resurrected storing HubbleParam/Hubble in deprecated GADGET2_HEADER

src/io/snap_io.cc

@@ -415,13 +415,13 @@ void snap_io::read_ic(const char *fname)
   Sp->NumPart += add_numpart;
 #endif
 
-
-
 #ifdef GADGET2_HEADER
 #ifndef INITIAL_CONDITIONS_CONTAIN_ENTROPY
-  if(header.flag_entropy_instead_u) Terminate("Initial condition file contains entropy, but INITIAL_CONDITIONS_CONTAIN_ENTROPY is not set\n");
-#else    
-  if(! header.flag_entropy_instead_u)Terminate("Initial condition file contains uthermal, but INITIAL_CONDITIONS_CONTAIN_ENTROPY is set\n");
+  if(header.flag_entropy_instead_u)
+    Terminate("Initial condition file contains entropy, but INITIAL_CONDITIONS_CONTAIN_ENTROPY is not set\n");
+#else
+  if(!header.flag_entropy_instead_u)
+    Terminate("Initial condition file contains uthermal, but INITIAL_CONDITIONS_CONTAIN_ENTROPY is set\n");
 #endif
 #endif
 
@@ -736,6 +736,11 @@ void snap_io::fill_file_header(int writeTask, int lastTask, long long *n_type, l
   header.Omega0      = All.Omega0;
   header.OmegaLambda = All.OmegaLambda;
 
+#if !(defined(REARRANGE_OPTION) && defined(MERGERTREE))
+  header.HubbleParam = All.HubbleParam;
+  header.Hubble      = All.Hubble;
+#endif
+
 #ifdef OUTPUT_IN_DOUBLEPRECISION
   header.flag_doubleprecision = 1;
 #else

src/io/snap_io.h

@@ -79,10 +79,13 @@ class snap_io : public IO_Def
     double BoxSize;                                /**< box-size of simulation in case periodic boundaries were used */
     double Omega0;                                 /**< matter density in units of critical density */
     double OmegaLambda;                            /**< cosmological constant parameter */
-    long long Ntrees;                              // this replaces the storage space for HubbleParam
-    long long TotNtrees;                           // this replaces the storage space for Hubble
-    //  double HubbleParam;                             /**< little 'h' to scale units systems */
-    //   double Hubble;                                  /**< Hubble constant in internal units */
+#if defined(REARRANGE_OPTION) && defined(MERGERTREE)
+    long long Ntrees;     // this replaces the storage space for HubbleParam
+    long long TotNtrees;  // this replaces the storage space for Hubble
+#else
+    double HubbleParam; /**< little 'h' to scale units systems */
+    double Hubble;      /**< Hubble constant in internal units */
+#endif
     unsigned int npartTotalHighWord[NTYPES_HEADER]; /**< High word of the total number of particles of each type */
     int flag_entropy_instead_u;                     /**< flags that IC-file contains entropy instead of u */
     int flag_doubleprecision;                       /**< flags that snapshot contains double-precision instead of single precision */