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/**CFile****************************************************************
FileName [seqShare.c]
SystemName [ABC: Logic synthesis and verification system.]
PackageName [Construction and manipulation of sequential AIGs.]
Synopsis [Latch sharing at the fanout stems.]
Author [Alan Mishchenko]
Affiliation [UC Berkeley]
Date [Ver. 1.0. Started - June 20, 2005.]
Revision [$Id: seqShare.c,v 1.00 2005/06/20 00:00:00 alanmi Exp $]
***********************************************************************/
#include "seqInt.h"
////////////////////////////////////////////////////////////////////////
/// DECLARATIONS ///
////////////////////////////////////////////////////////////////////////
static void Seq_NodeShareFanouts( Abc_Obj_t * pNode, Vec_Ptr_t * vNodes );
static void Seq_NodeShareOne( Abc_Obj_t * pNode, Abc_InitType_t Init, Vec_Ptr_t * vNodes );
////////////////////////////////////////////////////////////////////////
/// FUNCTION DEFINITIONS ///
////////////////////////////////////////////////////////////////////////
/**Function*************************************************************
Synopsis [Transforms the sequential AIG to take fanout sharing into account.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
void Seq_NtkShareFanouts( Abc_Ntk_t * pNtk )
{
Vec_Ptr_t * vNodes;
Abc_Obj_t * pObj;
int i;
vNodes = Vec_PtrAlloc( 10 );
// share the PI latches
Abc_NtkForEachPi( pNtk, pObj, i )
Seq_NodeShareFanouts( pObj, vNodes );
// share the node latches
Abc_NtkForEachNode( pNtk, pObj, i )
Seq_NodeShareFanouts( pObj, vNodes );
Vec_PtrFree( vNodes );
}
/**Function*************************************************************
Synopsis [Transforms the node to take fanout sharing into account.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
void Seq_NodeShareFanouts( Abc_Obj_t * pNode, Vec_Ptr_t * vNodes )
{
Abc_Obj_t * pFanout;
Abc_InitType_t Type;
int nLatches[4], i;
// skip the node with only one fanout
if ( Abc_ObjFanoutNum(pNode) < 2 )
return;
// clean the the fanout counters
for ( i = 0; i < 4; i++ )
nLatches[i] = 0;
// find the number of fanouts having latches of each type
Abc_ObjForEachFanout( pNode, pFanout, i )
{
if ( Abc_ObjFanoutL(pNode, pFanout) == 0 )
continue;
Type = Seq_NodeGetInitLast( pFanout, Abc_ObjFanoutEdgeNum(pNode, pFanout) );
nLatches[Type]++;
}
// decide what to do
if ( nLatches[ABC_INIT_ZERO] > 1 && nLatches[ABC_INIT_ONE] > 1 ) // 0-group and 1-group
{
Seq_NodeShareOne( pNode, ABC_INIT_ZERO, vNodes ); // shares 0 and DC
Seq_NodeShareOne( pNode, ABC_INIT_ONE, vNodes ); // shares 1 and DC
}
else if ( nLatches[ABC_INIT_ZERO] > 1 ) // 0-group
Seq_NodeShareOne( pNode, ABC_INIT_ZERO, vNodes ); // shares 0 and DC
else if ( nLatches[ABC_INIT_ONE] > 1 ) // 1-group
Seq_NodeShareOne( pNode, ABC_INIT_ONE, vNodes ); // shares 1 and DC
else if ( nLatches[ABC_INIT_DC] > 1 ) // DC-group
{
if ( nLatches[ABC_INIT_ZERO] > 0 )
Seq_NodeShareOne( pNode, ABC_INIT_ZERO, vNodes ); // shares 0 and DC
else
Seq_NodeShareOne( pNode, ABC_INIT_ONE, vNodes ); // shares 1 and DC
}
}
/**Function*************************************************************
Synopsis [Transforms the node to take fanout sharing into account.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
void Seq_NodeShareOne( Abc_Obj_t * pNode, Abc_InitType_t Init, Vec_Ptr_t * vNodes )
{
Vec_Ptr_t * vInits = Seq_NodeLats( pNode );
Abc_Obj_t * pFanout, * pBuffer;
Abc_InitType_t Type, InitNew;
int i;
// collect the fanouts that satisfy the property (have initial value Init or DC)
InitNew = ABC_INIT_DC;
Vec_PtrClear( vNodes );
Abc_ObjForEachFanout( pNode, pFanout, i )
{
if ( Abc_ObjFanoutL(pNode, pFanout) == 0 )
continue;
Type = Seq_NodeGetInitLast( pFanout, Abc_ObjFanoutEdgeNum(pNode, pFanout) );
if ( Type == Init )
InitNew = Init;
if ( Type == Init || Type == ABC_INIT_DC )
{
Vec_PtrPush( vNodes, pFanout );
Seq_NodeDeleteLast( pFanout, Abc_ObjFanoutEdgeNum(pNode, pFanout) );
}
}
// create the new buffer
pBuffer = Abc_NtkCreateNode( pNode->pNtk );
Abc_ObjAddFanin( pBuffer, pNode );
// grow storage for initial states
Vec_PtrGrow( vInits, 2 * pBuffer->Id + 2 );
for ( i = Vec_PtrSize(vInits); i < 2 * (int)pBuffer->Id + 2; i++ )
Vec_PtrPush( vInits, NULL );
Seq_NodeInsertFirst( pBuffer, 0, InitNew );
// redirect the fanouts
Vec_PtrForEachEntry( vNodes, pFanout, i )
Abc_ObjPatchFanin( pFanout, pNode, pBuffer );
}
////////////////////////////////////////////////////////////////////////
/// END OF FILE ///
////////////////////////////////////////////////////////////////////////
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