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+/**CFile****************************************************************
+
+ FileName [llb1Pivot.c]
+
+ SystemName [ABC: Logic synthesis and verification system.]
+
+ PackageName [BDD based reachability.]
+
+ Synopsis [Determining pivot variables.]
+
+ Author [Alan Mishchenko]
+
+ Affiliation [UC Berkeley]
+
+ Date [Ver. 1.0. Started - June 20, 2005.]
+
+ Revision [$Id: llb1Pivot.c,v 1.00 2005/06/20 00:00:00 alanmi Exp $]
+
+***********************************************************************/
+
+#include "llbInt.h"
+
+ABC_NAMESPACE_IMPL_START
+
+
+////////////////////////////////////////////////////////////////////////
+/// DECLARATIONS ///
+////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////
+/// FUNCTION DEFINITIONS ///
+////////////////////////////////////////////////////////////////////////
+
+/**Function*************************************************************
+
+ Synopsis []
+
+ Description []
+
+ SideEffects []
+
+ SeeAlso []
+
+***********************************************************************/
+int Llb_ManTracePaths_rec( Aig_Man_t * p, Aig_Obj_t * pObj, Aig_Obj_t * pPivot )
+{
+ Aig_Obj_t * pFanout;
+ int k, iFan;
+ if ( Aig_ObjIsTravIdPrevious(p, pObj) )
+ return 0;
+ if ( Aig_ObjIsTravIdCurrent(p, pObj) )
+ return 1;
+ if ( Saig_ObjIsLi(p, pObj) )
+ return 0;
+ if ( Saig_ObjIsPo(p, pObj) )
+ return 0;
+ if ( pObj == pPivot )
+ return 1;
+ assert( Aig_ObjIsCand(pObj) );
+ Aig_ObjForEachFanout( p, pObj, pFanout, iFan, k )
+ if ( !Llb_ManTracePaths_rec( p, pFanout, pPivot ) )
+ {
+ Aig_ObjSetTravIdPrevious(p, pObj);
+ return 0;
+ }
+ Aig_ObjSetTravIdCurrent(p, pObj);
+ return 1;
+}
+
+/**Function*************************************************************
+
+ Synopsis []
+
+ Description []
+
+ SideEffects []
+
+ SeeAlso []
+
+***********************************************************************/
+int Llb_ManTracePaths( Aig_Man_t * p, Aig_Obj_t * pPivot )
+{
+ Aig_Obj_t * pObj;
+ int i, Counter = 0;
+ Aig_ManIncrementTravId( p ); // prev = visited with path to LI (value 0)
+ Aig_ManIncrementTravId( p ); // cur = visited w/o path to LI (value 1)
+ Saig_ManForEachLo( p, pObj, i )
+ Counter += Llb_ManTracePaths_rec( p, pObj, pPivot );
+ return Counter;
+}
+
+/**Function*************************************************************
+
+ Synopsis []
+
+ Description []
+
+ SideEffects []
+
+ SeeAlso []
+
+***********************************************************************/
+void Llb_ManTestCuts( Aig_Man_t * p )
+{
+ Aig_Obj_t * pObj;
+ int i, Count;
+ Aig_ManFanoutStart( p );
+ Aig_ManForEachNode( p, pObj, i )
+ {
+ if ( Aig_ObjRefs(pObj) <= 1 )
+ continue;
+ Count = Llb_ManTracePaths( p, pObj );
+ printf( "Obj =%5d. Lev =%3d. Fanout =%5d. Count = %3d.\n",
+ i, Aig_ObjLevel(pObj), Aig_ObjRefs(pObj), Count );
+ }
+ Aig_ManFanoutStop( p );
+}
+
+/**Function*************************************************************
+
+ Synopsis []
+
+ Description []
+
+ SideEffects []
+
+ SeeAlso []
+
+***********************************************************************/
+void Llb_ManLabelLiCones_rec( Aig_Man_t * p, Aig_Obj_t * pObj )
+{
+ if ( pObj->fMarkB )
+ return;
+ pObj->fMarkB = 1;
+ assert( Aig_ObjIsNode(pObj) );
+ Llb_ManLabelLiCones_rec( p, Aig_ObjFanin0(pObj) );
+ Llb_ManLabelLiCones_rec( p, Aig_ObjFanin1(pObj) );
+}
+
+/**Function*************************************************************
+
+ Synopsis [Determine starting cut-points.]
+
+ Description []
+
+ SideEffects []
+
+ SeeAlso []
+
+***********************************************************************/
+void Llb_ManLabelLiCones( Aig_Man_t * p )
+{
+ Aig_Obj_t * pObj;
+ int i;
+ // mark const and PIs
+ Aig_ManConst1(p)->fMarkB = 1;
+ Aig_ManForEachPi( p, pObj, i )
+ pObj->fMarkB = 1;
+ // mark cones
+ Saig_ManForEachLi( p, pObj, i )
+ Llb_ManLabelLiCones_rec( p, Aig_ObjFanin0(pObj) );
+}
+
+/**Function*************************************************************
+
+ Synopsis [Determine starting cut-points.]
+
+ Description []
+
+ SideEffects []
+
+ SeeAlso []
+
+***********************************************************************/
+void Llb_ManMarkInternalPivots( Aig_Man_t * p )
+{
+ Vec_Ptr_t * vMuxes;
+ Aig_Obj_t * pObj;
+ int i, Counter = 0;
+
+ // remove refs due to MUXes
+ vMuxes = Aig_ManMuxesCollect( p );
+ Aig_ManMuxesDeref( p, vMuxes );
+
+ // mark nodes feeding into LIs
+ Aig_ManCleanMarkB( p );
+ Llb_ManLabelLiCones( p );
+
+ // mark internal nodes
+ Aig_ManFanoutStart( p );
+ Aig_ManForEachNode( p, pObj, i )
+ if ( pObj->fMarkB && pObj->nRefs > 1 )
+ {
+ if ( Llb_ManTracePaths(p, pObj) > 0 )
+ pObj->fMarkA = 1;
+ Counter++;
+ }
+ Aig_ManFanoutStop( p );
+// printf( "TracePath tried = %d.\n", Counter );
+
+ // mark nodes feeding into LIs
+ Aig_ManCleanMarkB( p );
+
+ // add refs due to MUXes
+ Aig_ManMuxesRef( p, vMuxes );
+ Vec_PtrFree( vMuxes );
+}
+
+/**Function*************************************************************
+
+ Synopsis [Determine starting cut-points.]
+
+ Description []
+
+ SideEffects []
+
+ SeeAlso []
+
+***********************************************************************/
+Vec_Int_t * Llb_ManMarkPivotNodes( Aig_Man_t * p, int fUseInternal )
+{
+ Vec_Int_t * vVar2Obj;
+ Aig_Obj_t * pObj;
+ int i;
+ // mark inputs/outputs
+ Aig_ManForEachPi( p, pObj, i )
+ pObj->fMarkA = 1;
+ Saig_ManForEachLi( p, pObj, i )
+ pObj->fMarkA = 1;
+
+ // mark internal pivot nodes
+ if ( fUseInternal )
+ Llb_ManMarkInternalPivots( p );
+
+ // assign variable numbers
+ Aig_ManConst1(p)->fMarkA = 0;
+ vVar2Obj = Vec_IntAlloc( 100 );
+ Aig_ManForEachPi( p, pObj, i )
+ Vec_IntPush( vVar2Obj, Aig_ObjId(pObj) );
+ Aig_ManForEachNode( p, pObj, i )
+ if ( pObj->fMarkA )
+ Vec_IntPush( vVar2Obj, Aig_ObjId(pObj) );
+ Saig_ManForEachLi( p, pObj, i )
+ Vec_IntPush( vVar2Obj, Aig_ObjId(pObj) );
+ return vVar2Obj;
+}
+
+////////////////////////////////////////////////////////////////////////
+/// END OF FILE ///
+////////////////////////////////////////////////////////////////////////
+
+
+ABC_NAMESPACE_IMPL_END
+