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/**CFile****************************************************************
FileName [fxuReduce.c]
PackageName [MVSIS 2.0: Multi-valued logic synthesis system.]
Synopsis [Procedures to reduce the number of considered cube pairs.]
Author [MVSIS Group]
Affiliation [UC Berkeley]
Date [Ver. 1.0. Started - February 1, 2003.]
Revision [$Id: fxuReduce.c,v 1.0 2003/02/01 00:00:00 alanmi Exp $]
***********************************************************************/
#include "base/abc/abc.h"
#include "fxuInt.h"
#include "fxu.h"
ABC_NAMESPACE_IMPL_START
////////////////////////////////////////////////////////////////////////
/// DECLARATIONS ///
////////////////////////////////////////////////////////////////////////
static int Fxu_CountPairDiffs( char * pCover, unsigned char pDiffs[] );
////////////////////////////////////////////////////////////////////////
/// FUNCTION DEFINITIONS ///
////////////////////////////////////////////////////////////////////////
/**Function*************************************************************
Synopsis [Precomputes the pairs to use for creating two-cube divisors.]
Description [This procedure takes the matrix with variables and cubes
allocated (p), the original covers of the nodes (i-sets) and their number
(ppCovers,nCovers). The maximum number of pairs to compute and the total
number of pairs in existence. This procedure adds to the storage of
divisors exactly the given number of pairs (nPairsMax) while taking
first those pairs that have the smallest number of literals in their
cube-free form.]
SideEffects []
SeeAlso []
***********************************************************************/
int Fxu_PreprocessCubePairs( Fxu_Matrix * p, Vec_Ptr_t * vCovers, int nPairsTotal, int nPairsMax )
{
unsigned char * pnLitsDiff; // storage for the counters of diff literals
int * pnPairCounters; // the counters of pairs for each number of diff literals
Fxu_Cube * pCubeFirst, * pCubeLast;
Fxu_Cube * pCube1, * pCube2;
Fxu_Var * pVar;
int nCubes, nBitsMax, nSum;
int CutOffNum = -1, CutOffQuant = -1; // Suppress "might be used uninitialized"
int iPair, iQuant, k, c;
// abctime clk = Abc_Clock();
char * pSopCover;
int nFanins;
assert( nPairsMax < nPairsTotal );
// allocate storage for counter of diffs
pnLitsDiff = ABC_FALLOC( unsigned char, nPairsTotal );
// go through the covers and precompute the distances between the pairs
iPair = 0;
nBitsMax = -1;
for ( c = 0; c < vCovers->nSize; c++ )
if ( (pSopCover = (char *)vCovers->pArray[c]) )
{
nFanins = Abc_SopGetVarNum(pSopCover);
// precompute the differences
Fxu_CountPairDiffs( pSopCover, pnLitsDiff + iPair );
// update the counter
nCubes = Abc_SopGetCubeNum( pSopCover );
iPair += nCubes * (nCubes - 1) / 2;
if ( nBitsMax < nFanins )
nBitsMax = nFanins;
}
assert( iPair == nPairsTotal );
// allocate storage for counters of cube pairs by difference
pnPairCounters = ABC_FALLOC( int, 2 * nBitsMax );
memset( pnPairCounters, 0, sizeof(int) * 2 * nBitsMax );
// count the number of different pairs
for ( k = 0; k < nPairsTotal; k++ )
pnPairCounters[ pnLitsDiff[k] ]++;
// determine what pairs to take starting from the lower
// so that there would be exactly pPairsMax pairs
if ( pnPairCounters[0] != 0 )
{
ABC_FREE( pnLitsDiff );
ABC_FREE( pnPairCounters );
printf( "The SOPs of the nodes contain duplicated cubes. Run \"bdd; sop\" before \"fx\".\n" );
return 0;
}
if ( pnPairCounters[1] != 0 )
{
ABC_FREE( pnLitsDiff );
ABC_FREE( pnPairCounters );
printf( "The SOPs of the nodes are not SCC-free. Run \"bdd; sop\" before \"fx\".\n" );
return 0;
}
assert( pnPairCounters[0] == 0 ); // otherwise, covers are not dup-free
assert( pnPairCounters[1] == 0 ); // otherwise, covers are not SCC-free
nSum = 0;
for ( k = 0; k < 2 * nBitsMax; k++ )
{
nSum += pnPairCounters[k];
if ( nSum >= nPairsMax )
{
CutOffNum = k;
CutOffQuant = pnPairCounters[k] - (nSum - nPairsMax);
break;
}
}
ABC_FREE( pnPairCounters );
// set to 0 all the pairs above the cut-off number and quantity
iQuant = 0;
iPair = 0;
for ( k = 0; k < nPairsTotal; k++ )
if ( pnLitsDiff[k] > CutOffNum )
pnLitsDiff[k] = 0;
else if ( pnLitsDiff[k] == CutOffNum )
{
if ( iQuant++ >= CutOffQuant )
pnLitsDiff[k] = 0;
else
iPair++;
}
else
iPair++;
assert( iPair == nPairsMax );
// collect the corresponding pairs and add the divisors
iPair = 0;
for ( c = 0; c < vCovers->nSize; c++ )
if ( (pSopCover = (char *)vCovers->pArray[c]) )
{
// get the var
pVar = p->ppVars[2*c+1];
// get the first cube
pCubeFirst = pVar->pFirst;
// get the last cube
pCubeLast = pCubeFirst;
for ( k = 0; k < pVar->nCubes; k++ )
pCubeLast = pCubeLast->pNext;
assert( pCubeLast == NULL || pCubeLast->pVar != pVar );
// go through the cube pairs
for ( pCube1 = pCubeFirst; pCube1 != pCubeLast; pCube1 = pCube1->pNext )
for ( pCube2 = pCube1->pNext; pCube2 != pCubeLast; pCube2 = pCube2->pNext )
if ( pnLitsDiff[iPair++] )
{ // create the divisors for this pair
Fxu_MatrixAddDivisor( p, pCube1, pCube2 );
}
}
assert( iPair == nPairsTotal );
ABC_FREE( pnLitsDiff );
//ABC_PRT( "Preprocess", Abc_Clock() - clk );
return 1;
}
/**Function*************************************************************
Synopsis [Counts the differences in each cube pair in the cover.]
Description [Takes the cover (pCover) and the array where the
diff counters go (pDiffs). The array pDiffs should have as many
entries as there are different pairs of cubes in the cover: n(n-1)/2.
Fills out the array pDiffs with the following info: For each cube
pair, included in the array is the number of literals in both cubes
after they are made cube free.]
SideEffects []
SeeAlso []
***********************************************************************/
int Fxu_CountPairDiffs( char * pCover, unsigned char pDiffs[] )
{
char * pCube1, * pCube2;
int nOnes, nCubePairs, nFanins, v;
nCubePairs = 0;
nFanins = Abc_SopGetVarNum(pCover);
Abc_SopForEachCube( pCover, nFanins, pCube1 )
Abc_SopForEachCube( pCube1, nFanins, pCube2 )
{
if ( pCube1 == pCube2 )
continue;
nOnes = 0;
for ( v = 0; v < nFanins; v++ )
nOnes += (pCube1[v] != pCube2[v]);
pDiffs[nCubePairs++] = nOnes;
}
return 1;
}
////////////////////////////////////////////////////////////////////////
/// END OF FILE ///
////////////////////////////////////////////////////////////////////////
ABC_NAMESPACE_IMPL_END
|
