abcLatch.c

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/**CFile****************************************************************

  FileName    [abcLatch.c]

  SystemName  [ABC: Logic synthesis and verification system.]

  PackageName [Network and node package.]

  Synopsis    [Procedures working with latches.]

  Author      [Alan Mishchenko]
  
  Affiliation [UC Berkeley]

  Date        [Ver. 1.0. Started - June 20, 2005.]

  Revision    [$Id: abcLatch.c,v 1.00 2005/06/20 00:00:00 alanmi Exp $]

***********************************************************************/

#include "abc.h"
#include "misc/extra/extraBdd.h"

ABC_NAMESPACE_IMPL_START

////////////////////////////////////////////////////////////////////////
///                        DECLARATIONS                              ///
////////////////////////////////////////////////////////////////////////

////////////////////////////////////////////////////////////////////////
///                     FUNCTION DEFINITIONS                         ///
////////////////////////////////////////////////////////////////////////

/**Function*************************************************************

  Synopsis    [Checks if latches form self-loop.]

  Description []
               
  SideEffects []

  SeeAlso     []

***********************************************************************/
int Abc_NtkLatchIsSelfFeed_rec( Abc_Obj_t * pLatch, Abc_Obj_t * pLatchRoot )
{
    Abc_Obj_t * pFanin;
    assert( Abc_ObjIsLatch(pLatch) );
    if ( pLatch == pLatchRoot )
        return 1;
    pFanin = Abc_ObjFanin0(Abc_ObjFanin0(pLatch));
    if ( !Abc_ObjIsBo(pFanin) || !Abc_ObjIsLatch(Abc_ObjFanin0(pFanin)) )
        return 0;
    return Abc_NtkLatchIsSelfFeed_rec( Abc_ObjFanin0(pFanin), pLatch );
}

/**Function*************************************************************

  Synopsis    [Checks if latches form self-loop.]

  Description []
               
  SideEffects []

  SeeAlso     []

***********************************************************************/
int Abc_NtkLatchIsSelfFeed( Abc_Obj_t * pLatch )
{
    Abc_Obj_t * pFanin;
    assert( Abc_ObjIsLatch(pLatch) );
    pFanin = Abc_ObjFanin0(Abc_ObjFanin0(pLatch));
    if ( !Abc_ObjIsBo(pFanin) || !Abc_ObjIsLatch(Abc_ObjFanin0(pFanin)) )
        return 0;
    return Abc_NtkLatchIsSelfFeed_rec( Abc_ObjFanin0(pFanin), pLatch );
}

/**Function*************************************************************

  Synopsis    [Checks if latches form self-loop.]

  Description []
               
  SideEffects []

  SeeAlso     []

***********************************************************************/
int Abc_NtkCountSelfFeedLatches( Abc_Ntk_t * pNtk )
{
    Abc_Obj_t * pLatch;
    int i, Counter;
    Counter = 0;
    Abc_NtkForEachLatch( pNtk, pLatch, i )
    {
//        if ( Abc_NtkLatchIsSelfFeed(pLatch) && Abc_ObjFanoutNum(pLatch) > 1 )
//            printf( "Fanouts = %d.\n", Abc_ObjFanoutNum(pLatch) );
        Counter += Abc_NtkLatchIsSelfFeed( pLatch );
    }
    return Counter;
}

/**Function*************************************************************

  Synopsis    [Replaces self-feeding latches by latches with constant inputs.]

  Description []
               
  SideEffects []

  SeeAlso     []

***********************************************************************/
int Abc_NtkRemoveSelfFeedLatches( Abc_Ntk_t * pNtk )
{
    Abc_Obj_t * pLatch, * pConst1;
    int i, Counter;
    Counter = 0;
    Abc_NtkForEachLatch( pNtk, pLatch, i )
    {
        if ( Abc_NtkLatchIsSelfFeed( pLatch ) )
        {
            if ( Abc_NtkIsStrash(pNtk) )
                pConst1 = Abc_AigConst1(pNtk);
            else
                pConst1 = Abc_NtkCreateNodeConst1(pNtk);
            Abc_ObjPatchFanin( Abc_ObjFanin0(pLatch), Abc_ObjFanin0(Abc_ObjFanin0(pLatch)), pConst1 );
            Counter++;
        }
    }
    return Counter;
}

/**Function*************************************************************

  Synopsis    [Pipelines the network with latches.]

  Description []
               
  SideEffects [Does not check the names of the added latches!!!]

  SeeAlso     []

***********************************************************************/
void Abc_NtkLatchPipe( Abc_Ntk_t * pNtk, int nLatches )
{
    Vec_Ptr_t * vNodes;
    Abc_Obj_t * pObj, * pLatch, * pFanin, * pFanout;
    int i, k, nTotal, nDigits;
    if ( nLatches < 1 )
        return;
    nTotal = nLatches * Abc_NtkPiNum(pNtk);
    nDigits = Abc_Base10Log( nTotal );
    vNodes = Vec_PtrAlloc( 100 );
    Abc_NtkForEachPi( pNtk, pObj, i )
    {
        // remember current fanins of the PI
        Abc_NodeCollectFanouts( pObj, vNodes );
        // create the latches
        for ( pFanin = pObj, k = 0; k < nLatches; k++, pFanin = pLatch )
        {
            pLatch = Abc_NtkCreateLatch( pNtk );
            Abc_ObjAddFanin( pLatch, pFanin );
            Abc_LatchSetInitDc( pLatch );
            // create the name of the new latch
            Abc_ObjAssignName( pLatch, Abc_ObjNameDummy("LL", i*nLatches + k, nDigits), NULL );
        }
        // patch the PI fanouts
        Vec_PtrForEachEntry( Abc_Obj_t *, vNodes, pFanout, k )
            Abc_ObjPatchFanin( pFanout, pObj, pFanin );
    }
    Vec_PtrFree( vNodes );
    Abc_NtkLogicMakeSimpleCos( pNtk, 0 );
}

/**Function*************************************************************

  Synopsis    [Strashes one logic node using its SOP.]

  Description []
               
  SideEffects []

  SeeAlso     []

***********************************************************************/
Vec_Int_t * Abc_NtkCollectLatchValues( Abc_Ntk_t * pNtk )
{
    Vec_Int_t * vValues;
    Abc_Obj_t * pLatch;
    int i;
    vValues = Vec_IntAlloc( Abc_NtkLatchNum(pNtk) );
    Abc_NtkForEachLatch( pNtk, pLatch, i )
        Vec_IntPush( vValues, Abc_LatchIsInit1(pLatch) );
    return vValues;
}

/**Function*************************************************************

  Synopsis    [Derives latch init string.]

  Description []
               
  SideEffects []

  SeeAlso     []

***********************************************************************/
char * Abc_NtkCollectLatchValuesStr( Abc_Ntk_t * pNtk )
{
    char * pInits;
    Abc_Obj_t * pLatch;
    int i;
    pInits = ABC_ALLOC( char, Abc_NtkLatchNum(pNtk) + 1 );
    Abc_NtkForEachLatch( pNtk, pLatch, i )
    {
        if ( Abc_LatchIsInit0(pLatch) )
            pInits[i] = '0';
        else if ( Abc_LatchIsInit1(pLatch) )
            pInits[i] = '1';
        else if ( Abc_LatchIsInitDc(pLatch) )
            pInits[i] = 'x';
        else
            assert( 0 );
    }
    pInits[i] = 0;
    return pInits;
}

/**Function*************************************************************

  Synopsis    [Strashes one logic node using its SOP.]

  Description []
               
  SideEffects []

  SeeAlso     []

***********************************************************************/
void Abc_NtkInsertLatchValues( Abc_Ntk_t * pNtk, Vec_Int_t * vValues )
{
    Abc_Obj_t * pLatch;
    int i;
    Abc_NtkForEachLatch( pNtk, pLatch, i )
        pLatch->pData = (void *)(ABC_PTRINT_T)(vValues? (Vec_IntEntry(vValues,i)? ABC_INIT_ONE : ABC_INIT_ZERO) : ABC_INIT_DC);
}

/**Function*************************************************************

  Synopsis    [Creates latch with the given initial value.]

  Description []
               
  SideEffects []

  SeeAlso     []

***********************************************************************/
Abc_Obj_t * Abc_NtkAddLatch( Abc_Ntk_t * pNtk, Abc_Obj_t * pDriver, Abc_InitType_t Init )
{
    Abc_Obj_t * pLatchOut, * pLatch, * pLatchIn;
    pLatchOut = Abc_NtkCreateBo(pNtk);
    pLatch    = Abc_NtkCreateLatch(pNtk);
    pLatchIn  = Abc_NtkCreateBi(pNtk);
    Abc_ObjAssignName( pLatchOut, Abc_ObjName(pLatch), "_lo" );
    Abc_ObjAssignName( pLatchIn,  Abc_ObjName(pLatch), "_li" );
    Abc_ObjAddFanin( pLatchOut, pLatch );
    Abc_ObjAddFanin( pLatch, pLatchIn );
    if ( pDriver )
    Abc_ObjAddFanin( pLatchIn, pDriver );
    pLatch->pData = (void *)Init;
    return pLatchOut;
}

/**Function*************************************************************

  Synopsis    [Creates MUX.]

  Description []
               
  SideEffects []

  SeeAlso     []

***********************************************************************/
void Abc_NtkNodeConvertToMux( Abc_Ntk_t * pNtk, Abc_Obj_t * pNodeC, Abc_Obj_t * pNode1, Abc_Obj_t * pNode0, Abc_Obj_t * pMux )
{
    assert( Abc_NtkIsLogic(pNtk) );
    Abc_ObjAddFanin( pMux, pNodeC );
    Abc_ObjAddFanin( pMux, pNode1 );
    Abc_ObjAddFanin( pMux, pNode0 );
    if ( Abc_NtkHasSop(pNtk) )
        pMux->pData = Abc_SopRegister( (Mem_Flex_t *)pNtk->pManFunc, "11- 1\n0-1 1\n" );
    else if ( Abc_NtkHasBdd(pNtk) )
        pMux->pData = Cudd_bddIte((DdManager *)pNtk->pManFunc,Cudd_bddIthVar((DdManager *)pNtk->pManFunc,0),Cudd_bddIthVar((DdManager *)pNtk->pManFunc,1),Cudd_bddIthVar((DdManager *)pNtk->pManFunc,2)), Cudd_Ref( (DdNode *)pMux->pData );
    else if ( Abc_NtkHasAig(pNtk) )
        pMux->pData = Hop_Mux((Hop_Man_t *)pNtk->pManFunc,Hop_IthVar((Hop_Man_t *)pNtk->pManFunc,0),Hop_IthVar((Hop_Man_t *)pNtk->pManFunc,1),Hop_IthVar((Hop_Man_t *)pNtk->pManFunc,2));
    else
        assert( 0 );
}

/**Function*************************************************************

  Synopsis    [Converts registers with DC values into additional PIs.]

  Description []
               
  SideEffects []

  SeeAlso     []

***********************************************************************/
void Abc_NtkConvertDcLatches( Abc_Ntk_t * pNtk )
{
    Abc_Obj_t * pCtrl, * pLatch, * pMux, * pPi;
    Abc_InitType_t Init = ABC_INIT_ZERO;
    int i, fFound = 0, Counter;
    // check if there are latches with DC values
    Abc_NtkForEachLatch( pNtk, pLatch, i )
        if ( Abc_LatchIsInitDc(pLatch) )
        {
            fFound = 1;
            break;
        }
    if ( !fFound )
        return;
    // add control latch
    pCtrl = Abc_NtkAddLatch( pNtk, Abc_NtkCreateNodeConst1(pNtk), Init );
    // add fanouts for each latch with DC values
    Counter = 0;
    Abc_NtkForEachLatch( pNtk, pLatch, i )
    {
        if ( !Abc_LatchIsInitDc(pLatch) )
            continue;
        // change latch value
        pLatch->pData = (void *)Init;
        // if the latch output has the same name as a PO, rename it
        if ( Abc_NodeFindCoFanout( Abc_ObjFanout0(pLatch) ) )
        {
            Nm_ManDeleteIdName( pLatch->pNtk->pManName, Abc_ObjFanout0(pLatch)->Id );
            Abc_ObjAssignName( Abc_ObjFanout0(pLatch), Abc_ObjName(pLatch), "_lo" );
        }
        // create new PIs
        pPi = Abc_NtkCreatePi( pNtk );
        Abc_ObjAssignName( pPi, Abc_ObjName(pLatch), "_pi" );
        // create a new node and transfer fanout from latch output to the new node
        pMux = Abc_NtkCreateNode( pNtk );
        Abc_ObjTransferFanout( Abc_ObjFanout0(pLatch), pMux );
        // convert the node into a mux
        Abc_NtkNodeConvertToMux( pNtk, pCtrl, Abc_ObjFanout0(pLatch), pPi, pMux );
        Counter++;
    }
    printf( "The number of converted latches with DC values = %d.\n", Counter );
}

/**Function*************************************************************

  Synopsis    [Transfors the array of latch names into that of latch numbers.]

  Description []
               
  SideEffects []

  SeeAlso     []

***********************************************************************/
Vec_Ptr_t * Abc_NtkConverLatchNamesIntoNumbers( Abc_Ntk_t * pNtk )
{
    Vec_Ptr_t * vResult, * vNames;
    Vec_Int_t * vNumbers;
    Abc_Obj_t * pObj;
    char * pName;
    int i, k, Num;
    if ( pNtk->vOnehots == NULL )
        return NULL;
    // set register numbers
    Abc_NtkForEachLatch( pNtk, pObj, i )
        pObj->pNext = (Abc_Obj_t *)(ABC_PTRINT_T)i;
    // add the numbers
    vResult = Vec_PtrAlloc( Vec_PtrSize(pNtk->vOnehots) );
    Vec_PtrForEachEntry( Vec_Ptr_t *, pNtk->vOnehots, vNames, i )
    {
        vNumbers = Vec_IntAlloc( Vec_PtrSize(vNames) );
        Vec_PtrForEachEntry( char *, vNames, pName, k )
        {
            Num = Nm_ManFindIdByName( pNtk->pManName, pName, ABC_OBJ_BO );
            if ( Num < 0 )
                continue;
            pObj = Abc_NtkObj( pNtk, Num );
            if ( Abc_ObjFaninNum(pObj) != 1 || !Abc_ObjIsLatch(Abc_ObjFanin0(pObj)) )
                continue;
            Vec_IntPush( vNumbers, (int)(ABC_PTRINT_T)pObj->pNext );
        }
        if ( Vec_IntSize( vNumbers ) > 1 )
        {
            Vec_PtrPush( vResult, vNumbers );
printf( "Converted %d one-hot registers.\n", Vec_IntSize(vNumbers) );
        }
        else
            Vec_IntFree( vNumbers );
    }
    // clean the numbers
    Abc_NtkForEachLatch( pNtk, pObj, i )
        pObj->pNext = NULL;
    return vResult;
}


/**Function*************************************************************

  Synopsis    [Converts registers with DC values into additional PIs.]

  Description []
               
  SideEffects []

  SeeAlso     []

***********************************************************************/
Abc_Ntk_t * Abc_NtkConvertOnehot( Abc_Ntk_t * pNtk )
{
    Vec_Ptr_t * vNodes;
    Abc_Ntk_t * pNtkNew;
    Abc_Obj_t * pObj, * pFanin, * pObjNew, * pObjLiNew, * pObjLoNew;
    int i, k, nFlops, nStates, iState, pfCompl[32];
    assert( Abc_NtkIsLogic(pNtk) );
    nFlops = Abc_NtkLatchNum(pNtk);
    if ( nFlops == 0 )
        return Abc_NtkDup( pNtk );
    if ( nFlops > 16 )
    {
        printf( "Cannot reencode %d flops because it will lead to 2^%d states.\n", nFlops, nFlops );
        return NULL;
    }
    // check if there are latches with DC values
    iState = 0;
    Abc_NtkForEachLatch( pNtk, pObj, i )
    {
        if ( Abc_LatchIsInitDc(pObj) )
        {
            printf( "Cannot process logic network with don't-care init values. Run \"zero\".\n" );
            return NULL;
        }
        if ( Abc_LatchIsInit1(pObj) )
            iState |= (1 << i);
    }
    // transfer logic to SOPs
    Abc_NtkToSop( pNtk, 0 );
    // create new network
    pNtkNew = Abc_NtkStartFromNoLatches( pNtk, pNtk->ntkType, pNtk->ntkFunc );
    nStates = (1 << nFlops);
    for ( i = 0; i < nStates; i++ )
    {
        pObjNew   = Abc_NtkCreateLatch( pNtkNew );
        pObjLiNew = Abc_NtkCreateBi( pNtkNew );
        pObjLoNew = Abc_NtkCreateBo( pNtkNew );
        Abc_ObjAddFanin( pObjNew, pObjLiNew );
        Abc_ObjAddFanin( pObjLoNew, pObjNew );
        if ( i == iState )
            Abc_LatchSetInit1( pObjNew );
        else
            Abc_LatchSetInit0( pObjNew );
    }
    Abc_NtkAddDummyBoxNames( pNtkNew );
    assert( Abc_NtkLatchNum(pNtkNew) == nStates );
    assert( Abc_NtkPiNum(pNtkNew) == Abc_NtkPiNum(pNtk) );
    assert( Abc_NtkPoNum(pNtkNew) == Abc_NtkPoNum(pNtk) );
    assert( Abc_NtkCiNum(pNtkNew) == Abc_NtkPiNum(pNtkNew) + nStates );
    assert( Abc_NtkCoNum(pNtkNew) == Abc_NtkPoNum(pNtkNew) + nStates );
    assert( Abc_NtkCiNum(pNtk) == Abc_NtkPiNum(pNtk) + nFlops );
    assert( Abc_NtkCoNum(pNtk) == Abc_NtkPoNum(pNtk) + nFlops );
    // create hot-to-log transformers
    for ( i = 0; i < nFlops; i++ ) 
    {
        pObjNew = Abc_NtkCreateNode( pNtkNew );
        for ( k = 0; k < nStates; k++ )
            if ( (k >> i) & 1 )
                Abc_ObjAddFanin( pObjNew, Abc_NtkCi(pNtkNew, Abc_NtkPiNum(pNtkNew)+k) );
        assert( Abc_ObjFaninNum(pObjNew) == nStates/2 );
        pObjNew->pData = Abc_SopCreateOr( (Mem_Flex_t *)pNtkNew->pManFunc, nStates/2, NULL );
        // save the new flop
        pObj = Abc_NtkCi( pNtk, Abc_NtkPiNum(pNtk) + i );
        pObj->pCopy = pObjNew;
    }
    // duplicate the nodes
    vNodes = Abc_NtkDfs( pNtk, 0 );
    Vec_PtrForEachEntry( Abc_Obj_t *, vNodes, pObj, i )
    {
        pObj->pCopy = Abc_NtkDupObj( pNtkNew, pObj, 1 );
        Abc_ObjForEachFanin( pObj, pFanin, k )
            Abc_ObjAddFanin( pObj->pCopy, pFanin->pCopy );
    }
    Vec_PtrFree( vNodes );
    // connect the POs
    Abc_NtkForEachPo( pNtk, pObj, i )
        Abc_ObjAddFanin( pObj->pCopy, Abc_ObjNotCond(Abc_ObjFanin0(pObj)->pCopy, Abc_ObjFaninC0(pObj)) );
    // write entries into the nodes
    Abc_NtkForEachCo( pNtk, pObj, i )
        pObj->pCopy = Abc_ObjNotCond(Abc_ObjFanin0(pObj)->pCopy, Abc_ObjFaninC0(pObj));
    // create log-to-hot transformers
    for ( k = 0; k < nStates; k++ )
    {
        pObjNew = Abc_NtkCreateNode( pNtkNew );
        for ( i = 0; i < nFlops; i++ )
        {
            pObj = Abc_NtkCo( pNtk, Abc_NtkPoNum(pNtk) + i );
            Abc_ObjAddFanin( pObjNew, Abc_ObjRegular(pObj->pCopy) );
            pfCompl[i] = Abc_ObjIsComplement(pObj->pCopy) ^ !((k >> i) & 1);
        }
        pObjNew->pData = Abc_SopCreateAnd( (Mem_Flex_t *)pNtkNew->pManFunc, nFlops, pfCompl );
        // connect it to the flop input
        Abc_ObjAddFanin( Abc_NtkCo(pNtkNew, Abc_NtkPoNum(pNtkNew)+k), pObjNew );
    }
    if ( !Abc_NtkCheck( pNtkNew ) )
        fprintf( stdout, "Abc_NtkConvertOnehot(): Network check has failed.\n" );
    return pNtkNew;
}

ABC_NAMESPACE_IMPL_END

#include "aig/gia/giaAig.h"

ABC_NAMESPACE_IMPL_START


/**Function*************************************************************

  Synopsis    [Performs retiming with classes.]

  Description []
               
  SideEffects []

  SeeAlso     []

***********************************************************************/
Aig_Man_t * Abc_NtkRetimeWithClassesAig( Aig_Man_t * pMan, Vec_Int_t * vClasses, Vec_Int_t ** pvClasses, int fVerbose )
{
    Aig_Man_t * pManNew;
    Gia_Man_t * pGia, * pGiaNew;
    pGia = Gia_ManFromAigSimple( pMan );
    assert( Gia_ManRegNum(pGia) == Vec_IntSize(vClasses) );
    pGia->vFlopClasses = vClasses;
    pGiaNew = Gia_ManRetimeForward( pGia, 10, fVerbose );
    *pvClasses = pGiaNew->vFlopClasses; 
    pGiaNew->vFlopClasses = NULL;
    pManNew = Gia_ManToAig( pGiaNew, 0 );
    Gia_ManStop( pGiaNew );
    Gia_ManStop( pGia );
    return pManNew;
}

/**Function*************************************************************

  Synopsis    [Performs retiming with classes.]

  Description []
               
  SideEffects []

  SeeAlso     []

***********************************************************************/
Abc_Ntk_t * Abc_NtkRetimeWithClassesNtk( Abc_Ntk_t * pNtk, Vec_Int_t * vClasses, Vec_Int_t ** pvClasses, int fVerbose )
{
    extern Aig_Man_t * Abc_NtkToDar( Abc_Ntk_t * pNtk, int fExors, int fRegisters );
    extern Abc_Ntk_t * Abc_NtkFromDarSeqSweep( Abc_Ntk_t * pNtkOld, Aig_Man_t * pMan );
    Abc_Ntk_t * pNtkAig, * pNtkAigRet, * pNtkRes;
    Aig_Man_t * pMan, * pManNew;
    pNtkAig    = Abc_NtkStrash( pNtk, 0, 1, 0 );
    pMan       = Abc_NtkToDar( pNtkAig, 0, 1 );
    pManNew    = Abc_NtkRetimeWithClassesAig( pMan, vClasses, pvClasses, fVerbose );
    pNtkAigRet = Abc_NtkFromDarSeqSweep( pNtkAig, pManNew );
    pNtkRes    = Abc_NtkToLogic( pNtkAigRet );
    Abc_NtkDelete( pNtkAigRet );
    Abc_NtkDelete( pNtkAig );
    Aig_ManStop( pManNew );
    Aig_ManStop( pMan );
    return pNtkRes;
}

/**Function*************************************************************

  Synopsis    [Returns self-loops back into the network.]

  Description []
               
  SideEffects []

  SeeAlso     []

***********************************************************************/
void Abc_NtkTransformBack( Abc_Ntk_t * pNtkOld, Abc_Ntk_t * pNtkNew, Vec_Ptr_t * vControls, Vec_Int_t * vClasses )
{
    Abc_Obj_t * pObj, * pNodeNew, * pCtrl, * pDriver;
    int i, Class;
    assert( Abc_NtkPoNum(pNtkOld) == Abc_NtkPoNum(pNtkNew) );
    // match the POs of the old into new
    Abc_NtkForEachPo( pNtkOld, pObj, i )
        pObj->pCopy = Abc_NtkPo( pNtkNew, i );
    // remap the flops
    Vec_PtrForEachEntry( Abc_Obj_t *, vControls, pObj, i )
    {
        assert( Abc_ObjIsPo(pObj) && pObj->pNtk == pNtkOld );
        Vec_PtrWriteEntry( vControls, i, pObj->pCopy );
    }
    // create self-loops
    assert( Abc_NtkLatchNum(pNtkNew) == Vec_IntSize(vClasses) );
    Abc_NtkForEachLatch( pNtkNew, pObj, i )
    {
        Class = Vec_IntEntry( vClasses, i );
        if ( Class == -1 )
            continue;
        pDriver = Abc_ObjFanin0(Abc_ObjFanin0(pObj));
        pCtrl = (Abc_Obj_t *)Vec_PtrEntry( vControls, Class );
        pCtrl = Abc_ObjFanin0( pCtrl );
        pNodeNew = Abc_NtkCreateNode( pNtkNew );
        Abc_ObjAddFanin( pNodeNew, pCtrl );
        Abc_ObjAddFanin( pNodeNew, pDriver );
        Abc_ObjAddFanin( pNodeNew, Abc_ObjFanout0(pObj) );
        Abc_ObjSetData( pNodeNew, Abc_SopRegister((Mem_Flex_t *)pNtkNew->pManFunc, "0-1 1\n11- 1\n") );
        Abc_ObjPatchFanin( Abc_ObjFanin0(pObj), pDriver, pNodeNew );
    }
    // remove the useless POs
    Vec_PtrForEachEntry( Abc_Obj_t *, vControls, pObj, i )
        Abc_NtkDeleteObj( pObj );
}

/**Function*************************************************************

  Synopsis    [Classify flops.]

  Description []
               
  SideEffects []

  SeeAlso     []

***********************************************************************/
Abc_Ntk_t * Abc_NtkCRetime( Abc_Ntk_t * pNtk, int fVerbose )
{
    Abc_Ntk_t * pNtkNew;
    Vec_Ptr_t * vControls;
    Vec_Int_t * vFlopClasses, * vFlopClassesNew;
    Abc_Obj_t * pObj, * pDriver, * pFlopOut, * pObjPo;
    int i, iFlop, CountN = 0, Count2 = 0, Count1 = 0, Count0 = 0;

    // duplicate the AIG
    pNtk = Abc_NtkDup( pNtk );

    // update registers
    vControls    = Vec_PtrAlloc( 100 );
    vFlopClasses = Vec_IntAlloc( 100 );
    Abc_NtkForEachLatch( pNtk, pObj, i )
    {
        pFlopOut = Abc_ObjFanout0(pObj);
        pDriver = Abc_ObjFanin0( Abc_ObjFanin0(pObj) );
        if ( Abc_ObjFaninNum(pDriver) != 3 )
        {
            Vec_IntPush( vFlopClasses, -1 );
            CountN++;
            continue;
        }
        if ( Abc_ObjFanin(pDriver, 1) != pFlopOut && Abc_ObjFanin(pDriver, 2) != pFlopOut )
        {
            Vec_IntPush( vFlopClasses, -1 );
            Count2++;
            continue;
        }
        if ( Abc_ObjFanin(pDriver, 1) == pFlopOut )
        {
            Vec_IntPush( vFlopClasses, -1 );
            Count1++;
            continue;
        }
        assert( Abc_ObjFanin(pDriver, 2) == pFlopOut );
        Count0++;
        Vec_PtrPushUnique( vControls, Abc_ObjFanin0(pDriver) );
        // set the flop class
        iFlop = Vec_PtrFind( vControls, Abc_ObjFanin0(pDriver) );
        Vec_IntPush( vFlopClasses, iFlop );
        // update
        Abc_ObjPatchFanin( Abc_ObjFanin0(pObj), pDriver, Abc_ObjFanin(pDriver, 1) );
    }
    if ( Count1 )
        printf( "Opposite phase enable is present in %d flops (out of %d).\n", Count1, Abc_NtkLatchNum(pNtk) );
    if ( fVerbose )
    printf( "CountN = %4d. Count2 = %4d. Count1 = %4d. Count0 = %4d. Ctrls = %d.\n", 
        CountN, Count2, Count1, Count0, Vec_PtrSize(vControls) );

    // add the controls to the list of POs
    Vec_PtrForEachEntry( Abc_Obj_t *, vControls, pObj, i )
    {
        pObjPo = Abc_NtkCreatePo( pNtk );
        Abc_ObjAddFanin( pObjPo, pObj );
        Abc_ObjAssignName( pObjPo, Abc_ObjName(pObjPo), NULL );
        Vec_PtrWriteEntry( vControls, i, pObjPo );
    }
    Abc_NtkOrderCisCos( pNtk );
    Abc_NtkCleanup( pNtk, fVerbose );

    // performs retiming with classes
    pNtkNew = Abc_NtkRetimeWithClassesNtk( pNtk, vFlopClasses, &vFlopClassesNew, fVerbose );
    Abc_NtkTransformBack( pNtk, pNtkNew, vControls, vFlopClassesNew );
//    assert( Abc_NtkPoNum(pNtkNew) == Abc_NtkPoNum(pNtk) );
    Abc_NtkDelete( pNtk );

    Vec_PtrFree( vControls );
//    Vec_IntFree( vFlopClasses );
    Vec_IntFree( vFlopClassesNew );
    return pNtkNew;
}

/**Function*************************************************************

  Synopsis    [Resimulates CEX and return the ID of the PO that failed.]

  Description []
               
  SideEffects []

  SeeAlso     []

***********************************************************************/
int Abc_NtkVerifyCex( Abc_Ntk_t * pNtk, Abc_Cex_t * p )
{
    Abc_Obj_t * pObj;
    int RetValue, i, k, iBit = 0;
    assert( Abc_NtkIsStrash(pNtk) );
    assert( p->nPis  == Abc_NtkPiNum(pNtk) );
    assert( p->nRegs == Abc_NtkLatchNum(pNtk) );
    Abc_NtkCleanMarkC( pNtk );
    Abc_AigConst1(pNtk)->fMarkC = 1;
    // initialize flops
    Abc_NtkForEachLatch( pNtk, pObj, i )
        Abc_ObjFanout0(pObj)->fMarkC = Abc_InfoHasBit(p->pData, iBit++);
    // simulate timeframes
    for ( i = 0; i <= p->iFrame; i++ )
    {
        Abc_NtkForEachPi( pNtk, pObj, k )
            pObj->fMarkC = Abc_InfoHasBit(p->pData, iBit++);
        Abc_NtkForEachNode( pNtk, pObj, k )
            pObj->fMarkC = (Abc_ObjFanin0(pObj)->fMarkC ^ Abc_ObjFaninC0(pObj)) & 
                           (Abc_ObjFanin1(pObj)->fMarkC ^ Abc_ObjFaninC1(pObj));
        Abc_NtkForEachCo( pNtk, pObj, k )
            pObj->fMarkC = Abc_ObjFanin0(pObj)->fMarkC ^ Abc_ObjFaninC0(pObj);
        Abc_NtkForEachLatch( pNtk, pObj, k )
            Abc_ObjFanout0(pObj)->fMarkC = Abc_ObjFanin0(pObj)->fMarkC;
    }
    assert( iBit == p->nBits );
    // figure out the number of failed output
    RetValue = -1;
    Abc_NtkForEachPo( pNtk, pObj, i )
    {
        if ( pObj->fMarkC )
        {
            RetValue = i;
            break;
        }
    }
    Abc_NtkCleanMarkC( pNtk );
    return RetValue;
}

////////////////////////////////////////////////////////////////////////
///                       END OF FILE                                ///
////////////////////////////////////////////////////////////////////////


ABC_NAMESPACE_IMPL_END