noexcept;
 
   void OutputMeshStructure(const int dim, const bool dump_mesh_structure = true);