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/**CFile****************************************************************
FileName [rwrDec.c]
SystemName [ABC: Logic synthesis and verification system.]
PackageName [DAG-aware AIG rewriting package.]
Synopsis [Evaluation and decomposition procedures.]
Author [Alan Mishchenko]
Affiliation [UC Berkeley]
Date [Ver. 1.0. Started - June 20, 2005.]
Revision [$Id: rwrDec.c,v 1.00 2005/06/20 00:00:00 alanmi Exp $]
***********************************************************************/
#include "rwr.h"
#include "ft.h"
////////////////////////////////////////////////////////////////////////
/// DECLARATIONS ///
////////////////////////////////////////////////////////////////////////
static Vec_Int_t * Rwr_CutEvaluate( Rwr_Man_t * p, Abc_Obj_t * pRoot, Rwr_Cut_t * pCut, int NodeMax, int LevelMax );
////////////////////////////////////////////////////////////////////////
/// FUNCTION DEFITIONS ///
////////////////////////////////////////////////////////////////////////
/**Function*************************************************************
Synopsis [Performs rewriting for one node.]
Description [This procedure considers all the cuts computed for the node
and tries to rewrite each of them using the "forest" of different AIG
structures precomputed and stored in the RWR manager.
Determines the best rewriting and computes the gain in the number of AIG
nodes in the final network. In the end, p->vFanins contains information
about the best cut that can be used for rewriting, while p->vForm gives
the decomposition tree (represented using factored form data structure).
Returns gain in the number of nodes or -1 if node cannot be rewritten.]
SideEffects []
SeeAlso []
***********************************************************************/
int Rwr_NodeRewrite( Rwr_Man_t * p, Abc_Obj_t * pNode )
{
Vec_Int_t * vForm;
Rwr_Cut_t * pCut;
int Required, nNodesSaved;
int i, BestGain = -1;
// compute the cuts for this node
Rwr_NodeComputeCuts( p, pNode );
// get the required times
Required = Vec_IntEntry( p->vReqTimes, pNode->Id );
// label MFFC with current ID
nNodesSaved = Abc_NodeMffcLabel( pNode );
// go through the cuts
for ( pCut = (Rwr_Cut_t *)pNode->pCopy, pCut = pCut->pNext; pCut; pCut = pCut->pNext )
{
// evaluate the cut
vForm = Rwr_CutEvaluate( p, pNode, pCut, nNodesSaved, Required );
// check if the cut is better than the currently best one
if ( vForm != NULL && BestGain < (int)pCut->Volume )
{
assert( pCut->Volume >= 0 );
BestGain = pCut->Volume;
// save this form
p->vForm = vForm;
// collect fanins
Vec_PtrClear( p->vFanins );
for ( i = 0; i < (int)pCut->nLeaves; i++ )
Vec_PtrPush( p->vFanins, pCut->ppLeaves[i] );
}
}
return BestGain;
}
/**Function*************************************************************
Synopsis [Evaluates the cut.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
Vec_Int_t * Rwr_CutEvaluate( Rwr_Man_t * p, Abc_Obj_t * pRoot, Rwr_Cut_t * pCut, int NodeMax, int LevelMax )
{
Vec_Ptr_t Vector = {0,0,0}, * vFanins = &Vector;
Vec_Ptr_t * vSubgraphs;
Vec_Int_t * vFormBest;
Rwr_Node_t * pNode;
int GainCur, GainBest = -1, i;
// find the matching class of subgraphs
vSubgraphs = Vec_VecEntry( p->vClasses, p->pMap[pCut->uTruth] );
// determine the best subgraph
Vec_PtrForEachEntry( vSubgraphs, pNode, i )
{
// create the fanin array
vFanins->nSize = pCut->nLeaves;
vFanins->pArray = pCut->ppLeaves;
// detect how many unlabeled nodes will be reused
GainCur = Abc_NodeStrashDecCount( pRoot->pNtk->pManFunc, vFanins, (Vec_Int_t *)pNode->pNext,
p->vLevNums, NodeMax, LevelMax );
if ( GainBest < GainCur )
{
GainBest = GainCur;
vFormBest = (Vec_Int_t *)pNode->pNext;
}
}
if ( GainBest == -1 )
return NULL;
pCut->Volume = GainBest;
return vFormBest;
}
/**Function*************************************************************
Synopsis [Adds one node.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
int Rwr_TravCollect_rec( Rwr_Man_t * p, Rwr_Node_t * pNode, Vec_Int_t * vForm )
{
Ft_Node_t Node, NodeA, NodeB;
int Node0, Node1;
// elementary variable
if ( pNode->fUsed )
return ((pNode->Id - 1) << 1);
// previously visited node
if ( pNode->TravId == p->nTravIds )
return pNode->Volume;
pNode->TravId = p->nTravIds;
// solve for children
Node0 = Rwr_TravCollect_rec( p, Rwr_Regular(pNode->p0), vForm );
Node1 = Rwr_TravCollect_rec( p, Rwr_Regular(pNode->p1), vForm );
// create the decomposition node(s)
if ( pNode->fExor )
{
assert( !Rwr_IsComplement(pNode->p0) );
assert( !Rwr_IsComplement(pNode->p1) );
NodeA.fIntern = 1;
NodeA.fConst = 0;
NodeA.fCompl = 0;
NodeA.fCompl0 = !(Node0 & 1);
NodeA.fCompl1 = (Node1 & 1);
NodeA.iFanin0 = (Node0 >> 1);
NodeA.iFanin1 = (Node1 >> 1);
Vec_IntPush( vForm, Ft_Node2Int(NodeA) );
NodeB.fIntern = 1;
NodeB.fConst = 0;
NodeB.fCompl = 0;
NodeB.fCompl0 = (Node0 & 1);
NodeB.fCompl1 = !(Node1 & 1);
NodeB.iFanin0 = (Node0 >> 1);
NodeB.iFanin1 = (Node1 >> 1);
Vec_IntPush( vForm, Ft_Node2Int(NodeB) );
Node.fIntern = 1;
Node.fConst = 0;
Node.fCompl = 0;
Node.fCompl0 = 1;
Node.fCompl1 = 1;
Node.iFanin0 = vForm->nSize - 2;
Node.iFanin1 = vForm->nSize - 1;
Vec_IntPush( vForm, Ft_Node2Int(Node) );
}
else
{
Node.fIntern = 1;
Node.fConst = 0;
Node.fCompl = 0;
Node.fCompl0 = Rwr_IsComplement(pNode->p0) ^ (Node0 & 1);
Node.fCompl1 = Rwr_IsComplement(pNode->p1) ^ (Node1 & 1);
Node.iFanin0 = (Node0 >> 1);
Node.iFanin1 = (Node1 >> 1);
Vec_IntPush( vForm, Ft_Node2Int(Node) );
}
// save the number of this node
pNode->Volume = ((vForm->nSize - 1) << 1) | pNode->fExor;
return pNode->Volume;
}
/**Function*************************************************************
Synopsis [Preprocesses subgraphs rooted at this node.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
void Rwr_NodePreprocess( Rwr_Man_t * p, Rwr_Node_t * pNode )
{
Vec_Int_t * vForm;
int i, Root;
vForm = Vec_IntAlloc( 10 );
for ( i = 0; i < 5; i++ )
Vec_IntPush( vForm, 0 );
// collect the nodes
Rwr_ManIncTravId( p );
Root = Rwr_TravCollect_rec( p, pNode, vForm );
if ( Root & 1 )
Ft_FactorComplement( vForm );
pNode->pNext = (Rwr_Node_t *)vForm;
}
/**Function*************************************************************
Synopsis [Preprocesses computed library of subgraphs.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
void Rwr_ManPreprocess( Rwr_Man_t * p )
{
Rwr_Node_t * pNode;
int i, k;
// put the nodes into the structure
p->vClasses = Vec_VecAlloc( 222 );
for ( i = 0; i < p->nFuncs; i++ )
for ( pNode = p->pTable[i]; pNode; pNode = pNode->pNext )
Vec_VecPush( p->vClasses, p->pMap[pNode->uTruth], pNode );
// compute decomposition forms for each node
Vec_VecForEachEntry( p->vClasses, pNode, i, k )
Rwr_NodePreprocess( p, pNode );
}
////////////////////////////////////////////////////////////////////////
/// END OF FILE ///
////////////////////////////////////////////////////////////////////////
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