/**CFile****************************************************************
FileName [darCut.c]
SystemName [ABC: Logic synthesis and verification system.]
PackageName [DAG-aware AIG rewriting.]
Synopsis [Computation of 4-input cuts.]
Author [Alan Mishchenko]
Affiliation [UC Berkeley]
Date [Ver. 1.0. Started - April 28, 2007.]
Revision [$Id: darCut.c,v 1.00 2007/04/28 00:00:00 alanmi Exp $]
***********************************************************************/
#include "darInt.h"
ABC_NAMESPACE_IMPL_START
////////////////////////////////////////////////////////////////////////
/// DECLARATIONS ///
////////////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////////////
/// FUNCTION DEFINITIONS ///
////////////////////////////////////////////////////////////////////////
/**Function*************************************************************
Synopsis [Prints one cut.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
void Dar_CutPrint( Dar_Cut_t * pCut )
{
unsigned i;
printf( "{" );
for ( i = 0; i < pCut->nLeaves; i++ )
printf( " %d", pCut->pLeaves[i] );
printf( " }\n" );
}
/**Function*************************************************************
Synopsis [Prints one cut.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
void Dar_ObjCutPrint( Aig_Man_t * p, Aig_Obj_t * pObj )
{
Dar_Cut_t * pCut;
int i;
printf( "Cuts for node %d:\n", pObj->Id );
Dar_ObjForEachCut( pObj, pCut, i )
Dar_CutPrint( pCut );
// printf( "\n" );
}
/**Function*************************************************************
Synopsis [Returns the number of 1s in the machine word.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
static inline int Dar_WordCountOnes( unsigned uWord )
{
uWord = (uWord & 0x55555555) + ((uWord>>1) & 0x55555555);
uWord = (uWord & 0x33333333) + ((uWord>>2) & 0x33333333);
uWord = (uWord & 0x0F0F0F0F) + ((uWord>>4) & 0x0F0F0F0F);
uWord = (uWord & 0x00FF00FF) + ((uWord>>8) & 0x00FF00FF);
return (uWord & 0x0000FFFF) + (uWord>>16);
}
/**Function*************************************************************
Synopsis [Compute the cost of the cut.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
static inline int Dar_CutFindValue( Dar_Man_t * p, Dar_Cut_t * pCut )
{
Aig_Obj_t * pLeaf;
int i, Value, nOnes;
assert( pCut->fUsed );
Value = 0;
nOnes = 0;
Dar_CutForEachLeaf( p->pAig, pCut, pLeaf, i )
{
if ( pLeaf == NULL )
return 0;
assert( pLeaf != NULL );
Value += pLeaf->nRefs;
nOnes += (pLeaf->nRefs == 1);
}
if ( pCut->nLeaves < 2 )
return 1001;
// Value = Value * 100 / pCut->nLeaves;
if ( Value > 1000 )
Value = 1000;
if ( nOnes > 3 )
Value = 5 - nOnes;
return Value;
}
/**Function*************************************************************
Synopsis [Returns the next free cut to use.]
Description [Uses the cut with the smallest value.]
SideEffects []
SeeAlso []
***********************************************************************/
static inline Dar_Cut_t * Dar_CutFindFree( Dar_Man_t * p, Aig_Obj_t * pObj )
{
Dar_Cut_t * pCut, * pCutMax;
int i;
pCutMax = NULL;
Dar_ObjForEachCutAll( pObj, pCut, i )
{
if ( pCut->fUsed == 0 )
return pCut;
if ( pCut->nLeaves < 3 )
continue;
if ( pCutMax == NULL || pCutMax->Value > pCut->Value )
pCutMax = pCut;
}
if ( pCutMax == NULL )
{
Dar_ObjForEachCutAll( pObj, pCut, i )
{
if ( pCut->nLeaves < 2 )
continue;
if ( pCutMax == NULL || pCutMax->Value > pCut->Value )
pCutMax = pCut;
}
}
if ( pCutMax == NULL )
{
Dar_ObjForEachCutAll( pObj, pCut, i )
{
if ( pCutMax == NULL || pCutMax->Value > pCut->Value )
pCutMax = pCut;
}
}
assert( pCutMax != NULL );
pCutMax->fUsed = 0;
return pCutMax;
}
/**Function*************************************************************
Synopsis [Returns 1 if pDom is contained in pCut.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
static inline int Dar_CutCheckDominance( Dar_Cut_t * pDom, Dar_Cut_t * pCut )
{
int i, k;
assert( pDom->fUsed && pCut->fUsed );
for ( i = 0; i < (int)pDom->nLeaves; i++ )
{
for ( k = 0; k < (int)pCut->nLeaves; k++ )
if ( pDom->pLeaves[i] == pCut->pLeaves[k] )
break;
if ( k == (int)pCut->nLeaves ) // 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 []
***********************************************************************/
static inline int Dar_CutFilter( Aig_Obj_t * pObj, Dar_Cut_t * pCut )
{
Dar_Cut_t * pTemp;
int i;
assert( pCut->fUsed );
// go through the cuts of the node
Dar_ObjForEachCut( pObj, pTemp, i )
{
if ( pTemp == pCut )
continue;
if ( pTemp->nLeaves > pCut->nLeaves )
{
// skip the non-contained cuts
if ( (pTemp->uSign & pCut->uSign) != pCut->uSign )
continue;
// check containment seriously
if ( Dar_CutCheckDominance( pCut, pTemp ) )
{
// remove contained cut
pTemp->fUsed = 0;
}
}
else
{
// skip the non-contained cuts
if ( (pTemp->uSign & pCut->uSign) != pTemp->uSign )
continue;
// check containment seriously
if ( Dar_CutCheckDominance( pTemp, pCut ) )
{
// remove the given cut
pCut->fUsed = 0;
return 1;
}
}
}
return 0;
}
/**Function*************************************************************
Synopsis [Merges two cuts.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
static inline int Dar_CutMergeOrdered( Dar_Cut_t * pC, Dar_Cut_t * pC0, Dar_Cut_t * pC1 )
{
int i, k, c;
assert( pC0->nLeaves >= pC1->nLeaves );
// the case of the largest cut sizes
if ( pC0->nLeaves == 4 && pC1->nLeaves == 4 )
{
if ( pC0->uSign != pC1->uSign )
return 0;
for ( i = 0; i < (int)pC0->nLeaves; i++ )
if ( pC0->pLeaves[i] != pC1->pLeaves[i] )
return 0;
for ( i = 0; i < (int)pC0->nLeaves; i++ )
pC->pLeaves[i] = pC0->pLeaves[i];
pC->nLeaves = pC0->nLeaves;
return 1;
}
// the case when one of the cuts is the largest
if ( pC0->nLeaves == 4 )
{
if ( (pC0->uSign & pC1->uSign) != pC1->uSign )
return 0;
for ( i = 0; i < (int)pC1->nLeaves; i++ )
{
for ( k = (int)pC0->nLeaves - 1; k >= 0; k-- )
if ( pC0->pLeaves[k] == pC1->pLeaves[i] )
break;
if ( k == -1 ) // did not find
return 0;
}
for ( i = 0; i < (int)pC0->nLeaves; i++ )
pC->pLeaves[i] = pC0->pLeaves[i];
pC->nLeaves = pC0->nLeaves;
return 1;
}
// compare two cuts with different numbers
i = k = 0;
for ( c = 0; c < 4; c++ )
{
if ( k == (int)pC1->nLeaves )
{
if ( i == (int)pC0->nLeaves )
{
pC->nLeaves = c;
return 1;
}
pC->pLeaves[c] = pC0->pLeaves[i++];
continue;
}
if ( i == (int)pC0->nLeaves )
{
if ( k == (int)pC1->nLeaves )
{
pC->nLeaves = c;
return 1;
}
pC->pLeaves[c] = pC1->pLeaves[k++];
continue;
}
if ( pC0->pLeaves[i] < pC1->pLeaves[k] )
{
pC->pLeaves[c] = pC0->pLeaves[i++];
continue;
}
if ( pC0->pLeaves[i] > pC1->pLeaves[k] )
{
pC->pLeaves[c] = pC1->pLeaves[k++];
continue;
}
pC->pLeaves[c] = pC0->pLeaves[i++];
k++;
}
if ( i < (int)pC0->nLeaves || k < (int)pC1->nLeaves )
return 0;
pC->nLeaves = c;
return 1;
}
/**Function*************************************************************
Synopsis [Prepares the object for FPGA mapping.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
static inline int Dar_CutMerge( Dar_Cut_t * pCut, Dar_Cut_t * pCut0, Dar_Cut_t * pCut1 )
{
assert( !pCut->fUsed );
// merge the nodes
if ( pCut0->nLeaves <= pCut1->nLeaves )
{
if ( !Dar_CutMergeOrdered( pCut, pCut1, pCut0 ) )
return 0;
}
else
{
if ( !Dar_CutMergeOrdered( pCut, pCut0, pCut1 ) )
return 0;
}
pCut->uSign = pCut0->uSign | pCut1->uSign;
pCut->fUsed = 1;
return 1;
}
/**Function*************************************************************
Synopsis [Computes the stretching phase of the cut w.r.t. the merged cut.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
static inline unsigned Dar_CutTruthPhase( Dar_Cut_t * pCut, Dar_Cut_t * pCut1 )
{
unsigned uPhase = 0;
int i, k;
for ( i = k = 0; i < (int)pCut->nLeaves; i++ )
{
if ( k == (int)pCut1->nLeaves )
break;
if ( pCut->pLeaves[i] < pCut1->pLeaves[k] )
continue;
assert( pCut->pLeaves[i] == pCut1->pLeaves[k] );
uPhase |= (1 << i);
k++;
}
return uPhase;
}
/**Function*************************************************************
Synopsis [Swaps two advancent variables of the truth table.]
Description [Swaps variable iVar and iVar+1.]
SideEffects []
SeeAlso []
***********************************************************************/
static inline unsigned Dar_CutTruthSwapAdjacentVars( unsigned uTruth, int iVar )
{
assert( iVar >= 0 && iVar <= 2 );
if ( iVar == 0 )
return (uTruth & 0x99999999) | ((uTruth & 0x22222222) << 1) | ((uTruth & 0x44444444) >> 1);
if ( iVar == 1 )
return (uTruth & 0xC3C3C3C3) | ((uTruth & 0x0C0C0C0C) << 2) | ((uTruth & 0x30303030) >> 2);
if ( iVar == 2 )
return (uTruth & 0xF00FF00F) | ((uTruth & 0x00F000F0) << 4) | ((uTruth & 0x0F000F00) >> 4);
assert( 0 );
return 0;
}
/**Function*************************************************************
Synopsis [Expands the truth table according to the phase.]
Description [The input and output truth tables are in pIn/pOut. The current number
of variables is nVars. The total number of variables in nVarsAll. The last argument
(Phase) contains shows where the variables should go.]
SideEffects []
SeeAlso []
***********************************************************************/
static inline unsigned Dar_CutTruthStretch( unsigned uTruth, int nVars, unsigned Phase )
{
int i, k, Var = nVars - 1;
for ( i = 3; i >= 0; i-- )
if ( Phase & (1 << i) )
{
for ( k = Var; k < i; k++ )
uTruth = Dar_CutTruthSwapAdjacentVars( uTruth, k );
Var--;
}
assert( Var == -1 );
return uTruth;
}
/**Function*************************************************************
Synopsis [Shrinks the truth table according to the phase.]
Description [The input and output truth tables are in pIn/pOut. The current number
of variables is nVars. The total number of variables in nVarsAll. The last argument
(Phase) contains shows what variables should remain.]
SideEffects []
SeeAlso []
***********************************************************************/
static inline unsigned Dar_CutTruthShrink( unsigned uTruth, int nVars, unsigned Phase )
{
int i, k, Var = 0;
for ( i = 0; i < 4; i++ )
if ( Phase & (1 << i) )
{
for ( k = i-1; k >= Var; k-- )
uTruth = Dar_CutTruthSwapAdjacentVars( uTruth, k );
Var++;
}
return uTruth;
}
/**Function*************************************************************
Synopsis [Performs truth table computation.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
static inline unsigned Dar_CutTruth( Dar_Cut_t * pCut, Dar_Cut_t * pCut0, Dar_Cut_t * pCut1, int fCompl0, int fCompl1 )
{
unsigned uTruth0 = fCompl0 ? ~pCut0->uTruth : pCut0->uTruth;
unsigned uTruth1 = fCompl1 ? ~pCut1->uTruth : pCut1->uTruth;
uTruth0 = Dar_CutTruthStretch( uTruth0, pCut0->nLeaves, Dar_CutTruthPhase(pCut, pCut0) );
uTruth1 = Dar_CutTruthStretch( uTruth1, pCut1->nLeaves, Dar_CutTruthPhase(pCut, pCut1) );
return uTruth0 & uTruth1;
}
/**Function*************************************************************
Synopsis [Minimize support of the cut.]
Description [Returns 1 if the node's support has changed]
SideEffects []
SeeAlso []
***********************************************************************/
static inline int Dar_CutSuppMinimize( Dar_Cut_t * pCut )
{
unsigned uMasks[4][2] = {
{ 0x5555, 0xAAAA },
{ 0x3333, 0xCCCC },
{ 0x0F0F, 0xF0F0 },
{ 0x00FF, 0xFF00 }
};
unsigned uPhase = 0, uTruth = 0xFFFF & pCut->uTruth;
int i, k, nLeaves;
assert( pCut->fUsed );
// compute the support of the cut's function
nLeaves = pCut->nLeaves;
for ( i = 0; i < (int)pCut->nLeaves; i++ )
if ( (uTruth & uMasks[i][0]) == ((uTruth & uMasks[i][1]) >> (1 << i)) )
nLeaves--;
else
uPhase |= (1 << i);
if ( nLeaves == (int)pCut->nLeaves )
return 0;
// shrink the truth table
uTruth = Dar_CutTruthShrink( uTruth, pCut->nLeaves, uPhase );
pCut->uTruth = 0xFFFF & uTruth;
// update leaves and signature
pCut->uSign = 0;
for ( i = k = 0; i < (int)pCut->nLeaves; i++ )
{
if ( !(uPhase & (1 << i)) )
continue;
pCut->pLeaves[k++] = pCut->pLeaves[i];
pCut->uSign |= Aig_ObjCutSign( pCut->pLeaves[i] );
}
assert( k == nLeaves );
pCut->nLeaves = nLeaves;
return 1;
}
/**Function*************************************************************
Synopsis []
Description []
SideEffects []
SeeAlso []
***********************************************************************/
void Dar_ManCutsFree( Dar_Man_t * p )
{
if ( p->pMemCuts == NULL )
return;
Aig_MmFixedStop( p->pMemCuts, 0 );
p->pMemCuts = NULL;
// Aig_ManCleanData( p );
}
/**Function*************************************************************
Synopsis []
Description []
SideEffects []
SeeAlso []
***********************************************************************/
Dar_Cut_t * Dar_ObjPrepareCuts( Dar_Man_t * p, Aig_Obj_t * pObj )
{
Dar_Cut_t * pCutSet, * pCut;
int i;
assert( Dar_ObjCuts(pObj) == NULL );
pObj->nCuts = p->pPars->nCutsMax;
// create the cutset of the node
pCutSet = (Dar_Cut_t *)Aig_MmFixedEntryFetch( p->pMemCuts );
memset( pCutSet, 0, p->pPars->nCutsMax * sizeof(Dar_Cut_t) );
Dar_ObjSetCuts( pObj, pCutSet );
Dar_ObjForEachCutAll( pObj, pCut, i )
pCut->fUsed = 0;
Vec_PtrPush( p->vCutNodes, pObj );
// add unit cut if needed
pCut = pCutSet;
pCut->fUsed = 1;
if ( Aig_ObjIsConst1(pObj) )
{
pCut->nLeaves = 0;
pCut->uSign = 0;
pCut->uTruth = 0xFFFF;
}
else
{
pCut->nLeaves = 1;
pCut->pLeaves[0] = pObj->Id;
pCut->uSign = Aig_ObjCutSign( pObj->Id );
pCut->uTruth = 0xAAAA;
}
pCut->Value = Dar_CutFindValue( p, pCut );
if ( p->nCutMemUsed < Aig_MmFixedReadMemUsage(p->pMemCuts)/(1<<20) )
p->nCutMemUsed = Aig_MmFixedReadMemUsage(p->pMemCuts)/(1<<20);
return pCutSet;
}
/**Function*************************************************************
Synopsis []
Description []
SideEffects []
SeeAlso []
***********************************************************************/
void Dar_ManCutsRestart( Dar_Man_t * p, Aig_Obj_t * pRoot )
{
Aig_Obj_t * pObj;
int i;
Dar_ObjSetCuts( Aig_ManConst1(p->pAig), NULL );
Vec_PtrForEachEntry( Aig_Obj_t *, p->vCutNodes, pObj, i )
if ( !Aig_ObjIsNone(pObj) )
Dar_ObjSetCuts( pObj, NULL );
Vec_PtrClear( p->vCutNodes );
Aig_MmFixedRestart( p->pMemCuts );
Dar_ObjPrepareCuts( p, Aig_ManConst1(p->pAig) );
}
/**Function*************************************************************
Synopsis []
Description []
SideEffects []
SeeAlso []
***********************************************************************/
Dar_Cut_t * Dar_ObjComputeCuts( Dar_Man_t * p, Aig_Obj_t * pObj )
{
Aig_Obj_t * pFanin0 = Aig_ObjReal_rec( Aig_ObjChild0(pObj) );
Aig_Obj_t * pFanin1 = Aig_ObjReal_rec( Aig_ObjChild1(pObj) );
Aig_Obj_t * pFaninR0 = Aig_Regular(pFanin0);
Aig_Obj_t * pFaninR1 = Aig_Regular(pFanin1);
Dar_Cut_t * pCutSet, * pCut0, * pCut1, * pCut;
int i, k, RetValue;
assert( !Aig_IsComplement(pObj) );
assert( Aig_ObjIsNode(pObj) );
assert( Dar_ObjCuts(pObj) == NULL );
assert( Dar_ObjCuts(pFaninR0) != NULL );
assert( Dar_ObjCuts(pFaninR1) != NULL );
// set up the first cut
pCutSet = Dar_ObjPrepareCuts( p, pObj );
// make sure fanins cuts are computed
Dar_ObjForEachCut( pFaninR0, pCut0, i )
Dar_ObjForEachCut( pFaninR1, pCut1, k )
{
p->nCutsAll++;
// make sure K-feasible cut exists
if ( Dar_WordCountOnes(pCut0->uSign | pCut1->uSign) > 4 )
continue;
// get the next cut of this node
pCut = Dar_CutFindFree( p, pObj );
// create the new cut
if ( !Dar_CutMerge( pCut, pCut0, pCut1 ) )
{
assert( !pCut->fUsed );
continue;
}
p->nCutsTried++;
// check dominance
if ( Dar_CutFilter( pObj, pCut ) )
{
assert( !pCut->fUsed );
continue;
}
// compute truth table
pCut->uTruth = 0xFFFF & Dar_CutTruth( pCut, pCut0, pCut1, Aig_IsComplement(pFanin0), Aig_IsComplement(pFanin1) );
// minimize support of the cut
if ( Dar_CutSuppMinimize( pCut ) )
{
RetValue = Dar_CutFilter( pObj, pCut );
assert( !RetValue );
}
// assign the value of the cut
pCut->Value = Dar_CutFindValue( p, pCut );
// if the cut contains removed node, do not use it
if ( pCut->Value == 0 )
{
p->nCutsSkipped++;
pCut->fUsed = 0;
}
else if ( pCut->nLeaves < 2 )
return pCutSet;
}
// count the number of nontrivial cuts cuts
Dar_ObjForEachCut( pObj, pCut, i )
p->nCutsUsed += pCut->fUsed;
// discount trivial cut
p->nCutsUsed--;
return pCutSet;
}
/**Function*************************************************************
Synopsis []
Description []
SideEffects []
SeeAlso []
***********************************************************************/
Dar_Cut_t * Dar_ObjComputeCuts_rec( Dar_Man_t * p, Aig_Obj_t * pObj )
{
if ( Dar_ObjCuts(pObj) )
return Dar_ObjCuts(pObj);
if ( Aig_ObjIsPi(pObj) )
return Dar_ObjPrepareCuts( p, pObj );
if ( Aig_ObjIsBuf(pObj) )
return Dar_ObjComputeCuts_rec( p, Aig_ObjFanin0(pObj) );
Dar_ObjComputeCuts_rec( p, Aig_ObjFanin0(pObj) );
Dar_ObjComputeCuts_rec( p, Aig_ObjFanin1(pObj) );
return Dar_ObjComputeCuts( p, pObj );
}
////////////////////////////////////////////////////////////////////////
/// END OF FILE ///
////////////////////////////////////////////////////////////////////////
ABC_NAMESPACE_IMPL_END