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/**CFile****************************************************************
FileName [ifMap.c]
SystemName [ABC: Logic synthesis and verification system.]
PackageName [FPGA mapping based on priority cuts.]
Synopsis [Mapping procedures.]
Author [Alan Mishchenko]
Affiliation [UC Berkeley]
Date [Ver. 1.0. Started - November 21, 2006.]
Revision [$Id: ifMap.c,v 1.00 2006/11/21 00:00:00 alanmi Exp $]
***********************************************************************/
#include "if.h"
////////////////////////////////////////////////////////////////////////
/// DECLARATIONS ///
////////////////////////////////////////////////////////////////////////
/*
Ideas to try:
- reverse order of area recovery
- ordering of the outputs by size
- merging Delay, Delay2, and Area
- expand/reduce area recovery
*/
////////////////////////////////////////////////////////////////////////
/// FUNCTION DEFINITIONS ///
////////////////////////////////////////////////////////////////////////
/**Function*************************************************************
Synopsis [Counts the number of 1s in the signature.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
static inline int If_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 [Finds the best cut.]
Description [Mapping modes: delay (0), area flow (1), area (2).]
SideEffects []
SeeAlso []
***********************************************************************/
void If_ObjPerformMapping( If_Man_t * p, If_Obj_t * pObj, int Mode )
{
If_Cut_t * pCut0, * pCut1, * pCut;
int i, k, iCut, Temp;
// prepare
if ( Mode == 0 )
pObj->EstRefs = (float)pObj->nRefs;
else if ( Mode == 1 )
pObj->EstRefs = (float)((2.0 * pObj->EstRefs + pObj->nRefs) / 3.0);
else if ( Mode == 2 && pObj->nRefs > 0 )
If_CutDeref( p, If_ObjCutBest(pObj), 100 );
// recompute the parameters of the best cut
p->nCuts = 0;
p->nCutsMerged++;
if ( Mode )
{
pCut = If_ObjCutBest(pObj);
pCut->Delay = If_CutDelay( p, pCut );
assert( pCut->Delay <= pObj->Required + p->fEpsilon );
pCut->Area = (Mode == 2)? If_CutAreaDerefed( p, pCut, 100 ) : If_CutFlow( p, pCut );
// save the best cut from the previous iteration
If_CutCopy( p->ppCuts[p->nCuts++], pCut );
p->nCutsMerged++;
}
// prepare room for the next cut
iCut = p->nCuts;
pCut = p->ppCuts[iCut];
// generate cuts
If_ObjForEachCut( pObj->pFanin0, pCut0, i )
If_ObjForEachCut( pObj->pFanin1, pCut1, k )
{
// make sure K-feasible cut exists
if ( If_WordCountOnes(pCut0->uSign | pCut1->uSign) > p->pPars->nLutSize )
continue;
// prefilter using arrival times
if ( Mode && (pCut0->Delay > pObj->Required + p->fEpsilon || pCut1->Delay > pObj->Required + p->fEpsilon) )
continue;
// merge the nodes
if ( !If_CutMerge( pCut0, pCut1, pCut ) )
continue;
// check if this cut is contained in any of the available cuts
pCut->uSign = pCut0->uSign | pCut1->uSign;
if ( If_CutFilter( p, pCut ) )
continue;
// check if the cut satisfies the required times
pCut->Delay = If_CutDelay( p, pCut );
if ( Mode && pCut->Delay > pObj->Required + p->fEpsilon )
continue;
// the cuts have been successfully merged
// compute the truth table
if ( p->pPars->fTruth )
If_CutComputeTruth( p, pCut, pCut0, pCut1, pObj->fCompl0, pObj->fCompl1 );
// compute the application-specific cost and depth
Temp = p->pPars->pFuncCost? p->pPars->pFuncCost(If_CutTruth(pCut), pCut->nLimit) : 0;
pCut->Cost = (Temp & 0xffff); pCut->Depth = (Temp >> 16);
// compute area of the cut (this area may depend on the application specific cost)
pCut->Area = (Mode == 2)? If_CutAreaDerefed( p, pCut, 100 ) : If_CutFlow( p, pCut );
// make sure the cut is the last one (after filtering it may not be so)
assert( pCut == p->ppCuts[iCut] );
p->ppCuts[iCut] = p->ppCuts[p->nCuts];
p->ppCuts[p->nCuts] = pCut;
// count the cut
p->nCuts++;
p->nCutsMerged++;
// prepare room for the next cut
iCut = p->nCuts;
pCut = p->ppCuts[iCut];
}
//printf( "%d ", p->nCuts );
assert( p->nCuts > 0 );
// sort if we have more cuts
If_ManSortCuts( p, Mode );
// decide how many cuts to use
pObj->nCuts = IF_MIN( p->nCuts + 1, p->nCutsUsed );
// take the first
If_ObjForEachCutStart( pObj, pCut, i, 1 )
If_CutCopy( pCut, p->ppCuts[i-1] );
assert( If_ObjCutBest(pObj)->nLeaves > 1 );
// assign delay of the trivial cut
If_ObjCutTriv(pObj)->Delay = If_ObjCutBest(pObj)->Delay;
//printf( "%d %d ", pObj->Id, (int)If_ObjCutBest(pObj)->Delay );
//printf( "%d %d ", pObj->Id, pObj->nCuts );
// ref the selected cut
if ( Mode == 2 && pObj->nRefs > 0 )
If_CutRef( p, If_ObjCutBest(pObj), 100 );
// find the largest cut
if ( p->nCutsMax < pObj->nCuts )
p->nCutsMax = pObj->nCuts;
}
////////////////////////////////////////////////////////////////////////
/// END OF FILE ///
////////////////////////////////////////////////////////////////////////
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