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/**CFile****************************************************************
FileName [saigRetFwd.c]
SystemName [ABC: Logic synthesis and verification system.]
PackageName [Sequential AIG package.]
Synopsis [Most-forward retiming.]
Author [Alan Mishchenko]
Affiliation [UC Berkeley]
Date [Ver. 1.0. Started - June 20, 2005.]
Revision [$Id: saigRetFwd.c,v 1.00 2005/06/20 00:00:00 alanmi Exp $]
***********************************************************************/
#include "saig.h"
ABC_NAMESPACE_IMPL_START
////////////////////////////////////////////////////////////////////////
/// DECLARATIONS ///
////////////////////////////////////////////////////////////////////////
static inline Aig_Obj_t * Aig_ObjFanoutStatic( Aig_Obj_t * pObj, int i ) { return ((Aig_Obj_t **)pObj->pData)[i]; }
static inline void Aig_ObjSetFanoutStatic( Aig_Obj_t * pObj, Aig_Obj_t * pFan ) { ((Aig_Obj_t **)pObj->pData)[pObj->nRefs++] = pFan; }
#define Aig_ObjForEachFanoutStatic( pObj, pFan, i ) \
for ( i = 0; (i < (int)(pObj)->nRefs) && ((pFan) = Aig_ObjFanoutStatic(pObj, i)); i++ )
////////////////////////////////////////////////////////////////////////
/// FUNCTION DEFINITIONS ///
////////////////////////////////////////////////////////////////////////
/**Function*************************************************************
Synopsis [Allocate static fanout for all nodes in the AIG manager.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
Aig_Obj_t ** Aig_ManStaticFanoutStart( Aig_Man_t * p )
{
Aig_Obj_t ** ppFanouts, * pObj;
int i, nFanouts, nFanoutsAlloc;
// allocate fanouts
nFanoutsAlloc = 2 * Aig_ManObjNumMax(p) - Aig_ManPiNum(p) - Aig_ManPoNum(p);
ppFanouts = ABC_ALLOC( Aig_Obj_t *, nFanoutsAlloc );
// mark up storage
nFanouts = 0;
Aig_ManForEachObj( p, pObj, i )
{
pObj->pData = ppFanouts + nFanouts;
nFanouts += pObj->nRefs;
pObj->nRefs = 0;
}
assert( nFanouts < nFanoutsAlloc );
// add fanouts
Aig_ManForEachObj( p, pObj, i )
{
if ( Aig_ObjChild0(pObj) )
Aig_ObjSetFanoutStatic( Aig_ObjFanin0(pObj), pObj );
if ( Aig_ObjChild1(pObj) )
Aig_ObjSetFanoutStatic( Aig_ObjFanin1(pObj), pObj );
}
return ppFanouts;
}
/**Function*************************************************************
Synopsis [Marks the objects reachable from the given object.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
void Aig_ManMarkAutonomous_rec( Aig_Man_t * p, Aig_Obj_t * pObj )
{
Aig_Obj_t * pFanout;
int i;
if ( Aig_ObjIsTravIdCurrent(p, pObj) )
return;
Aig_ObjSetTravIdCurrent(p, pObj);
Aig_ObjForEachFanoutStatic( pObj, pFanout, i )
Aig_ManMarkAutonomous_rec( p, pFanout );
}
/**Function*************************************************************
Synopsis [Marks with current trav ID nodes reachable from Const1 and PIs.]
Description [Returns the number of unreachable registers.]
SideEffects []
SeeAlso []
***********************************************************************/
void Saig_ManMarkAutonomous( Aig_Man_t * p )
{
Aig_Obj_t ** ppFanouts;
Aig_Obj_t * pObj, * pObjLi, * pObjLo;
int i;
// temporarily connect register outputs to register inputs
Saig_ManForEachLiLo( p, pObjLi, pObjLo, i )
{
pObjLo->pFanin0 = pObjLi;
pObjLi->nRefs = 1;
}
// mark nodes reachable from Const1 and PIs
Aig_ManIncrementTravId( p );
ppFanouts = Aig_ManStaticFanoutStart( p );
Aig_ManMarkAutonomous_rec( p, Aig_ManConst1(p) );
Saig_ManForEachPi( p, pObj, i )
Aig_ManMarkAutonomous_rec( p, pObj );
ABC_FREE( ppFanouts );
// disconnect LIs/LOs and label unreachable registers
Saig_ManForEachLiLo( p, pObjLi, pObjLo, i )
{
assert( pObjLo->pFanin0 && pObjLi->nRefs == 1 );
pObjLo->pFanin0 = NULL;
pObjLi->nRefs = 0;
}
}
/**Function*************************************************************
Synopsis [Derives the cut for forward retiming.]
Description [Assumes topological ordering of the nodes.]
SideEffects []
SeeAlso []
***********************************************************************/
Aig_Man_t * Saig_ManRetimeForwardOne( Aig_Man_t * p, int * pnRegFixed, int * pnRegMoves )
{
Aig_Man_t * pNew;
Vec_Ptr_t * vCut;
Aig_Obj_t * pObj, * pFanin;
int i;
// mark the retimable nodes
Saig_ManMarkAutonomous( p );
// mark the retimable registers with the fresh trav ID
Aig_ManIncrementTravId( p );
*pnRegFixed = 0;
Saig_ManForEachLo( p, pObj, i )
if ( Aig_ObjIsTravIdPrevious(p, pObj) )
Aig_ObjSetTravIdCurrent(p, pObj);
else
(*pnRegFixed)++;
// mark all the nodes that can be retimed forward
*pnRegMoves = 0;
Aig_ManForEachNode( p, pObj, i )
if ( Aig_ObjIsTravIdCurrent(p, Aig_ObjFanin0(pObj)) && Aig_ObjIsTravIdCurrent(p, Aig_ObjFanin1(pObj)) )
{
Aig_ObjSetTravIdCurrent(p, pObj);
(*pnRegMoves)++;
}
// mark the remaining registers
Saig_ManForEachLo( p, pObj, i )
Aig_ObjSetTravIdCurrent(p, pObj);
// find the cut (all such marked objects that fanout into unmarked nodes)
vCut = Vec_PtrAlloc( 1000 );
Aig_ManIncrementTravId( p );
Aig_ManForEachObj( p, pObj, i )
{
if ( Aig_ObjIsTravIdPrevious(p, pObj) )
continue;
pFanin = Aig_ObjFanin0(pObj);
if ( pFanin && Aig_ObjIsTravIdPrevious(p, pFanin) )
{
Vec_PtrPush( vCut, pFanin );
Aig_ObjSetTravIdCurrent( p, pFanin );
}
pFanin = Aig_ObjFanin1(pObj);
if ( pFanin && Aig_ObjIsTravIdPrevious(p, pFanin) )
{
Vec_PtrPush( vCut, pFanin );
Aig_ObjSetTravIdCurrent( p, pFanin );
}
}
// finally derive the new manager
pNew = Saig_ManRetimeDupForward( p, vCut );
Vec_PtrFree( vCut );
return pNew;
}
/**Function*************************************************************
Synopsis [Derives the cut for forward retiming.]
Description [Assumes topological ordering of the nodes.]
SideEffects []
SeeAlso []
***********************************************************************/
Aig_Man_t * Saig_ManRetimeForward( Aig_Man_t * p, int nMaxIters, int fVerbose )
{
Aig_Man_t * pNew, * pTemp;
int i, clk, nRegFixed, nRegMoves = 1;
pNew = p;
for ( i = 0; i < nMaxIters && nRegMoves > 0; i++ )
{
clk = clock();
pNew = Saig_ManRetimeForwardOne( pTemp = pNew, &nRegFixed, &nRegMoves );
if ( fVerbose )
{
printf( "%2d : And = %6d. Reg = %5d. Unret = %5d. Move = %6d. ",
i + 1, Aig_ManNodeNum(pTemp), Aig_ManRegNum(pTemp), nRegFixed, nRegMoves );
ABC_PRT( "Time", clock() - clk );
}
if ( pTemp != p )
Aig_ManStop( pTemp );
}
clk = clock();
pNew = Aig_ManReduceLaches( pNew, fVerbose );
if ( fVerbose )
{
ABC_PRT( "Register sharing time", clock() - clk );
}
return pNew;
}
////////////////////////////////////////////////////////////////////////
/// END OF FILE ///
////////////////////////////////////////////////////////////////////////
ABC_NAMESPACE_IMPL_END
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