abc/src/base/abci/abcBalance.c

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

  FileName    [abcBalance.c]

  SystemName  [ABC: Logic synthesis and verification system.]

  PackageName [Network and node package.]

  Synopsis    [Performs global balancing of the AIG by the number of levels.]

  Author      [Alan Mishchenko]
  
  Affiliation [UC Berkeley]

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

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

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

#include "abc.h"

////////////////////////////////////////////////////////////////////////
///                        DECLARATIONS                              ///
////////////////////////////////////////////////////////////////////////
 
static void        Abc_NtkBalancePerform( Abc_Ntk_t * pNtk, Abc_Ntk_t * pNtkAig, bool fDuplicate );
static Abc_Obj_t * Abc_NodeBalance_rec( Abc_Ntk_t * pNtkNew, Abc_Obj_t * pNode, Vec_Vec_t * vStorage, bool fDuplicate );
static Vec_Ptr_t * Abc_NodeBalanceCone( Abc_Obj_t * pNode, Vec_Vec_t * vSuper, int fDuplicate );
static int         Abc_NodeBalanceCone_rec( Abc_Obj_t * pNode, Vec_Ptr_t * vSuper, bool fFirst, bool fDuplicate );

////////////////////////////////////////////////////////////////////////
///                     FUNCTION DEFITIONS                           ///
////////////////////////////////////////////////////////////////////////

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

  Synopsis    [Balances the AIG network.]

  Description []
               
  SideEffects []

  SeeAlso     []

***********************************************************************/
Abc_Ntk_t * Abc_NtkBalance( Abc_Ntk_t * pNtk, bool fDuplicate )
{
    Abc_Ntk_t * pNtkAig;
    assert( Abc_NtkIsStrash(pNtk) );
    // perform balancing
    pNtkAig = Abc_NtkStartFrom( pNtk, ABC_TYPE_STRASH, ABC_FUNC_AIG );
    Abc_NtkBalancePerform( pNtk, pNtkAig, fDuplicate );
    Abc_NtkFinalize( pNtk, pNtkAig );
    // make sure everything is okay
    if ( !Abc_NtkCheck( pNtkAig ) )
    {
        printf( "Abc_NtkBalance: The network check has failed.\n" );
        Abc_NtkDelete( pNtkAig );
        return NULL;
    }
    return pNtkAig;
}

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

  Synopsis    [Balances the AIG network.]

  Description []
               
  SideEffects []

  SeeAlso     []

***********************************************************************/
void Abc_NtkBalancePerform( Abc_Ntk_t * pNtk, Abc_Ntk_t * pNtkAig, bool fDuplicate )
{
    int fCheck = 1;
    ProgressBar * pProgress;
    Vec_Vec_t * vStorage;
    Abc_Obj_t * pNode, * pDriver;
    int i;

    // copy the constant node
    Abc_AigConst1(pNtk->pManFunc)->pCopy = Abc_AigConst1(pNtkAig->pManFunc);
    // set the level of PIs of AIG according to the arrival times of the old network
    Abc_NtkSetNodeLevelsArrival( pNtk );
    // allocate temporary storage for supergates
    vStorage = Vec_VecStart( Abc_AigGetLevelNum(pNtk) + 1 );
    // perform balancing of POs
    pProgress = Extra_ProgressBarStart( stdout, Abc_NtkCoNum(pNtk) );
    Abc_NtkForEachCo( pNtk, pNode, i )
    {
        Extra_ProgressBarUpdate( pProgress, i, NULL );
        // strash the driver node
        pDriver = Abc_ObjFanin0(pNode);
        Abc_NodeBalance_rec( pNtkAig, pDriver, vStorage, fDuplicate );
    }
    Extra_ProgressBarStop( pProgress );
    Vec_VecFree( vStorage );
}

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

  Synopsis    [Rebalances the multi-input node rooted at pNodeOld.]

  Description []
               
  SideEffects []

  SeeAlso     []

***********************************************************************/
Abc_Obj_t * Abc_NodeBalance_rec( Abc_Ntk_t * pNtkNew, Abc_Obj_t * pNodeOld, Vec_Vec_t * vStorage, bool fDuplicate )
{
    Abc_Aig_t * pMan = pNtkNew->pManFunc;
    Abc_Obj_t * pNodeNew, * pNode1, * pNode2;
    Vec_Ptr_t * vSuper;
    int i;
    assert( !Abc_ObjIsComplement(pNodeOld) );
    // return if the result if known
    if ( pNodeOld->pCopy )
        return pNodeOld->pCopy;
    assert( Abc_ObjIsNode(pNodeOld) );
    // get the implication supergate
    vSuper = Abc_NodeBalanceCone( pNodeOld, vStorage, fDuplicate );
    if ( vSuper->nSize == 0 )
    { // it means that the supergate contains two nodes in the opposite polarity
        pNodeOld->pCopy = Abc_ObjNot(Abc_AigConst1(pMan));
        return pNodeOld->pCopy;
    }
    // for each old node, derive the new well-balanced node
    for ( i = 0; i < vSuper->nSize; i++ )
    {
        pNodeNew = Abc_NodeBalance_rec( pNtkNew, Abc_ObjRegular(vSuper->pArray[i]), vStorage, fDuplicate );
        vSuper->pArray[i] = Abc_ObjNotCond( pNodeNew, Abc_ObjIsComplement(vSuper->pArray[i]) );
    }
    // sort the new nodes by level in the decreasing order
    Vec_PtrSort( vSuper, Abc_NodeCompareLevelsDecrease );
    // balance the nodes
    assert( vSuper->nSize > 1 );
    while ( vSuper->nSize > 1 )
    {
        pNode1 = Vec_PtrPop(vSuper);
        pNode2 = Vec_PtrPop(vSuper);
        Abc_VecObjPushUniqueOrderByLevel( vSuper, Abc_AigAnd(pMan, pNode1, pNode2) );
    }
    // make sure the balanced node is not assigned
    assert( pNodeOld->pCopy == NULL );
    // mark the old node with the new node
    pNodeOld->pCopy = vSuper->pArray[0];
    return pNodeOld->pCopy;
}

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

  Synopsis    [Collects the nodes in the cone delimited by fMarkA==1.]

  Description [Returns -1 if the AND-cone has the same node in both polarities.
  Returns 1 if the AND-cone has the same node in the same polarity. Returns 0
  if the AND-cone has no repeated nodes.]
               
  SideEffects []

  SeeAlso     []

***********************************************************************/
Vec_Ptr_t * Abc_NodeBalanceCone( Abc_Obj_t * pNode, Vec_Vec_t * vStorage, int fDuplicate )
{
    Vec_Ptr_t * vNodes;
    int RetValue, i;
    assert( !Abc_ObjIsComplement(pNode) );
    vNodes = Vec_VecEntry( vStorage, pNode->Level );
    Vec_PtrClear( vNodes );
    RetValue = Abc_NodeBalanceCone_rec( pNode, vNodes, 1, fDuplicate );
    assert( vNodes->nSize > 0 );
    for ( i = 0; i < vNodes->nSize; i++ )
        Abc_ObjRegular((Abc_Obj_t *)vNodes->pArray[i])->fMarkB = 0;
    if ( RetValue == -1 )
        vNodes->nSize = 0;
    return vNodes;
}


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

  Synopsis    [Collects the nodes in the cone delimited by fMarkA==1.]

  Description [Returns -1 if the AND-cone has the same node in both polarities.
  Returns 1 if the AND-cone has the same node in the same polarity. Returns 0
  if the AND-cone has no repeated nodes.]
               
  SideEffects []

  SeeAlso     []

***********************************************************************/
int Abc_NodeBalanceCone_rec( Abc_Obj_t * pNode, Vec_Ptr_t * vSuper, bool fFirst, bool fDuplicate )
{
    int RetValue1, RetValue2, i;
    // check if the node is visited
    if ( Abc_ObjRegular(pNode)->fMarkB )
    {
        // check if the node occurs in the same polarity
        for ( i = 0; i < vSuper->nSize; i++ )
            if ( vSuper->pArray[i] == pNode )
                return 1;
        // check if the node is present in the opposite polarity
        for ( i = 0; i < vSuper->nSize; i++ )
            if ( vSuper->pArray[i] == Abc_ObjNot(pNode) )
                return -1;
        assert( 0 );
        return 0;
    }
    // if the new node is complemented or a PI, another gate begins
    if ( !fFirst && (Abc_ObjIsComplement(pNode) || !Abc_ObjIsNode(pNode) || !fDuplicate && (Abc_ObjFanoutNum(pNode) > 1)) )
    {
        Vec_PtrPush( vSuper, pNode );
        Abc_ObjRegular(pNode)->fMarkB = 1;
        return 0;
    }
    assert( !Abc_ObjIsComplement(pNode) );
    assert( Abc_ObjIsNode(pNode) );
    // go through the branches
    RetValue1 = Abc_NodeBalanceCone_rec( Abc_ObjChild0(pNode), vSuper, 0, fDuplicate );
    RetValue2 = Abc_NodeBalanceCone_rec( Abc_ObjChild1(pNode), vSuper, 0, fDuplicate );
    if ( RetValue1 == -1 || RetValue2 == -1 )
        return -1;
    // return 1 if at least one branch has a duplicate
    return RetValue1 || RetValue2;
}


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///                       END OF FILE                                ///
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