Add PBC rounding to the positions and add lock free array to protect the cells from race conditions

bfps/cpp/particles/lock_free_bool_array.hpp

+#ifndef LOCK_FREE_BOOL_ARRAY_HPP
+#define LOCK_FREE_BOOL_ARRAY_HPP
+
+#include <vector>
+#include <memory>
+
+class lock_free_bool_array{
+    std::vector<std::unique_ptr<long int>> keys;
+
+public:
+    explicit lock_free_bool_array(const long int inNbKeys = 512){
+        keys.resize(inNbKeys);
+        for(std::unique_ptr<long int>& k : keys){
+            k.reset(new long int(0));
+        }
+    }
+
+    void lock(const int inKey){
+        volatile long int* k = keys[inKey%keys.size()].get();
+        long int res = 1;
+        int cpt = 0;
+        while(res == 1){
+            res = __sync_val_compare_and_swap(k, 0, res);
+            cpt++;
+        }
+    }
+
+    void unlock(const int inKey){
+        volatile long int* k = keys[inKey%keys.size()].get();
+        assert(k && *k);
+        (*k) = 0;
+    }
+};
+
+#endif

bfps/cpp/particles/p2p_tree.hpp

@@ -15,7 +15,7 @@ class p2p_tree{
     }
 
     long int get_cell_coord_y_from_index(const long int index) const{
-        return (index - get_cell_coord_z_from_index(index)*(nb_cell_levels[IDX_X]*nb_cell_levels[IDX_Y]))
+        return (index % (nb_cell_levels[IDX_X]*nb_cell_levels[IDX_Y]))
                 / nb_cell_levels[IDX_X];
     }