pns_dp_meander_placer.cpp

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/*
 * KiRouter - a push-and-(sometimes-)shove PCB router
 *
 * Copyright (C) 2013-2014 CERN
 * Copyright The KiCad Developers, see AUTHORS.txt for contributors.
 * Author: Tomasz Wlostowski <[email protected]>
 *
 * This program is free software: you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the
 * Free Software Foundation, either version 3 of the License, or (at your
 * option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
#include <optional>
#include <algorithm>
 
#include <core/typeinfo.h>
 
#include <board_connected_item.h>
 
#include "pns_node.h"
#include "pns_itemset.h"
#include "pns_topology.h"
#include "pns_dp_meander_placer.h"
#include "pns_diff_pair.h"
#include "pns_router.h"
#include "pns_solid.h"
 
 
namespace PNS {
 
DP_MEANDER_PLACER::DP_MEANDER_PLACER( ROUTER* aRouter ) :
    MEANDER_PLACER_BASE( aRouter )
{
    m_world       = nullptr;
    m_currentNode = nullptr;
 
    m_padToDieLengthP = 0;
    m_padToDieLengthN = 0;
 
    m_padToDieDelayP = 0;
    m_padToDieDelayN = 0;
 
    // Init temporary variables (do not leave uninitialized members)
    m_initialSegment = nullptr;
    m_lastLength     = 0;
    m_lastDelay = 0;
    m_lastStatus     = TOO_SHORT;
 
    m_netClass = nullptr;
}
 
 
DP_MEANDER_PLACER::~DP_MEANDER_PLACER()
{
}
 
 
const LINE DP_MEANDER_PLACER::Trace() const
{
    return m_currentTraceP;
}
 
 
const DIFF_PAIR& DP_MEANDER_PLACER::GetOriginPair()
{
    return m_originPair;
}
 
 
NODE* DP_MEANDER_PLACER::CurrentNode( bool aLoopsRemoved ) const
{
    if( !m_currentNode )
        return m_world;
 
    return m_currentNode;
}
 
 
bool DP_MEANDER_PLACER::Start( const VECTOR2I& aP, ITEM* aStartItem )
{
    if( !aStartItem || !aStartItem->OfKind( ITEM::SEGMENT_T | ITEM::ARC_T ) )
    {
        Router()->SetFailureReason( _( "Please select a track whose length you want to tune." ) );
        return false;
    }
 
    m_initialSegment = static_cast<LINKED_ITEM*>( aStartItem );
    m_currentNode    = nullptr;
    m_currentStart   = getSnappedStartPoint( m_initialSegment, aP );
 
    m_world = Router()->GetWorld()->Branch();
 
    TOPOLOGY topo( m_world );
 
    if( !topo.AssembleDiffPair( m_initialSegment, m_originPair ) )
    {
        Router()->SetFailureReason( _( "Unable to find complementary differential pair "
                                       "net for length tuning. Make sure the names of the nets "
                                       "belonging to a differential pair end with either _N/_P "
                                       "or +/-." ) );
        return false;
    }
 
    if( m_originPair.Gap() < 0 )
        m_originPair.SetGap( Router()->Sizes().DiffPairGap() );
 
    if( !m_originPair.PLine().SegmentCount() || !m_originPair.NLine().SegmentCount() )
        return false;
 
    m_tunedPathP = topo.AssembleTuningPath( Router()->GetInterface(), m_originPair.PLine().GetLink( 0 ), &m_startPad_p,
                                            &m_endPad_p );
 
    m_padToDieLengthP = 0;
    m_padToDieDelayP = 0;
 
    if( m_startPad_p )
    {
        m_padToDieLengthP += m_startPad_p->GetPadToDie();
        m_padToDieDelayP += m_startPad_p->GetPadToDieDelay();
    }
 
    if( m_endPad_p )
    {
        m_padToDieLengthP += m_endPad_p->GetPadToDie();
        m_padToDieDelayP += m_endPad_p->GetPadToDieDelay();
    }
 
    m_tunedPathN = topo.AssembleTuningPath( Router()->GetInterface(), m_originPair.NLine().GetLink( 0 ), &m_startPad_n,
                                            &m_endPad_n );
 
    m_padToDieLengthN = 0;
    m_padToDieDelayN = 0;
 
    if( m_startPad_n )
    {
        m_padToDieLengthN += m_startPad_n->GetPadToDie();
        m_padToDieDelayN += m_startPad_n->GetPadToDieDelay();
    }
 
    if( m_endPad_n )
    {
        m_padToDieLengthN += m_endPad_n->GetPadToDie();
        m_padToDieDelayN += m_endPad_n->GetPadToDieDelay();
    }
 
    m_world->Remove( m_originPair.PLine() );
    m_world->Remove( m_originPair.NLine() );
 
    m_currentWidth = m_originPair.Width();
 
    const BOARD_CONNECTED_ITEM* conItem = static_cast<BOARD_CONNECTED_ITEM*>( aStartItem->GetSourceItem() );
    m_netClass = conItem->GetEffectiveNetClass();
 
    m_baselineLength = origPathLength();
    m_baselineDelay = m_settings.m_isTimeDomain ? origPathDelay() : 0;
 
    initChainExtras();
 
    calculateTimeDomainTargets();
 
    return true;
}
 
 
void DP_MEANDER_PLACER::release()
{
}
 
 
long long int DP_MEANDER_PLACER::origPathLength() const
{
    long long int totalP = m_padToDieLengthP + lineLength( m_tunedPathP, m_startPad_p, m_endPad_p );
    long long int totalN = m_padToDieLengthN + lineLength( m_tunedPathN, m_startPad_n, m_endPad_n );
    return std::max( totalP, totalN );
}
 
 
int64_t DP_MEANDER_PLACER::origPathDelay() const
{
    const int64_t totalP = m_padToDieDelayP + lineDelay( m_tunedPathP, m_startPad_p, m_endPad_p );
    const int64_t totalN = m_padToDieDelayN + lineDelay( m_tunedPathN, m_startPad_n, m_endPad_n );
    return std::max( totalP, totalN );
}
 
 
const SEG DP_MEANDER_PLACER::baselineSegment( const DIFF_PAIR::COUPLED_SEGMENTS& aCoupledSegs )
{
    const VECTOR2I a( ( aCoupledSegs.coupledP.A + aCoupledSegs.coupledN.A ) / 2 );
    const VECTOR2I b( ( aCoupledSegs.coupledP.B + aCoupledSegs.coupledN.B ) / 2 );
 
    return SEG( a, b );
}
 
 
bool DP_MEANDER_PLACER::pairOrientation( const DIFF_PAIR::COUPLED_SEGMENTS& aPair )
{
    VECTOR2I midp = ( aPair.coupledP.A + aPair.coupledN.A ) / 2;
 
    //DrawDebugPoint(midp, 6);
 
    return aPair.coupledP.Side( midp ) > 0;
}
 
 
bool DP_MEANDER_PLACER::Move( const VECTOR2I& aP, ITEM* aEndItem )
{
    // Reuse the chain-extras aggregate captured at Start(). Other nets in the chain are
    // not edited during a tuning session, so we don't need to walk the BOARD again.
    const long long extraDelay = m_chainExtrasValid ? m_chainExtrasDelay : 0;
 
    m_settings.m_signalExtraDelay = extraDelay;
 
    // Derive per-net budget from chain target, accounting for stubs not in the PNS path.
    // Take the tighter of chain budget and existing per-net constraint.
    if( m_settings.m_targetSignalLength.Opt() != MEANDER_SETTINGS::LENGTH_UNCONSTRAINED )
    {
        const long long otherLen = chainNarrowingOffset();
 
        long long budgetMin = std::max( 0LL, m_settings.m_targetSignalLength.Min() - otherLen );
        long long budgetOpt = std::max( 0LL, m_settings.m_targetSignalLength.Opt() - otherLen );
        long long budgetMax = std::max( budgetOpt, m_settings.m_targetSignalLength.Max() - otherLen );
 
        if( m_settings.m_targetLength.Opt() == MEANDER_SETTINGS::LENGTH_UNCONSTRAINED )
        {
            m_settings.m_targetLength.SetMin( budgetMin );
            m_settings.m_targetLength.SetOpt( budgetOpt );
            m_settings.m_targetLength.SetMax( budgetMax );
        }
        else
        {
            m_settings.m_targetLength.SetMin( std::max( m_settings.m_targetLength.Min(), budgetMin ) );
            m_settings.m_targetLength.SetOpt( std::min( m_settings.m_targetLength.Opt(), budgetOpt ) );
            m_settings.m_targetLength.SetMax( std::min( m_settings.m_targetLength.Max(), budgetMax ) );
        }
    }
 
    calculateTimeDomainTargets();
 
    if( m_currentStart == aP )
        return false;
 
    DIFF_PAIR::COUPLED_SEGMENTS_VEC coupledSegments;
 
    if( m_currentNode )
        delete m_currentNode;
 
    m_currentNode = m_world->Branch();
 
    SHAPE_LINE_CHAIN preP, tunedP, postP;
    SHAPE_LINE_CHAIN preN, tunedN, postN;
 
    m_originPair.CP().Split( m_currentStart, aP, preP, tunedP, postP );
    m_originPair.CN().Split( m_currentStart, aP, preN, tunedN, postN );
 
    tunedP.Simplify();
    tunedN.Simplify();
 
    // Bail out early if the tuned sections are empty (issue #22041). This can happen when the
    // split points are too close together or outside the line chain.
    if( tunedP.PointCount() == 0 || tunedN.PointCount() == 0 )
    {
        m_finalShapeP = m_originPair.CP();
        m_finalShapeN = m_originPair.CN();
        m_lastLength  = origPathLength();
        m_lastStatus  = TOO_SHORT;
 
        return false;
    }
 
    auto updateStatus =
            [&]()
            {
                if( m_lastLength > m_settings.m_targetLength.Max() )
                    m_lastStatus = TOO_LONG;
                else if( m_lastLength < m_settings.m_targetLength.Min() )
                    m_lastStatus = TOO_SHORT;
                else
                    m_lastStatus = TUNED;
            };
 
    DIFF_PAIR tuned( m_originPair );
 
    tuned.SetShape( tunedP, tunedN );
 
    tuned.CoupledSegmentPairs( coupledSegments );
 
    if( coupledSegments.size() == 0 )
    {
        // Tuning started at an uncoupled area of the DP; we won't get a valid result until the
        // cursor is moved far enough along a coupled area.  Prevent the track from disappearing and
        // the length from being zero by just using the original.
        m_finalShapeP = m_originPair.CP();
        m_finalShapeN = m_originPair.CN();
        m_lastLength  = origPathLength();
        updateStatus();
 
        return false;
    }
 
    m_result = MEANDERED_LINE( this, true );
    m_result.SetWidth( tuned.Width() );
 
    int offset = ( tuned.Gap() + tuned.Width() ) / 2;
 
    if( pairOrientation( coupledSegments[0] ) )
        offset *= -1;
 
    m_result.SetBaselineOffset( offset );
 
    for( const ITEM* item : m_tunedPathP.CItems() )
    {
        if( const LINE* l = dyn_cast<const LINE*>( item ) )
        {
            PNS_DBG( Dbg(), AddShape, &l->CLine(), YELLOW, 10000, wxT( "tuned-path-p" ) );
 
            m_router->GetInterface()->DisplayPathLine( l->CLine(), 1 );
        }
    }
 
    for( const ITEM* item : m_tunedPathN.CItems() )
    {
        if( const LINE* l = dyn_cast<const LINE*>( item ) )
        {
            PNS_DBG( Dbg(), AddShape, &l->CLine(), YELLOW, 10000, wxT( "tuned-path-n" ) );
 
            m_router->GetInterface()->DisplayPathLine( l->CLine(), 1 );
        }
    }
 
    struct GET_ITEM_RET
    {
        std::optional<SHAPE_ARC> arc;
        VECTOR2I                 startPt;
        VECTOR2I                 endPt;
    };
 
    auto getItem = [&]( const SHAPE_LINE_CHAIN& aChain, int aIndex, int aLastIndex )
    {
        std::optional<SHAPE_ARC> optArc;
        VECTOR2I                 startPt;
        VECTOR2I                 endPt;
 
        if( aChain.IsArcSegment( aIndex ) )
        {
            SHAPE_ARC arc = aChain.Arc( aChain.ArcIndex( aIndex ) );
            optArc = arc;
            startPt = arc.GetStart();
            endPt = arc.GetEnd();
        }
        else
        {
            SEG seg = aChain.GetSegment( aIndex );
            startPt = seg.A;
            endPt = seg.B;
        }
 
        return GET_ITEM_RET{ optArc, startPt, endPt };
    };
 
    auto checkIndex = [&]( bool& aOk, int aCurIndex, int aLastIndex ) -> bool
    {
        aOk = aCurIndex <= aLastIndex && aCurIndex != -1;
        return aOk;
    };
 
    int curIndexP = 0, curIndexN = 0;
 
    auto addCornersUntilIndex = [&]( int aLastIndexP, int aLastIndexN )
    {
        while( true )
        {
            bool p_ok, n_ok;
            checkIndex( p_ok, curIndexP, aLastIndexP );
            checkIndex( n_ok, curIndexN, aLastIndexN );
 
            if( !p_ok && !n_ok )
                break;
 
            auto p_item = getItem( tunedP, curIndexP, aLastIndexP );
            auto n_item = getItem( tunedN, curIndexN, aLastIndexN );
 
            if( !p_item.arc && !n_item.arc )
            {
                m_result.AddCorner( p_item.startPt, n_item.startPt );
            }
            else if( p_item.arc && n_item.arc )
            {
                m_result.AddArc( *p_item.arc, *n_item.arc );
            }
            else if( p_item.arc && !n_item.arc )
            {
                m_result.AddCorner( p_item.startPt, n_item.startPt );
 
                // Find arc in N
                while( checkIndex( n_ok, curIndexN, aLastIndexN ) )
                {
                    curIndexN = tunedN.NextShape( curIndexN );
                    n_item = getItem( tunedN, curIndexN, aLastIndexN );
 
                    if( n_item.arc )
                    {
                        m_result.AddArc( *p_item.arc, *n_item.arc );
                        break;
                    }
                    else
                    {
                        m_result.AddCorner( p_item.startPt, n_item.startPt );
                    }
                }
            }
            else if( !p_item.arc && n_item.arc )
            {
                m_result.AddCorner( p_item.startPt, n_item.startPt );
 
                // Find arc in P
                while( checkIndex( p_ok, curIndexP, aLastIndexP ) )
                {
                    curIndexP = tunedP.NextShape( curIndexP );
                    p_item = getItem( tunedP, curIndexP, aLastIndexP );
 
                    if( p_item.arc )
                    {
                        m_result.AddArc( *p_item.arc, *n_item.arc );
                        break;
                    }
                    else
                    {
                        m_result.AddCorner( p_item.startPt, n_item.startPt );
                    }
                }
            }
 
            if( p_ok )
                curIndexP = tunedP.NextShape( curIndexP );
 
            if( n_ok )
                curIndexN = tunedN.NextShape( curIndexN );
        }
    };
 
    for( const DIFF_PAIR::COUPLED_SEGMENTS& sp : coupledSegments )
    {
        SEG  base = baselineSegment( sp );
        bool side = false;
 
        if( m_settings.m_initialSide == 0 )
            side = base.Side( aP ) < 0;
        else
            side = m_settings.m_initialSide < 0;
 
        PNS_DBG( Dbg(), AddShape, base, GREEN, 10000, wxT( "dp-baseline" ) );
 
        addCornersUntilIndex( sp.indexP, sp.indexN );
 
        m_result.MeanderSegment( base, side );
    }
 
    addCornersUntilIndex( tunedP.PointCount() - 1, tunedN.PointCount() - 1 );
 
    m_result.AddCorner( tunedP.CLastPoint(), tunedN.CLastPoint() );
 
    long long int dpLen = origPathLength();
    int64_t       dpDelay = origPathDelay();
 
    m_lastStatus = TUNED;
 
    if( dpLen > m_settings.m_targetLength.Max() )
    {
        m_lastStatus = TOO_LONG;
        m_lastLength = dpLen;
        m_lastDelay = dpDelay;
    }
    else
    {
        m_lastLength = dpLen - std::max( tunedP.Length(), tunedN.Length() );
 
        if( m_settings.m_isTimeDomain )
        {
            int64_t tunedPDelay = m_router->GetInterface()->CalculateDelayForShapeLineChain(
                    tunedP, GetOriginPair().Width(), true, GetOriginPair().Gap(), m_router->GetCurrentLayer(),
                    m_netClass );
            int64_t tunedNDelay = m_router->GetInterface()->CalculateDelayForShapeLineChain(
                    tunedN, GetOriginPair().Width(), true, GetOriginPair().Gap(), m_router->GetCurrentLayer(),
                    m_netClass );
 
            m_lastDelay = dpDelay - std::max( tunedPDelay, tunedNDelay );
        }
 
        tuneLineLength( m_result, m_settings.m_targetLength.Opt() - dpLen );
    }
 
    if( m_lastStatus != TOO_LONG )
    {
        tunedP.Clear();
        tunedN.Clear();
 
        for( MEANDER_SHAPE* m : m_result.Meanders() )
        {
            if( m->Type() != MT_EMPTY )
            {
                tunedP.Append( m->CLine( 0 ) );
                tunedN.Append( m->CLine( 1 ) );
            }
        }
 
        m_lastLength += std::max( tunedP.Length(), tunedN.Length() );
 
        if( m_settings.m_isTimeDomain )
        {
            int64_t tunedPDelay = m_router->GetInterface()->CalculateDelayForShapeLineChain(
                    tunedP, GetOriginPair().Width(), true, GetOriginPair().Gap(), m_router->GetCurrentLayer(),
                    m_netClass );
            int64_t tunedNDelay = m_router->GetInterface()->CalculateDelayForShapeLineChain(
                    tunedN, GetOriginPair().Width(), true, GetOriginPair().Gap(), m_router->GetCurrentLayer(),
                    m_netClass );
 
            m_lastDelay += std::max( tunedPDelay, tunedNDelay );
        }
 
        updateStatus();
    }
 
    m_finalShapeP.Clear();
    m_finalShapeN.Clear();
 
    if( m_settings.m_keepEndpoints )
    {
        preP.Simplify();
        tunedP.Simplify();
        postP.Simplify();
 
        m_finalShapeP.Append( preP );
        m_finalShapeP.Append( tunedP );
        m_finalShapeP.Append( postP );
 
        preN.Simplify();
        tunedN.Simplify();
        postN.Simplify();
 
        m_finalShapeN.Append( preN );
        m_finalShapeN.Append( tunedN );
        m_finalShapeN.Append( postN );
    }
    else
    {
        m_finalShapeP.Append( preP );
        m_finalShapeP.Append( tunedP );
        m_finalShapeP.Append( postP );
        m_finalShapeP.Simplify();
 
        m_finalShapeN.Append( preN );
        m_finalShapeN.Append( tunedN );
        m_finalShapeN.Append( postN );
        m_finalShapeN.Simplify();
    }
 
    return true;
}
 
 
bool DP_MEANDER_PLACER::FixRoute( const VECTOR2I& aP, ITEM* aEndItem, bool aForceFinish )
{
    LINE lP( m_originPair.PLine(), m_finalShapeP );
    LINE lN( m_originPair.NLine(), m_finalShapeN );
 
    m_currentNode->Add( lP );
    m_currentNode->Add( lN );
 
    CommitPlacement();
 
    return true;
}
 
 
bool DP_MEANDER_PLACER::AbortPlacement()
{
    m_world->KillChildren();
    return true;
}
 
 
bool DP_MEANDER_PLACER::HasPlacedAnything() const
{
     return m_originPair.CP().SegmentCount() > 0 || m_originPair.CN().SegmentCount() > 0;
}
 
 
bool DP_MEANDER_PLACER::CommitPlacement()
{
    if( m_currentNode )
        Router()->CommitRouting( m_currentNode );
 
    m_currentNode = nullptr;
    return true;
}
 
 
bool DP_MEANDER_PLACER::CheckFit( MEANDER_SHAPE* aShape )
{
    LINE l1( m_originPair.PLine(), aShape->CLine( 0 ) );
    LINE l2( m_originPair.NLine(), aShape->CLine( 1 ) );
 
    if( m_currentNode->CheckColliding( &l1 ) )
        return false;
 
    if( m_currentNode->CheckColliding( &l2 ) )
        return false;
 
    int w = aShape->Width();
    int clearance = w + w * 3;
 
    return m_result.CheckSelfIntersections( aShape, clearance );
}
 
 
const ITEM_SET DP_MEANDER_PLACER::Traces()
{
    m_currentTraceP = LINE( m_originPair.PLine(), m_finalShapeP );
    m_currentTraceN = LINE( m_originPair.NLine(), m_finalShapeN );
 
    ITEM_SET traces;
 
    traces.Add( &m_currentTraceP );
    traces.Add( &m_currentTraceN );
 
    return traces;
}
 
 
const ITEM_SET DP_MEANDER_PLACER::TunedPath()
{
    ITEM_SET lines;
 
    for( ITEM* item : m_tunedPathN )
        lines.Add( item );
 
    for( ITEM* item : m_tunedPathP )
        lines.Add( item );
 
    return lines;
}
 
 
const VECTOR2I& DP_MEANDER_PLACER::CurrentStart() const
{
    return m_currentStart;
}
 
 
const VECTOR2I& DP_MEANDER_PLACER::CurrentEnd() const
{
    return m_currentEnd;
}
 
 
int DP_MEANDER_PLACER::CurrentLayer() const
{
    return m_initialSegment->Layers().Start();
}
 
 
long long int DP_MEANDER_PLACER::TuningLengthResult() const
{
    if( m_lastLength )
        return m_lastLength;
    else
        return origPathLength();
}
 
 
int64_t DP_MEANDER_PLACER::TuningDelayResult() const
{
    if( m_lastDelay )
        return m_lastDelay;
    else
        return origPathDelay();
}
 
 
DP_MEANDER_PLACER::TUNING_STATUS DP_MEANDER_PLACER::TuningStatus() const
{
    return m_lastStatus;
}
 
 
const std::vector<NET_HANDLE> DP_MEANDER_PLACER::CurrentNets() const
{
    std::vector<NET_HANDLE> rv;
    rv.push_back( m_originPair.NetP() );
    rv.push_back( m_originPair.NetN() );
    return rv;
}
 
 
void DP_MEANDER_PLACER::calculateTimeDomainTargets()
{
    // If this is a time domain tuning, calculate the target length for the desired total delay
    if( m_settings.m_isTimeDomain )
    {
        const int64_t curDelayChain = origPathDelay();
        const int64_t curDelayPair = curDelayChain - m_settings.m_signalExtraDelay; // subtract other nets
 
        bool useSignalTarget = ( m_settings.m_targetSignalLengthDelay.Opt() != MEANDER_SETTINGS::DELAY_UNCONSTRAINED );
        const MINOPTMAX<long long int>& targetDelaySet = useSignalTarget ? m_settings.m_targetSignalLengthDelay
                                                                         : m_settings.m_targetLengthDelay;
 
        int64_t desiredDelayMin = targetDelaySet.Min();
        int64_t desiredDelayOpt = targetDelaySet.Opt();
        int64_t desiredDelayMax = targetDelaySet.Max();
 
        if( useSignalTarget )
        {
            desiredDelayMin = std::max<int64_t>( 0, desiredDelayMin - m_settings.m_signalExtraDelay );
            desiredDelayOpt = std::max<int64_t>( 0, desiredDelayOpt - m_settings.m_signalExtraDelay );
            desiredDelayMax = std::max<int64_t>( desiredDelayOpt, desiredDelayMax - m_settings.m_signalExtraDelay );
        }
 
        const int64_t curDelay = useSignalTarget ? curDelayPair : curDelayChain;
 
        const int64_t delayDifferenceOpt = desiredDelayOpt - curDelay;
 
        const int64_t curLength = origPathLength();
        const int64_t lengthDiffMin = m_router->GetInterface()->CalculateLengthForDelay(
                desiredDelayOpt - desiredDelayMin, GetOriginPair().Width(), true, GetOriginPair().Gap(),
                m_router->GetCurrentLayer(), m_netClass );
        int64_t lengthDiffOpt = m_router->GetInterface()->CalculateLengthForDelay(
                std::abs( delayDifferenceOpt ), GetOriginPair().Width(), true, GetOriginPair().Gap(),
                m_router->GetCurrentLayer(), m_netClass );
        const int64_t lengthDiffMax = m_router->GetInterface()->CalculateLengthForDelay(
                desiredDelayMax - desiredDelayOpt, GetOriginPair().Width(), true, GetOriginPair().Gap(),
                m_router->GetCurrentLayer(), m_netClass );
 
        lengthDiffOpt = delayDifferenceOpt > 0 ? lengthDiffOpt : -lengthDiffOpt;
 
        m_settings.m_targetLength.SetMin( curLength + lengthDiffOpt - lengthDiffMin );
        m_settings.m_targetLength.SetOpt( curLength + lengthDiffOpt );
        m_settings.m_targetLength.SetMax( curLength + lengthDiffOpt + lengthDiffMax );
    }
}
}