diff --git a/src/aig/gia/gia.h b/src/aig/gia/gia.h
index 68266bb2d..dab6770bb 100644
--- a/src/aig/gia/gia.h
+++ b/src/aig/gia/gia.h
@@ -241,6 +241,9 @@ struct Gia_Man_t_
     Vec_Int_t      vSuppVars;     // used variables
     Vec_Int_t      vVarMap;       // used variables
     Gia_Dat_t *    pUData;
+    // retiming data
+    Vec_Str_t *    vStopsF;
+    Vec_Str_t *    vStopsB;    
 };
 
 
diff --git a/src/aig/gia/giaMan.c b/src/aig/gia/giaMan.c
index 0efb5b29f..a48da5c29 100644
--- a/src/aig/gia/giaMan.c
+++ b/src/aig/gia/giaMan.c
@@ -156,6 +156,8 @@ void Gia_ManStop( Gia_Man_t * p )
     Vec_IntErase( &p->vHash );
     Vec_IntErase( &p->vHTable );
     Vec_IntErase( &p->vRefs );
+    Vec_StrFreeP( &p->vStopsF );
+    Vec_StrFreeP( &p->vStopsB );    
     ABC_FREE( p->pData2 );
     ABC_FREE( p->pTravIds );
     ABC_FREE( p->pPlacement );
diff --git a/src/aig/gia/giaMini.c b/src/aig/gia/giaMini.c
index c0473fea3..85647eac5 100644
--- a/src/aig/gia/giaMini.c
+++ b/src/aig/gia/giaMini.c
@@ -1228,6 +1228,98 @@ void Gia_MiniAigGenerateFromFile()
     Mini_AigStop( p );
 }
 
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+Vec_Str_t * Gia_ManRetimableF( Gia_Man_t * p, int * pRst, int * pSet, int * pEna )
+{
+    Vec_Str_t * vStops = Vec_StrStart( Gia_ManObjNum(p) );
+    Vec_Int_t * vTemps = Vec_IntStartFull( 3*Gia_ManObjNum(p) );
+    Gia_Obj_t * pObj, * pObjRi, * pObjRo; int i;
+    char * pStops = Vec_StrArray(vStops);
+    assert( Gia_ManRegNum(p) > 0 );
+    Gia_ManForEachRiRo( p, pObjRi, pObjRo, i ) {
+        Vec_IntWriteEntry( vTemps, 3*Gia_ObjId(p, pObjRo) + 0, pRst[i] );
+        Vec_IntWriteEntry( vTemps, 3*Gia_ObjId(p, pObjRo) + 1, pSet[i] );
+        Vec_IntWriteEntry( vTemps, 3*Gia_ObjId(p, pObjRo) + 2, pEna[i] );
+    }
+    Gia_ManForEachAnd( p, pObj, i ) {
+        int * pFan0 = Vec_IntEntryP( vTemps, 3*Gia_ObjFaninId0(pObj, i) );
+        int * pFan1 = Vec_IntEntryP( vTemps, 3*Gia_ObjFaninId1(pObj, i) );
+        int * pNode = Vec_IntEntryP( vTemps, 3*i );
+        pStops[i] = (char)1;
+        if ( pFan0[0] != -1 && pFan0[0] == pFan1[0] && pFan0[1] == pFan1[1] && pFan0[2] == pFan1[2] )
+            pStops[i] = (char)0, pNode[0] = pFan0[0], pNode[1] = pFan0[1], pNode[2] = pFan0[2]; 
+    }
+    Vec_IntFree( vTemps );
+    return vStops;
+}
+Vec_Str_t * Gia_ManRetimableB( Gia_Man_t * p, int * pRst, int * pSet, int * pEna )
+{
+    Vec_Str_t * vStops = Vec_StrStart( Gia_ManObjNum(p) );
+    Vec_Int_t * vTemps = Vec_IntStartFull( 3*Gia_ManObjNum(p) );
+    Gia_Obj_t * pObj, * pObjRi, * pObjRo; int i, n;
+    char * pStops = Vec_StrArray(vStops);
+    assert( Gia_ManRegNum(p) > 0 );
+    Gia_ManForEachRiRo( p, pObjRi, pObjRo, i ) {
+        Vec_IntWriteEntry( vTemps, 3*Gia_ObjFaninId0p(p, pObjRi) + 0, pRst[i] );
+        Vec_IntWriteEntry( vTemps, 3*Gia_ObjFaninId0p(p, pObjRi) + 1, pSet[i] );
+        Vec_IntWriteEntry( vTemps, 3*Gia_ObjFaninId0p(p, pObjRi) + 2, pEna[i] );        
+    }
+    Gia_ManForEachAndReverse( p, pObj, i ) {
+        int   iFans[2] = { Gia_ObjFaninId0(pObj, i), Gia_ObjFaninId1(pObj, i) };
+        int * pFans[2] = { Vec_IntEntryP( vTemps, 3*iFans[0] ), Vec_IntEntryP( vTemps, 3*iFans[1] ) };
+        int * pNode = Vec_IntEntryP( vTemps, 3*i );
+        if ( pNode[0] == -1 )
+            continue;
+        for ( n = 0; n < 2; n++ )
+            if ( pFans[n][0] == -1 )
+                pStops[iFans[n]] = (char)1, pFans[n][0] = pNode[0], pFans[n][1] = pNode[1], pFans[n][2] = pNode[2];
+            else if ( pFans[n][0] != pNode[0] || pFans[n][1] != pNode[1] || pFans[n][2] != pNode[2] )
+                pStops[iFans[n]] = (char)0;
+    }
+    pStops[0] = (char)0;
+    Gia_ManForEachCi( p, pObj, i )
+        pStops[Gia_ObjId(p, pObj)] = (char)0;
+    Gia_ManForEachAnd( p, pObj, i )
+        pStops[i] = (char)!pStops[i];      
+    Vec_IntFree( vTemps );    
+    return vStops;
+}
+
+/**Function*************************************************************
+
+  Synopsis    []
+
+  Description []
+               
+  SideEffects []
+
+  SeeAlso     []
+
+***********************************************************************/
+void Abc_FrameSetRetimingData( Abc_Frame_t * pAbc, int * pRst, int * pSet, int * pEna )
+{
+    Gia_Man_t * pGia;
+    if ( pAbc == NULL )
+        printf( "ABC framework is not initialized by calling Abc_Start()\n" );
+    pGia = Abc_FrameReadGia( pAbc );
+    if ( pGia == NULL )
+        printf( "Current network in ABC framework is not defined.\n" );
+    assert( pGia->vStopsF == NULL );
+    assert( pGia->vStopsB == NULL );
+    pGia->vStopsF = Gia_ManRetimableF( pGia, pRst, pSet, pEna );
+    pGia->vStopsB = Gia_ManRetimableB( pGia, pRst, pSet, pEna );    
+}
+
 ////////////////////////////////////////////////////////////////////////
 ///                       END OF FILE                                ///
 ////////////////////////////////////////////////////////////////////////
diff --git a/src/aig/gia/giaSif.c b/src/aig/gia/giaSif.c
index db7629fb3..c52ab4dd9 100644
--- a/src/aig/gia/giaSif.c
+++ b/src/aig/gia/giaSif.c
@@ -490,13 +490,16 @@ int Gia_ManSifCheckIter( Gia_Man_t * p, Vec_Int_t * vCuts, Vec_Int_t * vTimes, i
 }
 int Gia_ManSifCheckPeriod( Gia_Man_t * p, Vec_Int_t * vCuts, Vec_Int_t * vTimes, int nLutSize, int Period, int * pIters )
 {
-    Gia_Obj_t * pObj; int i, Id, nSize = nLutSize+1;
+    Gia_Obj_t * pObj; int i, Id, Stop, nSize = nLutSize+1;
     assert( Gia_ManRegNum(p) > 0 );
     Gia_ManForEachCiId( p, Id, i )
         Vec_IntWriteEntry( vCuts, Id*nSize, 1 );
     Gia_ManForEachCiId( p, Id, i )
         Vec_IntWriteEntry( vCuts, Id*nSize+1, Id << 8 );
     Vec_IntFill( vTimes, Gia_ManObjNum(p), -Period );
+    if ( p->vStopsF )
+        Vec_StrForEachEntry( p->vStopsF, Stop, i )
+            if ( Stop ) Vec_IntWriteEntry( vTimes, i, 0 );
     Vec_IntWriteEntry( vTimes, 0, 0 );
     Gia_ManForEachPi( p, pObj, i )
         Vec_IntWriteEntry( vTimes, Gia_ObjId(p, pObj), 0 );
@@ -510,6 +513,10 @@ int Gia_ManSifCheckPeriod( Gia_Man_t * p, Vec_Int_t * vCuts, Vec_Int_t * vTimes,
         Gia_ManForEachObj( p, pObj, i )
             if ( Vec_IntEntry(vTimes, Gia_ObjId(p, pObj)) > 2*Period )
                 return 0;
+        if ( p->vStopsB )
+            Vec_StrForEachEntry( p->vStopsB, Stop, i )
+                if ( Stop && Vec_IntEntry(vTimes, i) > Period )
+                    return 0;              
     }
     return 0;
 }
diff --git a/src/base/main/abcapis.h b/src/base/main/abcapis.h
index d34306baf..e1e05f4c7 100644
--- a/src/base/main/abcapis.h
+++ b/src/base/main/abcapis.h
@@ -106,6 +106,9 @@ extern ABC_DLL int *  Abc_FrameReadBoxes( Abc_Frame_t * pAbc );
 extern ABC_DLL int    Abc_FrameReadProbStatus( Abc_Frame_t * pAbc );   
 extern ABC_DLL void * Abc_FrameReadCex( Abc_Frame_t * pAbc );    
 
+// procedure to set retiming data
+extern ABC_DLL void   Abc_FrameSetRetimingData( Abc_Frame_t * pAbc, int * pRst, int * pSet, int * pEna );
+
 // procedure to return sequential equivalences
 extern ABC_DLL int *  Abc_FrameReadMiniAigEquivClasses( Abc_Frame_t * pAbc );