78 lines
2.2 KiB
C++
78 lines
2.2 KiB
C++
/* 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);
|
|
}
|