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/**CFile****************************************************************
FileName [retIncrem.c]
SystemName [ABC: Logic synthesis and verification system.]
PackageName [Retiming package.]
Synopsis [Incremental retiming in one direction.]
Author [Alan Mishchenko]
Affiliation [UC Berkeley]
Date [Ver. 1.0. Started - Oct 31, 2006.]
Revision [$Id: retIncrem.c,v 1.00 2006/10/31 00:00:00 alanmi Exp $]
***********************************************************************/
#include "retInt.h"
////////////////////////////////////////////////////////////////////////
/// DECLARATIONS ///
////////////////////////////////////////////////////////////////////////
static int Abc_NtkRetimeOneWay( Abc_Ntk_t * pNtk, int fForward, int fVerbose );
////////////////////////////////////////////////////////////////////////
/// FUNCTION DEFINITIONS ///
////////////////////////////////////////////////////////////////////////
/**Function*************************************************************
Synopsis [Performs retiming in one direction.]
Description [Currently does not retime over black boxes.]
SideEffects []
SeeAlso []
***********************************************************************/
int Abc_NtkRetimeIncremental( Abc_Ntk_t * pNtk, int fForward, int fMinDelay, int fOneStep, int fVerbose )
{
Abc_Ntk_t * pNtkCopy = NULL;
Vec_Ptr_t * vBoxes;
st_table * tLatches;
int nLatches = Abc_NtkLatchNum(pNtk);
int nIdMaxStart = Abc_NtkObjNumMax(pNtk);
int RetValue;
int nIterLimit = -1; // Suppress "might be used uninitialized"
if ( Abc_NtkNodeNum(pNtk) == 0 )
return 0;
// reorder CI/CO/latch inputs
Abc_NtkOrderCisCos( pNtk );
if ( fMinDelay )
{
nIterLimit = fOneStep? 1 : 2 * Abc_NtkLevel(pNtk);
pNtkCopy = Abc_NtkDup( pNtk );
tLatches = Abc_NtkRetimePrepareLatches( pNtkCopy );
st_free_table( tLatches );
}
// collect latches and remove CIs/COs
tLatches = Abc_NtkRetimePrepareLatches( pNtk );
// share the latches
Abc_NtkRetimeShareLatches( pNtk, 0 );
// save boxes
vBoxes = pNtk->vBoxes; pNtk->vBoxes = NULL;
// perform the retiming
if ( fMinDelay )
Abc_NtkRetimeMinDelay( pNtk, pNtkCopy, nIterLimit, fForward, fVerbose );
else
Abc_NtkRetimeOneWay( pNtk, fForward, fVerbose );
if ( fMinDelay )
Abc_NtkDelete( pNtkCopy );
// share the latches
Abc_NtkRetimeShareLatches( pNtk, 0 );
// restore boxes
pNtk->vBoxes = vBoxes;
// finalize the latches
RetValue = Abc_NtkRetimeFinalizeLatches( pNtk, tLatches, nIdMaxStart );
st_free_table( tLatches );
if ( RetValue == 0 )
return 0;
// fix the COs
// Abc_NtkLogicMakeSimpleCos( pNtk, 0 );
// check for correctness
if ( !Abc_NtkCheck( pNtk ) )
fprintf( stdout, "Abc_NtkRetimeForward(): Network check has failed.\n" );
// return the number of latches saved
return nLatches - Abc_NtkLatchNum(pNtk);
}
/**Function*************************************************************
Synopsis [Prepares the network for retiming.]
Description [Hash latches into their number in the original network.]
SideEffects []
SeeAlso []
***********************************************************************/
st_table * Abc_NtkRetimePrepareLatches( Abc_Ntk_t * pNtk )
{
st_table * tLatches;
Abc_Obj_t * pLatch, * pLatchIn, * pLatchOut, * pFanin;
int i, nOffSet = Abc_NtkBoxNum(pNtk) - Abc_NtkLatchNum(pNtk);
// collect latches and remove CIs/COs
tLatches = st_init_table( st_ptrcmp, st_ptrhash );
Abc_NtkForEachLatch( pNtk, pLatch, i )
{
// map latch into its true number
st_insert( tLatches, (void *)(ABC_PTRUINT_T)pLatch, (void *)(ABC_PTRUINT_T)(i-nOffSet) );
// disconnect LI
pLatchIn = Abc_ObjFanin0(pLatch);
pFanin = Abc_ObjFanin0(pLatchIn);
Abc_ObjTransferFanout( pLatchIn, pFanin );
Abc_ObjDeleteFanin( pLatchIn, pFanin );
// disconnect LO
pLatchOut = Abc_ObjFanout0(pLatch);
pFanin = Abc_ObjFanin0(pLatchOut);
if ( Abc_ObjFanoutNum(pLatchOut) > 0 )
Abc_ObjTransferFanout( pLatchOut, pFanin );
Abc_ObjDeleteFanin( pLatchOut, pFanin );
}
return tLatches;
}
/**Function*************************************************************
Synopsis [Finalizes the latches after retiming.]
Description [Reuses the LIs/LOs for old latches.]
SideEffects []
SeeAlso []
***********************************************************************/
int Abc_NtkRetimeFinalizeLatches( Abc_Ntk_t * pNtk, st_table * tLatches, int nIdMaxStart )
{
Vec_Ptr_t * vCisOld, * vCosOld, * vBoxesOld, * vCisNew, * vCosNew, * vBoxesNew;
Abc_Obj_t * pObj, * pLatch, * pLatchIn, * pLatchOut;
int i, Index;
// create new arrays
vCisOld = pNtk->vCis; pNtk->vCis = NULL; vCisNew = Vec_PtrAlloc( 100 );
vCosOld = pNtk->vCos; pNtk->vCos = NULL; vCosNew = Vec_PtrAlloc( 100 );
vBoxesOld = pNtk->vBoxes; pNtk->vBoxes = NULL; vBoxesNew = Vec_PtrAlloc( 100 );
// copy boxes and their CIs/COs
Vec_PtrForEachEntryStop( vCisOld, pObj, i, Vec_PtrSize(vCisOld) - st_count(tLatches) )
Vec_PtrPush( vCisNew, pObj );
Vec_PtrForEachEntryStop( vCosOld, pObj, i, Vec_PtrSize(vCosOld) - st_count(tLatches) )
Vec_PtrPush( vCosNew, pObj );
Vec_PtrForEachEntryStop( vBoxesOld, pObj, i, Vec_PtrSize(vBoxesOld) - st_count(tLatches) )
Vec_PtrPush( vBoxesNew, pObj );
// go through the latches
Abc_NtkForEachObj( pNtk, pLatch, i )
{
if ( !Abc_ObjIsLatch(pLatch) )
continue;
if ( Abc_ObjId(pLatch) >= (unsigned)nIdMaxStart )
{
// this is a new latch
pLatchIn = Abc_NtkCreateBi(pNtk);
pLatchOut = Abc_NtkCreateBo(pNtk);
Abc_ObjAssignName( pLatchOut, Abc_ObjName(pLatch), "_out" );
Abc_ObjAssignName( pLatchIn, Abc_ObjName(pLatch), "_in" );
}
else
{
// this is an old latch
// get its number in the original order
if ( !st_lookup( tLatches, (char *)pLatch, (char **)&Index ) )
{
printf( "Abc_NtkRetimeFinalizeLatches(): Internal error.\n" );
return 0;
}
assert( pLatch == Vec_PtrEntry(vBoxesOld, Vec_PtrSize(vBoxesOld) - st_count(tLatches) + Index) );
// reconnect with the old LIs/LOs
pLatchIn = Vec_PtrEntry( vCosOld, Vec_PtrSize(vCosOld) - st_count(tLatches) + Index );
pLatchOut = Vec_PtrEntry( vCisOld, Vec_PtrSize(vCisOld) - st_count(tLatches) + Index );
}
// connect
Abc_ObjAddFanin( pLatchIn, Abc_ObjFanin0(pLatch) );
Abc_ObjPatchFanin( pLatch, Abc_ObjFanin0(pLatch), pLatchIn );
if ( Abc_ObjFanoutNum(pLatch) > 0 )
Abc_ObjTransferFanout( pLatch, pLatchOut );
Abc_ObjAddFanin( pLatchOut, pLatch );
// add to the arrays
Vec_PtrPush( vCisNew, pLatchOut );
Vec_PtrPush( vCosNew, pLatchIn );
Vec_PtrPush( vBoxesNew, pLatch );
}
// ABC_FREE useless Cis/Cos
Vec_PtrForEachEntry( vCisOld, pObj, i )
if ( !Abc_ObjIsPi(pObj) && Abc_ObjFaninNum(pObj) == 0 && Abc_ObjFanoutNum(pObj) == 0 )
Abc_NtkDeleteObj(pObj);
Vec_PtrForEachEntry( vCosOld, pObj, i )
if ( !Abc_ObjIsPo(pObj) && Abc_ObjFaninNum(pObj) == 0 && Abc_ObjFanoutNum(pObj) == 0 )
Abc_NtkDeleteObj(pObj);
// set the new arrays
pNtk->vCis = vCisNew; Vec_PtrFree( vCisOld );
pNtk->vCos = vCosNew; Vec_PtrFree( vCosOld );
pNtk->vBoxes = vBoxesNew; Vec_PtrFree( vBoxesOld );
return 1;
}
/**Function*************************************************************
Synopsis [Performs retiming one way, forward or backward.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
int Abc_NtkRetimeOneWay( Abc_Ntk_t * pNtk, int fForward, int fVerbose )
{
Abc_Ntk_t * pNtkNew = NULL; // Suppress "might be used uninitialized"
Vec_Int_t * vValues = NULL; // Suppress "might be used uninitialized"
Abc_Obj_t * pObj;
int i, fChanges, nTotalMoves = 0, nTotalMovesLimit = 10000;
if ( fForward )
Abc_NtkRetimeTranferToCopy( pNtk );
else
{
// save initial values of the latches
vValues = Abc_NtkRetimeCollectLatchValues( pNtk );
// start the network for initial value computation
pNtkNew = Abc_NtkRetimeBackwardInitialStart( pNtk );
}
// try to move latches forward whenever possible
do {
fChanges = 0;
Abc_NtkForEachObj( pNtk, pObj, i )
{
if ( !Abc_ObjIsNode(pObj) )
continue;
if ( Abc_NtkRetimeNodeIsEnabled( pObj, fForward ) )
{
Abc_NtkRetimeNode( pObj, fForward, 1 );
fChanges = 1;
nTotalMoves++;
if ( nTotalMoves >= nTotalMovesLimit )
{
printf( "Stopped after %d latch moves.\n", nTotalMoves );
break;
}
}
}
} while ( fChanges && nTotalMoves < nTotalMovesLimit );
// transfer the initial state back to the latches
if ( fForward )
Abc_NtkRetimeTranferFromCopy( pNtk );
else
{
Abc_NtkRetimeBackwardInitialFinish( pNtk, pNtkNew, vValues, fVerbose );
Abc_NtkDelete( pNtkNew );
Vec_IntFree( vValues );
}
return 0;
}
/**Function*************************************************************
Synopsis [Returns 1 if retiming forward/backward is possible.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
int Abc_NtkRetimeNodeIsEnabled( Abc_Obj_t * pObj, int fForward )
{
Abc_Obj_t * pNext;
int i;
assert( Abc_ObjIsNode(pObj) );
if ( fForward )
{
Abc_ObjForEachFanin( pObj, pNext, i )
if ( !Abc_ObjIsLatch(pNext) )
return 0;
}
else
{
Abc_ObjForEachFanout( pObj, pNext, i )
if ( !Abc_ObjIsLatch(pNext) )
return 0;
}
return 1;
}
/**Function*************************************************************
Synopsis [Retimes the node backward or forward.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
void Abc_NtkRetimeNode( Abc_Obj_t * pObj, int fForward, int fInitial )
{
Abc_Ntk_t * pNtkNew = NULL;
Vec_Ptr_t * vNodes;
Abc_Obj_t * pNext, * pLatch;
int i;
vNodes = Vec_PtrAlloc( 10 );
if ( fForward )
{
// compute the initial value
if ( fInitial )
pObj->pCopy = (void *)(ABC_PTRUINT_T)Abc_ObjSopSimulate( pObj );
// collect fanins
Abc_NodeCollectFanins( pObj, vNodes );
// make the node point to the fanins fanins
Vec_PtrForEachEntry( vNodes, pNext, i )
{
assert( Abc_ObjIsLatch(pNext) );
Abc_ObjPatchFanin( pObj, pNext, Abc_ObjFanin0(pNext) );
if ( Abc_ObjFanoutNum(pNext) == 0 )
Abc_NtkDeleteObj(pNext);
}
// add a new latch on top
pNext = Abc_NtkCreateLatch(pObj->pNtk);
if ( Abc_ObjFanoutNum(pObj) > 0 )
Abc_ObjTransferFanout( pObj, pNext );
Abc_ObjAddFanin( pNext, pObj );
// set the initial value
if ( fInitial )
pNext->pCopy = pObj->pCopy;
}
else
{
// compute the initial value
if ( fInitial )
{
pNtkNew = Abc_ObjFanout0(pObj)->pCopy->pNtk;
Abc_NtkDupObj( pNtkNew, pObj, 0 );
Abc_ObjForEachFanout( pObj, pNext, i )
{
assert( Abc_ObjFaninNum(pNext->pCopy) == 0 );
Abc_ObjAddFanin( pNext->pCopy, pObj->pCopy );
}
}
// collect fanouts
Abc_NodeCollectFanouts( pObj, vNodes );
// make the fanouts fanouts point to the node
Vec_PtrForEachEntry( vNodes, pNext, i )
{
assert( Abc_ObjIsLatch(pNext) );
Abc_ObjTransferFanout( pNext, pObj );
Abc_NtkDeleteObj( pNext );
}
// add new latches to the fanins
Abc_ObjForEachFanin( pObj, pNext, i )
{
pLatch = Abc_NtkCreateLatch(pObj->pNtk);
Abc_ObjPatchFanin( pObj, pNext, pLatch );
Abc_ObjAddFanin( pLatch, pNext );
// create buffer isomorphic to this latch
if ( fInitial )
{
pLatch->pCopy = Abc_NtkCreateNodeBuf( pNtkNew, NULL );
Abc_ObjAddFanin( pObj->pCopy, pLatch->pCopy );
}
}
}
Vec_PtrFree( vNodes );
}
/**Function*************************************************************
Synopsis [Returns the number of compatible fanout latches.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
int Abc_NtkRetimeCheckCompatibleLatchFanouts( Abc_Obj_t * pObj )
{
Abc_Obj_t * pFanout;
int i, nLatches = 0, Init = -1;
Abc_ObjForEachFanout( pObj, pFanout, i )
{
if ( !Abc_ObjIsLatch(pFanout) )
continue;
if ( Init == -1 )
{
Init = (int)(ABC_PTRUINT_T)pObj->pData;
nLatches++;
}
else if ( Init == (int)(ABC_PTRUINT_T)pObj->pData )
nLatches++;
}
return nLatches;
}
/**Function*************************************************************
Synopsis [Retimes the node backward or forward.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
void Abc_NtkRetimeShareLatches( Abc_Ntk_t * pNtk, int fInitial )
{
Vec_Ptr_t * vNodes;
Abc_Obj_t * pFanin, * pLatchTop, * pLatchCur;
int i, k;
vNodes = Vec_PtrAlloc( 10 );
// consider latch fanins
Abc_NtkForEachObj( pNtk, pFanin, i )
{
if ( Abc_NtkRetimeCheckCompatibleLatchFanouts(pFanin) <= 1 )
continue;
// get the first latch
pLatchTop = NULL;
Abc_ObjForEachFanout( pFanin, pLatchTop, k )
if ( Abc_ObjIsLatch(pLatchTop) )
break;
assert( pLatchTop && Abc_ObjIsLatch(pLatchTop) );
// redirect compatible fanout latches to the first latch
Abc_NodeCollectFanouts( pFanin, vNodes );
Vec_PtrForEachEntry( vNodes, pLatchCur, k )
{
if ( !Abc_ObjIsLatch(pLatchCur) )
continue;
if ( pLatchCur == pLatchTop )
continue;
if ( pLatchCur->pData != pLatchTop->pData )
continue;
// connect the initial state
if ( fInitial )
Abc_ObjAddFanin( pLatchCur->pCopy, pLatchTop->pCopy );
// redirect the fanouts
Abc_ObjTransferFanout( pLatchCur, pLatchTop );
Abc_NtkDeleteObj(pLatchCur);
}
}
Vec_PtrFree( vNodes );
}
////////////////////////////////////////////////////////////////////////
/// END OF FILE ///
////////////////////////////////////////////////////////////////////////
|
