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/**CFile****************************************************************
FileName [ntlDfs.c]
SystemName [ABC: Logic synthesis and verification system.]
PackageName [Netlist representation.]
Synopsis [DFS traversal.]
Author [Alan Mishchenko]
Affiliation [UC Berkeley]
Date [Ver. 1.0. Started - June 20, 2005.]
Revision [$Id: ntlDfs.c,v 1.00 2005/06/20 00:00:00 alanmi Exp $]
***********************************************************************/
#include "ntl.h"
////////////////////////////////////////////////////////////////////////
/// DECLARATIONS ///
////////////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////////////
/// FUNCTION DEFINITIONS ///
////////////////////////////////////////////////////////////////////////
/**Function*************************************************************
Synopsis [Collects the nodes in a topological order.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
int Ntl_ManDfs_rec( Ntl_Man_t * p, Ntl_Net_t * pNet )
{
Ntl_Obj_t * pObj;
Ntl_Net_t * pNetFanin;
int i;
// skip visited
if ( pNet->nVisits == 2 )
return 1;
// if the node is on the path, this is a combinational loop
if ( pNet->nVisits == 1 )
return 0;
// mark the node as the one on the path
pNet->nVisits = 1;
// derive the box
pObj = pNet->pDriver;
assert( Ntl_ObjIsNode(pObj) || Ntl_ObjIsBox(pObj) );
// visit the input nets of the box
Ntl_ObjForEachFanin( pObj, pNetFanin, i )
if ( !Ntl_ManDfs_rec( p, pNetFanin ) )
return 0;
// add box inputs/outputs to COs/CIs
if ( Ntl_ObjIsBox(pObj) )
{
int LevelCur, LevelMax = -AIG_INFINITY;
Vec_IntPush( p->vBox1Cos, Aig_ManPoNum(p->pAig) );
Ntl_ObjForEachFanin( pObj, pNetFanin, i )
{
LevelCur = Aig_ObjLevel( Aig_Regular(pNetFanin->pFunc) );
LevelMax = AIG_MAX( LevelMax, LevelCur );
Vec_PtrPush( p->vCos, pNetFanin );
Aig_ObjCreatePo( p->pAig, pNetFanin->pFunc );
}
Ntl_ObjForEachFanout( pObj, pNetFanin, i )
{
Vec_PtrPush( p->vCis, pNetFanin );
pNetFanin->pFunc = Aig_ObjCreatePi( p->pAig );
Aig_ObjSetLevel( pNetFanin->pFunc, LevelMax + 1 );
}
//printf( "Creating fake PO with ID = %d.\n", Aig_ManPo(p->pAig, Vec_IntEntryLast(p->vBox1Cos))->Id );
}
// store the node
Vec_PtrPush( p->vNodes, pObj );
if ( Ntl_ObjIsNode(pObj) )
pNet->pFunc = Ntl_ManExtractAigNode( pObj );
pNet->nVisits = 2;
return 1;
}
/**Function*************************************************************
Synopsis [Performs DFS.]
Description [Checks for combinational loops. Collects PI/PO nets.
Collects nodes in the topological order.]
SideEffects []
SeeAlso []
***********************************************************************/
int Ntl_ManDfs( Ntl_Man_t * p )
{
Ntl_Mod_t * pRoot;
Ntl_Obj_t * pObj;
Ntl_Net_t * pNet;
int i, nUselessObjects;
assert( Vec_PtrSize(p->vCis) == 0 );
assert( Vec_PtrSize(p->vCos) == 0 );
assert( Vec_PtrSize(p->vNodes) == 0 );
assert( Vec_IntSize(p->vBox1Cos) == 0 );
// get the root model
pRoot = Vec_PtrEntry( p->vModels, 0 );
// collect primary inputs
Ntl_ModelForEachPi( pRoot, pObj, i )
{
assert( Ntl_ObjFanoutNum(pObj) == 1 );
pNet = Ntl_ObjFanout0(pObj);
Vec_PtrPush( p->vCis, pNet );
pNet->pFunc = Aig_ObjCreatePi( p->pAig );
if ( pNet->nVisits )
{
printf( "Ntl_ManDfs(): Primary input appears twice in the list.\n" );
return 0;
}
pNet->nVisits = 2;
}
// collect latch outputs
Ntl_ModelForEachLatch( pRoot, pObj, i )
{
assert( Ntl_ObjFanoutNum(pObj) == 1 );
pNet = Ntl_ObjFanout0(pObj);
Vec_PtrPush( p->vCis, pNet );
pNet->pFunc = Aig_ObjCreatePi( p->pAig );
if ( pNet->nVisits )
{
printf( "Ntl_ManDfs(): Latch output is duplicated or defined as a primary input.\n" );
return 0;
}
pNet->nVisits = 2;
}
// visit the nodes starting from primary outputs
Ntl_ModelForEachPo( pRoot, pObj, i )
{
pNet = Ntl_ObjFanin0(pObj);
if ( !Ntl_ManDfs_rec( p, pNet ) )
{
printf( "Ntl_ManDfs(): Error: Combinational loop is detected.\n" );
Vec_PtrClear( p->vCis );
Vec_PtrClear( p->vCos );
Vec_PtrClear( p->vNodes );
return 0;
}
Vec_PtrPush( p->vCos, pNet );
Aig_ObjCreatePo( p->pAig, pNet->pFunc );
}
// visit the nodes starting from latch inputs outputs
Ntl_ModelForEachLatch( pRoot, pObj, i )
{
pNet = Ntl_ObjFanin0(pObj);
if ( !Ntl_ManDfs_rec( p, pNet ) )
{
printf( "Ntl_ManDfs(): Error: Combinational loop is detected.\n" );
Vec_PtrClear( p->vCis );
Vec_PtrClear( p->vCos );
Vec_PtrClear( p->vNodes );
return 0;
}
Vec_PtrPush( p->vCos, pNet );
Aig_ObjCreatePo( p->pAig, pNet->pFunc );
}
// report the number of dangling objects
nUselessObjects = Ntl_ModelNodeNum(pRoot) + Ntl_ModelBoxNum(pRoot) - Vec_PtrSize(p->vNodes);
if ( nUselessObjects )
printf( "The number of nodes that do not feed into POs = %d.\n", nUselessObjects );
return 1;
}
////////////////////////////////////////////////////////////////////////
/// END OF FILE ///
////////////////////////////////////////////////////////////////////////
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