path: root/src/base/io/ioUtil.c

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

  FileName    [ioUtil.c]

  SystemName  [ABC: Logic synthesis and verification system.]

  PackageName [Command processing package.]

  Synopsis    [Procedures to write the network in BENCH format.]

  Author      [Alan Mishchenko]
  
  Affiliation [UC Berkeley]

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

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

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

#include "ioAbc.h"
#include "main.h"

ABC_NAMESPACE_IMPL_START


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

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

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

  Synopsis    [Returns the file type.]

  Description []
               
  SideEffects []

  SeeAlso     []

***********************************************************************/
Io_FileType_t Io_ReadFileType( char * pFileName )
{
    char * pExt;
    if ( pFileName == NULL )
        return IO_FILE_NONE;
    pExt = Extra_FileNameExtension( pFileName );
    if ( pExt == NULL )
        return IO_FILE_NONE;
    if ( !strcmp( pExt, "aig" ) )
        return IO_FILE_AIGER;
    if ( !strcmp( pExt, "baf" ) )
        return IO_FILE_BAF;
    if ( !strcmp( pExt, "bblif" ) )
        return IO_FILE_BBLIF;
    if ( !strcmp( pExt, "blif" ) )
        return IO_FILE_BLIF;
    if ( !strcmp( pExt, "bench" ) )
        return IO_FILE_BENCH;
    if ( !strcmp( pExt, "cnf" ) )
        return IO_FILE_CNF;
    if ( !strcmp( pExt, "dot" ) )
        return IO_FILE_DOT;
    if ( !strcmp( pExt, "edif" ) )
        return IO_FILE_EDIF;
    if ( !strcmp( pExt, "eqn" ) )
        return IO_FILE_EQN;
    if ( !strcmp( pExt, "gml" ) )
        return IO_FILE_GML;
    if ( !strcmp( pExt, "list" ) )
        return IO_FILE_LIST;
    if ( !strcmp( pExt, "mv" ) )
        return IO_FILE_BLIFMV;
    if ( !strcmp( pExt, "pla" ) )
        return IO_FILE_PLA;
    if ( !strcmp( pExt, "smv" ) )
        return IO_FILE_SMV;
    if ( !strcmp( pExt, "v" ) )
        return IO_FILE_VERILOG;
    return IO_FILE_UNKNOWN;
}

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

  Synopsis    [Read the network from a file.]

  Description []
               
  SideEffects []

  SeeAlso     []

***********************************************************************/
Abc_Ntk_t * Io_ReadNetlist( char * pFileName, Io_FileType_t FileType, int fCheck )
{
    FILE * pFile;
    Abc_Ntk_t * pNtk;
    if ( FileType == IO_FILE_NONE || FileType == IO_FILE_UNKNOWN )
    {
        fprintf( stdout, "The generic file reader requires a known file extension.\n" );
        return NULL;
    }
    // check if the file exists
    pFile = fopen( pFileName, "r" );
    if ( pFile == NULL )
    {
        fprintf( stdout, "Cannot open input file \"%s\". ", pFileName );
        if ( (pFileName = Extra_FileGetSimilarName( pFileName, ".blif", ".bench", ".pla", ".baf", ".aig" )) )
            fprintf( stdout, "Did you mean \"%s\"?", pFileName );
        fprintf( stdout, "\n" );
       return NULL;
    }
    fclose( pFile );
    // read the AIG
    if ( FileType == IO_FILE_AIGER || FileType == IO_FILE_BAF || FileType == IO_FILE_BBLIF )
    {
        if ( FileType == IO_FILE_AIGER )
            pNtk = Io_ReadAiger( pFileName, fCheck );
        else if ( FileType == IO_FILE_BAF )
            pNtk = Io_ReadBaf( pFileName, fCheck );
        else // if ( FileType == IO_FILE_BBLIF )
            pNtk = Io_ReadBblif( pFileName, fCheck );
        if ( pNtk == NULL )
        {
            fprintf( stdout, "Reading AIG from file has failed.\n" );
            return NULL;
        }
        return pNtk;
    }
    // read the new netlist
    if ( FileType == IO_FILE_BLIF )
//        pNtk = Io_ReadBlif( pFileName, fCheck );
        pNtk = Io_ReadBlifMv( pFileName, 0, fCheck );
    else if ( Io_ReadFileType(pFileName) == IO_FILE_BLIFMV )
        pNtk = Io_ReadBlifMv( pFileName, 1, fCheck );
    else if ( FileType == IO_FILE_BENCH )
        pNtk = Io_ReadBench( pFileName, fCheck );
    else if ( FileType == IO_FILE_EDIF )
        pNtk = Io_ReadEdif( pFileName, fCheck );
    else if ( FileType == IO_FILE_EQN )
        pNtk = Io_ReadEqn( pFileName, fCheck );
    else if ( FileType == IO_FILE_PLA )
        pNtk = Io_ReadPla( pFileName, 0, fCheck );
    else if ( FileType == IO_FILE_VERILOG )
        pNtk = Io_ReadVerilog( pFileName, fCheck );
    else 
    {
        fprintf( stderr, "Unknown file format.\n" );
        return NULL;
    }
    if ( pNtk == NULL )
    {
        fprintf( stdout, "Reading network from file has failed.\n" );
        return NULL;
    }
    if ( Abc_NtkBlackboxNum(pNtk) || Abc_NtkWhiteboxNum(pNtk) )
        fprintf( stdout, "Warning: The network contains hierarchy.\n" );
    return pNtk;
}

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

  Synopsis    []

  Description []
               
  SideEffects []

  SeeAlso     []

***********************************************************************/
Vec_Ptr_t *temporaryLtlStore( Abc_Ntk_t *pNtk )
{
    Vec_Ptr_t *tempStore;
    char *pFormula;
    int i;

    if( pNtk && Vec_PtrSize( pNtk->vLtlProperties ) > 0 )
    {
        tempStore = Vec_PtrAlloc( Vec_PtrSize( pNtk->vLtlProperties ) );
        Vec_PtrForEachEntry( char *, pNtk->vLtlProperties, pFormula, i )
            Vec_PtrPush( tempStore, pFormula );
        assert( Vec_PtrSize( tempStore ) == Vec_PtrSize( pNtk->vLtlProperties ) );
        return tempStore;
    }
    else
        return NULL;
}

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

  Synopsis    []

  Description []
               
  SideEffects []

  SeeAlso     []

***********************************************************************/
void updateLtlStoreOfNtk( Abc_Ntk_t *pNtk, Vec_Ptr_t *tempLtlStore )
{
    int i;
    char *pFormula;

    assert( tempLtlStore != NULL );
    Vec_PtrForEachEntry( char *, tempLtlStore, pFormula, i )
        Vec_PtrPush( pNtk->vLtlProperties, pFormula );
}

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

  Synopsis    [Read the network from a file.]

  Description []
               
  SideEffects []

  SeeAlso     []

***********************************************************************/
Abc_Ntk_t * Io_Read( char * pFileName, Io_FileType_t FileType, int fCheck )
{
    Abc_Ntk_t * pNtk, * pTemp;
    Vec_Ptr_t * vLtl;
    // get the netlist
    pNtk = Io_ReadNetlist( pFileName, FileType, fCheck );
    vLtl = temporaryLtlStore( pNtk );
    if ( pNtk == NULL )
        return NULL;
    if ( !Abc_NtkIsNetlist(pNtk) )
        return pNtk;
    // flatten logic hierarchy
    assert( Abc_NtkIsNetlist(pNtk) );
    if ( Abc_NtkWhiteboxNum(pNtk) > 0 )
    {
        pNtk = Abc_NtkFlattenLogicHierarchy( pTemp = pNtk );
        Abc_NtkDelete( pTemp );
        if ( pNtk == NULL )
        {
            fprintf( stdout, "Flattening logic hierarchy has failed.\n" );
            return NULL;
        }
    }
    // convert blackboxes
    if ( Abc_NtkBlackboxNum(pNtk) > 0 )
    {
        printf( "Hierarchy reader converted %d instances of blackboxes.\n", Abc_NtkBlackboxNum(pNtk) );
        pNtk = Abc_NtkConvertBlackboxes( pTemp = pNtk );
        Abc_NtkDelete( pTemp );
        if ( pNtk == NULL )
        {
            fprintf( stdout, "Converting blackboxes has failed.\n" );
            return NULL;
        }
    }
    // consider the case of BLIF-MV
    if ( Io_ReadFileType(pFileName) == IO_FILE_BLIFMV )
    {
//Abc_NtkPrintStats( stdout, pNtk, 0 );
//    Io_WriteBlifMv( pNtk, "_temp_.mv" );
        pNtk = Abc_NtkStrashBlifMv( pTemp = pNtk );
        Abc_NtkDelete( pTemp );
        if ( pNtk == NULL )
        {
            fprintf( stdout, "Converting BLIF-MV to AIG has failed.\n" );
            return NULL;
        }
        return pNtk;
    }
    // convert the netlist into the logic network
    pNtk = Abc_NtkToLogic( pTemp = pNtk );
    if( vLtl )
        updateLtlStoreOfNtk( pNtk, vLtl );
    Abc_NtkDelete( pTemp );
    if ( pNtk == NULL )
    {
        fprintf( stdout, "Converting netlist to logic network after reading has failed.\n" );
        return NULL;
    }
    return pNtk;
}

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

  Synopsis    [Write the network into file.]

  Description []
               
  SideEffects []

  SeeAlso     []

***********************************************************************/
void Io_Write( Abc_Ntk_t * pNtk, char * pFileName, Io_FileType_t FileType )
{
    Abc_Ntk_t * pNtkTemp, * pNtkCopy;
    // check if the current network is available
    if ( pNtk == NULL )
    {
        fprintf( stdout, "Empty network.\n" );
        return;
    }
    // check if the file extension if given
    if ( FileType == IO_FILE_NONE || FileType == IO_FILE_UNKNOWN )
    {
        fprintf( stdout, "The generic file writer requires a known file extension.\n" );
        return;
    }
    // write the AIG formats
    if ( FileType == IO_FILE_AIGER || FileType == IO_FILE_BAF )
    {
        if ( !Abc_NtkIsStrash(pNtk) )
        {
            fprintf( stdout, "Writing this format is only possible for structurally hashed AIGs.\n" );
            return;
        }
        if ( FileType == IO_FILE_AIGER )
            Io_WriteAiger( pNtk, pFileName, 1, 0 );
        else //if ( FileType == IO_FILE_BAF )
            Io_WriteBaf( pNtk, pFileName );
        return;
    }
    // write non-netlist types
    if ( FileType == IO_FILE_CNF )
    {
        Io_WriteCnf( pNtk, pFileName, 0 );
        return;
    }
    if ( FileType == IO_FILE_DOT )
    {
        Io_WriteDot( pNtk, pFileName );
        return;
    }
    if ( FileType == IO_FILE_GML )
    {
        Io_WriteGml( pNtk, pFileName );
        return;
    }
    if ( FileType == IO_FILE_BBLIF )
    {
        if ( !Abc_NtkIsLogic(pNtk) )
        {
            fprintf( stdout, "Writing Binary BLIF is only possible for logic networks.\n" );
            return;
        }
        if ( !Abc_NtkHasSop(pNtk) )
            Abc_NtkToSop( pNtk, 0 );
        Io_WriteBblif( pNtk, pFileName );
        return;
    }
/*
    if ( FileType == IO_FILE_BLIFMV )
    {
        Io_WriteBlifMv( pNtk, pFileName );
        return;
    }
*/
    // convert logic network into netlist
    if ( FileType == IO_FILE_PLA )
    {
        if ( Abc_NtkLevel(pNtk) > 1 )
        {
            fprintf( stdout, "PLA writing is available for collapsed networks.\n" );
            return;
        }
        if ( Abc_NtkIsComb(pNtk) )
            pNtkTemp = Abc_NtkToNetlist( pNtk );
        else
        {
            fprintf( stdout, "Latches are writen into the PLA file at PI/PO pairs.\n" );
            pNtkCopy = Abc_NtkDup( pNtk );
            Abc_NtkMakeComb( pNtkCopy, 0 );
            pNtkTemp = Abc_NtkToNetlist( pNtk );
            Abc_NtkDelete( pNtkCopy );
        }
        if ( !Abc_NtkToSop( pNtk, 1 ) )
            return;
    }
    else if ( FileType == IO_FILE_BENCH )
    {
        if ( !Abc_NtkIsStrash(pNtk) )
        {
            fprintf( stdout, "Writing traditional BENCH is available for AIGs only (use \"write_bench\").\n" );
            return;
        }
        pNtkTemp = Abc_NtkToNetlistBench( pNtk );
    }
    else if ( FileType == IO_FILE_SMV )
    {
        if ( !Abc_NtkIsStrash(pNtk) )
        {
            fprintf( stdout, "Writing traditional SMV is available for AIGs only.\n" );
            return;
        }
        pNtkTemp = Abc_NtkToNetlistBench( pNtk );
    }
    else
        pNtkTemp = Abc_NtkToNetlist( pNtk );

    if ( pNtkTemp == NULL )
    {
        fprintf( stdout, "Converting to netlist has failed.\n" );
        return;
    }

    if ( FileType == IO_FILE_BLIF )
    {
        if ( !Abc_NtkHasSop(pNtkTemp) && !Abc_NtkHasMapping(pNtkTemp) )
            Abc_NtkToSop( pNtkTemp, 0 );
        Io_WriteBlif( pNtkTemp, pFileName, 1, 0, 0 );
    }
    else if ( FileType == IO_FILE_BLIFMV )
    {
        if ( !Abc_NtkConvertToBlifMv( pNtkTemp ) )
            return;
        Io_WriteBlifMv( pNtkTemp, pFileName );
    }
    else if ( FileType == IO_FILE_BENCH )
        Io_WriteBench( pNtkTemp, pFileName );
    else if ( FileType == IO_FILE_BOOK )
        Io_WriteBook( pNtkTemp, pFileName );
    else if ( FileType == IO_FILE_PLA )
        Io_WritePla( pNtkTemp, pFileName );
    else if ( FileType == IO_FILE_EQN )
    {
        if ( !Abc_NtkHasAig(pNtkTemp) )
            Abc_NtkToAig( pNtkTemp );
        Io_WriteEqn( pNtkTemp, pFileName );
    }
    else if ( FileType == IO_FILE_SMV )
        Io_WriteSmv( pNtkTemp, pFileName );
    else if ( FileType == IO_FILE_VERILOG )
    {
        if ( !Abc_NtkHasAig(pNtkTemp) && !Abc_NtkHasMapping(pNtkTemp) )
            Abc_NtkToAig( pNtkTemp );
        Io_WriteVerilog( pNtkTemp, pFileName );
    }
    else 
        fprintf( stderr, "Unknown file format.\n" );
    Abc_NtkDelete( pNtkTemp );
}

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

  Synopsis    [Write the network into file.]

  Description []
               
  SideEffects []

  SeeAlso     []

***********************************************************************/
void Io_WriteHie( Abc_Ntk_t * pNtk, char * pBaseName, char * pFileName )
{
    Abc_Ntk_t * pNtkTemp, * pNtkResult, * pNtkBase = NULL;
    // check if the current network is available
    if ( pNtk == NULL )
    {
        fprintf( stdout, "Empty network.\n" );
        return;
    }

    // read the base network
    assert( Abc_NtkIsStrash(pNtk) || Abc_NtkIsLogic(pNtk) );
    if ( Io_ReadFileType(pBaseName) == IO_FILE_BLIF )
        pNtkBase = Io_ReadBlifMv( pBaseName, 0, 1 );
    else if ( Io_ReadFileType(pBaseName) == IO_FILE_BLIFMV )
        pNtkBase = Io_ReadBlifMv( pBaseName, 1, 1 );
    else if ( Io_ReadFileType(pBaseName) == IO_FILE_VERILOG )
        pNtkBase = Io_ReadVerilog( pBaseName, 1 );
    else 
        fprintf( stderr, "Unknown input file format.\n" );
    if ( pNtkBase == NULL )
        return;

    // flatten logic hierarchy if present
    if ( Abc_NtkWhiteboxNum(pNtkBase) > 0 )
    {
        pNtkBase = Abc_NtkFlattenLogicHierarchy( pNtkTemp = pNtkBase );
        if ( pNtkBase == NULL )
            return;
        Abc_NtkDelete( pNtkTemp );
    }

    // reintroduce the boxes into the netlist
    if ( Io_ReadFileType(pBaseName) == IO_FILE_BLIFMV ) 
    {
        if ( Abc_NtkBlackboxNum(pNtkBase) > 0 )
        {
            printf( "Hierarchy writer does not support BLIF-MV with blackboxes.\n" );
            Abc_NtkDelete( pNtkBase );
            return;
        }
        // convert the current network to BLIF-MV
        assert( !Abc_NtkIsNetlist(pNtk) );
        pNtkResult = Abc_NtkToNetlist( pNtk );
        if ( !Abc_NtkConvertToBlifMv( pNtkResult ) )
            return;
        // reintroduce the network
        pNtkResult = Abc_NtkInsertBlifMv( pNtkBase, pNtkTemp = pNtkResult );
        Abc_NtkDelete( pNtkTemp );
    }
    else if ( Abc_NtkBlackboxNum(pNtkBase) > 0 )
    {
        // derive the netlist
        pNtkResult = Abc_NtkToNetlist( pNtk );
        pNtkResult = Abc_NtkInsertNewLogic( pNtkBase, pNtkTemp = pNtkResult );
        Abc_NtkDelete( pNtkTemp );
        if ( pNtkResult )
            printf( "Hierarchy writer reintroduced %d instances of blackboxes.\n", Abc_NtkBlackboxNum(pNtkBase) );
    }
    else
    {
        printf( "Warning: The output network does not contain blackboxes.\n" );
        pNtkResult = Abc_NtkToNetlist( pNtk );
    }
    Abc_NtkDelete( pNtkBase );
    if ( pNtkResult == NULL )
        return;

    // write the resulting network
    if ( Io_ReadFileType(pFileName) == IO_FILE_BLIF )
    {
        if ( !Abc_NtkHasSop(pNtkResult) && !Abc_NtkHasMapping(pNtkResult) )
            Abc_NtkToSop( pNtkResult, 0 );
        Io_WriteBlif( pNtkResult, pFileName, 1, 0, 0 );
    }
    else if ( Io_ReadFileType(pFileName) == IO_FILE_VERILOG )
    {
        if ( !Abc_NtkHasAig(pNtkResult) && !Abc_NtkHasMapping(pNtkResult) )
            Abc_NtkToAig( pNtkResult );
        Io_WriteVerilog( pNtkResult, pFileName );
    }
    else if ( Io_ReadFileType(pFileName) == IO_FILE_BLIFMV )
    {
        Io_WriteBlifMv( pNtkResult, pFileName );
    }
    else 
        fprintf( stderr, "Unknown output file format.\n" );

    Abc_NtkDelete( pNtkResult );
}

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

  Synopsis    [Creates PI terminal and net.]

  Description []
               
  SideEffects []

  SeeAlso     []

***********************************************************************/
Abc_Obj_t * Io_ReadCreatePi( Abc_Ntk_t * pNtk, char * pName )
{
    Abc_Obj_t * pNet, * pTerm;
    // get the PI net
    pNet  = Abc_NtkFindNet( pNtk, pName );
    if ( pNet )
        printf( "Warning: PI \"%s\" appears twice in the list.\n", pName );
    pNet  = Abc_NtkFindOrCreateNet( pNtk, pName );
    // add the PI node
    pTerm = Abc_NtkCreatePi( pNtk );
    Abc_ObjAddFanin( pNet, pTerm );
    return pTerm;
}

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

  Synopsis    [Creates PO terminal and net.]

  Description []
               
  SideEffects []

  SeeAlso     []

***********************************************************************/
Abc_Obj_t * Io_ReadCreatePo( Abc_Ntk_t * pNtk, char * pName )
{
    Abc_Obj_t * pNet, * pTerm;
    // get the PO net
    pNet  = Abc_NtkFindNet( pNtk, pName );
    if ( pNet && Abc_ObjFaninNum(pNet) == 0 )
        printf( "Warning: PO \"%s\" appears twice in the list.\n", pName );
    pNet  = Abc_NtkFindOrCreateNet( pNtk, pName );
    // add the PO node
    pTerm = Abc_NtkCreatePo( pNtk );
    Abc_ObjAddFanin( pTerm, pNet );
    return pTerm;
}

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

  Synopsis    [Creates PO terminal and net.]

  Description []
               
  SideEffects []

  SeeAlso     []

***********************************************************************/
Abc_Obj_t * Io_ReadCreateAssert( Abc_Ntk_t * pNtk, char * pName )
{
    Abc_Obj_t * pNet, * pTerm;
    // get the PO net
    pNet  = Abc_NtkFindNet( pNtk, pName );
    if ( pNet && Abc_ObjFaninNum(pNet) == 0 )
        printf( "Warning: Assert \"%s\" appears twice in the list.\n", pName );
    pNet  = Abc_NtkFindOrCreateNet( pNtk, pName );
    // add the PO node
    pTerm = Abc_NtkCreateAssert( pNtk );
    Abc_ObjAddFanin( pTerm, pNet );
    return pTerm;
}

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

  Synopsis    [Create a latch with the given input/output.]

  Description [By default, the latch value is unknown (ABC_INIT_NONE).]
               
  SideEffects []

  SeeAlso     []

***********************************************************************/
Abc_Obj_t * Io_ReadCreateLatch( Abc_Ntk_t * pNtk, char * pNetLI, char * pNetLO )
{
    Abc_Obj_t * pLatch, * pTerm, * pNet;
    // get the LI net
    pNet = Abc_NtkFindOrCreateNet( pNtk, pNetLI );
    // add the BO terminal
    pTerm = Abc_NtkCreateBi( pNtk );
    Abc_ObjAddFanin( pTerm, pNet );
    // add the latch box
    pLatch = Abc_NtkCreateLatch( pNtk );
    Abc_ObjAddFanin( pLatch, pTerm  );
    // add the BI terminal
    pTerm = Abc_NtkCreateBo( pNtk );
    Abc_ObjAddFanin( pTerm, pLatch );
    // get the LO net
    pNet = Abc_NtkFindOrCreateNet( pNtk, pNetLO );
    Abc_ObjAddFanin( pNet, pTerm );
    // set latch name
    Abc_ObjAssignName( pLatch, pNetLO, "L" );
    return pLatch;
}

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

  Synopsis    [Create the reset latch with data=1 and init=0.]

  Description []
               
  SideEffects []

  SeeAlso     []

***********************************************************************/
Abc_Obj_t * Io_ReadCreateResetLatch( Abc_Ntk_t * pNtk, int fBlifMv )
{
    Abc_Obj_t * pLatch, * pNode;
    Abc_Obj_t * pNetLI, * pNetLO;
    // create latch with 0 init value
//    pLatch = Io_ReadCreateLatch( pNtk, "_resetLI_", "_resetLO_" );
    pNetLI = Abc_NtkCreateNet( pNtk );
    pNetLO = Abc_NtkCreateNet( pNtk );
    Abc_ObjAssignName( pNetLI, Abc_ObjName(pNetLI), NULL );
    Abc_ObjAssignName( pNetLO, Abc_ObjName(pNetLO), NULL );
    pLatch = Io_ReadCreateLatch( pNtk, Abc_ObjName(pNetLI), Abc_ObjName(pNetLO) );
    // set the initial value
    Abc_LatchSetInit0( pLatch );
    // feed the latch with constant1- node
//    pNode = Abc_NtkCreateNode( pNtk );   
//    pNode->pData = Abc_SopRegister( (Extra_MmFlex_t *)pNtk->pManFunc, "2\n1\n" );
    pNode = Abc_NtkCreateNodeConst1( pNtk );
    Abc_ObjAddFanin( Abc_ObjFanin0(Abc_ObjFanin0(pLatch)), pNode );
    return pLatch;
}

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

  Synopsis    [Create node and the net driven by it.]

  Description []
               
  SideEffects []

  SeeAlso     []

***********************************************************************/
Abc_Obj_t * Io_ReadCreateNode( Abc_Ntk_t * pNtk, char * pNameOut, char * pNamesIn[], int nInputs )
{
    Abc_Obj_t * pNet, * pNode;
    int i;
    // create a new node 
    pNode = Abc_NtkCreateNode( pNtk );
    // add the fanin nets
    for ( i = 0; i < nInputs; i++ )
    {
        pNet = Abc_NtkFindOrCreateNet( pNtk, pNamesIn[i] );
        Abc_ObjAddFanin( pNode, pNet );
    }
    // add the fanout net
    pNet = Abc_NtkFindOrCreateNet( pNtk, pNameOut );
    Abc_ObjAddFanin( pNet, pNode );
    return pNode;
}

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

  Synopsis    [Create a constant 0 node driving the net with this name.]

  Description [Assumes that the net already exists.]
               
  SideEffects []

  SeeAlso     []

***********************************************************************/
Abc_Obj_t * Io_ReadCreateConst( Abc_Ntk_t * pNtk, char * pName, int fConst1 )
{
    Abc_Obj_t * pNet, * pTerm;
    pTerm = fConst1? Abc_NtkCreateNodeConst1(pNtk) : Abc_NtkCreateNodeConst0(pNtk);
    pNet  = Abc_NtkFindNet(pNtk, pName);    assert( pNet );
    Abc_ObjAddFanin( pNet, pTerm );
    return pTerm;
}

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

  Synopsis    [Create an inverter or buffer for the given net.]

  Description [Assumes that the nets already exist.]
               
  SideEffects []

  SeeAlso     []

***********************************************************************/
Abc_Obj_t * Io_ReadCreateInv( Abc_Ntk_t * pNtk, char * pNameIn, char * pNameOut )
{
    Abc_Obj_t * pNet, * pNode;
    pNet  = Abc_NtkFindNet(pNtk, pNameIn);     assert( pNet );
    pNode = Abc_NtkCreateNodeInv(pNtk, pNet);
    pNet  = Abc_NtkFindNet(pNtk, pNameOut);    assert( pNet );
    Abc_ObjAddFanin( pNet, pNode );
    return pNode;
}

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

  Synopsis    [Create an inverter or buffer for the given net.]

  Description [Assumes that the nets already exist.]
               
  SideEffects []

  SeeAlso     []

***********************************************************************/
Abc_Obj_t * Io_ReadCreateBuf( Abc_Ntk_t * pNtk, char * pNameIn, char * pNameOut )
{
    Abc_Obj_t * pNet, * pNode;
    pNet  = Abc_NtkFindNet(pNtk, pNameIn);     assert( pNet );
    pNode = Abc_NtkCreateNodeBuf(pNtk, pNet);
    pNet  = Abc_NtkFindNet(pNtk, pNameOut);    assert( pNet );
    Abc_ObjAddFanin( pNet, pNode );
    return pNet;
}


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

  Synopsis    [Provide an fopen replacement with path lookup]

  Description [Provide an fopen replacement where the path stored
               in pathvar MVSIS variable is used to look up the path
               for name. Returns NULL if file cannot be opened.]
               
  SideEffects []

  SeeAlso     []

***********************************************************************/
FILE * Io_FileOpen( const char * FileName, const char * PathVar, const char * Mode, int fVerbose )
{
    char * t = 0, * c = 0, * i;

    if ( PathVar == 0 )
    {
        return fopen( FileName, Mode );
    }
    else
    {
        if ( (c = Abc_FrameReadFlag( (char*)PathVar )) )
        {
            char ActualFileName[4096];
            FILE * fp = 0;
            t = Extra_UtilStrsav( c );
            for (i = strtok( t, ":" ); i != 0; i = strtok( 0, ":") )
            {
#ifdef WIN32
                _snprintf ( ActualFileName, 4096, "%s/%s", i, FileName );
#else
                snprintf ( ActualFileName, 4096, "%s/%s", i, FileName );
#endif
                if ( ( fp = fopen ( ActualFileName, Mode ) ) )
                {
                    if ( fVerbose )
                    fprintf ( stdout, "Using file %s\n", ActualFileName );
                    ABC_FREE( t );
                    return fp;
                }
            }
            ABC_FREE( t );
            return 0;
        }
        else
        {
            return fopen( FileName, Mode );
        }
    }
}

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


ABC_NAMESPACE_IMPL_END