/**Function********************************************************************
Synopsis [Computes the difference of two ZDDs.]
Description [Computes the difference of two ZDDs. Returns a pointer to the
result if successful; NULL otherwise.]
SideEffects [None]
SeeAlso [Cudd_zddDiffConst]
******************************************************************************/
DdNode *
Cudd_zddDiff(
DdManager * dd,
DdNode * P,
DdNode * Q)
{
DdNode *res;
do {
dd->reordered = 0;
res = cuddZddDiff(dd, P, Q);
} while (dd->reordered == 1);
return(res);
} /* end of Cudd_zddDiff */
/**
@brief Computes the difference of two ZDDs.
@return a pointer to the result if successful; NULL otherwise.
@sideeffect None
*/
DdNode *
Cudd_zddDiff(
DdManager * dd,
DdNode * P,
DdNode * Q)
{
DdNode *res;
do {
dd->reordered = 0;
res = cuddZddDiff(dd, P, Q);
} while (dd->reordered == 1);
if (dd->errorCode == CUDD_TIMEOUT_EXPIRED && dd->timeoutHandler) {
dd->timeoutHandler(dd, dd->tohArg);
}
return(res);
} /* end of Cudd_zddDiff */
/**Function********************************************************************
Synopsis [Performs the recursive step of Cudd_zddDiff.]
Description []
SideEffects [None]
SeeAlso []
******************************************************************************/
DdNode *
cuddZddDiff(
DdManager * zdd,
DdNode * P,
DdNode * Q)
{
int p_top, q_top;
DdNode *empty = DD_ZERO(zdd), *t, *e, *res;
DdManager *table = zdd;
statLine(zdd);
if (P == empty)
return(empty);
if (Q == empty)
return(P);
if (P == Q)
return(empty);
/* Check cache. The cache is shared by Cudd_zddDiffConst(). */
res = cuddCacheLookup2Zdd(table, cuddZddDiff, P, Q);
if (res != NULL && res != DD_NON_CONSTANT)
return(res);
if (cuddIsConstant(P))
p_top = P->index;
else
p_top = zdd->permZ[P->index];
if (cuddIsConstant(Q))
q_top = Q->index;
else
q_top = zdd->permZ[Q->index];
if (p_top < q_top) {
e = cuddZddDiff(zdd, cuddE(P), Q);
if (e == NULL) return(NULL);
cuddRef(e);
res = cuddZddGetNode(zdd, P->index, cuddT(P), e);
if (res == NULL) {
Cudd_RecursiveDerefZdd(table, e);
return(NULL);
}
cuddDeref(e);
} else if (p_top > q_top) {
res = cuddZddDiff(zdd, P, cuddE(Q));
if (res == NULL) return(NULL);
} else {
t = cuddZddDiff(zdd, cuddT(P), cuddT(Q));
if (t == NULL) return(NULL);
cuddRef(t);
e = cuddZddDiff(zdd, cuddE(P), cuddE(Q));
if (e == NULL) {
Cudd_RecursiveDerefZdd(table, t);
return(NULL);
}
cuddRef(e);
res = cuddZddGetNode(zdd, P->index, t, e);
if (res == NULL) {
Cudd_RecursiveDerefZdd(table, t);
Cudd_RecursiveDerefZdd(table, e);
return(NULL);
}
cuddDeref(t);
cuddDeref(e);
}
cuddCacheInsert2(table, cuddZddDiff, P, Q, res);
return(res);
} /* end of cuddZddDiff */