/**CFile****************************************************************
FileName [cswCut.c]
SystemName [ABC: Logic synthesis and verification system.]
PackageName [Cut sweeping.]
Synopsis []
Author [Alan Mishchenko]
Affiliation [UC Berkeley]
Date [Ver. 1.0. Started - July 11, 2007.]
Revision [$Id: cswCut.c,v 1.00 2007/07/11 00:00:00 alanmi Exp $]
***********************************************************************/
#include "cswInt.h"
ABC_NAMESPACE_IMPL_START
////////////////////////////////////////////////////////////////////////
/// DECLARATIONS ///
////////////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////////////
/// FUNCTION DEFINITIONS ///
////////////////////////////////////////////////////////////////////////
/**Function*************************************************************
Synopsis [Compute the cost of the cut.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
static inline int Csw_CutFindCost( Csw_Man_t * p, Csw_Cut_t * pCut )
{
Aig_Obj_t * pLeaf;
int i, Cost = 0;
assert( pCut->nFanins > 0 );
Csw_CutForEachLeaf( p->pManRes, pCut, pLeaf, i )
{
// Cost += pLeaf->nRefs;
Cost += Csw_ObjRefs( p, pLeaf );
// printf( "%d ", pLeaf->nRefs );
}
//printf( "\n" );
return Cost * 100 / pCut->nFanins;
}
/**Function*************************************************************
Synopsis [Compute the cost of the cut.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
static inline float Csw_CutFindCost2( Csw_Man_t * p, Csw_Cut_t * pCut )
{
Aig_Obj_t * pLeaf;
float Cost = 0.0;
int i;
assert( pCut->nFanins > 0 );
Csw_CutForEachLeaf( p->pManRes, pCut, pLeaf, i )
Cost += (float)1.0/pLeaf->nRefs;
return 1/Cost;
}
/**Function*************************************************************
Synopsis [Returns the next free cut to use.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
static inline Csw_Cut_t * Csw_CutFindFree( Csw_Man_t * p, Aig_Obj_t * pObj )
{
Csw_Cut_t * pCut, * pCutMax;
int i;
pCutMax = NULL;
Csw_ObjForEachCut( p, pObj, pCut, i )
{
if ( pCut->nFanins == 0 )
return pCut;
if ( pCutMax == NULL || pCutMax->Cost < pCut->Cost )
pCutMax = pCut;
}
assert( pCutMax != NULL );
pCutMax->nFanins = 0;
return pCutMax;
}
/**Function*************************************************************
Synopsis [Computes the stretching phase of the cut w.r.t. the merged cut.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
static inline unsigned Cut_TruthPhase( Csw_Cut_t * pCut, Csw_Cut_t * pCut1 )
{
unsigned uPhase = 0;
int i, k;
for ( i = k = 0; i < pCut->nFanins; i++ )
{
if ( k == pCut1->nFanins )
break;
if ( pCut->pFanins[i] < pCut1->pFanins[k] )
continue;
assert( pCut->pFanins[i] == pCut1->pFanins[k] );
uPhase |= (1 << i);
k++;
}
return uPhase;
}
/**Function*************************************************************
Synopsis [Performs truth table computation.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
unsigned * Csw_CutComputeTruth( Csw_Man_t * p, Csw_Cut_t * pCut, Csw_Cut_t * pCut0, Csw_Cut_t * pCut1, int fCompl0, int fCompl1 )
{
// permute the first table
if ( fCompl0 )
Kit_TruthNot( p->puTemp[0], Csw_CutTruth(pCut0), p->nLeafMax );
else
Kit_TruthCopy( p->puTemp[0], Csw_CutTruth(pCut0), p->nLeafMax );
Kit_TruthStretch( p->puTemp[2], p->puTemp[0], pCut0->nFanins, p->nLeafMax, Cut_TruthPhase(pCut, pCut0), 0 );
// permute the second table
if ( fCompl1 )
Kit_TruthNot( p->puTemp[1], Csw_CutTruth(pCut1), p->nLeafMax );
else
Kit_TruthCopy( p->puTemp[1], Csw_CutTruth(pCut1), p->nLeafMax );
Kit_TruthStretch( p->puTemp[3], p->puTemp[1], pCut1->nFanins, p->nLeafMax, Cut_TruthPhase(pCut, pCut1), 0 );
// produce the resulting table
Kit_TruthAnd( Csw_CutTruth(pCut), p->puTemp[2], p->puTemp[3], p->nLeafMax );
// assert( pCut->nFanins >= Kit_TruthSupportSize( Csw_CutTruth(pCut), p->nLeafMax ) );
return Csw_CutTruth(pCut);
}
/**Function*************************************************************
Synopsis [Performs support minimization for the truth table.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
int Csw_CutSupportMinimize( Csw_Man_t * p, Csw_Cut_t * pCut )
{
unsigned * pTruth;
int uSupp, nFansNew, i, k;
// get truth table
pTruth = Csw_CutTruth( pCut );
// get support
uSupp = Kit_TruthSupport( pTruth, p->nLeafMax );
// get the new support size
nFansNew = Kit_WordCountOnes( uSupp );
// check if there are redundant variables
if ( nFansNew == pCut->nFanins )
return nFansNew;
assert( nFansNew < pCut->nFanins );
// minimize support
Kit_TruthShrink( p->puTemp[0], pTruth, nFansNew, p->nLeafMax, uSupp, 1 );
for ( i = k = 0; i < pCut->nFanins; i++ )
if ( uSupp & (1 << i) )
pCut->pFanins[k++] = pCut->pFanins[i];
assert( k == nFansNew );
pCut->nFanins = nFansNew;
// assert( nFansNew == Kit_TruthSupportSize( pTruth, p->nLeafMax ) );
//Extra_PrintBinary( stdout, pTruth, (1<<p->nLeafMax) ); printf( "\n" );
return nFansNew;
}
/**Function*************************************************************
Synopsis [Returns 1 if pDom is contained in pCut.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
static inline int Csw_CutCheckDominance( Csw_Cut_t * pDom, Csw_Cut_t * pCut )
{
int i, k;
for ( i = 0; i < (int)pDom->nFanins; i++ )
{
for ( k = 0; k < (int)pCut->nFanins; k++ )
if ( pDom->pFanins[i] == pCut->pFanins[k] )
break;
if ( k == (int)pCut->nFanins ) // node i in pDom is not contained in pCut
return 0;
}
// every node in pDom is contained in pCut
return 1;
}
/**Function*************************************************************
Synopsis [Returns 1 if the cut is contained.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
int Csw_CutFilter( Csw_Man_t * p, Aig_Obj_t * pObj, Csw_Cut_t * pCut )
{
Csw_Cut_t * pTemp;
int i;
// go through the cuts of the node
Csw_ObjForEachCut( p, pObj, pTemp, i )
{
if ( pTemp->nFanins < 2 )
continue;
if ( pTemp == pCut )
continue;
if ( pTemp->nFanins > pCut->nFanins )
{
// skip the non-contained cuts
if ( (pTemp->uSign & pCut->uSign) != pCut->uSign )
continue;
// check containment seriously
if ( Csw_CutCheckDominance( pCut, pTemp ) )
{
// remove contained cut
pTemp->nFanins = 0;
}
}
else
{
// skip the non-contained cuts
if ( (pTemp->uSign & pCut->uSign) != pTemp->uSign )
continue;
// check containment seriously
if ( Csw_CutCheckDominance( pTemp, pCut ) )
{
// remove the given
pCut->nFanins = 0;
return 1;
}
}
}
return 0;
}
/**Function*************************************************************
Synopsis [Merges two cuts.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
static inline int Csw_CutMergeOrdered( Csw_Man_t * p, Csw_Cut_t * pC0, Csw_Cut_t * pC1, Csw_Cut_t * pC )
{
int i, k, c;
assert( pC0->nFanins >= pC1->nFanins );
// the case of the largest cut sizes
if ( pC0->nFanins == p->nLeafMax && pC1->nFanins == p->nLeafMax )
{
for ( i = 0; i < pC0->nFanins; i++ )
if ( pC0->pFanins[i] != pC1->pFanins[i] )
return 0;
for ( i = 0; i < pC0->nFanins; i++ )
pC->pFanins[i] = pC0->pFanins[i];
pC->nFanins = pC0->nFanins;
return 1;
}
// the case when one of the cuts is the largest
if ( pC0->nFanins == p->nLeafMax )
{
for ( i = 0; i < pC1->nFanins; i++ )
{
for ( k = pC0->nFanins - 1; k >= 0; k-- )
if ( pC0->pFanins[k] == pC1->pFanins[i] )
break;
if ( k == -1 ) // did not find
return 0;
}
for ( i = 0; i < pC0->nFanins; i++ )
pC->pFanins[i] = pC0->pFanins[i];
pC->nFanins = pC0->nFanins;
return 1;
}
// compare two cuts with different numbers
i = k = 0;
for ( c = 0; c < p->nLeafMax; c++ )
{
if ( k == pC1->nFanins )
{
if ( i == pC0->nFanins )
{
pC->nFanins = c;
return 1;
}
pC->pFanins[c] = pC0->pFanins[i++];
continue;
}
if ( i == pC0->nFanins )
{
if ( k == pC1->nFanins )
{
pC->nFanins = c;
return 1;
}
pC->pFanins[c] = pC1->pFanins[k++];
continue;
}
if ( pC0->pFanins[i] < pC1->pFanins[k] )
{
pC->pFanins[c] = pC0->pFanins[i++];
continue;
}
if ( pC0->pFanins[i] > pC1->pFanins[k] )
{
pC->pFanins[c] = pC1->pFanins[k++];
continue;
}
pC->pFanins[c] = pC0->pFanins[i++];
k++;
}
if ( i < pC0->nFanins || k < pC1->nFanins )
return 0;
pC->nFanins = c;
return 1;
}
/**Function*************************************************************
Synopsis [Prepares the object for FPGA mapping.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
int Csw_CutMerge( Csw_Man_t * p, Csw_Cut_t * pCut0, Csw_Cut_t * pCut1, Csw_Cut_t * pCut )
{
assert( p->nLeafMax > 0 );
// merge the nodes
if ( pCut0->nFanins < pCut1->nFanins )
{
if ( !Csw_CutMergeOrdered( p, pCut1, pCut0, pCut ) )
return 0;
}
else
{
if ( !Csw_CutMergeOrdered( p, pCut0, pCut1, pCut ) )
return 0;
}
pCut->uSign = pCut0->uSign | pCut1->uSign;
return 1;
}
/**Function*************************************************************
Synopsis [Consider cut with more than 2 fanins having 2 true variables.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
Aig_Obj_t * Csw_ObjTwoVarCut( Csw_Man_t * p, Csw_Cut_t * pCut )
{
Aig_Obj_t * pRes, * pIn0, * pIn1;
int nVars, uTruth, fCompl = 0;
assert( pCut->nFanins > 2 );
// minimize support of this cut
nVars = Csw_CutSupportMinimize( p, pCut );
assert( nVars == 2 );
// get the fanins
pIn0 = Aig_ManObj( p->pManRes, pCut->pFanins[0] );
pIn1 = Aig_ManObj( p->pManRes, pCut->pFanins[1] );
// derive the truth table
uTruth = 0xF & *Csw_CutTruth(pCut);
if ( uTruth == 14 || uTruth == 13 || uTruth == 11 || uTruth == 7 )
{
uTruth = 0xF & ~uTruth;
fCompl = 1;
}
// compute the result
pRes = NULL;
if ( uTruth == 1 ) // 0001 // 1110 14
pRes = Aig_And( p->pManRes, Aig_Not(pIn0), Aig_Not(pIn1) );
if ( uTruth == 2 ) // 0010 // 1101 13
pRes = Aig_And( p->pManRes, pIn0 , Aig_Not(pIn1) );
if ( uTruth == 4 ) // 0100 // 1011 11
pRes = Aig_And( p->pManRes, Aig_Not(pIn0), pIn1 );
if ( uTruth == 8 ) // 1000 // 0111 7
pRes = Aig_And( p->pManRes, pIn0 , pIn1 );
if ( pRes )
pRes = Aig_NotCond( pRes, fCompl );
return pRes;
}
/**Function*************************************************************
Synopsis []
Description []
SideEffects []
SeeAlso []
***********************************************************************/
Csw_Cut_t * Csw_ObjPrepareCuts( Csw_Man_t * p, Aig_Obj_t * pObj, int fTriv )
{
Csw_Cut_t * pCutSet, * pCut;
int i;
// create the cutset of the node
pCutSet = (Csw_Cut_t *)Aig_MmFixedEntryFetch( p->pMemCuts );
Csw_ObjSetCuts( p, pObj, pCutSet );
Csw_ObjForEachCut( p, pObj, pCut, i )
{
pCut->nFanins = 0;
pCut->iNode = pObj->Id;
pCut->nCutSize = p->nCutSize;
pCut->nLeafMax = p->nLeafMax;
}
// add unit cut if needed
if ( fTriv )
{
pCut = pCutSet;
pCut->Cost = 0;
pCut->iNode = pObj->Id;
pCut->nFanins = 1;
pCut->pFanins[0] = pObj->Id;
pCut->uSign = Aig_ObjCutSign( pObj->Id );
memset( Csw_CutTruth(pCut), 0xAA, sizeof(unsigned) * p->nTruthWords );
}
return pCutSet;
}
/**Function*************************************************************
Synopsis [Derives cuts for one node and sweeps this node.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
Aig_Obj_t * Csw_ObjSweep( Csw_Man_t * p, Aig_Obj_t * pObj, int fTriv )
{
int fUseResub = 1;
Csw_Cut_t * pCut0, * pCut1, * pCut, * pCutSet;
Aig_Obj_t * pFanin0 = Aig_ObjFanin0(pObj);
Aig_Obj_t * pFanin1 = Aig_ObjFanin1(pObj);
Aig_Obj_t * pObjNew;
unsigned * pTruth;
int i, k, nVars, nFanins, iVar;
clock_t clk;
assert( !Aig_IsComplement(pObj) );
if ( !Aig_ObjIsNode(pObj) )
return pObj;
if ( Csw_ObjCuts(p, pObj) )
return pObj;
// the node is not processed yet
assert( Csw_ObjCuts(p, pObj) == NULL );
assert( Aig_ObjIsNode(pObj) );
// set up the first cut
pCutSet = Csw_ObjPrepareCuts( p, pObj, fTriv );
// compute pair-wise cut combinations while checking table
Csw_ObjForEachCut( p, pFanin0, pCut0, i )
if ( pCut0->nFanins > 0 )
Csw_ObjForEachCut( p, pFanin1, pCut1, k )
if ( pCut1->nFanins > 0 )
{
// make sure K-feasible cut exists
if ( Kit_WordCountOnes(pCut0->uSign | pCut1->uSign) > p->nLeafMax )
continue;
// get the next cut of this node
pCut = Csw_CutFindFree( p, pObj );
clk = clock();
// assemble the new cut
if ( !Csw_CutMerge( p, pCut0, pCut1, pCut ) )
{
assert( pCut->nFanins == 0 );
continue;
}
// check containment
if ( Csw_CutFilter( p, pObj, pCut ) )
{
assert( pCut->nFanins == 0 );
continue;
}
// create its truth table
pTruth = Csw_CutComputeTruth( p, pCut, pCut0, pCut1, Aig_ObjFaninC0(pObj), Aig_ObjFaninC1(pObj) );
// support minimize the truth table
nFanins = pCut->nFanins;
// nVars = Csw_CutSupportMinimize( p, pCut ); // leads to quality degradation
nVars = Kit_TruthSupportSize( pTruth, p->nLeafMax );
p->timeCuts += clock() - clk;
// check for trivial truth tables
if ( nVars == 0 )
{
p->nNodesTriv0++;
return Aig_NotCond( Aig_ManConst1(p->pManRes), !(pTruth[0] & 1) );
}
if ( nVars == 1 )
{
p->nNodesTriv1++;
iVar = Kit_WordFindFirstBit( Kit_TruthSupport(pTruth, p->nLeafMax) );
assert( iVar < pCut->nFanins );
return Aig_NotCond( Aig_ManObj(p->pManRes, pCut->pFanins[iVar]), (pTruth[0] & 1) );
}
if ( nVars == 2 && nFanins > 2 && fUseResub )
{
if ( (pObjNew = Csw_ObjTwoVarCut( p, pCut )) )
{
p->nNodesTriv2++;
return pObjNew;
}
}
// check if an equivalent node with the same cut exists
clk = clock();
pObjNew = pCut->nFanins > 2 ? Csw_TableCutLookup( p, pCut ) : NULL;
p->timeHash += clock() - clk;
if ( pObjNew )
{
p->nNodesCuts++;
return pObjNew;
}
// assign the cost
pCut->Cost = Csw_CutFindCost( p, pCut );
assert( pCut->nFanins > 0 );
assert( pCut->Cost > 0 );
}
p->nNodesTried++;
// load the resulting cuts into the table
clk = clock();
Csw_ObjForEachCut( p, pObj, pCut, i )
{
if ( pCut->nFanins > 2 )
{
assert( pCut->Cost > 0 );
Csw_TableCutInsert( p, pCut );
}
}
p->timeHash += clock() - clk;
// return the node if could not replace it
return pObj;
}
////////////////////////////////////////////////////////////////////////
/// END OF FILE ///
////////////////////////////////////////////////////////////////////////
ABC_NAMESPACE_IMPL_END