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/**CFile****************************************************************
FileName [ifTruth.c]
SystemName [ABC: Logic synthesis and verification system.]
PackageName [FPGA mapping based on priority cuts.]
Synopsis [Computation of truth tables of the cuts.]
Author [Alan Mishchenko]
Affiliation [UC Berkeley]
Date [Ver. 1.0. Started - November 21, 2006.]
Revision [$Id: ifTruth.c,v 1.00 2006/11/21 00:00:00 alanmi Exp $]
***********************************************************************/
#include "if.h"
ABC_NAMESPACE_IMPL_START
////////////////////////////////////////////////////////////////////////
/// DECLARATIONS ///
////////////////////////////////////////////////////////////////////////
static int If_CutTruthMinimize( If_Man_t * p, If_Cut_t * pCut );
////////////////////////////////////////////////////////////////////////
/// FUNCTION DEFINITIONS ///
////////////////////////////////////////////////////////////////////////
/**Function*************************************************************
Synopsis [Several simple procedures working with truth tables.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
static inline int If_TruthWordNum( int nVars ) { return nVars <= 5 ? 1 : (1 << (nVars - 5)); }
static inline void If_TruthNot( unsigned * pOut, unsigned * pIn, int nVars )
{
int w;
for ( w = If_TruthWordNum(nVars)-1; w >= 0; w-- )
pOut[w] = ~pIn[w];
}
static inline void If_TruthCopy( unsigned * pOut, unsigned * pIn, int nVars )
{
int w;
for ( w = If_TruthWordNum(nVars)-1; w >= 0; w-- )
pOut[w] = pIn[w];
}
static inline void If_TruthNand( unsigned * pOut, unsigned * pIn0, unsigned * pIn1, int nVars )
{
int w;
for ( w = If_TruthWordNum(nVars)-1; w >= 0; w-- )
pOut[w] = ~(pIn0[w] & pIn1[w]);
}
static inline void If_TruthAnd( unsigned * pOut, unsigned * pIn0, unsigned * pIn1, int nVars )
{
int w;
for ( w = If_TruthWordNum(nVars)-1; w >= 0; w-- )
pOut[w] = pIn0[w] & pIn1[w];
}
/**Function*************************************************************
Synopsis [Swaps two adjacent variables in the truth table.]
Description [Swaps var number Start and var number Start+1 (0-based numbers).
The input truth table is pIn. The output truth table is pOut.]
SideEffects []
SeeAlso []
***********************************************************************/
void If_TruthSwapAdjacentVars( unsigned * pOut, unsigned * pIn, int nVars, int iVar )
{
static unsigned PMasks[4][3] = {
{ 0x99999999, 0x22222222, 0x44444444 },
{ 0xC3C3C3C3, 0x0C0C0C0C, 0x30303030 },
{ 0xF00FF00F, 0x00F000F0, 0x0F000F00 },
{ 0xFF0000FF, 0x0000FF00, 0x00FF0000 }
};
int nWords = If_TruthWordNum( nVars );
int i, k, Step, Shift;
assert( iVar < nVars - 1 );
if ( iVar < 4 )
{
Shift = (1 << iVar);
for ( i = 0; i < nWords; i++ )
pOut[i] = (pIn[i] & PMasks[iVar][0]) | ((pIn[i] & PMasks[iVar][1]) << Shift) | ((pIn[i] & PMasks[iVar][2]) >> Shift);
}
else if ( iVar > 4 )
{
Step = (1 << (iVar - 5));
for ( k = 0; k < nWords; k += 4*Step )
{
for ( i = 0; i < Step; i++ )
pOut[i] = pIn[i];
for ( i = 0; i < Step; i++ )
pOut[Step+i] = pIn[2*Step+i];
for ( i = 0; i < Step; i++ )
pOut[2*Step+i] = pIn[Step+i];
for ( i = 0; i < Step; i++ )
pOut[3*Step+i] = pIn[3*Step+i];
pIn += 4*Step;
pOut += 4*Step;
}
}
else // if ( iVar == 4 )
{
for ( i = 0; i < nWords; i += 2 )
{
pOut[i] = (pIn[i] & 0x0000FFFF) | ((pIn[i+1] & 0x0000FFFF) << 16);
pOut[i+1] = (pIn[i+1] & 0xFFFF0000) | ((pIn[i] & 0xFFFF0000) >> 16);
}
}
}
/**Function*************************************************************
Synopsis [Implements given permutation of variables.]
Description [Permutes truth table in-place (returns it in pIn).]
SideEffects []
SeeAlso []
***********************************************************************/
void If_CutTruthPermute( unsigned * pOut, unsigned * pIn, int nVars, float * pDelays, int * pVars )
{
unsigned * pTemp;
float tTemp;
int i, Temp, Counter = 0, fChange = 1;
while ( fChange )
{
fChange = 0;
for ( i = 0; i < nVars - 1; i++ )
{
if ( pDelays[i] >= pDelays[i+1] )
// if ( pDelays[i] <= pDelays[i+1] )
continue;
tTemp = pDelays[i]; pDelays[i] = pDelays[i+1]; pDelays[i+1] = tTemp;
Temp = pVars[i]; pVars[i] = pVars[i+1]; pVars[i+1] = Temp;
if ( pOut && pIn )
If_TruthSwapAdjacentVars( pOut, pIn, nVars, i );
pTemp = pOut; pOut = pIn; pIn = pTemp;
fChange = 1;
Counter++;
}
}
if ( pOut && pIn && (Counter & 1) )
If_TruthCopy( pOut, pIn, nVars );
}
/**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 []
***********************************************************************/
void If_TruthStretch( unsigned * pOut, unsigned * pIn, int nVars, int nVarsAll, unsigned Phase )
{
unsigned * pTemp;
int i, k, Var = nVars - 1, Counter = 0;
for ( i = nVarsAll - 1; i >= 0; i-- )
if ( Phase & (1 << i) )
{
for ( k = Var; k < i; k++ )
{
If_TruthSwapAdjacentVars( pOut, pIn, nVarsAll, k );
pTemp = pIn; pIn = pOut; pOut = pTemp;
Counter++;
}
Var--;
}
assert( Var == -1 );
// swap if it was moved an even number of times
if ( !(Counter & 1) )
If_TruthCopy( pOut, pIn, nVarsAll );
}
/**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 []
***********************************************************************/
void If_TruthShrink( unsigned * pOut, unsigned * pIn, int nVars, int nVarsAll, unsigned Phase, int fReturnIn )
{
unsigned * pTemp;
int i, k, Var = 0, Counter = 0;
for ( i = 0; i < nVarsAll; i++ )
if ( Phase & (1 << i) )
{
for ( k = i-1; k >= Var; k-- )
{
If_TruthSwapAdjacentVars( pOut, pIn, nVarsAll, k );
pTemp = pIn; pIn = pOut; pOut = pTemp;
Counter++;
}
Var++;
}
assert( Var == nVars );
// swap if it was moved an even number of times
if ( fReturnIn ^ !(Counter & 1) )
If_TruthCopy( pOut, pIn, nVarsAll );
}
/**Function*************************************************************
Synopsis [Returns 1 if TT depends on the given variable.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
int If_CutTruthVarInSupport( unsigned * pTruth, int nVars, int iVar )
{
int nWords = If_TruthWordNum( nVars );
int i, k, Step;
assert( iVar < nVars );
switch ( iVar )
{
case 0:
for ( i = 0; i < nWords; i++ )
if ( (pTruth[i] & 0x55555555) != ((pTruth[i] & 0xAAAAAAAA) >> 1) )
return 1;
return 0;
case 1:
for ( i = 0; i < nWords; i++ )
if ( (pTruth[i] & 0x33333333) != ((pTruth[i] & 0xCCCCCCCC) >> 2) )
return 1;
return 0;
case 2:
for ( i = 0; i < nWords; i++ )
if ( (pTruth[i] & 0x0F0F0F0F) != ((pTruth[i] & 0xF0F0F0F0) >> 4) )
return 1;
return 0;
case 3:
for ( i = 0; i < nWords; i++ )
if ( (pTruth[i] & 0x00FF00FF) != ((pTruth[i] & 0xFF00FF00) >> 8) )
return 1;
return 0;
case 4:
for ( i = 0; i < nWords; i++ )
if ( (pTruth[i] & 0x0000FFFF) != ((pTruth[i] & 0xFFFF0000) >> 16) )
return 1;
return 0;
default:
Step = (1 << (iVar - 5));
for ( k = 0; k < nWords; k += 2*Step )
{
for ( i = 0; i < Step; i++ )
if ( pTruth[i] != pTruth[Step+i] )
return 1;
pTruth += 2*Step;
}
return 0;
}
}
/**Function*************************************************************
Synopsis [Returns support of the function.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
unsigned If_CutTruthSupport( unsigned * pTruth, int nVars, int * pnSuppSize )
{
int i, Support = 0;
int nSuppSize = 0;
for ( i = 0; i < nVars; i++ )
if ( If_CutTruthVarInSupport( pTruth, nVars, i ) )
{
Support |= (1 << i);
nSuppSize++;
}
*pnSuppSize = nSuppSize;
return Support;
}
/**Function*************************************************************
Synopsis [Computes the stretching phase of the cut w.r.t. the merged cut.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
static inline unsigned If_CutTruthPhase( If_Cut_t * pCut, If_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 [Performs truth table computation.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
int If_CutComputeTruth( If_Man_t * p, If_Cut_t * pCut, If_Cut_t * pCut0, If_Cut_t * pCut1, int fCompl0, int fCompl1 )
{
extern void If_CutFactorTest( unsigned * pTruth, int nVars );
// permute the first table
if ( fCompl0 ^ pCut0->fCompl )
If_TruthNot( p->puTemp[0], If_CutTruth(pCut0), pCut->nLimit );
else
If_TruthCopy( p->puTemp[0], If_CutTruth(pCut0), pCut->nLimit );
If_TruthStretch( p->puTemp[2], p->puTemp[0], pCut0->nLeaves, pCut->nLimit, If_CutTruthPhase(pCut, pCut0) );
// permute the second table
if ( fCompl1 ^ pCut1->fCompl )
If_TruthNot( p->puTemp[1], If_CutTruth(pCut1), pCut->nLimit );
else
If_TruthCopy( p->puTemp[1], If_CutTruth(pCut1), pCut->nLimit );
If_TruthStretch( p->puTemp[3], p->puTemp[1], pCut1->nLeaves, pCut->nLimit, If_CutTruthPhase(pCut, pCut1) );
// produce the resulting table
assert( pCut->fCompl == 0 );
if ( pCut->fCompl )
If_TruthNand( If_CutTruth(pCut), p->puTemp[2], p->puTemp[3], pCut->nLimit );
else
If_TruthAnd( If_CutTruth(pCut), p->puTemp[2], p->puTemp[3], pCut->nLimit );
// minimize the support of the cut
if ( p->pPars->fCutMin )
return If_CutTruthMinimize( p, pCut );
// perform
// If_CutFactorTest( If_CutTruth(pCut), pCut->nLimit );
// printf( "%d ", If_CutLeaveNum(pCut) - If_CutTruthSupportSize(If_CutTruth(pCut), If_CutLeaveNum(pCut)) );
return 0;
}
/**Function*************************************************************
Synopsis [Minimize support of the cut.]
Description [Returns 1 if the node's support has changed]
SideEffects []
SeeAlso []
***********************************************************************/
int If_CutTruthMinimize( If_Man_t * p, If_Cut_t * pCut )
{
unsigned uSupport;
int nSuppSize, i, k;
// compute the support of the cut's function
uSupport = If_CutTruthSupport( If_CutTruth(pCut), If_CutLeaveNum(pCut), &nSuppSize );
if ( nSuppSize == If_CutLeaveNum(pCut) )
return 0;
// TEMPORARY
if ( nSuppSize < 2 )
{
p->nSmallSupp++;
return 2;
}
// if ( If_CutLeaveNum(pCut) - nSuppSize > 1 )
// return 0;
//printf( "%d %d ", If_CutLeaveNum(pCut), nSuppSize );
// pCut->fUseless = 1;
// shrink the truth table
If_TruthShrink( p->puTemp[0], If_CutTruth(pCut), nSuppSize, pCut->nLimit, uSupport, 1 );
// update leaves and signature
pCut->uSign = 0;
for ( i = k = 0; i < If_CutLeaveNum(pCut); i++ )
{
if ( !(uSupport & (1 << i)) )
continue;
pCut->pLeaves[k++] = pCut->pLeaves[i];
pCut->uSign |= If_ObjCutSign( pCut->pLeaves[i] );
}
assert( k == nSuppSize );
pCut->nLeaves = nSuppSize;
// verify the result
// uSupport = If_CutTruthSupport( If_CutTruth(pCut), If_CutLeaveNum(pCut), &nSuppSize );
// assert( nSuppSize == If_CutLeaveNum(pCut) );
return 1;
}
////////////////////////////////////////////////////////////////////////
/// END OF FILE ///
////////////////////////////////////////////////////////////////////////
ABC_NAMESPACE_IMPL_END
|
