/**Function********************************************************************
Synopsis [Computes the classical symmetry information for the function.]
Description [Uses the naive way of comparing cofactors.]
SideEffects []
SeeAlso []
******************************************************************************/
Extra_SymmInfo_t * Extra_SymmPairsComputeNaive( DdManager * dd, DdNode * bFunc )
{
DdNode * bSupp, * bTemp;
int nSuppSize;
Extra_SymmInfo_t * p;
int i, k;
// compute the support
bSupp = Cudd_Support( dd, bFunc ); Cudd_Ref( bSupp );
nSuppSize = Extra_bddSuppSize( dd, bSupp );
//printf( "Support = %d. ", nSuppSize );
//Extra_bddPrint( dd, bSupp );
//printf( "%d ", nSuppSize );
// allocate the storage for symmetry info
p = Extra_SymmPairsAllocate( nSuppSize );
// assign the variables
p->nVarsMax = dd->size;
for ( i = 0, bTemp = bSupp; bTemp != b1; bTemp = cuddT(bTemp), i++ )
p->pVars[i] = bTemp->index;
// go through the candidate pairs and check using Idea1
for ( i = 0; i < nSuppSize; i++ )
for ( k = i+1; k < nSuppSize; k++ )
{
p->pSymms[k][i] = p->pSymms[i][k] = Extra_bddCheckVarsSymmetricNaive( dd, bFunc, p->pVars[i], p->pVars[k] );
if ( p->pSymms[i][k] )
p->nSymms++;
}
Cudd_RecursiveDeref( dd, bSupp );
return p;
} /* end of Extra_SymmPairsComputeNaive */
/**Function********************************************************************
Synopsis [Creates the symmetry information structure from ZDD.]
Description [ZDD representation of symmetries is the set of cubes, each
of which has two variables in the positive polarity. These variables correspond
to the symmetric variable pair.]
SideEffects []
SeeAlso []
******************************************************************************/
Extra_SymmInfo_t * Extra_SymmPairsCreateFromZdd( DdManager * dd, DdNode * zPairs, DdNode * bSupp )
{
int i;
int nSuppSize;
Extra_SymmInfo_t * p;
int * pMapVars2Nums;
DdNode * bTemp;
DdNode * zSet, * zCube, * zTemp;
int iVar1, iVar2;
nSuppSize = Extra_bddSuppSize( dd, bSupp );
// allocate and clean the storage for symmetry info
p = Extra_SymmPairsAllocate( nSuppSize );
// allocate the storage for the temporary map
pMapVars2Nums = ABC_ALLOC( int, dd->size );
memset( pMapVars2Nums, 0, dd->size * sizeof(int) );
// assign the variables
p->nVarsMax = dd->size;
// p->nNodes = Cudd_DagSize( zPairs );
p->nNodes = 0;
for ( i = 0, bTemp = bSupp; bTemp != b1; bTemp = cuddT(bTemp), i++ )
{
p->pVars[i] = bTemp->index;
pMapVars2Nums[bTemp->index] = i;
}
// write the symmetry info into the structure
zSet = zPairs; Cudd_Ref( zSet );
while ( zSet != z0 )
{
// get the next cube
zCube = Extra_zddSelectOneSubset( dd, zSet ); Cudd_Ref( zCube );
// add these two variables to the data structure
assert( cuddT( cuddT(zCube) ) == z1 );
iVar1 = zCube->index/2;
iVar2 = cuddT(zCube)->index/2;
if ( pMapVars2Nums[iVar1] < pMapVars2Nums[iVar2] )
p->pSymms[ pMapVars2Nums[iVar1] ][ pMapVars2Nums[iVar2] ] = 1;
else
p->pSymms[ pMapVars2Nums[iVar2] ][ pMapVars2Nums[iVar1] ] = 1;
// count the symmetric pairs
p->nSymms ++;
// update the cuver and deref the cube
zSet = Cudd_zddDiff( dd, zTemp = zSet, zCube ); Cudd_Ref( zSet );
Cudd_RecursiveDerefZdd( dd, zTemp );
Cudd_RecursiveDerefZdd( dd, zCube );
} // for each cube
Cudd_RecursiveDerefZdd( dd, zSet );
ABC_FREE( pMapVars2Nums );
return p;
} /* end of Extra_SymmPairsCreateFromZdd */
/**Function*************************************************************
Synopsis [Merges two nodes.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
Extra_ImageNode_t * Extra_CombineTwoNodes( DdManager * dd, DdNode * bCube,
Extra_ImageNode_t * pNode1, Extra_ImageNode_t * pNode2 )
{
Extra_ImageNode_t * pNode;
Extra_ImagePart_t * pPart;
// create a new partition
pPart = ABC_ALLOC( Extra_ImagePart_t, 1 );
memset( pPart, 0, sizeof(Extra_ImagePart_t) );
// create the function
pPart->bFunc = Cudd_bddAndAbstract( dd, pNode1->pPart->bFunc, pNode2->pPart->bFunc, bCube );
Cudd_Ref( pPart->bFunc );
// update the support the partition
pPart->bSupp = Cudd_bddAndAbstract( dd, pNode1->pPart->bSupp, pNode2->pPart->bSupp, bCube );
Cudd_Ref( pPart->bSupp );
// update the numbers
pPart->nSupp = Extra_bddSuppSize( dd, pPart->bSupp );
pPart->nNodes = Cudd_DagSize( pPart->bFunc );
pPart->iPart = -1;
/*
ABC_PRB( dd, pNode1->pPart->bSupp );
ABC_PRB( dd, pNode2->pPart->bSupp );
ABC_PRB( dd, pPart->bSupp );
*/
// create a new node
pNode = ABC_ALLOC( Extra_ImageNode_t, 1 );
memset( pNode, 0, sizeof(Extra_ImageNode_t) );
pNode->dd = dd;
pNode->pPart = pPart;
pNode->pNode1 = pNode1;
pNode->pNode2 = pNode2;
// compute the image
pNode->bImage = Cudd_bddAndAbstract( dd, pNode1->bImage, pNode2->bImage, bCube );
Cudd_Ref( pNode->bImage );
// save the cube
if ( bCube != b1 )
{
pNode->bCube = bCube; Cudd_Ref( bCube );
}
return pNode;
}
/**Function********************************************************************
Synopsis [Performs a recursive step of Extra_SymmPairsCompute.]
Description [Returns the set of symmetric variable pairs represented as a set
of two-literal ZDD cubes. Both variables always appear in the positive polarity
in the cubes. This function works without building new BDD nodes. Some relatively
small number of ZDD nodes may be built to ensure proper bookkeeping of the
symmetry information.]
SideEffects []
SeeAlso []
******************************************************************************/
DdNode *
extraZddSymmPairsCompute(
DdManager * dd, /* the manager */
DdNode * bFunc, /* the function whose symmetries are computed */
DdNode * bVars ) /* the set of variables on which this function depends */
{
DdNode * zRes;
DdNode * bFR = Cudd_Regular(bFunc);
if ( cuddIsConstant(bFR) )
{
int nVars, i;
// determine how many vars are in the bVars
nVars = Extra_bddSuppSize( dd, bVars );
if ( nVars < 2 )
return z0;
else
{
DdNode * bVarsK;
// create the BDD bVarsK corresponding to K = 2;
bVarsK = bVars;
for ( i = 0; i < nVars-2; i++ )
bVarsK = cuddT( bVarsK );
return extraZddTuplesFromBdd( dd, bVarsK, bVars );
}
}
assert( bVars != b1 );
if ( (zRes = cuddCacheLookup2Zdd(dd, extraZddSymmPairsCompute, bFunc, bVars)) )
return zRes;
else
{
DdNode * zRes0, * zRes1;
DdNode * zTemp, * zPlus, * zSymmVars;
DdNode * bF0, * bF1;
DdNode * bVarsNew;
int nVarsExtra;
int LevelF;
// every variable in bF should be also in bVars, therefore LevelF cannot be above LevelV
// if LevelF is below LevelV, scroll through the vars in bVars to the same level as F
// count how many extra vars are there in bVars
nVarsExtra = 0;
LevelF = dd->perm[bFR->index];
for ( bVarsNew = bVars; LevelF > dd->perm[bVarsNew->index]; bVarsNew = cuddT(bVarsNew) )
nVarsExtra++;
// the indexes (level) of variables should be synchronized now
assert( bFR->index == bVarsNew->index );
// cofactor the function
if ( bFR != bFunc ) // bFunc is complemented
{
bF0 = Cudd_Not( cuddE(bFR) );
bF1 = Cudd_Not( cuddT(bFR) );
}
else
{
bF0 = cuddE(bFR);
bF1 = cuddT(bFR);
}
// solve subproblems
zRes0 = extraZddSymmPairsCompute( dd, bF0, cuddT(bVarsNew) );
if ( zRes0 == NULL )
return NULL;
cuddRef( zRes0 );
// if there is no symmetries in the negative cofactor
// there is no need to test the positive cofactor
if ( zRes0 == z0 )
zRes = zRes0; // zRes takes reference
else
{
zRes1 = extraZddSymmPairsCompute( dd, bF1, cuddT(bVarsNew) );
if ( zRes1 == NULL )
{
Cudd_RecursiveDerefZdd( dd, zRes0 );
return NULL;
}
cuddRef( zRes1 );
// only those variables are pair-wise symmetric
// that are pair-wise symmetric in both cofactors
// therefore, intersect the solutions
zRes = cuddZddIntersect( dd, zRes0, zRes1 );
if ( zRes == NULL )
{
Cudd_RecursiveDerefZdd( dd, zRes0 );
Cudd_RecursiveDerefZdd( dd, zRes1 );
return NULL;
}
cuddRef( zRes );
Cudd_RecursiveDerefZdd( dd, zRes0 );
Cudd_RecursiveDerefZdd( dd, zRes1 );
}
// consider the current top-most variable and find all the vars
// that are pairwise symmetric with it
// these variables are returned as a set of ZDD singletons
zSymmVars = extraZddGetSymmetricVars( dd, bF1, bF0, cuddT(bVarsNew) );
if ( zSymmVars == NULL )
{
Cudd_RecursiveDerefZdd( dd, zRes );
return NULL;
}
cuddRef( zSymmVars );
// attach the topmost variable to the set, to get the variable pairs
// use the positive polarity ZDD variable for the purpose
// there is no need to do so, if zSymmVars is empty
if ( zSymmVars == z0 )
Cudd_RecursiveDerefZdd( dd, zSymmVars );
else
{
zPlus = cuddZddGetNode( dd, 2*bFR->index, zSymmVars, z0 );
if ( zPlus == NULL )
{
Cudd_RecursiveDerefZdd( dd, zRes );
Cudd_RecursiveDerefZdd( dd, zSymmVars );
return NULL;
}
cuddRef( zPlus );
cuddDeref( zSymmVars );
// add these variable pairs to the result
zRes = cuddZddUnion( dd, zTemp = zRes, zPlus );
if ( zRes == NULL )
{
Cudd_RecursiveDerefZdd( dd, zTemp );
Cudd_RecursiveDerefZdd( dd, zPlus );
return NULL;
}
cuddRef( zRes );
Cudd_RecursiveDerefZdd( dd, zTemp );
Cudd_RecursiveDerefZdd( dd, zPlus );
}
// only zRes is referenced at this point
// if we skipped some variables, these variables cannot be symmetric with
// any variables that are currently in the support of bF, but they can be
// symmetric with the variables that are in bVars but not in the support of bF
if ( nVarsExtra )
{
// it is possible to improve this step:
// (1) there is no need to enter here, if nVarsExtra < 2
// create the set of topmost nVarsExtra in bVars
DdNode * bVarsExtra;
int nVars;
// remove from bVars all the variable that are in the support of bFunc
bVarsExtra = extraBddReduceVarSet( dd, bVars, bFunc );
if ( bVarsExtra == NULL )
{
Cudd_RecursiveDerefZdd( dd, zRes );
return NULL;
}
cuddRef( bVarsExtra );
// determine how many vars are in the bVarsExtra
nVars = Extra_bddSuppSize( dd, bVarsExtra );
if ( nVars < 2 )
{
Cudd_RecursiveDeref( dd, bVarsExtra );
}
else
{
int i;
DdNode * bVarsK;
// create the BDD bVarsK corresponding to K = 2;
bVarsK = bVarsExtra;
for ( i = 0; i < nVars-2; i++ )
bVarsK = cuddT( bVarsK );
// create the 2 variable tuples
zPlus = extraZddTuplesFromBdd( dd, bVarsK, bVarsExtra );
if ( zPlus == NULL )
{
Cudd_RecursiveDeref( dd, bVarsExtra );
Cudd_RecursiveDerefZdd( dd, zRes );
return NULL;
}
cuddRef( zPlus );
Cudd_RecursiveDeref( dd, bVarsExtra );
// add these to the result
zRes = cuddZddUnion( dd, zTemp = zRes, zPlus );
if ( zRes == NULL )
{
Cudd_RecursiveDerefZdd( dd, zTemp );
Cudd_RecursiveDerefZdd( dd, zPlus );
return NULL;
}
cuddRef( zRes );
Cudd_RecursiveDerefZdd( dd, zTemp );
Cudd_RecursiveDerefZdd( dd, zPlus );
}
}
cuddDeref( zRes );
/* insert the result into cache */
cuddCacheInsert2(dd, extraZddSymmPairsCompute, bFunc, bVars, zRes);
return zRes;
}
} /* end of extraZddSymmPairsCompute */
/**Function*************************************************************
Synopsis [Builds the tree.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
int Extra_BuildTreeNode( DdManager * dd,
int nNodes, Extra_ImageNode_t ** pNodes,
int nVars, Extra_ImageVar_t ** pVars )
{
Extra_ImageNode_t * pNode1, * pNode2;
Extra_ImageVar_t * pVar;
Extra_ImageNode_t * pNode;
DdNode * bCube, * bTemp, * bSuppTemp, * bParts;
int iNode1, iNode2;
int iVarBest, nSupp, v;
// find the best variable
iVarBest = Extra_FindBestVariable( dd, nNodes, pNodes, nVars, pVars );
if ( iVarBest == -1 )
return 0;
pVar = pVars[iVarBest];
// this var cannot appear in one partition only
nSupp = Extra_bddSuppSize( dd, pVar->bParts );
assert( nSupp == pVar->nParts );
assert( nSupp != 1 );
// if it appears in only two partitions, quantify it
if ( pVar->nParts == 2 )
{
// get the nodes
iNode1 = pVar->bParts->index;
iNode2 = cuddT(pVar->bParts)->index;
pNode1 = pNodes[iNode1];
pNode2 = pNodes[iNode2];
// get the quantification cube
bCube = dd->vars[pVar->iNum]; Cudd_Ref( bCube );
// add the variables that appear only in these partitions
for ( v = 0; v < nVars; v++ )
if ( pVars[v] && v != iVarBest && pVars[v]->bParts == pVars[iVarBest]->bParts )
{
// add this var
bCube = Cudd_bddAnd( dd, bTemp = bCube, dd->vars[pVars[v]->iNum] ); Cudd_Ref( bCube );
Cudd_RecursiveDeref( dd, bTemp );
// clean this var
Cudd_RecursiveDeref( dd, pVars[v]->bParts );
ABC_FREE( pVars[v] );
}
// clean the best var
Cudd_RecursiveDeref( dd, pVars[iVarBest]->bParts );
ABC_FREE( pVars[iVarBest] );
// combines two nodes
pNode = Extra_CombineTwoNodes( dd, bCube, pNode1, pNode2 );
Cudd_RecursiveDeref( dd, bCube );
}
else // if ( pVar->nParts > 2 )
{
// find two smallest BDDs that have this var
Extra_FindBestPartitions( dd, pVar->bParts, nNodes, pNodes, &iNode1, &iNode2 );
pNode1 = pNodes[iNode1];
pNode2 = pNodes[iNode2];
// it is not possible that a var appears only in these two
// otherwise, it would have a different cost
bParts = Cudd_bddAnd( dd, dd->vars[iNode1], dd->vars[iNode2] ); Cudd_Ref( bParts );
for ( v = 0; v < nVars; v++ )
if ( pVars[v] && pVars[v]->bParts == bParts )
assert( 0 );
Cudd_RecursiveDeref( dd, bParts );
// combines two nodes
pNode = Extra_CombineTwoNodes( dd, b1, pNode1, pNode2 );
}
// clean the old nodes
pNodes[iNode1] = pNode;
pNodes[iNode2] = NULL;
// update the variables that appear in pNode[iNode2]
for ( bSuppTemp = pNode2->pPart->bSupp; bSuppTemp != b1; bSuppTemp = cuddT(bSuppTemp) )
{
pVar = pVars[bSuppTemp->index];
if ( pVar == NULL ) // this variable is not be quantified
continue;
// quantify this var
assert( Cudd_bddLeq( dd, pVar->bParts, dd->vars[iNode2] ) );
pVar->bParts = Cudd_bddExistAbstract( dd, bTemp = pVar->bParts, dd->vars[iNode2] ); Cudd_Ref( pVar->bParts );
Cudd_RecursiveDeref( dd, bTemp );
// add the new var
pVar->bParts = Cudd_bddAnd( dd, bTemp = pVar->bParts, dd->vars[iNode1] ); Cudd_Ref( pVar->bParts );
Cudd_RecursiveDeref( dd, bTemp );
// update the score
pVar->nParts = Extra_bddSuppSize( dd, pVar->bParts );
}
return 1;
}
