src/map/fpga/fpgaTime.c

Go to the documentation of this file.

#include "fpgaInt.h"



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][0];
    return tArrival;
}

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 );
}

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;
}

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 );
}

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 );
    }
*/
}

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][0];
        // 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 );
        }
    }
}



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 );
    }
}

---