Initial revision

buddy/examples/fdd/fdd.cxx

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+/* This program creates a transition relation for a finite state machine.
+ * This transition relation is then used to find the reachable statespace
+ * of the state machine. The state machine has 8 states with state 0 being
+ * the initial state. The transitions form a ring:
+ *
+ *    0 -> 1 -> 2 -> 3 -> 4 -> 5 -> -> 7 -> 0
+ */
+
+#include "fdd.h"
+
+/* Use the transition relation "transRel" to iterate through the statespace
+ */
+void findStateSpace(bdd transRel)
+{
+   using namespace std ;
+      /* Create a new pair for renaming the next-state variables to
+       * current-state variables */
+   bddPair *p = bdd_newpair();
+   fdd_setpair(p,1,0);
+
+      /* Get a BDD that represents all the current-state variables */
+   bdd currentStateVar = fdd_ithset(0);
+
+      /* Start with the initial state */
+   bdd reachedStates = fdd_ithvar(0,0);
+
+   bdd tmp = bddfalse;
+
+      /* Repeat until no new states are found */
+   do
+   {
+      tmp = reachedStates;
+
+         /* Calculate: Newset = (exists V_cur. transRel & Reached)[cur/next] */
+      bdd newset;
+      newset = reachedStates & transRel;
+      newset = bdd_exist(newset, currentStateVar);
+      newset = bdd_replace(newset, p);
+
+      cout << "Front: " << (newset - reachedStates) << endl;
+
+         /* Add the new states to the found states */
+      reachedStates = reachedStates | newset;
+   }
+   while (tmp != reachedStates);
+}
+
+
+int main() {
+   using namespace std ;
+      /* Initialize BuDDy and declare two interleaved FDD variable blocks
+       * with the domain [0..7] */
+   int domain[2] = {8,8};
+
+   bdd_init(100,100);
+   fdd_extdomain(domain, 2);
+
+      /* Initialize the transition relation with no transitions */
+   bdd T = bddfalse;
+
+      /* Add all the transitions (from state 'i' to state 'i+1') */
+   for (int i=0 ; i<8 ; i++)
+   {
+         /* Set the current state to be state 'i' */
+      bdd current = fdd_ithvar(0,i);
+      
+         /* Set the next state to be state 'i+1' */
+      bdd next = fdd_ithvar(1, (i+1) % 8);
+
+         /* Add the transition */
+      T = T | (current & next);
+   }
+
+   cout << fddset << "Transition relation: " << T << endl << endl;
+
+      /* Calculate the reachable statespace */
+   findStateSpace(T);
+}