diff --git a/src/map/scl/scl.c b/src/map/scl/scl.c
index 8671d958e..29798f8fa 100644
--- a/src/map/scl/scl.c
+++ b/src/map/scl/scl.c
@@ -1604,7 +1604,7 @@ int Scl_CommandUpsize( Abc_Frame_t * pAbc, int argc, char **argv )
         return 1;
     }
 
-    Abc_SclUpsizePerform( (SC_Lib *)pAbc->pLibScl, pNtk, pPars );
+    Abc_SclUpsizePerform( (SC_Lib *)pAbc->pLibScl, pNtk, pPars, NULL );
     return 0;
 
 usage:
@@ -1781,7 +1781,7 @@ int Scl_CommandDnsize( Abc_Frame_t * pAbc, int argc, char **argv )
         return 1;
     }
 
-    Abc_SclDnsizePerform( (SC_Lib *)pAbc->pLibScl, pNtk, pPars );
+    Abc_SclDnsizePerform( (SC_Lib *)pAbc->pLibScl, pNtk, pPars, NULL );
     return 0;
 
 usage:
diff --git a/src/map/scl/sclDnsize.c b/src/map/scl/sclDnsize.c
index 5be9e3a34..35f2c8247 100644
--- a/src/map/scl/sclDnsize.c
+++ b/src/map/scl/sclDnsize.c
@@ -239,7 +239,7 @@ void Abc_SclDnsizePrint( SC_Man * p, int Iter, int nAttempts, int nOverlaps, int
   SeeAlso     []
 
 ***********************************************************************/
-void Abc_SclDnsizePerformInt( SC_Lib * pLib, Abc_Ntk_t * pNtk, SC_SizePars * pPars )
+void Abc_SclDnsizePerformInt( SC_Lib * pLib, Abc_Ntk_t * pNtk, SC_SizePars * pPars, void * pFuncFanin )
 {
     SC_Man * p;
     Abc_Obj_t * pObj;
@@ -261,6 +261,7 @@ void Abc_SclDnsizePerformInt( SC_Lib * pLib, Abc_Ntk_t * pNtk, SC_SizePars * pPa
 
     // prepare the manager; collect init stats
     p = Abc_SclManStart( pLib, pNtk, pPars->fUseWireLoads, pPars->fUseDept, pPars->DelayUser, pPars->BuffTreeEst );
+    p->pFuncFanin = (float (*)(void *, Abc_Obj_t *, Abc_Obj_t *, int, int))pFuncFanin;
     p->timeTotal  = Abc_Clock();
     assert( p->vGatesBest == NULL );
     p->vGatesBest = Vec_IntDup( p->pNtk->vGates );
@@ -357,12 +358,12 @@ void Abc_SclDnsizePerformInt( SC_Lib * pLib, Abc_Ntk_t * pNtk, SC_SizePars * pPa
   SeeAlso     []
 
 ***********************************************************************/
-void Abc_SclDnsizePerform( SC_Lib * pLib, Abc_Ntk_t * pNtk, SC_SizePars * pPars )
+void Abc_SclDnsizePerform( SC_Lib * pLib, Abc_Ntk_t * pNtk, SC_SizePars * pPars, void * pFuncFanin )
 {
     Abc_Ntk_t * pNtkNew = pNtk;
     if ( pNtk->nBarBufs2 > 0 )
         pNtkNew = Abc_NtkDupDfsNoBarBufs( pNtk );
-    Abc_SclDnsizePerformInt( pLib, pNtkNew, pPars );
+    Abc_SclDnsizePerformInt( pLib, pNtkNew, pPars, pFuncFanin );
     if ( pNtk->nBarBufs2 > 0 )
         Abc_SclTransferGates( pNtk, pNtkNew );
     if ( pNtk->nBarBufs2 > 0 )
diff --git a/src/map/scl/sclSize.c b/src/map/scl/sclSize.c
index e09c56e67..b3bc2828d 100644
--- a/src/map/scl/sclSize.c
+++ b/src/map/scl/sclSize.c
@@ -270,21 +270,25 @@ void Abc_SclTimeNtkPrint( SC_Man * p, int fShowAll, int fPrintPath )
   SeeAlso     []
 
 ***********************************************************************/
-static inline void Abc_SclTimeFanin( SC_Man * p, SC_Timing * pTime, Abc_Obj_t * pObj, Abc_Obj_t * pFanin )
+static inline void Abc_SclTimeFanin( SC_Man * p, SC_Timing * pTime, Abc_Obj_t * pObj, Abc_Obj_t * pFanin, int k )
 {
     SC_Pair * pArrIn   = Abc_SclObjTime( p, pFanin );
     SC_Pair * pSlewIn  = Abc_SclObjSlew( p, pFanin );
     SC_Pair * pLoad    = Abc_SclObjLoad( p, pObj );
     SC_Pair * pArrOut  = Abc_SclObjTime( p, pObj );   // modified
     SC_Pair * pSlewOut = Abc_SclObjSlew( p, pObj );   // modified
+    if ( p->pFuncFanin ) pLoad->fall += p->pFuncFanin(p, pObj, pFanin, k, 0);
+    if ( p->pFuncFanin ) pLoad->rise += p->pFuncFanin(p, pObj, pFanin, k, 1);
     Scl_LibPinArrival( pTime, pArrIn, pSlewIn, pLoad, pArrOut, pSlewOut );
 }
-static inline void Abc_SclDeptFanin( SC_Man * p, SC_Timing * pTime, Abc_Obj_t * pObj, Abc_Obj_t * pFanin )
+static inline void Abc_SclDeptFanin( SC_Man * p, SC_Timing * pTime, Abc_Obj_t * pObj, Abc_Obj_t * pFanin, int k )
 {
     SC_Pair * pDepIn   = Abc_SclObjDept( p, pFanin );   // modified
     SC_Pair * pSlewIn  = Abc_SclObjSlew( p, pFanin );
     SC_Pair * pLoad    = Abc_SclObjLoad( p, pObj );
     SC_Pair * pDepOut  = Abc_SclObjDept( p, pObj );
+    if ( p->pFuncFanin ) pLoad->fall += p->pFuncFanin(p, pObj, pFanin, k, 0);
+    if ( p->pFuncFanin ) pLoad->rise += p->pFuncFanin(p, pObj, pFanin, k, 1);    
     Scl_LibPinDeparture( pTime, pDepIn, pSlewIn, pLoad, pDepOut );
 }
 static inline void Abc_SclDeptObj( SC_Man * p, Abc_Obj_t * pObj )
@@ -298,7 +302,7 @@ static inline void Abc_SclDeptObj( SC_Man * p, Abc_Obj_t * pObj )
         if ( Abc_ObjIsCo(pFanout) || Abc_ObjIsLatch(pFanout) )
             continue;
         pTime = Scl_CellPinTime( Abc_SclObjCell(pFanout), Abc_NodeFindFanin(pFanout, pObj) );
-        Abc_SclDeptFanin( p, pTime, pFanout, pObj );
+        Abc_SclDeptFanin( p, pTime, pFanout, pObj, Abc_NodeFindFanin(pFanout, pObj) );
     }
 }
 static inline float Abc_SclObjLoadValue( SC_Man * p, Abc_Obj_t * pObj )
@@ -368,9 +372,9 @@ void Abc_SclTimeNode( SC_Man * p, Abc_Obj_t * pObj, int fDept )
     {
         pTime = Scl_CellPinTime( pCell, k );
         if ( fDept )
-            Abc_SclDeptFanin( p, pTime, pObj, pFanin );
+            Abc_SclDeptFanin( p, pTime, pObj, pFanin, k );
         else
-            Abc_SclTimeFanin( p, pTime, pObj, pFanin );
+            Abc_SclTimeFanin( p, pTime, pObj, pFanin, k );
     }
     if ( p->EstLoadMax && Value > 1 )
     {
diff --git a/src/map/scl/sclSize.h b/src/map/scl/sclSize.h
index 3ec0d83e3..133ae6647 100644
--- a/src/map/scl/sclSize.h
+++ b/src/map/scl/sclSize.h
@@ -95,6 +95,7 @@ struct SC_Man_
     abctime        timeSize;      // incremental sizing
     abctime        timeTime;      // timing update
     abctime        timeOther;     // everything else
+    float        (*pFuncFanin)(void * p, Abc_Obj_t * pObj, Abc_Obj_t * pFanin, int iFanin, int fRise); // called to get info about the node's fanin
 };
 
 ////////////////////////////////////////////////////////////////////////
@@ -127,7 +128,7 @@ static inline double    Abc_SclObjSlackMax( SC_Man * p, Abc_Obj_t * pObj, float
 static inline void      Abc_SclObjDupFanin( SC_Man * p, Abc_Obj_t * pObj )          { assert( Abc_ObjIsCo(pObj) ); *Abc_SclObjTime(p, pObj) = *Abc_SclObjTime(p, Abc_ObjFanin0(pObj));  }
 static inline float     Abc_SclObjInDrive( SC_Man * p, Abc_Obj_t * pObj )           { return Vec_FltEntry( p->vInDrive, pObj->iData );                                    }
 static inline void      Abc_SclObjSetInDrive( SC_Man * p, Abc_Obj_t * pObj, float c){ Vec_FltWriteEntry( p->vInDrive, pObj->iData, c );                                   }
-
+static inline void      Abc_SclManSetFaninCallBack( SC_Man * p, void * pCallBack )  { p->pFuncFanin = (float (*)(void *, Abc_Obj_t *, Abc_Obj_t *, int, int))pCallBack;   } 
 
 ////////////////////////////////////////////////////////////////////////
 ///                     FUNCTION DEFINITIONS                         ///
@@ -551,7 +552,7 @@ extern int           Abc_SclCheckNtk( Abc_Ntk_t * p, int fVerbose );
 extern Abc_Ntk_t *   Abc_SclPerformBuffering( Abc_Ntk_t * p, int DegreeR, int Degree, int fUseInvs, int fVerbose );
 extern Abc_Ntk_t *   Abc_SclBufPerform( Abc_Ntk_t * pNtk, int FanMin, int FanMax, int fBufPis, int fSkipDup, int fVerbose );
 /*=== sclDnsize.c ===============================================================*/
-extern void          Abc_SclDnsizePerform( SC_Lib * pLib, Abc_Ntk_t * pNtk, SC_SizePars * pPars );
+extern void          Abc_SclDnsizePerform( SC_Lib * pLib, Abc_Ntk_t * pNtk, SC_SizePars * pPars, void * pFuncFanin );
 /*=== sclLoad.c ===============================================================*/
 extern Vec_Flt_t *   Abc_SclFindWireCaps( SC_WireLoad * pWL, int nFanoutMax );
 extern float         Abc_SclFindWireLoad( Vec_Flt_t * vWireCaps, int nFans );
@@ -573,7 +574,7 @@ extern void          Abc_SclTimePerform( SC_Lib * pLib, Abc_Ntk_t * pNtk, int nT
 extern void          Abc_SclPrintBuffers( SC_Lib * pLib, Abc_Ntk_t * pNtk, int fVerbose );
 /*=== sclUpsize.c ===============================================================*/
 extern int           Abc_SclCountNearCriticalNodes( SC_Man * p );
-extern void          Abc_SclUpsizePerform( SC_Lib * pLib, Abc_Ntk_t * pNtk, SC_SizePars * pPars );
+extern void          Abc_SclUpsizePerform( SC_Lib * pLib, Abc_Ntk_t * pNtk, SC_SizePars * pPars, void * pFuncFanin );
 /*=== sclUtil.c ===============================================================*/
 extern void          Abc_SclMioGates2SclGates( SC_Lib * pLib, Abc_Ntk_t * p );
 extern void          Abc_SclSclGates2MioGates( SC_Lib * pLib, Abc_Ntk_t * p );
diff --git a/src/map/scl/sclUpsize.c b/src/map/scl/sclUpsize.c
index 5c6307352..822278a33 100644
--- a/src/map/scl/sclUpsize.c
+++ b/src/map/scl/sclUpsize.c
@@ -865,7 +865,7 @@ void Abc_SclUpsizeRemoveDangling( SC_Man * p, Abc_Ntk_t * pNtk )
   SeeAlso     []
 
 ***********************************************************************/
-void Abc_SclUpsizePerformInt( SC_Lib * pLib, Abc_Ntk_t * pNtk, SC_SizePars * pPars )
+void Abc_SclUpsizePerformInt( SC_Lib * pLib, Abc_Ntk_t * pNtk, SC_SizePars * pPars, void * pFuncFanin )
 {
     SC_Man * p;
     Vec_Int_t * vPathPos = NULL;    // critical POs
@@ -891,6 +891,7 @@ void Abc_SclUpsizePerformInt( SC_Lib * pLib, Abc_Ntk_t * pNtk, SC_SizePars * pPa
         pPars->Window += (Abc_NtkNodeNum(pNtk) > 40000);
     // prepare the manager; collect init stats
     p = Abc_SclManStart( pLib, pNtk, pPars->fUseWireLoads, pPars->fUseDept, 0, pPars->BuffTreeEst );
+    p->pFuncFanin = (float (*)(void *, Abc_Obj_t *, Abc_Obj_t *, int, int))pFuncFanin;    
     p->timeTotal  = Abc_Clock();
     assert( p->vGatesBest == NULL );
     p->vGatesBest = Vec_IntDup( p->pNtk->vGates );
@@ -1024,12 +1025,12 @@ void Abc_SclUpsizePerformInt( SC_Lib * pLib, Abc_Ntk_t * pNtk, SC_SizePars * pPa
   SeeAlso     []
 
 ***********************************************************************/
-void Abc_SclUpsizePerform( SC_Lib * pLib, Abc_Ntk_t * pNtk, SC_SizePars * pPars )
+void Abc_SclUpsizePerform( SC_Lib * pLib, Abc_Ntk_t * pNtk, SC_SizePars * pPars, void * pFuncFanin )
 {
     Abc_Ntk_t * pNtkNew = pNtk;
     if ( pNtk->nBarBufs2 > 0 )
         pNtkNew = Abc_NtkDupDfsNoBarBufs( pNtk );
-    Abc_SclUpsizePerformInt( pLib, pNtkNew, pPars );
+    Abc_SclUpsizePerformInt( pLib, pNtkNew, pPars, pFuncFanin );
     if ( pNtk->nBarBufs2 > 0 )
         Abc_SclTransferGates( pNtk, pNtkNew );
     if ( pNtk->nBarBufs2 > 0 )