Version abc60412

16 files changed, 1099 insertions, 215 deletions

diff --git a/src/base/abc/abc.h b/src/base/abc/abc.h
index e0f0df99..32365b81 100644
--- a/src/base/abc/abc.h
+++ b/src/base/abc/abc.h
@@ -52,7 +52,8 @@ typedef enum {
     ABC_NTK_LOGIC,      // 2:  network with PIs/POs, latches, and nodes
     ABC_NTK_STRASH,     // 3:  structurally hashed AIG (two input AND gates with c-attributes on edges)
     ABC_NTK_SEQ,        // 4:  sequential AIG (two input AND gates with c- and latch-attributes on edges)
-    ABC_NTK_OTHER       // 5:  unused
+    ABC_NTK_BLACKBOX,   // 5:  black box about which nothing is known
+    ABC_NTK_OTHER       // 6:  unused
 } Abc_NtkType_t;
 
 // network functionality
@@ -62,7 +63,8 @@ typedef enum {
     ABC_FUNC_BDD,       // 2:  binary decision diagrams
     ABC_FUNC_AIG,       // 3:  and-inverter graphs
     ABC_FUNC_MAP,       // 4:  standard cell library
-    ABC_FUNC_OTHER      // 5:  unused
+    ABC_FUNC_BLACKBOX,  // 5:  black box about which nothing is known
+    ABC_FUNC_OTHER      // 6:  unused
 } Abc_NtkFunc_t;
 
 // Supported type/functionality combinations:
@@ -168,6 +170,7 @@ struct Abc_Ntk_t_
     int              nObjs;         // the number of live objs
     int              nNets;         // the number of live nets
     int              nNodes;        // the number of live nodes
+    int              nBoxes;        // the number of live nodes
     int              nLatches;      // the number of live latches
     int              nPis;          // the number of primary inputs
     int              nPos;          // the number of primary outputs
@@ -198,6 +201,11 @@ struct Abc_Ntk_t_
     // the backup network and the step number
     Abc_Ntk_t *      pNetBackup;    // the pointer to the previous backup network
     int              iStep;         // the generation number for the given network
+    // hierarchical design
+    stmm_table *     tName2Model;   // the table hashing names into network pointers (or NULL if no hierarchy)
+    Vec_Int_t *      pBlackBoxes;   // stores pairs (PI num, PO num) for each model, including the base model (or NULL if no hierarchy)
+    short            fHieVisited;   // flag to mark the visited network
+    short            fHiePath;      // flag to mark the network on the path
     // memory management
     Extra_MmFlex_t * pMmNames;      // memory manager for net names
     Extra_MmFixed_t* pMmObj;        // memory manager for objects
@@ -223,11 +231,13 @@ static inline bool        Abc_NtkIsNetlist( Abc_Ntk_t * pNtk )       { return pN
 static inline bool        Abc_NtkIsLogic( Abc_Ntk_t * pNtk )         { return pNtk->ntkType == ABC_NTK_LOGIC;   }
 static inline bool        Abc_NtkIsStrash( Abc_Ntk_t * pNtk )        { return pNtk->ntkType == ABC_NTK_STRASH;  }
 static inline bool        Abc_NtkIsSeq( Abc_Ntk_t * pNtk )           { return pNtk->ntkType == ABC_NTK_SEQ;     }
+static inline bool        Abc_NtkIsBlackbox( Abc_Ntk_t * pNtk )      { return pNtk->ntkType == ABC_NTK_BLACKBOX;}
 
 static inline bool        Abc_NtkHasSop( Abc_Ntk_t * pNtk )          { return pNtk->ntkFunc == ABC_FUNC_SOP;    }
 static inline bool        Abc_NtkHasBdd( Abc_Ntk_t * pNtk )          { return pNtk->ntkFunc == ABC_FUNC_BDD;    }
 static inline bool        Abc_NtkHasAig( Abc_Ntk_t * pNtk )          { return pNtk->ntkFunc == ABC_FUNC_AIG;    }
 static inline bool        Abc_NtkHasMapping( Abc_Ntk_t * pNtk )      { return pNtk->ntkFunc == ABC_FUNC_MAP;    }
+static inline bool        Abc_NtkHasBlackbox( Abc_Ntk_t * pNtk )     { return pNtk->ntkFunc == ABC_FUNC_BLACKBOX; }
 
 static inline bool        Abc_NtkIsSopNetlist( Abc_Ntk_t * pNtk )    { return pNtk->ntkFunc == ABC_FUNC_SOP && pNtk->ntkType == ABC_NTK_NETLIST;  }
 static inline bool        Abc_NtkIsMappedNetlist( Abc_Ntk_t * pNtk ) { return pNtk->ntkFunc == ABC_FUNC_MAP && pNtk->ntkType == ABC_NTK_NETLIST;  }
@@ -294,6 +304,7 @@ static inline Abc_Obj_t * Abc_ObjNotCond( Abc_Obj_t * p, int c )     { return (A
 
 // checking the object type
 static inline bool        Abc_ObjIsNode( Abc_Obj_t * pObj )          { return pObj->Type == ABC_OBJ_NODE;   }
+static inline bool        Abc_ObjIsBox( Abc_Obj_t * pObj )           { return pObj->Type == ABC_OBJ_BOX;    }
 static inline bool        Abc_ObjIsNet( Abc_Obj_t * pObj )           { return pObj->Type == ABC_OBJ_NET;    }
 static inline bool        Abc_ObjIsLatch( Abc_Obj_t * pObj )         { return pObj->Type == ABC_OBJ_LATCH;  }
 static inline bool        Abc_ObjIsPi( Abc_Obj_t * pObj )            { return pObj->Type == ABC_OBJ_PI;     }
@@ -376,6 +387,9 @@ static inline int         Abc_LatchInit( Abc_Obj_t * pLatch )        { assert(Ab
 #define Abc_NtkForEachNode( pNtk, pNode, i )                                                       \
     for ( i = 0; (i < Vec_PtrSize((pNtk)->vObjs)) && (((pNode) = Abc_NtkObj(pNtk, i)), 1); i++ )   \
         if ( (pNode) == NULL || !Abc_ObjIsNode(pNode) ) {} else
+#define Abc_NtkForEachBox( pNtk, pNode, i )                                                       \
+    for ( i = 0; (i < Vec_PtrSize((pNtk)->vObjs)) && (((pNode) = Abc_NtkObj(pNtk, i)), 1); i++ )   \
+        if ( (pNode) == NULL || !Abc_ObjIsBox(pNode) ) {} else
 #define Abc_AigForEachAnd( pNtk, pNode, i )                                                        \
     for ( i = 0; (i < Vec_PtrSize((pNtk)->vObjs)) && (((pNode) = Abc_NtkObj(pNtk, i)), 1); i++ )   \
         if ( (pNode) == NULL || !Abc_NodeIsAigAnd(pNode) ) {} else
@@ -510,6 +524,7 @@ extern Abc_Obj_t *        Abc_NtkFindCo( Abc_Ntk_t * pNtk, char * pName );
 extern Abc_Obj_t *        Abc_NtkFindNet( Abc_Ntk_t * pNtk, char * pName );
 extern Abc_Obj_t *        Abc_NtkFindOrCreateNet( Abc_Ntk_t * pNtk, char * pName );
 extern Abc_Obj_t *        Abc_NtkCreateNode( Abc_Ntk_t * pNtk );
+extern Abc_Obj_t *        Abc_NtkCreateBox( Abc_Ntk_t * pNtk );
 extern Abc_Obj_t *        Abc_NtkCreatePi( Abc_Ntk_t * pNtk );
 extern Abc_Obj_t *        Abc_NtkCreatePo( Abc_Ntk_t * pNtk );
 extern Abc_Obj_t *        Abc_NtkCreateLatch( Abc_Ntk_t * pNtk );
@@ -651,6 +666,7 @@ extern char *             Abc_SopFromTruthHex( char * pTruth );
 extern Abc_Ntk_t *        Abc_NtkStrash( Abc_Ntk_t * pNtk, bool fAllNodes, bool fCleanup );
 extern Abc_Obj_t *        Abc_NodeStrash( Abc_Ntk_t * pNtkNew, Abc_Obj_t * pNode );
 extern int                Abc_NtkAppend( Abc_Ntk_t * pNtk1, Abc_Ntk_t * pNtk2 );
+extern Abc_Ntk_t *        Abc_NtkTopmost( Abc_Ntk_t * pNtk, int nLevels );
 /*=== abcSweep.c ==========================================================*/
 extern int                Abc_NtkSweep( Abc_Ntk_t * pNtk, int fVerbose );
 extern int                Abc_NtkCleanup( Abc_Ntk_t * pNtk, int fVerbose );
@@ -698,6 +714,7 @@ extern int                Abc_NtkGetBddNodeNum( Abc_Ntk_t * pNtk );
 extern int                Abc_NtkGetClauseNum( Abc_Ntk_t * pNtk );
 extern double             Abc_NtkGetMappedArea( Abc_Ntk_t * pNtk );
 extern int                Abc_NtkGetExorNum( Abc_Ntk_t * pNtk );
+extern int                Abc_NtkGetMuxNum( Abc_Ntk_t * pNtk );
 extern int                Abc_NtkGetChoiceNum( Abc_Ntk_t * pNtk );
 extern int                Abc_NtkGetFaninMax( Abc_Ntk_t * pNtk );
 extern void               Abc_NtkCleanCopy( Abc_Ntk_t * pNtk );
diff --git a/src/base/abc/abcCheck.c b/src/base/abc/abcCheck.c
index 080164bd..5c152409 100644
--- a/src/base/abc/abcCheck.c
+++ b/src/base/abc/abcCheck.c
@@ -38,6 +38,8 @@ static bool Abc_NtkComparePis( Abc_Ntk_t * pNtk1, Abc_Ntk_t * pNtk2, int fComb )
 static bool Abc_NtkComparePos( Abc_Ntk_t * pNtk1, Abc_Ntk_t * pNtk2, int fComb );
 static bool Abc_NtkCompareLatches( Abc_Ntk_t * pNtk1, Abc_Ntk_t * pNtk2, int fComb );
 
+static int  Abc_NtkIsAcyclicHierarchy( Abc_Ntk_t * pNtk );
+
 ////////////////////////////////////////////////////////////////////////
 ///                     FUNCTION DEFINITIONS                         ///
 ////////////////////////////////////////////////////////////////////////
@@ -90,12 +92,12 @@ bool Abc_NtkDoCheck( Abc_Ntk_t * pNtk )
     Abc_Obj_t * pObj, * pNet, * pNode;
     int i;
 
-    if ( !Abc_NtkIsNetlist(pNtk) && !Abc_NtkIsLogic(pNtk) && !Abc_NtkIsStrash(pNtk) && !Abc_NtkIsSeq(pNtk) )
+    if ( !Abc_NtkIsNetlist(pNtk) && !Abc_NtkIsLogic(pNtk) && !Abc_NtkIsStrash(pNtk) && !Abc_NtkIsSeq(pNtk) && !Abc_NtkIsBlackbox(pNtk) )
     {
         fprintf( stdout, "NetworkCheck: Unknown network type.\n" );
         return 0;
     }
-    if ( !Abc_NtkHasSop(pNtk) && !Abc_NtkHasBdd(pNtk) && !Abc_NtkHasAig(pNtk) && !Abc_NtkHasMapping(pNtk) )
+    if ( !Abc_NtkHasSop(pNtk) && !Abc_NtkHasBdd(pNtk) && !Abc_NtkHasAig(pNtk) && !Abc_NtkHasMapping(pNtk) && !Abc_NtkHasBlackbox(pNtk) )
     {
         fprintf( stdout, "NetworkCheck: Unknown functionality type.\n" );
         return 0;
@@ -187,6 +189,27 @@ bool Abc_NtkDoCheck( Abc_Ntk_t * pNtk )
 //        }
         return Abc_NtkCheck( pNtk->pExdc );
     }
+
+    // check the hierarchy
+    if ( Abc_NtkIsNetlist(pNtk) && pNtk->tName2Model )
+    {
+        stmm_generator * gen;
+        Abc_Ntk_t * pNtkTemp;
+        char * pName;
+        // check other networks
+        stmm_foreach_item( pNtk->tName2Model, gen, &pName, (char **)&pNtkTemp )
+        {
+            pNtkTemp->fHiePath = pNtkTemp->fHieVisited = 0;
+            if ( !Abc_NtkCheck( pNtkTemp ) )
+                return 0;
+        }
+        // check acyclic dependency of the models
+        if ( !Abc_NtkIsAcyclicHierarchy( pNtk ) )
+        {
+            fprintf( stdout, "NetworkCheck: Network hierarchical dependences contains a cycle.\n" );
+            return 0;
+        }
+    }
     return 1;
 }
 
@@ -711,6 +734,64 @@ bool Abc_NtkCompareSignals( Abc_Ntk_t * pNtk1, Abc_Ntk_t * pNtk2, int fComb )
     return 1;
 }
 
+
+/**Function*************************************************************
+
+  Synopsis    [Returns 0 if the network hierachy contains a cycle.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Abc_NtkIsAcyclicHierarchy_rec( Abc_Ntk_t * pNtk )
+{
+    Abc_Ntk_t * pNtkNext;
+    Abc_Obj_t * pObj;
+    int i;
+    // return if visited
+    if ( pNtk->fHieVisited )
+        return 1;
+    pNtk->fHieVisited = 1;
+    // return if black box
+    if ( Abc_NtkIsBlackbox(pNtk) )
+        return 1;
+    assert( Abc_NtkIsNetlist(pNtk) );
+    // go through all the children networks
+    Abc_NtkForEachBox( pNtk, pObj, i )
+    {
+        pNtkNext = pObj->pData;
+        assert( pNtkNext != NULL );
+        if ( pNtkNext->fHiePath )
+            return 0;
+        pNtk->fHiePath = 1;
+        if ( !Abc_NtkIsAcyclicHierarchy_rec( pNtkNext ) )
+            return 0;
+        pNtk->fHiePath = 0;
+    }
+    return 1;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Returns 0 if the network hierachy contains a cycle.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Abc_NtkIsAcyclicHierarchy( Abc_Ntk_t * pNtk )
+{
+    assert( Abc_NtkIsNetlist(pNtk) && pNtk->tName2Model );
+    pNtk->fHiePath = 1;
+    return Abc_NtkIsAcyclicHierarchy_rec( pNtk );
+}
+
 ////////////////////////////////////////////////////////////////////////
 ///                       END OF FILE                                ///
 ////////////////////////////////////////////////////////////////////////
diff --git a/src/base/abc/abcDfs.c b/src/base/abc/abcDfs.c
index 9701c0e2..bd707c25 100644
--- a/src/base/abc/abcDfs.c
+++ b/src/base/abc/abcDfs.c
@@ -129,7 +129,7 @@ void Abc_NtkDfs_rec( Abc_Obj_t * pNode, Vec_Ptr_t * vNodes )
     // skip the CI
     if ( Abc_ObjIsCi(pNode) )
         return;
-    assert( Abc_ObjIsNode( pNode ) );
+    assert( Abc_ObjIsNode( pNode ) || Abc_ObjIsBox( pNode ) );
     // visit the transitive fanin of the node
     Abc_ObjForEachFanin( pNode, pFanin, i )
         Abc_NtkDfs_rec( Abc_ObjFanin0Ntk(pFanin), vNodes );
@@ -581,15 +581,15 @@ bool Abc_NtkIsAcyclic_rec( Abc_Obj_t * pNode )
     assert( !Abc_ObjIsNet(pNode) );
     if ( Abc_ObjIsCi(pNode) )
         return 1;
-    assert( Abc_ObjIsNode( pNode ) );
+    assert( Abc_ObjIsNode( pNode ) || Abc_ObjIsBox( pNode ) );
     // make sure the node is not visited
     assert( !Abc_NodeIsTravIdPrevious(pNode) );
     // check if the node is part of the combinational loop
     if ( Abc_NodeIsTravIdCurrent(pNode) )
     {
-        fprintf( stdout, "Network \"%s\" contains combinational loop!\n", pNtk->pName );
+        fprintf( stdout, "Network \"%s\" contains combinational loop!\n", Abc_NtkName(pNtk) );
         fprintf( stdout, "Node \"%s\" is encountered twice on the following path:\n", Abc_ObjName(pNode) );
-        fprintf( stdout, " %s", Abc_ObjName(pNode) );
+        fprintf( stdout, " %s", Abc_ObjIsNode(pNode)? Abc_ObjName(pNode) : Abc_NtkName(pNode->pData) );
         return 0;
     }
     // mark this node as a node on the current path
diff --git a/src/base/abc/abcNetlist.c b/src/base/abc/abcNetlist.c
index 737d63c2..75f3ed33 100644
--- a/src/base/abc/abcNetlist.c
+++ b/src/base/abc/abcNetlist.c
@@ -24,7 +24,9 @@
 ////////////////////////////////////////////////////////////////////////
 ///                        DECLARATIONS                              ///
 ////////////////////////////////////////////////////////////////////////
- 
+
+static Abc_Ntk_t * Abc_NtkNetlistToLogicHie( Abc_Ntk_t * pNtk );
+static void Abc_NtkNetlistToLogicHie_rec( Abc_Ntk_t * pNtkNew, Abc_Ntk_t * pNtkOld, int * pCounter );
 static void Abc_NtkAddPoBuffers( Abc_Ntk_t * pNtk );
 
 ////////////////////////////////////////////////////////////////////////
@@ -48,6 +50,9 @@ Abc_Ntk_t * Abc_NtkNetlistToLogic( Abc_Ntk_t * pNtk )
     Abc_Obj_t * pObj, * pFanin;
     int i, k;
     assert( Abc_NtkIsNetlist(pNtk) );
+    // consider simple case when there is hierarchy
+    if ( pNtk->tName2Model )
+        return Abc_NtkNetlistToLogicHie( pNtk );
     // start the network
     if ( !Abc_NtkHasMapping(pNtk) )
         pNtkNew = Abc_NtkStartFrom( pNtk, ABC_NTK_LOGIC, ABC_FUNC_SOP );
@@ -74,6 +79,157 @@ Abc_Ntk_t * Abc_NtkNetlistToLogic( Abc_Ntk_t * pNtk )
 
 /**Function*************************************************************
 
+  Synopsis    [Transform the netlist into a logic network.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Abc_Ntk_t * Abc_NtkNetlistToLogicHie( Abc_Ntk_t * pNtk )
+{
+    Abc_Ntk_t * pNtkNew; 
+    Abc_Obj_t * pObj;
+    int i, Counter = 0;
+    assert( Abc_NtkIsNetlist(pNtk) );
+    // start the network
+//    pNtkNew = Abc_NtkAlloc( Type, Func );
+    if ( !Abc_NtkHasMapping(pNtk) )
+        pNtkNew = Abc_NtkAlloc( ABC_NTK_LOGIC, ABC_FUNC_SOP );
+    else
+        pNtkNew = Abc_NtkAlloc( ABC_NTK_LOGIC, ABC_FUNC_MAP );
+    // duplicate the name and the spec
+    pNtkNew->pName = Extra_UtilStrsav(pNtk->pName);
+    pNtkNew->pSpec = Extra_UtilStrsav(pNtk->pSpec);
+    // clean the node copy fields
+    Abc_NtkForEachNode( pNtk, pObj, i )
+        pObj->pCopy = NULL;
+    // map the constant nodes
+    if ( Abc_NtkConst1(pNtk) )
+        Abc_NtkConst1(pNtk)->pCopy = Abc_NtkConst1(pNtkNew);
+    // clone PIs/POs and make old nets point to new terminals; create PI/PO names
+    Abc_NtkForEachPi( pNtk, pObj, i )
+    {
+        Abc_ObjFanout0(pObj)->pCopy = Abc_NtkDupObj(pNtkNew, pObj);
+        Abc_NtkLogicStoreName( pObj->pCopy, Abc_ObjName(pObj) );
+    }
+    Abc_NtkForEachPo( pNtk, pObj, i )
+    {
+        Abc_NtkDupObj(pNtkNew, pObj);
+        Abc_NtkLogicStoreName( pObj->pCopy, Abc_ObjName(pObj) );
+    }
+    // recursively flatten hierarchy, create internal logic, add new PI/PO names if there are black boxes
+    Abc_NtkNetlistToLogicHie_rec( pNtkNew, pNtk, &Counter );
+    if ( Counter )
+        printf( "Warning: The total of %d block boxes are transformed into PI/PO pairs.\n", Counter );
+    // add latches
+    Abc_NtkForEachLatch( pNtk, pObj, i )
+    {
+        Abc_ObjFanout0(pObj)->pCopy = Abc_NtkDupObj(pNtkNew, pObj);
+        Vec_PtrPush( pNtkNew->vCis, pObj->pCopy );
+        Vec_PtrPush( pNtkNew->vCos, pObj->pCopy );
+        Abc_NtkLogicStoreName( Abc_NtkLatch(pNtkNew,i), Abc_ObjName(pObj) );
+    }
+    // collect the CO nodes
+    Abc_NtkForEachCo( pNtk, pObj, i )
+        Abc_ObjAddFanin( pObj->pCopy, Abc_ObjFanin0(pObj)->pCopy );
+    // copy the timing information
+    Abc_ManTimeDup( pNtk, pNtkNew );
+    // fix the problem with CO pointing directly to CIs
+    Abc_NtkLogicMakeSimpleCos( pNtkNew, 0 );
+    // duplicate EXDC 
+    if ( pNtk->pExdc )
+        pNtkNew->pExdc = Abc_NtkNetlistToLogic( pNtk->pExdc );
+    if ( !Abc_NtkCheck( pNtkNew ) )
+        fprintf( stdout, "Abc_NtkNetlistToLogic(): Network check has failed.\n" );
+    return pNtkNew;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Transform the netlist into a logic network.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Abc_NtkNetlistToLogicHie_rec( Abc_Ntk_t * pNtkNew, Abc_Ntk_t * pNtkOld, int * pCounter )
+{
+    char Prefix[1000];
+    Vec_Ptr_t * vNodes;
+    Abc_Ntk_t * pNtkModel;
+    Abc_Obj_t * pNode, * pObj, * pFanin;
+    int i, k;
+    // collect nodes and boxes in topological order
+    vNodes = Abc_NtkDfs( pNtkOld, 0 );
+    // create logic for nodes and boxes
+    Vec_PtrForEachEntry( vNodes, pNode, i )
+    {
+        if ( Abc_ObjFaninNum(pNode) == 0 )
+            continue;
+        if ( Abc_ObjIsNode(pNode) )
+        {
+            // duplicate the node and save it in the fanout net
+            Abc_NtkDupObj( pNtkNew, pNode );
+            Abc_ObjForEachFanin( pNode, pFanin, k )
+                Abc_ObjAddFanin( pNode->pCopy, pFanin->pCopy );
+            Abc_ObjFanout0(pNode)->pCopy = pNode->pCopy;
+            continue;
+        }
+        assert( Abc_ObjIsBox(pNode) );
+        pNtkModel = pNode->pData;
+        // consider the case of the black box
+        if ( Abc_NtkIsBlackbox(pNtkModel) )
+        {
+            if ( pNtkNew->pBlackBoxes == NULL )
+            {
+                pNtkNew->pBlackBoxes = Vec_IntAlloc( 10 );
+                Vec_IntPush( pNtkNew->pBlackBoxes, (Abc_NtkPiNum(pNtkNew) << 16) | Abc_NtkPoNum(pNtkNew) );
+            }
+            sprintf( Prefix, "%s_%d_", Abc_NtkName(pNtkModel), *pCounter );
+            // create new PIs from the POs of the box
+            Abc_NtkForEachPo( pNtkModel, pObj, k )
+            {
+                pObj->pCopy = Abc_NtkCreatePi( pNtkNew );
+                Abc_ObjFanout(pNode, k)->pCopy = pObj->pCopy;
+                Abc_NtkLogicStoreNamePlus( pObj->pCopy, Prefix, Abc_ObjName(pObj) );
+            }
+            // create new POs from the PIs of the box
+            Abc_NtkForEachPi( pNtkModel, pObj, k )
+            {
+                pObj->pCopy = Abc_NtkCreatePo( pNtkNew );
+                Abc_ObjAddFanin( pObj->pCopy, Abc_ObjFanin(pNode, k)->pCopy );
+                Abc_NtkLogicStoreNamePlus( pObj->pCopy, Prefix, Abc_ObjName(pObj) );
+            }
+            (*pCounter)++;
+            Vec_IntPush( pNtkNew->pBlackBoxes, (Abc_NtkPiNum(pNtkNew) << 16) | Abc_NtkPoNum(pNtkNew) );
+        }
+        else
+        {
+            // map the constant nodes
+            if ( Abc_NtkConst1(pNtkModel) )
+                Abc_NtkConst1(pNtkModel)->pCopy = Abc_NtkConst1(pNtkNew);
+            // transfer the nodes to the box inputs
+            Abc_NtkForEachPi( pNtkModel, pObj, k )
+                Abc_ObjFanout0(pObj)->pCopy = Abc_ObjFanin(pNode, k)->pCopy;
+            // construct recursively
+            Abc_NtkNetlistToLogicHie_rec( pNtkNew, pNtkModel, pCounter );
+            // transfer the results back
+            Abc_NtkForEachPo( pNtkModel, pObj, k )
+                Abc_ObjFanout(pNode, k)->pCopy = Abc_ObjFanin0(pObj)->pCopy;    
+        }
+    }
+    Vec_PtrFree( vNodes );
+}
+
+
+/**Function*************************************************************
+
   Synopsis    [Transform the logic network into a netlist.]
 
   Description []
diff --git a/src/base/abc/abcNtk.c b/src/base/abc/abcNtk.c
index 60ad2412..0640d661 100644
--- a/src/base/abc/abcNtk.c
+++ b/src/base/abc/abcNtk.c
@@ -320,8 +320,17 @@ Abc_Ntk_t * Abc_NtkStartRead( char * pName )
 ***********************************************************************/
 void Abc_NtkFinalizeRead( Abc_Ntk_t * pNtk )
 {
-    Abc_Obj_t * pLatch;
+    Abc_Obj_t * pLatch, * pBox, * pObj;
     int i;
+    if ( pNtk->ntkType == ABC_NTK_BLACKBOX )
+    {
+        pBox = Abc_NtkCreateBox(pNtk);
+        Abc_NtkForEachPi( pNtk, pObj, i )
+            Abc_ObjAddFanin( pBox, Abc_ObjFanout0(pObj) );
+        Abc_NtkForEachPo( pNtk, pObj, i )
+            Abc_ObjAddFanin( Abc_ObjFanin0(pObj), pBox );
+        return;
+    }
     assert( Abc_NtkIsNetlist(pNtk) );
     // fix the net drivers
     Abc_NtkFixNonDrivenNets( pNtk );
@@ -788,6 +797,18 @@ void Abc_NtkDelete( Abc_Ntk_t * pNtk )
     }
     else if ( !Abc_NtkHasMapping(pNtk) )
         assert( 0 );
+    // free the hierarchy
+    if ( Abc_NtkIsNetlist(pNtk) && pNtk->tName2Model )
+    {
+        stmm_generator * gen;
+        Abc_Ntk_t * pNtkTemp;
+        char * pName;
+        stmm_foreach_item( pNtk->tName2Model, gen, &pName, (char **)&pNtkTemp )
+            Abc_NtkDelete( pNtkTemp );
+        stmm_free_table( pNtk->tName2Model );
+        if ( pNtk->pBlackBoxes ) 
+            Vec_IntFree( pNtk->pBlackBoxes );
+    }
     free( pNtk );
 }
 
diff --git a/src/base/abc/abcObj.c b/src/base/abc/abcObj.c
index 0ffe3298..68518ef0 100644
--- a/src/base/abc/abcObj.c
+++ b/src/base/abc/abcObj.c
@@ -128,6 +128,10 @@ void Abc_ObjAdd( Abc_Obj_t * pObj )
         Vec_PtrPush( pNtk->vCos, pObj );
         pNtk->nPos++;
     }
+    else if ( Abc_ObjIsBox(pObj) )
+    {
+        pNtk->nBoxes++;
+    }
     else
     {
         assert( 0 );
@@ -415,6 +419,25 @@ Abc_Obj_t * Abc_NtkCreateNode( Abc_Ntk_t * pNtk )
   SeeAlso     []
 
 ***********************************************************************/
+Abc_Obj_t * Abc_NtkCreateBox( Abc_Ntk_t * pNtk )
+{
+    Abc_Obj_t * pObj;
+    pObj = Abc_ObjAlloc( pNtk, ABC_OBJ_BOX );     
+    Abc_ObjAdd( pObj );
+    return pObj;
+}
+    
+/**Function*************************************************************
+
+  Synopsis    [Create the new node.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
 Abc_Obj_t * Abc_NtkCreatePi( Abc_Ntk_t * pNtk )
 {
     Abc_Obj_t * pObj;
diff --git a/src/base/abc/abcUtil.c b/src/base/abc/abcUtil.c
index 122cf589..8449c91d 100644
--- a/src/base/abc/abcUtil.c
+++ b/src/base/abc/abcUtil.c
@@ -249,6 +249,26 @@ int Abc_NtkGetExorNum( Abc_Ntk_t * pNtk )
 
 /**Function*************************************************************
 
+  Synopsis    [Counts the number of exors.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Abc_NtkGetMuxNum( Abc_Ntk_t * pNtk )
+{
+    Abc_Obj_t * pNode;
+    int i, Counter = 0;
+    Abc_NtkForEachNode( pNtk, pNode, i )
+        Counter += Abc_NodeIsMuxType(pNode);
+    return Counter;
+}
+
+/**Function*************************************************************
+
   Synopsis    [Returns 1 if it is an AIG with choice nodes.]
 
   Description []
diff --git a/src/base/abci/abc.c b/src/base/abci/abc.c
index 26ef2b66..697c3b32 100644
--- a/src/base/abci/abc.c
+++ b/src/base/abci/abc.c
@@ -68,6 +68,7 @@ static int Abc_CommandRr           ( Abc_Frame_t * pAbc, int argc, char ** argv
 
 static int Abc_CommandLogic        ( Abc_Frame_t * pAbc, int argc, char ** argv );
 static int Abc_CommandMiter        ( Abc_Frame_t * pAbc, int argc, char ** argv );
+static int Abc_CommandDemiter      ( Abc_Frame_t * pAbc, int argc, char ** argv );
 static int Abc_CommandFrames       ( Abc_Frame_t * pAbc, int argc, char ** argv );
 static int Abc_CommandSop          ( Abc_Frame_t * pAbc, int argc, char ** argv );
 static int Abc_CommandBdd          ( Abc_Frame_t * pAbc, int argc, char ** argv );
@@ -176,6 +177,7 @@ void Abc_Init( Abc_Frame_t * pAbc )
 
 //    Cmd_CommandAdd( pAbc, "Various",      "logic",         Abc_CommandLogic,            1 );
     Cmd_CommandAdd( pAbc, "Various",      "miter",         Abc_CommandMiter,            1 );
+    Cmd_CommandAdd( pAbc, "Various",      "demiter",       Abc_CommandDemiter,          1 );
     Cmd_CommandAdd( pAbc, "Various",      "frames",        Abc_CommandFrames,           1 );
     Cmd_CommandAdd( pAbc, "Various",      "sop",           Abc_CommandSop,              0 );
     Cmd_CommandAdd( pAbc, "Various",      "bdd",           Abc_CommandBdd,              0 );
@@ -3022,6 +3024,80 @@ usage:
   SeeAlso     []
 
 ***********************************************************************/
+int Abc_CommandDemiter( Abc_Frame_t * pAbc, int argc, char ** argv )
+{
+    FILE * pOut, * pErr;
+    Abc_Ntk_t * pNtk, * pNtkRes;
+    int fComb;
+    int c;
+    extern Abc_Ntk_t * Abc_NtkDemiter( Abc_Ntk_t * pNtk );
+
+    pNtk = Abc_FrameReadNtk(pAbc);
+    pOut = Abc_FrameReadOut(pAbc);
+    pErr = Abc_FrameReadErr(pAbc);
+
+    // set defaults
+    Extra_UtilGetoptReset();
+    while ( ( c = Extra_UtilGetopt( argc, argv, "ch" ) ) != EOF )
+    {
+        switch ( c )
+        {
+        case 'c':
+            fComb ^= 1;
+            break;
+        default:
+            goto usage;
+        }
+    }
+
+    if ( !Abc_NtkIsStrash(pNtk) )
+    {
+        fprintf( pErr, "The network is not strashed.\n" );
+        return 1;
+    }
+
+    if ( Abc_NtkPoNum(pNtk) != 1 )
+    {
+        fprintf( pErr, "The network is not a miter.\n" );
+        return 1;
+    }
+
+    if ( !Abc_ObjFanin0(Abc_NtkPo(pNtk,0))->fExor )
+    {
+        fprintf( pErr, "The miter's PO is not an EXOR.\n" );
+        return 1;
+    }
+
+    // get the new network
+    pNtkRes = Abc_NtkDemiter( pNtk );
+    if ( pNtkRes == NULL )
+    {
+        fprintf( pErr, "Miter computation has failed.\n" );
+        return 1;
+    }
+    // replace the current network
+//    Abc_FrameReplaceCurrentNetwork( pAbc, pNtkRes );
+    return 0;
+
+usage:
+    fprintf( pErr, "usage: demiter [-h]\n" );
+    fprintf( pErr, "\t        removes topmost EXOR from the miter to create two POs\n" );
+//    fprintf( pErr, "\t-c    : computes combinational miter (latches as POs) [default = %s]\n", fComb? "yes": "no" );
+    fprintf( pErr, "\t-h    : print the command usage\n");
+    return 1;
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
 int Abc_CommandFrames( Abc_Frame_t * pAbc, int argc, char ** argv )
 {
     FILE * pOut, * pErr;
@@ -4398,6 +4474,7 @@ int Abc_CommandTest( Abc_Frame_t * pAbc, int argc, char ** argv )
     FILE * pOut, * pErr;
     Abc_Ntk_t * pNtk;//, * pNtkRes;
     int c;
+    int nLevels;
 //    extern Abc_Ntk_t * Abc_NtkNewAig( Abc_Ntk_t * pNtk );
 
     pNtk = Abc_FrameReadNtk(pAbc);
@@ -4405,11 +4482,23 @@ int Abc_CommandTest( Abc_Frame_t * pAbc, int argc, char ** argv )
     pErr = Abc_FrameReadErr(pAbc);
 
     // set defaults
+    nLevels = 15;
     Extra_UtilGetoptReset();
-    while ( ( c = Extra_UtilGetopt( argc, argv, "h" ) ) != EOF )
+    while ( ( c = Extra_UtilGetopt( argc, argv, "Nh" ) ) != EOF )
     {
         switch ( c )
         {
+        case 'N':
+            if ( globalUtilOptind >= argc )
+            {
+                fprintf( pErr, "Command line switch \"-N\" should be followed by an integer.\n" );
+                goto usage;
+            }
+            nLevels = atoi(argv[globalUtilOptind]);
+            globalUtilOptind++;
+            if ( nLevels < 0 ) 
+                goto usage;
+            break;
         case 'h':
             goto usage;
         default:
@@ -4451,7 +4540,14 @@ int Abc_CommandTest( Abc_Frame_t * pAbc, int argc, char ** argv )
 //        Cut_CellDumpToFile();
 //    else
 //        Cut_CellPrecompute();
-        Cut_CellLoad();
+//        Cut_CellLoad();
+
+        {
+            Abc_Ntk_t * pNtkRes;
+            extern Abc_Ntk_t * Abc_NtkTopmost( Abc_Ntk_t * pNtk, int nLevels );
+            pNtkRes = Abc_NtkTopmost( pNtk, nLevels );
+            Abc_FrameReplaceCurrentNetwork( pAbc, pNtkRes );
+        }
 
     return 0;
 
diff --git a/src/base/abci/abcMiter.c b/src/base/abci/abcMiter.c
index 87ea57f3..76ec8a7e 100644
--- a/src/base/abci/abcMiter.c
+++ b/src/base/abci/abcMiter.c
@@ -953,6 +953,61 @@ void Abc_NtkAddFrame2( Abc_Ntk_t * pNtkFrames, Abc_Ntk_t * pNtk, int iFrame, Vec
     }
 }
 
+
+
+/**Function*************************************************************
+
+  Synopsis    [Derives the timeframes of the network.]
+
+  Description []
+
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Abc_Ntk_t * Abc_NtkDemiter( Abc_Ntk_t * pNtk )
+{
+    Abc_Obj_t * pNodeC, * pNodeA, * pNodeB, * pNode;
+    Abc_Obj_t * pPoNew;
+    Vec_Ptr_t * vNodes1, * vNodes2;
+    int nCommon, i;
+
+    assert( Abc_NtkIsStrash(pNtk) );
+    assert( Abc_NtkPoNum(pNtk) == 1 );
+    assert( Abc_ObjFanin0(Abc_NtkPo(pNtk,0))->fExor );
+    pNodeC = Abc_NodeRecognizeMux( Abc_ObjFanin0(Abc_NtkPo(pNtk,0)), &pNodeA, &pNodeB );
+    assert( Abc_ObjRegular(pNodeA) == Abc_ObjRegular(pNodeB) );
+
+    pPoNew = Abc_NtkCreatePo( pNtk );
+    Abc_ObjAddFanin( pPoNew, pNodeC );
+    Abc_NtkLogicStoreName( pPoNew, "addOut1" );
+
+    pPoNew = Abc_NtkCreatePo( pNtk );
+    Abc_ObjAddFanin( pPoNew, Abc_ObjRegular(pNodeA) );
+    Abc_NtkLogicStoreName( pPoNew, "addOut2" );
+
+    // mark the nodes in the first cone
+    pNodeA = Abc_ObjRegular(pNodeA);
+    vNodes1 = Abc_NtkDfsNodes( pNtk, &pNodeC, 1 );
+    vNodes2 = Abc_NtkDfsNodes( pNtk, &pNodeA, 1 );
+
+    Vec_PtrForEachEntry( vNodes1, pNode, i )
+        pNode->fMarkA = 1;
+    nCommon = 0;
+    Vec_PtrForEachEntry( vNodes2, pNode, i )
+        nCommon += pNode->fMarkA;
+    Vec_PtrForEachEntry( vNodes1, pNode, i )
+        pNode->fMarkA = 0;
+
+    printf( "First cone = %6d.  Second cone = %6d.  Common = %6d.\n", vNodes1->nSize, vNodes2->nSize, nCommon );
+    Vec_PtrFree( vNodes1 );
+    Vec_PtrFree( vNodes2 );
+
+
+    return pNtk;
+}
+
 ////////////////////////////////////////////////////////////////////////
 ///                       END OF FILE                                ///
 ////////////////////////////////////////////////////////////////////////
diff --git a/src/base/abci/abcPrint.c b/src/base/abci/abcPrint.c
index 56b70c5b..eec9e305 100644
--- a/src/base/abci/abcPrint.c
+++ b/src/base/abci/abcPrint.c
@@ -48,7 +48,7 @@
 ***********************************************************************/
 void Abc_NtkPrintStats( FILE * pFile, Abc_Ntk_t * pNtk, int fFactored )
 {
-    int Num;
+    int Num, Num2;
 
     fprintf( pFile, "%-13s:",       pNtk->pName );
     fprintf( pFile, " i/o = %4d/%4d", Abc_NtkPiNum(pNtk), Abc_NtkPoNum(pNtk) );
@@ -64,18 +64,23 @@ void Abc_NtkPrintStats( FILE * pFile, Abc_Ntk_t * pNtk, int fFactored )
         fprintf( pFile, "  nd = %5d", Abc_NtkNodeNum(pNtk) );
     }
     else if ( Abc_NtkHasAig(pNtk) )
-    {
+    {        
         fprintf( pFile, "  and = %5d", Abc_NtkNodeNum(pNtk) );
         if ( Num = Abc_NtkGetChoiceNum(pNtk) )
             fprintf( pFile, " (choice = %d)", Num );
         if ( Num = Abc_NtkGetExorNum(pNtk) )
             fprintf( pFile, " (exor = %d)", Num );
+        if ( Num2 = Abc_NtkGetMuxNum(pNtk) )
+            fprintf( pFile, " (mux = %d)", Num2-Num );
+        if ( Num2 )
+            fprintf( pFile, " (other = %d)", Abc_NtkNodeNum(pNtk)-3*Num2 );
     }
     else 
         fprintf( pFile, "  nd = %5d", Abc_NtkNodeNum(pNtk) );
 
     if ( Abc_NtkHasSop(pNtk) )   
     {
+
         fprintf( pFile, "  cube = %5d",  Abc_NtkGetCubeNum(pNtk) );
 //        fprintf( pFile, "  lit(sop) = %5d",  Abc_NtkGetLitNum(pNtk) );
         if ( fFactored )
diff --git a/src/base/abci/abcStrash.c b/src/base/abci/abcStrash.c
index cfbd4694..b546d8be 100644
--- a/src/base/abci/abcStrash.c
+++ b/src/base/abci/abcStrash.c
@@ -332,6 +332,74 @@ Abc_Obj_t * Abc_NodeStrashFactor( Abc_Ntk_t * pNtkNew, Abc_Obj_t * pRoot, char *
     return pAnd;
 }
 
+
+
+/**Function*************************************************************
+
+  Synopsis    [Copies the topmost levels of the network.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Abc_Obj_t * Abc_NtkTopmost_rec( Abc_Ntk_t * pNtkNew, Abc_Obj_t * pNode, int LevelCut )
+{
+    assert( Abc_ObjIsComplement(pNode) );
+    if ( pNode->pCopy )
+        return pNode->pCopy;
+    if ( pNode->Level <= (unsigned)LevelCut )
+        return pNode->pCopy = Abc_NtkCreatePi( pNtkNew );
+    Abc_NtkTopmost_rec( pNtkNew, Abc_ObjFanin0(pNode), LevelCut );
+    Abc_NtkTopmost_rec( pNtkNew, Abc_ObjFanin1(pNode), LevelCut );
+    return pNode->pCopy = Abc_AigAnd( pNtkNew->pManFunc, Abc_ObjChild0Copy(pNode), Abc_ObjChild1Copy(pNode) );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Copies the topmost levels of the network.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Abc_Ntk_t * Abc_NtkTopmost( Abc_Ntk_t * pNtk, int nLevels )
+{
+    Abc_Ntk_t * pNtkNew;
+    Abc_Obj_t * pObjNew, * pPoNew;
+    int LevelCut;
+    assert( Abc_NtkIsStrash(pNtk) );
+    assert( Abc_NtkCoNum(pNtk) == 1 );
+    // get the cutoff level
+    LevelCut = ABC_MAX( 0, Abc_AigGetLevelNum(pNtk) - nLevels );
+    // start the network
+    pNtkNew = Abc_NtkAlloc( ABC_NTK_STRASH, ABC_FUNC_AIG );
+    pNtkNew->pName = Extra_UtilStrsav(pNtk->pName);
+    Abc_NtkConst1(pNtk)->pCopy = Abc_NtkConst1(pNtkNew);
+    // create PIs below the cut and nodes above the cut
+    Abc_NtkCleanCopy( pNtk );
+    pObjNew = Abc_NtkTopmost_rec( pNtkNew, Abc_ObjFanin0(Abc_NtkPo(pNtk, 0)), LevelCut );
+    // add the PO node and name
+    pPoNew = Abc_NtkCreatePo(pNtkNew);
+    Abc_ObjAddFanin( pPoNew, pObjNew );
+    Abc_NtkAddDummyPiNames( pNtkNew );
+    Abc_NtkLogicStoreName( pPoNew, Abc_ObjName(Abc_NtkPo(pNtk, 0)) );
+    // make sure everything is okay
+    if ( !Abc_NtkCheck( pNtkNew ) )
+    {
+        printf( "Abc_NtkTopmost: The network check has failed.\n" );
+        Abc_NtkDelete( pNtkNew );
+        return NULL;
+    }
+    return pNtkNew;
+}
+
+
 ////////////////////////////////////////////////////////////////////////
 ///                       END OF FILE                                ///
 ////////////////////////////////////////////////////////////////////////
diff --git a/src/base/cmd/cmd.c b/src/base/cmd/cmd.c
index 0d90679d..93fe2b90 100644
--- a/src/base/cmd/cmd.c
+++ b/src/base/cmd/cmd.c
@@ -1264,7 +1264,7 @@ int CmdCommandSis( Abc_Frame_t * pAbc, int argc, char **argv )
         fprintf( pErr, "Cannot produce the intermediate network.\n" );
         goto usage;
     }
-    Io_WriteBlif( pNetlist, "_sis_in.blif", 1 );
+    Io_WriteBlifNetlist( pNetlist, "_sis_in.blif", 1 );
     Abc_NtkDelete( pNetlist );
 
     // create the file for sis
@@ -1405,7 +1405,7 @@ int CmdCommandMvsis( Abc_Frame_t * pAbc, int argc, char **argv )
         fprintf( pErr, "Cannot produce the intermediate network.\n" );
         goto usage;
     }
-    Io_WriteBlif( pNetlist, "_mvsis_in.blif", 1 );
+    Io_WriteBlifNetlist( pNetlist, "_mvsis_in.blif", 1 );
     Abc_NtkDelete( pNetlist );
 
     // create the file for MVSIS
@@ -1551,7 +1551,7 @@ int CmdCommandCapo( Abc_Frame_t * pAbc, int argc, char **argv )
         fprintf( pErr, "Cannot produce the intermediate network.\n" );
         goto usage;
     }
-    Io_WriteBlif( pNetlist, "_capo_in.blif", 1 );
+    Io_WriteBlifNetlist( pNetlist, "_capo_in.blif", 1 );
     Abc_NtkDelete( pNetlist );
 
     // create the file for Capo
diff --git a/src/base/io/io.c b/src/base/io/io.c
index 0aa5e415..614fa812 100644
--- a/src/base/io/io.c
+++ b/src/base/io/io.c
@@ -912,7 +912,7 @@ int IoCommandWriteBlif( Abc_Frame_t * pAbc, int argc, char **argv )
         return 0;
     }
     Io_WriteBlifLogic( pNtk, FileName, fWriteLatches );
-//    Io_WriteBlif( pNtk, FileName, fWriteLatches );
+//    Io_WriteBlifNetlist( pNtk, FileName, fWriteLatches );
     return 0;
 
 usage:
diff --git a/src/base/io/io.h b/src/base/io/io.h
index a9a61040..b408293e 100644
--- a/src/base/io/io.h
+++ b/src/base/io/io.h
@@ -77,8 +77,8 @@ extern FILE *             Io_FileOpen( const char * FileName, const char * PathV
 /*=== abcWriteBaf.c ==========================================================*/
 extern void               Io_WriteBaf( Abc_Ntk_t * pNtk, char * pFileName );
 /*=== abcWriteBlif.c ==========================================================*/
-extern void               Io_WriteBlif( Abc_Ntk_t * pNtk, char * pFileName, int fWriteLatches );
 extern void               Io_WriteBlifLogic( Abc_Ntk_t * pNtk, char * pFileName, int fWriteLatches );
+extern void               Io_WriteBlifNetlist( Abc_Ntk_t * pNtk, char * pFileName, int fWriteLatches );
 extern void               Io_WriteTimingInfo( FILE * pFile, Abc_Ntk_t * pNtk );
 /*=== abcWriteBench.c ==========================================================*/
 extern int                Io_WriteBench( Abc_Ntk_t * pNtk, char * FileName );
diff --git a/src/base/io/ioReadBlif.c b/src/base/io/ioReadBlif.c
index 39b85a10..9d74a782 100644
--- a/src/base/io/ioReadBlif.c
+++ b/src/base/io/ioReadBlif.c
@@ -33,11 +33,10 @@ struct Io_ReadBlif_t_
     char *               pFileName;    // the name of the file
     Extra_FileReader_t * pReader;      // the input file reader
     // current processing info
-    Abc_Ntk_t *          pNtk;         // the primary network
-    Abc_Ntk_t *          pNtkExdc;     // the exdc network
-    int                  fParsingExdc; // this flag is on, when we are parsing EXDC network
+    Abc_Ntk_t *          pNtkCur;      // the primary network
     int                  LineCur;      // the line currently parsed
     // temporary storage for tokens
+    Vec_Ptr_t *          vTokens;      // the current tokens
     Vec_Ptr_t *          vNewTokens;   // the temporary storage for the tokens
     Vec_Str_t *          vCubes;       // the temporary storage for the tokens
     // the error message
@@ -49,16 +48,19 @@ static Io_ReadBlif_t * Io_ReadBlifFile( char * pFileName );
 static void Io_ReadBlifFree( Io_ReadBlif_t * p );
 static void Io_ReadBlifPrintErrorMessage( Io_ReadBlif_t * p );
 static Vec_Ptr_t * Io_ReadBlifGetTokens( Io_ReadBlif_t * p );
-static Abc_Ntk_t * Io_ReadBlifNetwork( Io_ReadBlif_t * p );
 static char * Io_ReadBlifCleanName( char * pName );
 
+static Abc_Ntk_t * Io_ReadBlifNetwork( Io_ReadBlif_t * p );
+static Abc_Ntk_t * Io_ReadBlifNetworkOne( Io_ReadBlif_t * p );
 static int Io_ReadBlifNetworkInputs( Io_ReadBlif_t * p, Vec_Ptr_t * vTokens );
 static int Io_ReadBlifNetworkOutputs( Io_ReadBlif_t * p, Vec_Ptr_t * vTokens );
 static int Io_ReadBlifNetworkLatch( Io_ReadBlif_t * p, Vec_Ptr_t * vTokens );
 static int Io_ReadBlifNetworkNames( Io_ReadBlif_t * p, Vec_Ptr_t ** pvTokens );
 static int Io_ReadBlifNetworkGate( Io_ReadBlif_t * p, Vec_Ptr_t * vTokens );
+static int Io_ReadBlifNetworkSubcircuit( Io_ReadBlif_t * p, Vec_Ptr_t * vTokens );
 static int Io_ReadBlifNetworkInputArrival( Io_ReadBlif_t * p, Vec_Ptr_t * vTokens );
 static int Io_ReadBlifNetworkDefaultInputArrival( Io_ReadBlif_t * p, Vec_Ptr_t * vTokens );
+static int Io_ReadBlifNetworkConnectBoxes( Io_ReadBlif_t * p, Abc_Ntk_t * pNtkMaster );
 
 ////////////////////////////////////////////////////////////////////////
 ///                     FUNCTION DEFINITIONS                         ///
@@ -66,9 +68,9 @@ static int Io_ReadBlifNetworkDefaultInputArrival( Io_ReadBlif_t * p, Vec_Ptr_t *
 
 /**Function*************************************************************
 
-  Synopsis    [Reads the network from a BLIF file.]
+  Synopsis    [Reads the (hierarchical) network from the BLIF file.]
 
-  Description [Works only for flat (non-hierarchical) BLIF.]
+  Description []
                
   SideEffects []
 
@@ -78,34 +80,22 @@ static int Io_ReadBlifNetworkDefaultInputArrival( Io_ReadBlif_t * p, Vec_Ptr_t *
 Abc_Ntk_t * Io_ReadBlif( char * pFileName, int fCheck )
 {
     Io_ReadBlif_t * p;
-    Abc_Ntk_t * pNtk, * pNtkExdc;
+    Abc_Ntk_t * pNtk;
 
     // start the file
     p = Io_ReadBlifFile( pFileName );
     if ( p == NULL )
         return NULL;
 
-    // read the network
+    // read the hierarchical network
     pNtk = Io_ReadBlifNetwork( p );
     if ( pNtk == NULL )
     {
         Io_ReadBlifFree( p );
         return NULL;
     }
+    pNtk->pSpec = Extra_UtilStrsav( pFileName );
     Abc_NtkTimeInitialize( pNtk );
-
-    // read the EXDC network
-    if ( p->fParsingExdc )
-    {
-        pNtkExdc = Io_ReadBlifNetwork( p );
-        if ( pNtkExdc == NULL )
-        {
-            Abc_NtkDelete( pNtk );
-            Io_ReadBlifFree( p );
-            return NULL;
-        }
-        pNtk->pExdc = pNtkExdc;
-    }
     Io_ReadBlifFree( p );
 
     // make sure that everything is okay with the network structure
@@ -120,7 +110,7 @@ Abc_Ntk_t * Io_ReadBlif( char * pFileName, int fCheck )
 
 /**Function*************************************************************
 
-  Synopsis    [Starts the reading data structure.]
+  Synopsis    [Iteratively reads several networks in the hierarchical design.]
 
   Description []
                
@@ -129,141 +119,76 @@ Abc_Ntk_t * Io_ReadBlif( char * pFileName, int fCheck )
   SeeAlso     []
 
 ***********************************************************************/
-Io_ReadBlif_t * Io_ReadBlifFile( char * pFileName )
+Abc_Ntk_t * Io_ReadBlifNetwork( Io_ReadBlif_t * p )
 {
-    Extra_FileReader_t * pReader;
-    Io_ReadBlif_t * p;
-
-    // start the reader
-    pReader = Extra_FileReaderAlloc( pFileName, "#", "\n\r", " \t" );
+    Abc_Ntk_t * pNtk, * pNtkMaster;
 
-    if ( pReader == NULL )
+    // read the name of the master network
+    p->vTokens = Io_ReadBlifGetTokens(p);
+    if ( p->vTokens == NULL || strcmp( p->vTokens->pArray[0], ".model" ) )
+    {
+        p->LineCur = 0;
+        sprintf( p->sError, "Wrong input file format." );
+        Io_ReadBlifPrintErrorMessage( p );
         return NULL;
+    }
 
-    // start the reading data structure
-    p = ALLOC( Io_ReadBlif_t, 1 );
-    memset( p, 0, sizeof(Io_ReadBlif_t) );
-    p->pFileName  = pFileName;
-    p->pReader    = pReader;
-    p->Output     = stdout;
-    p->vNewTokens = Vec_PtrAlloc( 100 );
-    p->vCubes     = Vec_StrAlloc( 100 );
-    return p;
-}
-
-/**Function*************************************************************
-
-  Synopsis    [Frees the data structure.]
-
-  Description []
-               
-  SideEffects []
-
-  SeeAlso     []
-
-***********************************************************************/
-void Io_ReadBlifFree( Io_ReadBlif_t * p )
-{
-    Extra_FileReaderFree( p->pReader );
-    Vec_PtrFree( p->vNewTokens );
-    Vec_StrFree( p->vCubes );
-    free( p );
-}
-
-/**Function*************************************************************
-
-  Synopsis    [Prints the error message including the file name and line number.]
-
-  Description []
-               
-  SideEffects []
-
-  SeeAlso     []
-
-***********************************************************************/
-void Io_ReadBlifPrintErrorMessage( Io_ReadBlif_t * p )
-{
-    if ( p->LineCur == 0 ) // the line number is not given
-        fprintf( p->Output, "%s: %s\n", p->pFileName, p->sError );
-    else // print the error message with the line number
-        fprintf( p->Output, "%s (line %d): %s\n", p->pFileName, p->LineCur, p->sError );
-}
-
-/**Function*************************************************************
-
-  Synopsis    [Gets the tokens taking into account the line breaks.]
-
-  Description []
-               
-  SideEffects []
-
-  SeeAlso     []
-
-***********************************************************************/
-Vec_Ptr_t * Io_ReadBlifGetTokens( Io_ReadBlif_t * p )
-{
-    Vec_Ptr_t * vTokens;
-    char * pLastToken;
-    int i;
-
-    // get rid of the old tokens
-    if ( p->vNewTokens->nSize > 0 )
+    // read networks (with EXDC) 
+    pNtkMaster = NULL;
+    while ( p->vTokens )
     {
-        for ( i = 0; i < p->vNewTokens->nSize; i++ )
-            free( p->vNewTokens->pArray[i] );
-        p->vNewTokens->nSize = 0;
+        // read the network and its EXDC if present
+        pNtk = Io_ReadBlifNetworkOne( p );
+        if ( pNtk == NULL )
+            break;
+        if ( p->vTokens && strcmp(p->vTokens->pArray[0], ".exdc") == 0 )
+        {
+            pNtk->pExdc = Io_ReadBlifNetworkOne( p );
+            Abc_NtkFinalizeRead( pNtk->pExdc );
+            if ( pNtk->pExdc == NULL )
+                break;
+        }
+        // add this network as part of the hierarchy
+        if ( pNtkMaster == NULL ) // no master network so far
+        {
+            pNtkMaster = pNtk;
+            continue;
+        }
+        // make sure hierarchy does not have the network with this name
+        if ( pNtkMaster->tName2Model && stmm_is_member( pNtkMaster->tName2Model, pNtk->pName ) )
+        {
+            p->LineCur = 0;
+            sprintf( p->sError, "Model %s is multiply defined in the file.", pNtk->pName );
+            Io_ReadBlifPrintErrorMessage( p );
+            Abc_NtkDelete( pNtk );
+            Abc_NtkDelete( pNtkMaster );
+            pNtkMaster = NULL;
+            return NULL;
+        }
+        // add the network to the hierarchy
+        if ( pNtkMaster->tName2Model == NULL )
+            pNtkMaster->tName2Model = stmm_init_table(strcmp, stmm_strhash);
+        stmm_insert( pNtkMaster->tName2Model, pNtk->pName, (char *)pNtk );
     }
 
-    // get the new tokens
-    vTokens = Extra_FileReaderGetTokens(p->pReader);
-    if ( vTokens == NULL )
-        return vTokens;
-
-    // check if there is a transfer to another line
-    pLastToken = vTokens->pArray[vTokens->nSize - 1];
-    if ( pLastToken[ strlen(pLastToken)-1 ] != '\\' )
-        return vTokens;
-
-    // remove the slash
-    pLastToken[ strlen(pLastToken)-1 ] = 0;
-    if ( pLastToken[0] == 0 )
-        vTokens->nSize--;
-    // load them into the new array
-    for ( i = 0; i < vTokens->nSize; i++ )
-        Vec_PtrPush( p->vNewTokens, Extra_UtilStrsav(vTokens->pArray[i]) );
-
-    // load as long as there is the line break
-    while ( 1 )
+    // if there is a hierarchy, connect the boxes
+    if ( pNtkMaster && pNtkMaster->tName2Model )
     {
-        // get the new tokens
-        vTokens = Extra_FileReaderGetTokens(p->pReader);
-        if ( vTokens->nSize == 0 )
-            return p->vNewTokens;
-        // check if there is a transfer to another line
-        pLastToken = vTokens->pArray[vTokens->nSize - 1];
-        if ( pLastToken[ strlen(pLastToken)-1 ] == '\\' )
+        if ( Io_ReadBlifNetworkConnectBoxes( p, pNtkMaster ) )
         {
-            // remove the slash
-            pLastToken[ strlen(pLastToken)-1 ] = 0;
-            if ( pLastToken[0] == 0 )
-                vTokens->nSize--;
-            // load them into the new array
-            for ( i = 0; i < vTokens->nSize; i++ )
-                Vec_PtrPush( p->vNewTokens, Extra_UtilStrsav(vTokens->pArray[i]) );
-            continue;
+            Abc_NtkDelete( pNtkMaster );
+            return NULL;
         }
-        // otherwise, load them and break
-        for ( i = 0; i < vTokens->nSize; i++ )
-            Vec_PtrPush( p->vNewTokens, Extra_UtilStrsav(vTokens->pArray[i]) );
-        break;
     }
-    return p->vNewTokens;
+    else
+        Abc_NtkFinalizeRead( pNtkMaster );
+    // return the master network
+    return pNtkMaster;
 }
 
-
 /**Function*************************************************************
 
-  Synopsis    [Reads the BLIF file.]
+  Synopsis    [Reads one (main or exdc) network from the BLIF file.]
 
   Description []
                
@@ -272,74 +197,71 @@ Vec_Ptr_t * Io_ReadBlifGetTokens( Io_ReadBlif_t * p )
   SeeAlso     []
 
 ***********************************************************************/
-Abc_Ntk_t * Io_ReadBlifNetwork( Io_ReadBlif_t * p )
+Abc_Ntk_t * Io_ReadBlifNetworkOne( Io_ReadBlif_t * p )
 {
     ProgressBar * pProgress;
-    Vec_Ptr_t * vTokens;
-    char * pModelName, * pDirective;
+    Abc_Ntk_t * pNtk;
+    char * pDirective;
     int iLine, fTokensReady, fStatus;
 
+    // make sure the tokens are present
+    assert( p->vTokens != NULL );
+
+    // create the new network
+    p->pNtkCur = pNtk = Abc_NtkAlloc( ABC_NTK_NETLIST, ABC_FUNC_SOP );
     // read the model name
-    if ( !p->fParsingExdc )
-    {
-        // read the model name
-        vTokens = Io_ReadBlifGetTokens(p);
-        if ( vTokens == NULL || strcmp( vTokens->pArray[0], ".model" ) )
-        {
-            p->LineCur = 0;
-            sprintf( p->sError, "Wrong input file format." );
-            Io_ReadBlifPrintErrorMessage( p );
-            return NULL;
-        }
-        pModelName = vTokens->pArray[1];
-        // allocate the empty network
-        p->pNtk = Abc_NtkAlloc( ABC_NTK_NETLIST, ABC_FUNC_SOP );
-        p->pNtk->pName = Extra_UtilStrsav( pModelName );
-        p->pNtk->pSpec = Extra_UtilStrsav( p->pFileName );
-    }
-    else
-        p->pNtk = Abc_NtkAlloc( ABC_NTK_NETLIST, ABC_FUNC_SOP );
+    if ( strcmp( p->vTokens->pArray[0], ".model" ) == 0 )
+        pNtk->pName = Extra_UtilStrsav( p->vTokens->pArray[1] );
 
     // read the inputs/outputs
     pProgress = Extra_ProgressBarStart( stdout, Extra_FileReaderGetFileSize(p->pReader) );
     fTokensReady = fStatus = 0;
-    for ( iLine = 0; fTokensReady || (vTokens = Io_ReadBlifGetTokens(p)); iLine++ )
+    for ( iLine = 0; fTokensReady || (p->vTokens = Io_ReadBlifGetTokens(p)); iLine++ )
     {
         if ( iLine % 1000 == 0 )
         Extra_ProgressBarUpdate( pProgress, Extra_FileReaderGetCurPosition(p->pReader), NULL );
 
         // consider different line types
         fTokensReady = 0;
-        pDirective = vTokens->pArray[0];
+        pDirective = p->vTokens->pArray[0];
         if ( !strcmp( pDirective, ".names" ) )
-            { fStatus = Io_ReadBlifNetworkNames( p, &vTokens ); fTokensReady = 1; }
+            { fStatus = Io_ReadBlifNetworkNames( p, &p->vTokens ); fTokensReady = 1; }
         else if ( !strcmp( pDirective, ".gate" ) )
-            fStatus = Io_ReadBlifNetworkGate( p, vTokens );
+            fStatus = Io_ReadBlifNetworkGate( p, p->vTokens );
         else if ( !strcmp( pDirective, ".latch" ) )
-            fStatus = Io_ReadBlifNetworkLatch( p, vTokens );
+            fStatus = Io_ReadBlifNetworkLatch( p, p->vTokens );
         else if ( !strcmp( pDirective, ".inputs" ) )
-            fStatus = Io_ReadBlifNetworkInputs( p, vTokens );
+            fStatus = Io_ReadBlifNetworkInputs( p, p->vTokens );
         else if ( !strcmp( pDirective, ".outputs" ) )
-            fStatus = Io_ReadBlifNetworkOutputs( p, vTokens );
+            fStatus = Io_ReadBlifNetworkOutputs( p, p->vTokens );
         else if ( !strcmp( pDirective, ".input_arrival" ) )
-            fStatus = Io_ReadBlifNetworkInputArrival( p, vTokens );
+            fStatus = Io_ReadBlifNetworkInputArrival( p, p->vTokens );
         else if ( !strcmp( pDirective, ".default_input_arrival" ) )
-            fStatus = Io_ReadBlifNetworkDefaultInputArrival( p, vTokens );
+            fStatus = Io_ReadBlifNetworkDefaultInputArrival( p, p->vTokens );
+        else if ( !strcmp( pDirective, ".subckt" ) )
+            fStatus = Io_ReadBlifNetworkSubcircuit( p, p->vTokens );
         else if ( !strcmp( pDirective, ".exdc" ) )
-            { p->fParsingExdc = 1; break; }
+            break;
         else if ( !strcmp( pDirective, ".end" ) )
+        {
+            p->vTokens = Io_ReadBlifGetTokens(p);
             break;
+        }
+        else if ( !strcmp( pDirective, ".blackbox" ) )
+        {
+            pNtk->ntkType = ABC_NTK_BLACKBOX;
+            pNtk->ntkFunc = ABC_FUNC_BLACKBOX;
+        }
         else
             printf( "%s (line %d): Skipping directive \"%s\".\n", p->pFileName, 
                 Extra_FileReaderGetLineNumber(p->pReader, 0), pDirective );
-        if ( vTokens == NULL ) // some files do not have ".end" in the end
+        if ( p->vTokens == NULL ) // some files do not have ".end" in the end
             break;
         if ( fStatus == 1 )
             return NULL;
     }
     Extra_ProgressBarStop( pProgress );
-    Abc_NtkFinalizeRead( p->pNtk );
-    return p->pNtk;
+    return pNtk;
 }
 
 /**Function*************************************************************
@@ -357,7 +279,7 @@ int Io_ReadBlifNetworkInputs( Io_ReadBlif_t * p, Vec_Ptr_t * vTokens )
 {
     int i;
     for ( i = 1; i < vTokens->nSize; i++ )
-        Io_ReadCreatePi( p->pNtk, vTokens->pArray[i] );
+        Io_ReadCreatePi( p->pNtkCur, vTokens->pArray[i] );
     return 0;
 }
 
@@ -376,7 +298,7 @@ int Io_ReadBlifNetworkOutputs( Io_ReadBlif_t * p, Vec_Ptr_t * vTokens )
 {
     int i;
     for ( i = 1; i < vTokens->nSize; i++ )
-        Io_ReadCreatePo( p->pNtk, vTokens->pArray[i] );
+        Io_ReadCreatePo( p->pNtkCur, vTokens->pArray[i] );
     return 0;
 }
 
@@ -393,7 +315,7 @@ int Io_ReadBlifNetworkOutputs( Io_ReadBlif_t * p, Vec_Ptr_t * vTokens )
 ***********************************************************************/
 int Io_ReadBlifNetworkLatch( Io_ReadBlif_t * p, Vec_Ptr_t * vTokens )
 {
-    Abc_Ntk_t * pNtk = p->pNtk;
+    Abc_Ntk_t * pNtk = p->pNtkCur;
     Abc_Obj_t * pLatch;
     int ResetValue;
     if ( vTokens->nSize < 3 )
@@ -442,7 +364,7 @@ int Io_ReadBlifNetworkLatch( Io_ReadBlif_t * p, Vec_Ptr_t * vTokens )
 int Io_ReadBlifNetworkNames( Io_ReadBlif_t * p, Vec_Ptr_t ** pvTokens )
 {
     Vec_Ptr_t * vTokens = *pvTokens;
-    Abc_Ntk_t * pNtk = p->pNtk;
+    Abc_Ntk_t * pNtk = p->pNtkCur;
     Abc_Obj_t * pNode;
     char * pToken, Char, ** ppNames;
     int nFanins, nNames;
@@ -584,12 +506,12 @@ int Io_ReadBlifNetworkGate( Io_ReadBlif_t * p, Vec_Ptr_t * vTokens )
     }
 
     // if this is the first line with gate, update the network type
-    if ( Abc_NtkNodeNum(p->pNtk) == 0 )
+    if ( Abc_NtkNodeNum(p->pNtkCur) == 0 )
     {
-        assert( p->pNtk->ntkFunc == ABC_FUNC_SOP );
-        p->pNtk->ntkFunc = ABC_FUNC_MAP;
-        Extra_MmFlexStop( p->pNtk->pManFunc, 0 );
-        p->pNtk->pManFunc = pGenlib;
+        assert( p->pNtkCur->ntkFunc == ABC_FUNC_SOP );
+        p->pNtkCur->ntkFunc = ABC_FUNC_MAP;
+        Extra_MmFlexStop( p->pNtkCur->pManFunc, 0 );
+        p->pNtkCur->pManFunc = pGenlib;
     }
 
     // remove the formal parameter names
@@ -608,13 +530,53 @@ int Io_ReadBlifNetworkGate( Io_ReadBlif_t * p, Vec_Ptr_t * vTokens )
     // create the node
     ppNames = (char **)vTokens->pArray + 2;
     nNames  = vTokens->nSize - 3;
-    pNode   = Io_ReadCreateNode( p->pNtk, ppNames[nNames], ppNames, nNames );
+    pNode   = Io_ReadCreateNode( p->pNtkCur, ppNames[nNames], ppNames, nNames );
 
     // set the pointer to the functionality of the node
     Abc_ObjSetData( pNode, pGate );
     return 0;
 }
 
+/**Function*************************************************************
+
+  Synopsis    [Creates a multi-input multi-output box in the hierarchical design.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Io_ReadBlifNetworkSubcircuit( Io_ReadBlif_t * p, Vec_Ptr_t * vTokens )
+{
+    Abc_Obj_t * pBox;
+    Vec_Ptr_t * vNames;
+    char * pName;
+    int i;
+
+    // create a new node and add it to the network
+    if ( vTokens->nSize < 3 )
+    {
+        p->LineCur = Extra_FileReaderGetLineNumber(p->pReader, 0);
+        sprintf( p->sError, "The .subcircuit line has less than three tokens." );
+        Io_ReadBlifPrintErrorMessage( p );
+        return 1;
+    }
+
+    // store the names of formal/actual inputs/outputs of the box
+    vNames = Vec_PtrAlloc( 10 );
+    Vec_PtrForEachEntryStart( vTokens, pName, i, 1 )
+        Vec_PtrPush( vNames, Abc_NtkRegisterName(p->pNtkCur, pName) );
+
+    // create a new box and add it to the network
+    pBox = Abc_NtkCreateBox( p->pNtkCur );
+    // set the pointer to the node names
+    Abc_ObjSetData( pBox, vNames );
+    // remember the line of the file
+    pBox->pCopy = (void *)Extra_FileReaderGetLineNumber(p->pReader, 0);
+    return 0;
+}
 
 /**Function*************************************************************
 
@@ -663,7 +625,7 @@ int Io_ReadBlifNetworkInputArrival( Io_ReadBlif_t * p, Vec_Ptr_t * vTokens )
         Io_ReadBlifPrintErrorMessage( p );
         return 1;
     }
-    pNet = Abc_NtkFindNet( p->pNtk, vTokens->pArray[1] );
+    pNet = Abc_NtkFindNet( p->pNtkCur, vTokens->pArray[1] );
     if ( pNet == NULL )
     {
         p->LineCur = Extra_FileReaderGetLineNumber(p->pReader, 0);
@@ -681,7 +643,7 @@ int Io_ReadBlifNetworkInputArrival( Io_ReadBlif_t * p, Vec_Ptr_t * vTokens )
         return 1;
     }
     // set the arrival time
-    Abc_NtkTimeSetArrival( p->pNtk, Abc_ObjFanin0(pNet)->Id, (float)TimeRise, (float)TimeFall );
+    Abc_NtkTimeSetArrival( p->pNtkCur, Abc_ObjFanin0(pNet)->Id, (float)TimeRise, (float)TimeFall );
     return 0;
 }
 
@@ -720,10 +682,354 @@ int Io_ReadBlifNetworkDefaultInputArrival( Io_ReadBlif_t * p, Vec_Ptr_t * vToken
         return 1;
     }
     // set the arrival time
-    Abc_NtkTimeSetDefaultArrival( p->pNtk, (float)TimeRise, (float)TimeFall );
+    Abc_NtkTimeSetDefaultArrival( p->pNtkCur, (float)TimeRise, (float)TimeFall );
+    return 0;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Prints the error message including the file name and line number.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Io_ReadBlifPrintErrorMessage( Io_ReadBlif_t * p )
+{
+    if ( p->LineCur == 0 ) // the line number is not given
+        fprintf( p->Output, "%s: %s\n", p->pFileName, p->sError );
+    else // print the error message with the line number
+        fprintf( p->Output, "%s (line %d): %s\n", p->pFileName, p->LineCur, p->sError );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Gets the tokens taking into account the line breaks.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Vec_Ptr_t * Io_ReadBlifGetTokens( Io_ReadBlif_t * p )
+{
+    Vec_Ptr_t * vTokens;
+    char * pLastToken;
+    int i;
+
+    // get rid of the old tokens
+    if ( p->vNewTokens->nSize > 0 )
+    {
+        for ( i = 0; i < p->vNewTokens->nSize; i++ )
+            free( p->vNewTokens->pArray[i] );
+        p->vNewTokens->nSize = 0;
+    }
+
+    // get the new tokens
+    vTokens = Extra_FileReaderGetTokens(p->pReader);
+    if ( vTokens == NULL )
+        return vTokens;
+
+    // check if there is a transfer to another line
+    pLastToken = vTokens->pArray[vTokens->nSize - 1];
+    if ( pLastToken[ strlen(pLastToken)-1 ] != '\\' )
+        return vTokens;
+
+    // remove the slash
+    pLastToken[ strlen(pLastToken)-1 ] = 0;
+    if ( pLastToken[0] == 0 )
+        vTokens->nSize--;
+    // load them into the new array
+    for ( i = 0; i < vTokens->nSize; i++ )
+        Vec_PtrPush( p->vNewTokens, Extra_UtilStrsav(vTokens->pArray[i]) );
+
+    // load as long as there is the line break
+    while ( 1 )
+    {
+        // get the new tokens
+        vTokens = Extra_FileReaderGetTokens(p->pReader);
+        if ( vTokens->nSize == 0 )
+            return p->vNewTokens;
+        // check if there is a transfer to another line
+        pLastToken = vTokens->pArray[vTokens->nSize - 1];
+        if ( pLastToken[ strlen(pLastToken)-1 ] == '\\' )
+        {
+            // remove the slash
+            pLastToken[ strlen(pLastToken)-1 ] = 0;
+            if ( pLastToken[0] == 0 )
+                vTokens->nSize--;
+            // load them into the new array
+            for ( i = 0; i < vTokens->nSize; i++ )
+                Vec_PtrPush( p->vNewTokens, Extra_UtilStrsav(vTokens->pArray[i]) );
+            continue;
+        }
+        // otherwise, load them and break
+        for ( i = 0; i < vTokens->nSize; i++ )
+            Vec_PtrPush( p->vNewTokens, Extra_UtilStrsav(vTokens->pArray[i]) );
+        break;
+    }
+    return p->vNewTokens;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Starts the reading data structure.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Io_ReadBlif_t * Io_ReadBlifFile( char * pFileName )
+{
+    Extra_FileReader_t * pReader;
+    Io_ReadBlif_t * p;
+
+    // start the reader
+    pReader = Extra_FileReaderAlloc( pFileName, "#", "\n\r", " \t" );
+
+    if ( pReader == NULL )
+        return NULL;
+
+    // start the reading data structure
+    p = ALLOC( Io_ReadBlif_t, 1 );
+    memset( p, 0, sizeof(Io_ReadBlif_t) );
+    p->pFileName  = pFileName;
+    p->pReader    = pReader;
+    p->Output     = stdout;
+    p->vNewTokens = Vec_PtrAlloc( 100 );
+    p->vCubes     = Vec_StrAlloc( 100 );
+    return p;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Frees the data structure.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Io_ReadBlifFree( Io_ReadBlif_t * p )
+{
+    Extra_FileReaderFree( p->pReader );
+    Vec_PtrFree( p->vNewTokens );
+    Vec_StrFree( p->vCubes );
+    free( p );
+}
+
+
+/**Function*************************************************************
+
+  Synopsis    [Connect one box.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Io_ReadBlifNetworkConnectBoxesOneBox( Io_ReadBlif_t * p, Abc_Obj_t * pBox, stmm_table * tName2Model )
+{
+    Vec_Ptr_t * pNames;
+    Abc_Ntk_t * pNtkModel;
+    Abc_Obj_t * pObj, * pNet;
+    char * pName, * pActual;
+    int i, Length, Start;
+
+    // get the model for this box
+    pNames = pBox->pData;
+    if ( !stmm_lookup( tName2Model, Vec_PtrEntry(pNames, 0), (char **)&pNtkModel ) )
+    {
+        p->LineCur = (int)pBox->pCopy;
+        sprintf( p->sError, "Cannot find the model for subcircuit %s.", Vec_PtrEntry(pNames, 0) );
+        Io_ReadBlifPrintErrorMessage( p );
+        return 1;
+    }
+
+    // create the fanins of the box
+    Abc_NtkForEachPi( pNtkModel, pObj, i )
+        pObj->pCopy = NULL;
+    Vec_PtrForEachEntryStart( pNames, pName, i, 1 )
+    {
+        pActual = Io_ReadBlifCleanName(pName);
+        if ( pActual == NULL )
+        {
+            p->LineCur = (int)pBox->pCopy;
+            sprintf( p->sError, "Cannot parse formal/actual name pair \"%s\".", pName );
+            Io_ReadBlifPrintErrorMessage( p );
+            return 1;
+        }
+        Length = pActual - pName - 1;
+        pName[Length] = 0;
+        // find the PI net with this name
+        pObj = Abc_NtkFindNet( pNtkModel, pName );
+        if ( pObj == NULL )
+        {
+            p->LineCur = (int)pBox->pCopy;
+            sprintf( p->sError, "Cannot find formal input \"%s\" as an PI of model \"%s\".", pName, Vec_PtrEntry(pNames, 0) );
+            Io_ReadBlifPrintErrorMessage( p );
+            return 1;
+        }
+        // get the PI
+        pObj = Abc_ObjFanin0(pObj);
+        // quit if this is not a PI net
+        if ( !Abc_ObjIsPi(pObj) )
+        {
+            pName[Length] = '=';
+            Start = i;
+            break;
+        }
+        // remember the actual name in the net
+        if ( pObj->pCopy != NULL )
+        {
+            p->LineCur = (int)pBox->pCopy;
+            sprintf( p->sError, "Formal input \"%s\" is used more than once.", pName );
+            Io_ReadBlifPrintErrorMessage( p );
+            return 1;
+        }
+        pObj->pCopy = (void *)pActual;
+        // quit if we processed all PIs
+        if ( i == Abc_NtkPiNum(pNtkModel) )
+        {
+            Start = i+1;
+            break;
+        }
+    }
+    // create the fanins of the box
+    Abc_NtkForEachPi( pNtkModel, pObj, i )
+    {
+        pActual = (void *)pObj->pCopy;
+        if ( pActual == NULL )
+        {
+            p->LineCur = (int)pBox->pCopy;
+            sprintf( p->sError, "Formal input \"%s\" of model %s is not driven.", pName, Vec_PtrEntry(pNames, 0) );
+            Io_ReadBlifPrintErrorMessage( p );
+            return 1;
+        }
+        pNet = Abc_NtkFindOrCreateNet( pBox->pNtk, pActual );
+        Abc_ObjAddFanin( pBox, pNet );
+    }
+    Abc_NtkForEachPi( pNtkModel, pObj, i )
+        pObj->pCopy = NULL;
+
+    // create the fanouts of the box
+    Abc_NtkForEachPo( pNtkModel, pObj, i )
+        pObj->pCopy = NULL;
+    Vec_PtrForEachEntryStart( pNames, pName, i, Start )
+    {
+        pActual = Io_ReadBlifCleanName(pName);
+        if ( pActual == NULL )
+        {
+            p->LineCur = (int)pBox->pCopy;
+            sprintf( p->sError, "Cannot parse formal/actual name pair \"%s\".", pName );
+            Io_ReadBlifPrintErrorMessage( p );
+            return 1;
+        }
+        Length = pActual - pName - 1;
+        pName[Length] = 0;
+        // find the PO net with this name
+        pObj = Abc_NtkFindNet( pNtkModel, pName );
+        if ( pObj == NULL )
+        {
+            p->LineCur = (int)pBox->pCopy;
+            sprintf( p->sError, "Cannot find formal output \"%s\" as an PO of model \"%s\".", pName, Vec_PtrEntry(pNames, 0) );
+            Io_ReadBlifPrintErrorMessage( p );
+            return 1;
+        }
+        // get the PO
+        pObj = Abc_ObjFanout0(pObj);
+        if ( pObj->pCopy != NULL )
+        {
+            p->LineCur = (int)pBox->pCopy;
+            sprintf( p->sError, "Formal output \"%s\" is used more than once.", pName );
+            Io_ReadBlifPrintErrorMessage( p );
+            return 1;
+        }
+        pObj->pCopy = (void *)pActual;
+    }
+    // create the fanouts of the box
+    Abc_NtkForEachPo( pNtkModel, pObj, i )
+    {
+        pActual = (void *)pObj->pCopy;
+        if ( pActual == NULL )
+        {
+            p->LineCur = (int)pBox->pCopy;
+            sprintf( p->sError, "Formal output \"%s\" of model %s is not driven.", pName, Vec_PtrEntry(pNames, 0) );
+            Io_ReadBlifPrintErrorMessage( p );
+            return 1;
+        }
+        pNet = Abc_NtkFindOrCreateNet( pBox->pNtk, pActual );
+        Abc_ObjAddFanin( pNet, pBox );
+    }
+    Abc_NtkForEachPo( pNtkModel, pObj, i )
+        pObj->pCopy = NULL;
+
+    // remove the array of names, assign the pointer to the model
+    Vec_PtrFree( pBox->pData );
+    pBox->pData = pNtkModel;
     return 0;
 }
 
+/**Function*************************************************************
+
+  Synopsis    [Connect the boxes in the hierarchy of networks.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Io_ReadBlifNetworkConnectBoxesOne( Io_ReadBlif_t * p, Abc_Ntk_t * pNtk, stmm_table * tName2Model )
+{
+    Abc_Obj_t * pBox;
+    int i;
+    // go through the boxes
+    Abc_NtkForEachBox( pNtk, pBox, i )
+        if ( Io_ReadBlifNetworkConnectBoxesOneBox( p, pBox, tName2Model ) )
+            return 1;
+    Abc_NtkFinalizeRead( pNtk );
+    return 0;
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Connect the boxes in the hierarchy of networks.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+int Io_ReadBlifNetworkConnectBoxes( Io_ReadBlif_t * p, Abc_Ntk_t * pNtkMaster )
+{
+    stmm_generator * gen;
+    Abc_Ntk_t * pNtk;
+    char * pName;
+    // connect the master network
+    if ( Io_ReadBlifNetworkConnectBoxesOne( p, pNtkMaster, pNtkMaster->tName2Model ) )
+        return 1;
+    // connect other networks
+    stmm_foreach_item( pNtkMaster->tName2Model, gen, &pName, (char **)&pNtk )
+        if ( Io_ReadBlifNetworkConnectBoxesOne( p, pNtk, pNtkMaster->tName2Model ) )
+            return 1;
+    return 0;
+}
 
 ////////////////////////////////////////////////////////////////////////
 ///                       END OF FILE                                ///
diff --git a/src/base/io/ioWriteBlif.c b/src/base/io/ioWriteBlif.c
index 1b515a1e..1e27498d 100644
--- a/src/base/io/ioWriteBlif.c
+++ b/src/base/io/ioWriteBlif.c
@@ -26,6 +26,7 @@
 ///                        DECLARATIONS                              ///
 ////////////////////////////////////////////////////////////////////////
 
+static void Io_NtkWrite( FILE * pFile, Abc_Ntk_t * pNtk, int fWriteLatches );
 static void Io_NtkWriteOne( FILE * pFile, Abc_Ntk_t * pNtk, int fWriteLatches );
 static void Io_NtkWritePis( FILE * pFile, Abc_Ntk_t * pNtk, int fWriteLatches );
 static void Io_NtkWritePos( FILE * pFile, Abc_Ntk_t * pNtk, int fWriteLatches );
@@ -59,7 +60,7 @@ void Io_WriteBlifLogic( Abc_Ntk_t * pNtk, char * FileName, int fWriteLatches )
         fprintf( stdout, "Writing BLIF has failed.\n" );
         return;
     }
-    Io_WriteBlif( pNtkTemp, FileName, fWriteLatches );
+    Io_WriteBlifNetlist( pNtkTemp, FileName, fWriteLatches );
     Abc_NtkDelete( pNtkTemp );
 }
 
@@ -74,19 +75,48 @@ void Io_WriteBlifLogic( Abc_Ntk_t * pNtk, char * FileName, int fWriteLatches )
   SeeAlso     []
 
 ***********************************************************************/
-void Io_WriteBlif( Abc_Ntk_t * pNtk, char * FileName, int fWriteLatches )
+void Io_WriteBlifNetlist( Abc_Ntk_t * pNtk, char * FileName, int fWriteLatches )
 {
-    Abc_Ntk_t * pExdc;
+    stmm_generator * gen;
+    Abc_Ntk_t * pNtkTemp;
     FILE * pFile;
     assert( Abc_NtkIsNetlist(pNtk) );
+    // start writing the file
     pFile = fopen( FileName, "w" );
     if ( pFile == NULL )
     {
-        fprintf( stdout, "Io_WriteBlif(): Cannot open the output file.\n" );
+        fprintf( stdout, "Io_WriteBlifNetlist(): Cannot open the output file.\n" );
         return;
     }
-    // write the model name
     fprintf( pFile, "# Benchmark \"%s\" written by ABC on %s\n", pNtk->pName, Extra_TimeStamp() );
+    // write the master network
+    Io_NtkWrite( pFile, pNtk, fWriteLatches );
+    // write the hierarchy if present
+    if ( pNtk->tName2Model )
+    {
+        fprintf( pFile, "\n\n" );
+        stmm_foreach_item( pNtk->tName2Model, gen, NULL, (char **)&pNtkTemp )
+            Io_NtkWrite( pFile, pNtkTemp, fWriteLatches );
+    }
+    fclose( pFile );
+}
+
+/**Function*************************************************************
+
+  Synopsis    [Write the network into a BLIF file with the given name.]
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Io_NtkWrite( FILE * pFile, Abc_Ntk_t * pNtk, int fWriteLatches )
+{
+    Abc_Ntk_t * pExdc;
+    assert( Abc_NtkIsNetlist(pNtk) || Abc_NtkIsBlackbox(pNtk) );
+    // write the model name
     fprintf( pFile, ".model %s\n", Abc_NtkName(pNtk) );
     // write the network
     Io_NtkWriteOne( pFile, pNtk, fWriteLatches );
@@ -100,7 +130,6 @@ void Io_WriteBlif( Abc_Ntk_t * pNtk, char * FileName, int fWriteLatches )
     }
     // finalize the file
     fprintf( pFile, ".end\n" );
-    fclose( pFile );
 }
 
 /**Function*************************************************************
@@ -130,6 +159,13 @@ void Io_NtkWriteOne( FILE * pFile, Abc_Ntk_t * pNtk, int fWriteLatches )
     Io_NtkWritePos( pFile, pNtk, fWriteLatches );
     fprintf( pFile, "\n" );
 
+    // write the blackbox
+    if ( Abc_NtkIsBlackbox( pNtk ) )
+    {
+        fprintf( pFile, ".blackbox\n" );
+        return;
+    }
+
     // write the timing info
     Io_WriteTimingInfo( pFile, pNtk );