pack and unpack cells with the gcount.

src/cell.c

@@ -89,14 +89,18 @@ int cell_unpack(struct pcell *pc, struct cell *c, struct space *s) {
   c->ti_end_min = pc->ti_end_min;
   c->ti_end_max = pc->ti_end_max;
   c->count = pc->count;
+  c->gcount = pc->gcount;
   c->tag = pc->tag;
+  
+  /* Number of new cells created. */
+  int count = 1;
 
   /* Fill the progeny recursively, depth-first. */
-  int count = 1;
   for (int k = 0; k < 8; k++)
     if (pc->progeny[k] >= 0) {
       struct cell *temp = space_getcell(s);
       temp->count = 0;
+      temp->gcount = 0;
       temp->loc[0] = c->loc[0];
       temp->loc[1] = c->loc[1];
       temp->loc[2] = c->loc[2];
@@ -122,7 +126,7 @@ int cell_unpack(struct pcell *pc, struct cell *c, struct space *s) {
 }
 
 /**
- * @brief Link the cells recursively to the given part array.
+ * @brief Link the cells recursively to the given #part array.
  *
  * @param c The #cell.
  * @param parts The #part array.
@@ -130,7 +134,7 @@ int cell_unpack(struct pcell *pc, struct cell *c, struct space *s) {
  * @return The number of particles linked.
  */
 
-int cell_link(struct cell *c, struct part *parts) {
+int cell_link_parts(struct cell *c, struct part *parts) {
 
   c->parts = parts;
 
@@ -139,14 +143,40 @@ int cell_link(struct cell *c, struct part *parts) {
     int offset = 0;
     for (int k = 0; k < 8; k++) {
       if (c->progeny[k] != NULL)
-        offset += cell_link(c->progeny[k], &parts[offset]);
+        offset += cell_link_parts(c->progeny[k], &parts[offset]);
     }
   }
 
-  /* Return the total number of unpacked cells. */
+  /* Return the total number of linked particles. */
   return c->count;
 }
 
+/**
+ * @brief Link the cells recursively to the given #gpart array.
+ *
+ * @param c The #cell.
+ * @param gparts The #gpart array.
+ *
+ * @return The number of particles linked.
+ */
+
+int cell_link_gparts(struct cell *c, struct gpart *gparts) {
+
+  c->gparts = gparts;
+
+  /* Fill the progeny recursively, depth-first. */
+  if (c->split) {
+    int offset = 0;
+    for (int k = 0; k < 8; k++) {
+      if (c->progeny[k] != NULL)
+        offset += cell_link_gparts(c->progeny[k], &gparts[offset]);
+    }
+  }
+
+  /* Return the total number of linked particles. */
+  return c->gcount;
+}
+
 /**
  * @brief Pack the data of the given cell and all it's sub-cells.
  *
@@ -164,6 +194,7 @@ int cell_pack(struct cell *c, struct pcell *pc) {
   pc->ti_end_min = c->ti_end_min;
   pc->ti_end_max = c->ti_end_max;
   pc->count = c->count;
+  pc->gcount = c->gcount;
   c->tag = pc->tag = atomic_inc(&cell_next_tag) % cell_max_tag;
 
   /* Fill in the progeny, depth-first recursion. */

src/cell.h

@@ -44,7 +44,7 @@ struct pcell {
   int ti_end_min, ti_end_max;
 
   /* Number of particles in this cell. */
-  int count;
+  int count, gcount;
 
   /* tag used for MPI communication. */
   int tag;
@@ -175,7 +175,8 @@ void cell_gunlocktree(struct cell *c);
 int cell_pack(struct cell *c, struct pcell *pc);
 int cell_unpack(struct pcell *pc, struct cell *c, struct space *s);
 int cell_getsize(struct cell *c);
-int cell_link(struct cell *c, struct part *parts);
+int cell_link_parts(struct cell *c, struct part *parts);
+int cell_link_gparts(struct cell *c, struct gpart *gparts);
 void cell_init_parts(struct cell *c, void *data);
 void cell_convert_hydro(struct cell *c, void *data);
 void cell_clean_links(struct cell *c, void *data);