C++ Cudd_NotCond函数代码示例

/**Function*************************************************************

  Synopsis    [Converts graph to BDD.]

  Description []
               
  SideEffects []

  SeeAlso     []

***********************************************************************/
DdNode * Dec_GraphDeriveBdd( DdManager * dd, Dec_Graph_t * pGraph )
{
    DdNode * bFunc, * bFunc0, * bFunc1;
    Dec_Node_t * pNode;
    int i;

    // sanity checks
    assert( Dec_GraphLeaveNum(pGraph) >= 0 );
    assert( Dec_GraphLeaveNum(pGraph) <= pGraph->nSize );

    // check for constant function
    if ( Dec_GraphIsConst(pGraph) )
        return Cudd_NotCond( b1, Dec_GraphIsComplement(pGraph) );
    // check for a literal
    if ( Dec_GraphIsVar(pGraph) )
        return Cudd_NotCond( Cudd_bddIthVar(dd, Dec_GraphVarInt(pGraph)), Dec_GraphIsComplement(pGraph) );

    // assign the elementary variables
    Dec_GraphForEachLeaf( pGraph, pNode, i )
        pNode->pFunc = Cudd_bddIthVar( dd, i );

    // compute the function for each internal node
    Dec_GraphForEachNode( pGraph, pNode, i )
    {
        bFunc0 = Cudd_NotCond( Dec_GraphNode(pGraph, pNode->eEdge0.Node)->pFunc, pNode->eEdge0.fCompl ); 
        bFunc1 = Cudd_NotCond( Dec_GraphNode(pGraph, pNode->eEdge1.Node)->pFunc, pNode->eEdge1.fCompl ); 
        pNode->pFunc = Cudd_bddAnd( dd, bFunc0, bFunc1 );   Cudd_Ref( pNode->pFunc );
    }

/**Function********************************************************************

  Synopsis    [Implements the recursive step of Cudd_bddVarMap.]

  Description [Implements the recursive step of Cudd_bddVarMap.
  Returns a pointer to the result if successful; NULL otherwise.]

  SideEffects [None]

  SeeAlso     [Cudd_bddVarMap]

******************************************************************************/
static DdNode *
cuddBddVarMapRecur(
  DdManager *manager /* DD manager */,
  DdNode *f /* BDD to be remapped */)
{
    DdNode	*F, *T, *E;
    DdNode	*res;
    int		index;

    statLine(manager);
    F = Cudd_Regular(f);

    /* Check for terminal case of constant node. */
    if (cuddIsConstant(F)) {
	return(f);
    }

    /* If problem already solved, look up answer and return. */
    if (F->ref != 1 &&
	(res = cuddCacheLookup1(manager,Cudd_bddVarMap,F)) != NULL) {
	return(Cudd_NotCond(res,F != f));
    }

    /* Split and recur on children of this node. */
    T = cuddBddVarMapRecur(manager,cuddT(F));
    if (T == NULL) return(NULL);
    cuddRef(T);
    E = cuddBddVarMapRecur(manager,cuddE(F));
    if (E == NULL) {
	Cudd_IterDerefBdd(manager, T);
	return(NULL);
    }
    cuddRef(E);

    /* Move variable that should be in this position to this position
    ** by retrieving the single var BDD for that variable, and calling
    ** cuddBddIteRecur with the T and E we just created.
    */
    index = manager->map[F->index];
    res = cuddBddIteRecur(manager,manager->vars[index],T,E);
    if (res == NULL) {
	Cudd_IterDerefBdd(manager, T);
	Cudd_IterDerefBdd(manager, E);
	return(NULL);
    }
    cuddRef(res);
    Cudd_IterDerefBdd(manager, T);
    Cudd_IterDerefBdd(manager, E);

    /* Do not keep the result if the reference count is only 1, since
    ** it will not be visited again.
    */
    if (F->ref != 1) {
	cuddCacheInsert1(manager,Cudd_bddVarMap,F,res);
    }
    cuddDeref(res);
    return(Cudd_NotCond(res,F != f));

} /* end of cuddBddVarMapRecur */

/**Function********************************************************************

  Synopsis    [Checks whether a variable is dependent on others in a
  function.]

  Description [Checks whether a variable is dependent on others in a
  function.  Returns 1 if the variable is dependent; 0 otherwise. No
  new nodes are created.]

  SideEffects [None]

  SeeAlso     []

******************************************************************************/
int
Cudd_bddVarIsDependent(
  DdManager *dd,		/* manager */
  DdNode *f,			/* function */
  DdNode *var			/* variable */)
{
    DdNode *F, *res, *zero, *ft, *fe;
    unsigned topf, level;
    DD_CTFP cacheOp;
    int retval;

    /* NuSMV: begin add */
    abort(); /* NOT USED BY NUSMV */
    /* NuSMV: begin end */

    zero = Cudd_Not(DD_TRUE(dd));
    if (Cudd_IsConstant(f)) return(f == zero);

    /* From now on f is not constant. */
    F = Cudd_Regular(f);
    topf = (unsigned) dd->perm[F->index];
    level = (unsigned) dd->perm[var->index];

    /* Check terminal case. If topf > index of var, f does not depend on var.
    ** Therefore, var is not dependent in f. */
    if (topf > level) {
	return(0);
    }

    cacheOp = (DD_CTFP) Cudd_bddVarIsDependent;
    res = cuddCacheLookup2(dd,cacheOp,f,var);
    if (res != NULL) {
	return(res != zero);
    }

    /* Compute cofactors. */
    ft = Cudd_NotCond(cuddT(F), f != F);
    fe = Cudd_NotCond(cuddE(F), f != F);

    if (topf == level) {
	retval = Cudd_bddLeq(dd,ft,Cudd_Not(fe));
    } else {
	retval = Cudd_bddVarIsDependent(dd,ft,var) &&
	    Cudd_bddVarIsDependent(dd,fe,var);
    }

    cuddCacheInsert2(dd,cacheOp,f,var,Cudd_NotCond(zero,retval));

    return(retval);

} /* Cudd_bddVarIsDependent */

ABC_NAMESPACE_IMPL_START


////////////////////////////////////////////////////////////////////////
///                        DECLARATIONS                              ///
////////////////////////////////////////////////////////////////////////

////////////////////////////////////////////////////////////////////////
///                     FUNCTION DEFINITIONS                         ///
////////////////////////////////////////////////////////////////////////

/**Function*************************************************************

  Synopsis    [Converts graph to BDD.]

  Description []
               
  SideEffects []

  SeeAlso     []

***********************************************************************/
DdNode * Dec_GraphDeriveBdd( DdManager * dd, Dec_Graph_t * pGraph )
{
    DdNode * bFunc, * bFunc0, * bFunc1;
    Dec_Node_t * pNode = NULL; // Suppress "might be used uninitialized"
    int i;

    // sanity checks
    assert( Dec_GraphLeaveNum(pGraph) >= 0 );
    assert( Dec_GraphLeaveNum(pGraph) <= pGraph->nSize );

    // check for constant function
    if ( Dec_GraphIsConst(pGraph) )
        return Cudd_NotCond( b1, Dec_GraphIsComplement(pGraph) );
    // check for a literal
    if ( Dec_GraphIsVar(pGraph) )
        return Cudd_NotCond( Cudd_bddIthVar(dd, Dec_GraphVarInt(pGraph)), Dec_GraphIsComplement(pGraph) );

    // assign the elementary variables
    Dec_GraphForEachLeaf( pGraph, pNode, i )
        pNode->pFunc = Cudd_bddIthVar( dd, i );

    // compute the function for each internal node
    Dec_GraphForEachNode( pGraph, pNode, i )
    {
        bFunc0 = Cudd_NotCond( Dec_GraphNode(pGraph, pNode->eEdge0.Node)->pFunc, pNode->eEdge0.fCompl ); 
        bFunc1 = Cudd_NotCond( Dec_GraphNode(pGraph, pNode->eEdge1.Node)->pFunc, pNode->eEdge1.fCompl ); 
        pNode->pFunc = Cudd_bddAnd( dd, bFunc0, bFunc1 );   Cudd_Ref( (DdNode *)pNode->pFunc );
    }

/**Function*************************************************************

  Synopsis    [Derives the global BDD for one AIG node.]

  Description []
               
  SideEffects []

  SeeAlso     []

***********************************************************************/
DdNode * Bbr_NodeGlobalBdds_rec( DdManager * dd, Aig_Obj_t * pNode, int nBddSizeMax, int fDropInternal, ProgressBar * pProgress, int * pCounter, int fVerbose )
{
    DdNode * bFunc, * bFunc0, * bFunc1;
    assert( !Aig_IsComplement(pNode) );
    if ( Cudd_ReadKeys(dd)-Cudd_ReadDead(dd) > (unsigned)nBddSizeMax )
    {
//        Extra_ProgressBarStop( pProgress );
        if ( fVerbose )
        printf( "The number of live nodes reached %d.\n", nBddSizeMax );
        fflush( stdout );
        return NULL;
    }
    // if the result is available return
    if ( Aig_ObjGlobalBdd(pNode) == NULL )
    {
        // compute the result for both branches
        bFunc0 = Bbr_NodeGlobalBdds_rec( dd, Aig_ObjFanin0(pNode), nBddSizeMax, fDropInternal, pProgress, pCounter, fVerbose ); 
        if ( bFunc0 == NULL )
            return NULL;
        Cudd_Ref( bFunc0 );
        bFunc1 = Bbr_NodeGlobalBdds_rec( dd, Aig_ObjFanin1(pNode), nBddSizeMax, fDropInternal, pProgress, pCounter, fVerbose ); 
        if ( bFunc1 == NULL )
            return NULL;
        Cudd_Ref( bFunc1 );
        bFunc0 = Cudd_NotCond( bFunc0, Aig_ObjFaninC0(pNode) );
        bFunc1 = Cudd_NotCond( bFunc1, Aig_ObjFaninC1(pNode) );
        // get the final result
        bFunc = Cudd_bddAnd( dd, bFunc0, bFunc1 );   Cudd_Ref( bFunc );
        Cudd_RecursiveDeref( dd, bFunc0 );
        Cudd_RecursiveDeref( dd, bFunc1 );
        // add the number of used nodes
        (*pCounter)++;
        // set the result
        assert( Aig_ObjGlobalBdd(pNode) == NULL );
        Aig_ObjSetGlobalBdd( pNode, bFunc );
        // increment the progress bar
//        if ( pProgress )
//            Extra_ProgressBarUpdate( pProgress, *pCounter, NULL );
    }
    // prepare the return value
    bFunc = Aig_ObjGlobalBdd(pNode);
    // dereference BDD at the node
    if ( --pNode->nRefs == 0 && fDropInternal )
    {
        Cudd_Deref( bFunc );
        Aig_ObjSetGlobalBdd( pNode, NULL );
    }
    return bFunc;
}

/**Function*************************************************************

  Synopsis    [Returns the array of constraint candidates.]

  Description []
               
  SideEffects []

  SeeAlso     []

***********************************************************************/
DdNode * Llb_ManComputeIndCase_rec( Aig_Man_t * p, Aig_Obj_t * pObj, DdManager * dd, Vec_Ptr_t * vBdds )
{
    DdNode * bBdd0, * bBdd1;
    DdNode * bFunc = (DdNode *)Vec_PtrEntry( vBdds, Aig_ObjId(pObj) );
    if ( bFunc != NULL )
        return bFunc;
    assert( Aig_ObjIsNode(pObj) );
    bBdd0 = Llb_ManComputeIndCase_rec( p, Aig_ObjFanin0(pObj), dd, vBdds ); 
    bBdd1 = Llb_ManComputeIndCase_rec( p, Aig_ObjFanin1(pObj), dd, vBdds ); 
    bBdd0 = Cudd_NotCond( bBdd0, Aig_ObjFaninC0(pObj) );
    bBdd1 = Cudd_NotCond( bBdd1, Aig_ObjFaninC1(pObj) );
    bFunc = Cudd_bddAnd( dd, bBdd0, bBdd1 );  Cudd_Ref( bFunc );
    Vec_PtrWriteEntry( vBdds, Aig_ObjId(pObj), bFunc );
    return bFunc;
}

/**Function********************************************************************

  Synopsis    [Performs the recursive step for Cudd_addBddInterval.]

  Description [Performs the recursive step for Cudd_addBddInterval.
  Returns a pointer to the BDD if successful; NULL otherwise.]

  SideEffects [None]

  SeeAlso     [addBddDoThreshold addBddDoStrictThreshold]

******************************************************************************/
static DdNode *
addBddDoInterval(
  DdManager * dd,
  DdNode * f,
  DdNode * l,
  DdNode * u)
{
    DdNode *res, *T, *E;
    DdNode *fv, *fvn;
    int v;

    statLine(dd);
    /* Check terminal case. */
    if (cuddIsConstant(f)) {
	return(Cudd_NotCond(DD_TRUE(dd),cuddV(f) < cuddV(l) || cuddV(f) > cuddV(u)));
    }

    /* Check cache. */
    res = cuddCacheLookup(dd,DD_ADD_BDD_DO_INTERVAL_TAG,f,l,u);
    if (res != NULL) return(res);

    /* Recursive step. */
    v = f->index;
    fv = cuddT(f); fvn = cuddE(f);

    T = addBddDoInterval(dd,fv,l,u);
    if (T == NULL) return(NULL);
    cuddRef(T);

    E = addBddDoInterval(dd,fvn,l,u);
    if (E == NULL) {
	Cudd_RecursiveDeref(dd, T);
	return(NULL);
    }
    cuddRef(E);
    if (Cudd_IsComplement(T)) {
	res = (T == E) ? Cudd_Not(T) : cuddUniqueInter(dd,v,Cudd_Not(T),Cudd_Not(E));
	if (res == NULL) {
	    Cudd_RecursiveDeref(dd, T);
	    Cudd_RecursiveDeref(dd, E);
	    return(NULL);
	}
	res = Cudd_Not(res);
    } else {
	res = (T == E) ? T : cuddUniqueInter(dd,v,T,E);
	if (res == NULL) {
	    Cudd_RecursiveDeref(dd, T);
	    Cudd_RecursiveDeref(dd, E);
	    return(NULL);
	}
    }
    cuddDeref(T);
    cuddDeref(E);

    /* Store result. */
    cuddCacheInsert(dd,DD_ADD_BDD_DO_INTERVAL_TAG,f,l,u,res);

    return(res);

} /* end of addBddDoInterval */

/**Function********************************************************************

  Synopsis    [Performs the recursive step for Cudd_addBddStrictThreshold.]

  Description [Performs the recursive step for Cudd_addBddStrictThreshold.
  Returns a pointer to the BDD if successful; NULL otherwise.]

  SideEffects [None]

  SeeAlso     [addBddDoThreshold]

******************************************************************************/
static DdNode *
addBddDoStrictThreshold(
  DdManager * dd,
  DdNode * f,
  DdNode * val)
{
    DdNode *res, *T, *E;
    DdNode *fv, *fvn;
    int v;

    statLine(dd);
    /* Check terminal case. */
    if (cuddIsConstant(f)) {
	return(Cudd_NotCond(DD_TRUE(dd),cuddV(f) <= cuddV(val)));
    }

    /* Check cache. */
    res = cuddCacheLookup2(dd,addBddDoStrictThreshold,f,val);
    if (res != NULL) return(res);

    /* Recursive step. */
    v = f->index;
    fv = cuddT(f); fvn = cuddE(f);

    T = addBddDoStrictThreshold(dd,fv,val);
    if (T == NULL) return(NULL);
    cuddRef(T);

    E = addBddDoStrictThreshold(dd,fvn,val);
    if (E == NULL) {
	Cudd_RecursiveDeref(dd, T);
	return(NULL);
    }
    cuddRef(E);
    if (Cudd_IsComplement(T)) {
	res = (T == E) ? Cudd_Not(T) : cuddUniqueInter(dd,v,Cudd_Not(T),Cudd_Not(E));
	if (res == NULL) {
	    Cudd_RecursiveDeref(dd, T);
	    Cudd_RecursiveDeref(dd, E);
	    return(NULL);
	}
	res = Cudd_Not(res);
    } else {
	res = (T == E) ? T : cuddUniqueInter(dd,v,T,E);
	if (res == NULL) {
	    Cudd_RecursiveDeref(dd, T);
	    Cudd_RecursiveDeref(dd, E);
	    return(NULL);
	}
    }
    cuddDeref(T);
    cuddDeref(E);

    /* Store result. */
    cuddCacheInsert2(dd,addBddDoStrictThreshold,f,val,res);

    return(res);

} /* end of addBddDoStrictThreshold */

/**Function*************************************************************

  Synopsis    [Recursively derives the truth table for the cut.]

  Description []
               
  SideEffects []

  SeeAlso     []

***********************************************************************/
DdNode * Fpga_TruthsCutBdd_rec( DdManager * dd, Fpga_Cut_t * pCut, Fpga_NodeVec_t * vVisited )
{
    DdNode * bFunc, * bFunc0, * bFunc1;
    assert( !Fpga_IsComplement(pCut) );
    // if the cut is visited, return the result
    if ( pCut->uSign )
        return (DdNode *)pCut->uSign;
    // compute the functions of the children
    bFunc0 = Fpga_TruthsCutBdd_rec( dd, Fpga_CutRegular(pCut->pOne), vVisited );   Cudd_Ref( bFunc0 );
    bFunc0 = Cudd_NotCond( bFunc0, Fpga_CutIsComplement(pCut->pOne) );
    bFunc1 = Fpga_TruthsCutBdd_rec( dd, Fpga_CutRegular(pCut->pTwo), vVisited );   Cudd_Ref( bFunc1 );
    bFunc1 = Cudd_NotCond( bFunc1, Fpga_CutIsComplement(pCut->pTwo) );
    // get the function of the cut
    bFunc  = Cudd_bddAnd( dd, bFunc0, bFunc1 );   Cudd_Ref( bFunc );
    bFunc  = Cudd_NotCond( bFunc, pCut->Phase );
    Cudd_RecursiveDeref( dd, bFunc0 );
    Cudd_RecursiveDeref( dd, bFunc1 );
    assert( pCut->uSign == 0 );
    pCut->uSign = (unsigned)bFunc;
    // add this cut to the visited list
    Fpga_NodeVecPush( vVisited, (Fpga_Node_t *)pCut );
    return bFunc;
}

/**Function********************************************************************

  Synopsis    [Determines whether f is less than or equal to g.]

  Description [Returns 1 if f is less than or equal to g; 0 otherwise.
  No new nodes are created. This procedure works for arbitrary ADDs.
  For 0-1 ADDs Cudd_addEvalConst is more efficient.]

  SideEffects [None]

  SeeAlso     [Cudd_addIteConstant Cudd_addEvalConst Cudd_bddLeq]

******************************************************************************/
int
Cudd_addLeq(
  DdManager * dd,
  DdNode * f,
  DdNode * g)
{
    DdNode *tmp, *fv, *fvn, *gv, *gvn;
    unsigned int topf, topg, res;

    /* Terminal cases. */
    if (f == g) return(1);

    statLine(dd);
    if (cuddIsConstant(f)) {
	if (cuddIsConstant(g)) return(cuddV(f) <= cuddV(g));
	if (f == DD_MINUS_INFINITY(dd)) return(1);
	if (f == DD_PLUS_INFINITY(dd)) return(0); /* since f != g */
    }
    if (g == DD_PLUS_INFINITY(dd)) return(1);
    if (g == DD_MINUS_INFINITY(dd)) return(0); /* since f != g */

    /* Check cache. */
    tmp = cuddCacheLookup2(dd,(DD_CTFP)Cudd_addLeq,f,g);
    if (tmp != NULL) {
	return(tmp == DD_ONE(dd));
    }

    /* Compute cofactors. One of f and g is not constant. */
    topf = cuddI(dd,f->index);
    topg = cuddI(dd,g->index);
    if (topf <= topg) {
	fv = cuddT(f); fvn = cuddE(f);
    } else {
	fv = fvn = f;
    }
    if (topg <= topf) {
	gv = cuddT(g); gvn = cuddE(g);
    } else {
	gv = gvn = g;
    }

    res = Cudd_addLeq(dd,fvn,gvn) && Cudd_addLeq(dd,fv,gv);

    /* Store result in cache and return. */
    cuddCacheInsert2(dd,(DD_CTFP) Cudd_addLeq,f,g,
		     Cudd_NotCond(DD_ONE(dd),res==0));
    return(res);

} /* end of Cudd_addLeq */

    // construct the BDDs
//    pProgress = Extra_ProgressBarStart( stdout, Aig_ManNodeNum(p) );
    Aig_ManForEachCo( p, pObj, i )
    {
        bFunc = Bbr_NodeGlobalBdds_rec( dd, Aig_ObjFanin0(pObj), nBddSizeMax, fDropInternal, pProgress, &Counter, fVerbose );
        if ( bFunc == NULL )
        {
            if ( fVerbose )
            printf( "Constructing global BDDs is aborted.\n" );
            Aig_ManFreeGlobalBdds( p, dd );
            Cudd_Quit( dd ); 
            // reset references
            Aig_ManResetRefs( p );
            return NULL;
        }
        bFunc = Cudd_NotCond( bFunc, Aig_ObjFaninC0(pObj) );  Cudd_Ref( bFunc ); 
        Aig_ObjSetGlobalBdd( pObj, bFunc );
    }

/**Function********************************************************************

  Synopsis    [Computes the disjunction of two BDDs f and g.]

  Description [Computes the disjunction of two BDDs f and g. Returns a
  pointer to the resulting BDD if successful; (uintptr_t) 0 if the intermediate
  result blows up.]

  SideEffects [None]

  SeeAlso     [Cudd_bddIte Cudd_addApply Cudd_bddAnd Cudd_bddNand Cudd_bddNor
  Cudd_bddXor Cudd_bddXnor]

******************************************************************************/
DdNode *
Cudd_bddOr(
  DdManager * dd,
  DdNode * f,
  DdNode * g)
{
    DdNode *res;

    do {
	dd->reordered = 0;
	res = cuddBddAndRecur(dd,Cudd_Not(f),Cudd_Not(g));
    } while (dd->reordered == 1);
    res = Cudd_NotCond(res,res != (uintptr_t) 0);
    return(res);

} /* end of Cudd_bddOr */

/**Function********************************************************************

  Synopsis    [Computes the NAND of two BDDs f and g.]

  Description [Computes the NAND of two BDDs f and g. Returns a
  pointer to the resulting BDD if successful; NULL if the intermediate
  result blows up.]

  SideEffects [None]

  SeeAlso     [Cudd_bddIte Cudd_addApply Cudd_bddAnd Cudd_bddOr Cudd_bddNor
  Cudd_bddXor Cudd_bddXnor]

******************************************************************************/
DdNode *
Cudd_bddNand(
  DdManager * dd,
  DdNode * f,
  DdNode * g)
{
    DdNode *res;

    do {
        dd->reordered = 0;
        res = cuddBddAndRecur(dd,f,g);
    } while (dd->reordered == 1);
    res = Cudd_NotCond(res,res != NULL);
    return(res);

} /* end of Cudd_bddNand */

ABC_NAMESPACE_IMPL_START


////////////////////////////////////////////////////////////////////////
///                        DECLARATIONS                              ///
////////////////////////////////////////////////////////////////////////

////////////////////////////////////////////////////////////////////////
///                     FUNCTION DEFINITIONS                         ///
////////////////////////////////////////////////////////////////////////

/**Function*************************************************************

  Synopsis    [Computes the initial state and sets up the variable map.]

  Description []
               
  SideEffects []

  SeeAlso     []

***********************************************************************/
DdNode * Abc_NtkInitStateVarMap( DdManager * dd, Abc_Ntk_t * pNtk, int fVerbose )
{
    DdNode ** pbVarsX, ** pbVarsY;
    DdNode * bTemp, * bProd, * bVar;
    Abc_Obj_t * pLatch;
    int i;

    // set the variable mapping for Cudd_bddVarMap()
    pbVarsX = ABC_ALLOC( DdNode *, dd->size );
    pbVarsY = ABC_ALLOC( DdNode *, dd->size );
    bProd = b1;         Cudd_Ref( bProd );
    Abc_NtkForEachLatch( pNtk, pLatch, i )
    {
        pbVarsX[i] = dd->vars[ Abc_NtkPiNum(pNtk) + i ];
        pbVarsY[i] = dd->vars[ Abc_NtkCiNum(pNtk) + i ];
        // get the initial value of the latch
        bVar  = Cudd_NotCond( pbVarsX[i], !Abc_LatchIsInit1(pLatch) );
        bProd = Cudd_bddAnd( dd, bTemp = bProd, bVar );      Cudd_Ref( bProd );
        Cudd_RecursiveDeref( dd, bTemp ); 
    }

/**Function********************************************************************

  Synopsis    [Computes the disjunction of two BDDs f and g.  Returns
  NULL if too many nodes are required.]

  Description [Computes the disjunction of two BDDs f and g. Returns a
  pointer to the resulting BDD if successful; NULL if the intermediate
  result blows up or more new nodes than <code>limit</code> are
  required.]

  SideEffects [None]

  SeeAlso     [Cudd_bddOr]

******************************************************************************/
DdNode *
Cudd_bddOrLimit(
  DdManager * dd,
  DdNode * f,
  DdNode * g,
  unsigned int limit)
{
    DdNode *res;
    unsigned int saveLimit = dd->maxLive;

    dd->maxLive = (dd->keys - dd->dead) + (dd->keysZ - dd->deadZ) + limit;
    do {
	dd->reordered = 0;
	res = cuddBddAndRecur(dd,Cudd_Not(f),Cudd_Not(g));
    } while (dd->reordered == 1);
    dd->maxLive = saveLimit;
    res = Cudd_NotCond(res,res != NULL);
    return(res);

} /* end of Cudd_bddOrLimit */