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|
/**CFile****************************************************************
FileName [rwrTruth.c]
SystemName [ABC: Logic synthesis and verification system.]
PackageName [And-Inverter Graph package.]
Synopsis []
Author [Alan Mishchenko]
Affiliation [UC Berkeley]
Date [Ver. 1.0. Started - June 20, 2005.]
Revision [$Id: rwrTruth.c,v 1.00 2005/06/20 00:00:00 alanmi Exp $]
***********************************************************************/
#include "aig.h"
/* The code in this file was written with portability to 64-bits in mind.
The type "unsigned" is assumed to be 32-bit on any platform.
*/
////////////////////////////////////////////////////////////////////////
/// DECLARATIONS ///
////////////////////////////////////////////////////////////////////////
#define ABCTMAX 8 // the max number of vars
typedef struct Aig_Truth_t_ Aig_Truth_t;
struct Aig_Truth_t_
{
short nVars; // the number of variables
short nWords; // the number of 32-bit words
unsigned Truth[1<<(ABCTMAX-5)]; // the truth table
unsigned Cofs[2][1<<(ABCTMAX-6)]; // the truth table of cofactors
unsigned Data[4][1<<(ABCTMAX-7)]; // the truth table of cofactors
short Counts[ABCTMAX][2]; // the minterm counters
Aig_Node_t * pLeaves[ABCTMAX]; // the pointers to leaves
Aig_Man_t * pMan; // the AIG manager
};
static void Aig_TruthCount( Aig_Truth_t * p );
////////////////////////////////////////////////////////////////////////
/// FUNCTION DEFINITIONS ///
////////////////////////////////////////////////////////////////////////
/**Function*************************************************************
Synopsis [Creates the function given the truth table.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
Aig_Truth_t * Aig_TruthCreate( int nVars, unsigned * pTruth, Aig_Node_t ** pLeaves )
{
Aig_Truth_t * p;
int i;
p = ALLOC( Aig_Truth_t, 1 );
memset( p, 0, sizeof(Aig_Truth_t) );
p->nVars = nVars;
p->nWords = (nVars < 5)? 1 : (1 << (nVars-5));
for ( i = 0; i < p->nWords; i++ )
p->Truth[i] = pTruth[i];
if ( nVars < 5 )
p->Truth[0] &= (~0u >> (32-(1<<nVars)));
for ( i = 0; i < p->nVars; i++ )
p->pLeaves[i] = pLeaves[i];
Aig_TruthCount( p );
return p;
}
/**Function*************************************************************
Synopsis [Counts the number of miterms in the cofactors.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
static inline int Aig_WordCountOnes( unsigned val )
{
val = (val & 0x55555555) + ((val>>1) & 0x55555555);
val = (val & 0x33333333) + ((val>>2) & 0x33333333);
val = (val & 0x0F0F0F0F) + ((val>>4) & 0x0F0F0F0F);
val = (val & 0x00FF00FF) + ((val>>8) & 0x00FF00FF);
return (val & 0x0000FFFF) + (val>>8);
}
/**Function*************************************************************
Synopsis [Counts the number of miterms in the cofactors.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
void Aig_TruthCount( Aig_Truth_t * p )
{
static unsigned Masks[5][2] = {
{ 0x33333333, 0xAAAAAAAA },
{ 0x55555555, 0xCCCCCCCC },
{ 0x0F0F0F0F, 0xF0F0F0F0 },
{ 0x00FF00FF, 0xFF00FF00 },
{ 0x0000FFFF, 0xFFFF0000 }
};
int i, k;
assert( p->Counts[0][0] == 0 && p->Counts[0][1] == 0 );
for ( i = 0; i < p->nVars; i++ )
{
p->Counts[i][0] = p->Counts[i][1] = 0;
if ( i < 5 )
{
for ( k = 0; k < p->nWords; k++ )
{
p->Counts[i][0] += Aig_WordCountOnes( p->Truth[k] & Masks[i][0] );
p->Counts[i][1] += Aig_WordCountOnes( p->Truth[k] & Masks[i][1] );
}
}
else
{
for ( k = 0; k < p->nWords; k++ )
if ( i & (1 << (k-5)) )
p->Counts[i][1] += Aig_WordCountOnes( p->Truth[k] );
else
p->Counts[i][0] += Aig_WordCountOnes( p->Truth[k] );
}
}
/*
// normalize the variables
for ( i = 0; i < p->nVars; i++ )
if ( p->Counts[i][0] > p->Counts[i][1] )
{
k = p->Counts[i][0];
p->Counts[i][0] = p->Counts[i][1];
p->Counts[i][1] = k;
p->pLeaves[i] = Aig_Not( p->pLeaves[i] );
}
*/
}
/**Function*************************************************************
Synopsis [Extracts one part of the bitstring.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
static inline unsigned Aig_WordGetPart( unsigned * p, int Start, int Size )
{
return (p[Start/5] >> (Start%32)) & (~0u >> (32-Size));
}
/**Function*************************************************************
Synopsis [Inserts one part of the bitstring.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
static inline void Aig_WordSetPart( unsigned * p, int Start, unsigned Part )
{
p[Start/5] |= (Part << (Start%32));
}
/**Function*************************************************************
Synopsis [Computes the cofactor with respect to one variable.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
void Aig_TruthCofactor( int Var, int Pol, int nVars, unsigned * pTruth, unsigned * pResult )
{
if ( Var < 5 )
{
int nPartSize = ( 1 << Var );
int nParts = ( 1 << (nVars-Var-1) );
unsigned uPart;
int i;
for ( i = 0; i < nParts; i++ )
{
uPart = Aig_WordGetPart( pTruth, (2*i+Pol)*nPartSize, nPartSize );
Aig_WordSetPart( pResult, i*nPartSize, uPart );
}
if ( nVars <= 5 )
pResult[0] &= (~0u >> (32-(1<<(nVars-1))));
}
else
{
int nWords = (1 << (nVars-5));
int i, k = 0;
for ( i = 0; i < nWords; i++ )
if ( (i & (1 << (Var-5))) == Pol )
pResult[k++] = pTruth[i];
assert( k == nWords/2 );
}
}
/**Function*************************************************************
Synopsis [Computes the BDD of the truth table.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
DdNode * Aig_TruthToBdd_rec( DdManager * dd, unsigned * pTruth, int Shift, int nVars, int iVar )
{
DdNode * bCof0, * bCof1, * bRes;
if ( nVars == 1 )
return Cudd_NotCond( Cudd_ReadOne(dd), !Aig_WordGetPart(pTruth, Shift, 1) );
if ( nVars == 3 )
{
unsigned char * pChar = ((char *)pTruth) + Shift/8;
assert( Shift % 8 == 0 );
if ( *pChar == 0 )
return Cudd_ReadLogicZero(dd);
if ( *pChar == 0xFF )
return Cudd_ReadOne(dd);
}
if ( nVars == 5 )
{
unsigned * pWord = pTruth + Shift/32;
assert( Shift % 32 == 0 );
if ( *pWord == 0 )
return Cudd_ReadLogicZero(dd);
if ( *pWord == 0xFFFFFFFF )
return Cudd_ReadOne(dd);
}
bCof0 = Aig_TruthToBdd_rec( dd, pTruth, Shift, nVars-1, iVar+1 ); Cudd_Ref( bCof0 );
bCof1 = Aig_TruthToBdd_rec( dd, pTruth, Shift + (1 << (nVars-1)), nVars-1, iVar+1 ); Cudd_Ref( bCof1 );
bRes = Cudd_bddIte( dd, Cudd_bddIthVar(dd, iVar), bCof1, bCof0 ); Cudd_Ref( bRes );
Cudd_RecursiveDeref( dd, bCof0 );
Cudd_RecursiveDeref( dd, bCof1 );
Cudd_Deref( bRes );
return bRes;
}
/**Function*************************************************************
Synopsis [Computes the BDD of the truth table.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
DdNode * Aig_TruthToBdd( DdManager * dd, Aig_Truth_t * p )
{
return Aig_TruthToBdd_rec( dd, p->Truth, 0, p->nVars, 0 );
}
/**Function*************************************************************
Synopsis [Compare bistrings.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
static inline int Aig_WordCompare( unsigned * p0, unsigned * p1, int nWords )
{
int i;
for ( i = 0; i < nWords; i++ )
if ( p0[i] != p1[i] )
return 0;
return 1;
}
/**Function*************************************************************
Synopsis [Compare bistrings.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
static inline int Aig_WordCompareCompl( unsigned * p0, unsigned * p1, int nWords )
{
int i;
for ( i = 0; i < nWords; i++ )
if ( p0[i] != ~p1[i] )
return 0;
return 1;
}
/**Function*************************************************************
Synopsis [Computes the cofactor with respect to one variable.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
void Aig_TruthReplaceByCofactor( Aig_Truth_t * p, int iVar, unsigned * pTruth )
{
}
/**Function*************************************************************
Synopsis [Computes the cofactor with respect to one variable.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
Aig_Node_t * Aig_TruthDecompose( Aig_Truth_t * p )
{
Aig_Node_t * pVar;
int nOnesCof = ( 1 << (p->nVars-1) );
int nWordsCof = (p->nWords == 1 ? 1 : p->nWords/2);
int i;
// check for constant function
if ( p->nVars == 0 )
return Aig_NotCond( Aig_ManConst1(p->pMan), (p->Truth[0]&1)==0 );
// count the number of minterms in the cofactors
Aig_TruthCount( p );
// remove redundant variables and EXORs
for ( i = p->nVars - 1; i >= 0; i-- )
{
if ( p->Counts[i][0] == p->Counts[i][1] )
{
// compute cofactors
Aig_TruthCofactor( i, 0, p->nVars, p->Truth, p->Cofs[0] );
Aig_TruthCofactor( i, 1, p->nVars, p->Truth, p->Cofs[1] );
if ( Aig_WordCompare( p->Cofs[0], p->Cofs[1], nWordsCof ) )
{ // equal
// remove redundant variable
Aig_TruthReplaceByCofactor( p, i, p->Cofs[0] );
return Aig_TruthDecompose( p );
}
}
// check the case of EXOR
if ( p->Counts[i][0] == nOnesCof - p->Counts[i][1] )
{
// compute cofactors
Aig_TruthCofactor( i, 0, p->nVars, p->Truth, p->Cofs[0] );
Aig_TruthCofactor( i, 1, p->nVars, p->Truth, p->Cofs[1] );
if ( Aig_WordCompareCompl( p->Cofs[0], p->Cofs[1], nWordsCof ) )
{ // equal
pVar = p->pLeaves[i];
// remove redundant variable
Aig_TruthReplaceByCofactor( p, i, p->Cofs[0] );
// F = x' * F0 + x * F1 = x <+> F0 assuming that F0 == ~F1
return Aig_Xor( p->pMan, pVar, Aig_TruthDecompose( p ) );
}
}
}
// process variables with constant cofactors
for ( i = p->nVars - 1; i >= 0; i-- )
{
if ( p->Counts[i][0] != 0 && p->Counts[i][1] != 0 &&
p->Counts[i][0] != nOnesCof && p->Counts[i][1] != nOnesCof )
continue;
pVar = p->pLeaves[i];
if ( p->Counts[i][0] == 0 )
{
Aig_TruthCofactor( i, 1, p->nVars, p->Truth, p->Cofs[1] );
// remove redundant variable
Aig_TruthReplaceByCofactor( p, i, p->Cofs[1] );
// F = x' * 0 + x * F1 = x * F1
return Aig_And( p->pMan, pVar, Aig_TruthDecompose( p ) );
}
if ( p->Counts[i][1] == 0 )
{
Aig_TruthCofactor( i, 0, p->nVars, p->Truth, p->Cofs[0] );
// remove redundant variable
Aig_TruthReplaceByCofactor( p, i, p->Cofs[0] );
// F = x' * F0 + x * 0 = x' * F0
return Aig_And( p->pMan, Aig_Not(pVar), Aig_TruthDecompose( p ) );
}
if ( p->Counts[i][0] == nOnesCof )
{
Aig_TruthCofactor( i, 1, p->nVars, p->Truth, p->Cofs[1] );
// remove redundant variable
Aig_TruthReplaceByCofactor( p, i, p->Cofs[1] );
// F = x' * 1 + x * F1 = x' + F1
return Aig_Or( p->pMan, Aig_Not(pVar), Aig_TruthDecompose( p ) );
}
if ( p->Counts[i][1] == nOnesCof )
{
Aig_TruthCofactor( i, 0, p->nVars, p->Truth, p->Cofs[0] );
// remove redundant variable
Aig_TruthReplaceByCofactor( p, i, p->Cofs[0] );
// F = x' * F0 + x * 1 = x + F0
return Aig_Or( p->pMan, pVar, Aig_TruthDecompose( p ) );
}
assert( 0 );
}
}
////////////////////////////////////////////////////////////////////////
/// END OF FILE ///
////////////////////////////////////////////////////////////////////////
|
