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abc/src/map/fpga/fpgaTime.c

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/**CFile****************************************************************
FileName [fpgaTime.c]
PackageName [MVSIS 1.3: Multi-valued logic synthesis system.]
Synopsis [Technology mapping for variable-size-LUT FPGAs.]
Author [MVSIS Group]
Affiliation [UC Berkeley]
Date [Ver. 2.0. Started - August 18, 2004.]
Revision [$Id: fpgaTime.c,v 1.1 2005/01/23 06:59:42 alanmi Exp $]
***********************************************************************/
#include "fpgaInt.h"
////////////////////////////////////////////////////////////////////////
/// DECLARATIONS ///
////////////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////////////
/// FUNCTION DEFINITIONS ///
////////////////////////////////////////////////////////////////////////
/**Function*************************************************************
Synopsis [Computes the arrival times of the cut.]
Description [Computes the maximum arrival time of the cut leaves and
adds the delay of the LUT.]
SideEffects []
SeeAlso []
***********************************************************************/
float Fpga_TimeCutComputeArrival( Fpga_Man_t * pMan, Fpga_Cut_t * pCut )
{
int i;
float tArrival;
tArrival = -FPGA_FLOAT_LARGE;
for ( i = 0; i < pCut->nLeaves; i++ )
if ( tArrival < pCut->ppLeaves[i]->pCutBest->tArrival )
tArrival = pCut->ppLeaves[i]->pCutBest->tArrival;
tArrival += pMan->pLutLib->pLutDelays[pCut->nLeaves];
return tArrival;
}
/**Function*************************************************************
Synopsis [Computes the arrival times of the cut recursively.]
Description [When computing the arrival time for the previously unused
cuts, their arrival time may be incorrect because their fanins have
incorrect arrival time. This procedure is called to fix this problem.]
SideEffects []
SeeAlso []
***********************************************************************/
float Fpga_TimeCutComputeArrival_rec( Fpga_Man_t * pMan, Fpga_Cut_t * pCut )
{
int i;
for ( i = 0; i < pCut->nLeaves; i++ )
if ( pCut->ppLeaves[i]->nRefs == 0 )
Fpga_TimeCutComputeArrival_rec( pMan, pCut->ppLeaves[i]->pCutBest );
return Fpga_TimeCutComputeArrival( pMan, pCut );
}
/**Function*************************************************************
Synopsis [Computes the maximum arrival times.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
float Fpga_TimeComputeArrivalMax( Fpga_Man_t * p )
{
float fRequired;
int i;
if ( p->fLatchPaths && p->nLatches == 0 )
{
printf( "Delay optimization of latch path is not performed because there is no latches.\n" );
p->fLatchPaths = 0;
}
// get the critical PO arrival time
fRequired = -FPGA_FLOAT_LARGE;
if ( p->fLatchPaths )
{
for ( i = p->nOutputs - p->nLatches; i < p->nOutputs; i++ )
{
if ( Fpga_NodeIsConst(p->pOutputs[i]) )
continue;
fRequired = FPGA_MAX( fRequired, Fpga_Regular(p->pOutputs[i])->pCutBest->tArrival );
// printf( " %5.1f", Fpga_Regular(p->pOutputs[i])->pCutBest->tArrival );
}
// printf( "Required latches = %5.1f\n", fRequired );
}
else
{
for ( i = 0; i < p->nOutputs; i++ )
{
if ( Fpga_NodeIsConst(p->pOutputs[i]) )
continue;
fRequired = FPGA_MAX( fRequired, Fpga_Regular(p->pOutputs[i])->pCutBest->tArrival );
// printf( " %5.1f", Fpga_Regular(p->pOutputs[i])->pCutBest->tArrival );
}
// printf( "Required outputs = %5.1f\n", fRequired );
}
return fRequired;
}
/**Function*************************************************************
Synopsis [Computes the required times of all nodes.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
void Fpga_TimeComputeRequiredGlobal( Fpga_Man_t * p, int fFirstTime )
{
p->fRequiredGlo = Fpga_TimeComputeArrivalMax( p );
// update the required times according to the target
if ( p->DelayTarget != -1 )
{
if ( p->fRequiredGlo > p->DelayTarget + p->fEpsilon )
{
if ( fFirstTime )
printf( "Cannot meet the target required times (%4.2f). Mapping continues anyway.\n", p->DelayTarget );
}
else if ( p->fRequiredGlo < p->DelayTarget - p->fEpsilon )
{
if ( fFirstTime )
printf( "Relaxing the required times from (%4.2f) to the target (%4.2f).\n", p->fRequiredGlo, p->DelayTarget );
p->fRequiredGlo = p->DelayTarget;
}
}
Fpga_TimeComputeRequired( p, p->fRequiredGlo );
}
/**Function*************************************************************
Synopsis [Computes the required times of all nodes.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
void Fpga_TimeComputeRequired( Fpga_Man_t * p, float fRequired )
{
int i;
// clean the required times and the fanout counts for all nodes
for ( i = 0; i < p->vAnds->nSize; i++ )
p->vAnds->pArray[i]->tRequired = FPGA_FLOAT_LARGE;
// set the required times for the POs
if ( p->fLatchPaths )
for ( i = p->nOutputs - p->nLatches; i < p->nOutputs; i++ )
Fpga_Regular(p->pOutputs[i])->tRequired = fRequired;
else
for ( i = 0; i < p->nOutputs; i++ )
Fpga_Regular(p->pOutputs[i])->tRequired = fRequired;
// collect nodes reachable from POs in the DFS order through the best cuts
Fpga_TimePropagateRequired( p, p->vMapping );
/*
{
int Counter = 0;
for ( i = 0; i < p->vAnds->nSize; i++ )
if ( p->vAnds->pArray[i]->tRequired > FPGA_FLOAT_LARGE - 100 )
Counter++;
printf( "The number of nodes with large required times = %d.\n", Counter );
}
*/
}
/**Function*************************************************************
Synopsis [Computes the required times of the given nodes.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
void Fpga_TimePropagateRequired( Fpga_Man_t * p, Fpga_NodeVec_t * vNodes )
{
Fpga_Node_t * pNode, * pChild;
float fRequired;
int i, k;
// sorts the nodes in the decreasing order of levels
// Fpga_MappingSortByLevel( p, vNodes, 0 );
// the nodes area already sorted in Fpga_MappingSetRefsAndArea()
// go through the nodes in the reverse topological order
for ( k = 0; k < vNodes->nSize; k++ )
{
pNode = vNodes->pArray[k];
if ( !Fpga_NodeIsAnd(pNode) )
continue;
// get the required time for children
fRequired = pNode->tRequired - p->pLutLib->pLutDelays[pNode->pCutBest->nLeaves];
// update the required time of the children
for ( i = 0; i < pNode->pCutBest->nLeaves; i++ )
{
pChild = pNode->pCutBest->ppLeaves[i];
pChild->tRequired = FPGA_MIN( pChild->tRequired, fRequired );
}
}
}
/**Function*************************************************************
Synopsis [Computes the required times of all nodes.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
void Fpga_TimePropagateArrival( Fpga_Man_t * p )
{
Fpga_Node_t * pNode;
Fpga_Cut_t * pCut;
int i;
// clean the required times and the fanout counts for all nodes
for ( i = 0; i < p->vAnds->nSize; i++ )
{
pNode = p->vAnds->pArray[i];
for ( pCut = pNode->pCuts->pNext; pCut; pCut = pCut->pNext )
pCut->tArrival = Fpga_TimeCutComputeArrival( p, pCut );
}
}
////////////////////////////////////////////////////////////////////////
/// END OF FILE ///
////////////////////////////////////////////////////////////////////////
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