pns_meander_skew_placer.cpp

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/*
 * KiRouter - a push-and-(sometimes-)shove PCB router
 *
 * Copyright (C) 2013-2015 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 "pns_meander_skew_placer.h"
 
#include <core/typeinfo.h>
#include <board_connected_item.h>
 
#include "pns_node.h"
#include "pns_itemset.h"
#include "pns_topology.h"
#include "pns_solid.h"
 
#include "pns_router.h"
#include "pns_debug_decorator.h"
 
#include <board.h>
#include <netinfo.h>
 
namespace PNS {
 
MEANDER_SKEW_PLACER::MEANDER_SKEW_PLACER ( ROUTER* aRouter ) :
    MEANDER_PLACER ( aRouter )
{
    // Init temporary variables (do not leave uninitialized members)
    m_coupledLength = 0;
    m_coupledDelay = 0;
    m_padToDieLengthN = 0;
    m_padToDieLengthP = 0;
    m_padToDieDelayN = 0;
    m_padToDieDelayP = 0;
}
 
 
MEANDER_SKEW_PLACER::~MEANDER_SKEW_PLACER( )
{
}
 
 
bool MEANDER_SKEW_PLACER::Start( const VECTOR2I& aP, ITEM* aStartItem )
{
    if( !aStartItem || !aStartItem->OfKind( ITEM::SEGMENT_T | ITEM::ARC_T) )
    {
        Router()->SetFailureReason( _( "Please select a differential pair track 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();
    m_originLine = m_world->AssembleLine( m_initialSegment );
 
    TOPOLOGY topo( m_world );
    m_tunedPath = topo.AssembleTrivialPath( m_initialSegment, nullptr, true );
 
    if( !topo.AssembleDiffPair ( m_initialSegment, m_originPair ) )
    {
        Router()->SetFailureReason( _( "Unable to find complementary differential pair "
                                       "net for skew 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_originLine );
 
    m_currentWidth = m_originLine.Width();
    m_currentEnd = VECTOR2I( 0, 0 );
 
    const BOARD_CONNECTED_ITEM* conItem = static_cast<BOARD_CONNECTED_ITEM*>( aStartItem->GetSourceItem() );
    m_netClass = conItem->GetEffectiveNetClass();
    m_settings.m_netClass = m_netClass;
 
    bool pIsActive = ( m_originPair.NetP() == m_originLine.Net() );
    long long int lenP = m_padToDieLengthP + lineLength( m_tunedPathP, m_startPad_p, m_endPad_p );
    long long int lenN = m_padToDieLengthN + lineLength( m_tunedPathN, m_startPad_n, m_endPad_n );
    int64_t delayP = m_padToDieDelayP + lineDelay( m_tunedPathP, m_startPad_p, m_endPad_p );
    int64_t delayN = m_padToDieDelayN + lineDelay( m_tunedPathN, m_startPad_n, m_endPad_n );
 
    // Query interface for aggregate chain contribution (other nets in same chain)
    long long int extraSignalLen = 0;
    long long int extraSignalDelay = 0;
    Router()->GetInterface()->GetSignalAggregate( m_originPair.NetP(), m_originPair.NetN(),
                                                  extraSignalLen, extraSignalDelay );
 
    if( pIsActive )
    {
        m_coupledLength = lenN + extraSignalLen;
        m_lastLength = lenP + extraSignalLen;
        m_coupledDelay = delayN + extraSignalDelay;
        m_lastDelay = delayP + extraSignalDelay;
        m_tunedPath = m_tunedPathP;
    }
    else
    {
        m_coupledLength = lenP + extraSignalLen;
        m_lastLength = lenN + extraSignalLen;
        m_coupledDelay = delayP + extraSignalDelay;
        m_lastDelay = delayN + extraSignalDelay;
        m_tunedPath = m_tunedPathN;
    }
 
    m_baselineLength = origPathLength();
    m_baselineDelay = m_settings.m_isTimeDomain ? origPathDelay() : 0;
 
    initChainExtras();
 
    calculateTimeDomainTargets();
 
    return true;
}
 
 
long long int MEANDER_SKEW_PLACER::origPathLength() const
{
    if ( m_originPair.NetP() == m_originLine.Net() )
        return m_padToDieLengthP + lineLength( m_tunedPath, m_startPad_p, m_endPad_p );
 
    return m_padToDieLengthN + lineLength( m_tunedPath, m_startPad_n, m_endPad_n );
}
 
 
int64_t MEANDER_SKEW_PLACER::origPathDelay() const
{
    if( m_originPair.NetP() == m_originLine.Net() )
        return m_padToDieDelayP + lineDelay( m_tunedPath, m_startPad_p, m_endPad_p );
 
    return m_padToDieDelayN + lineDelay( m_tunedPath, m_startPad_n, m_endPad_n );
}
 
 
long long int MEANDER_SKEW_PLACER::CurrentSkew() const
{
    return m_lastLength - m_coupledLength; // Includes aggregate chain contribution if applicable
}
 
 
bool MEANDER_SKEW_PLACER::Move( const VECTOR2I& aP, ITEM* aEndItem )
{
    calculateTimeDomainTargets();
 
    bool isPositive = m_originPair.NetP() == m_originLine.Net();
 
    for( const ITEM* item : m_tunedPathP.CItems() )
    {
        if( const LINE* l = dyn_cast<const LINE*>( item ) )
        {
            PNS_DBG( Dbg(), AddItem, l, BLUE, 10000, wxT( "tuned-path-skew-p" ) );
 
            m_router->GetInterface()->DisplayPathLine( l->CLine(), isPositive ? 1 : 0 );
        }
    }
 
    for( const ITEM* item : m_tunedPathN.CItems() )
    {
        if( const LINE* l = dyn_cast<const LINE*>( item ) )
        {
            PNS_DBG( Dbg(), AddItem, l, YELLOW, 10000, wxT( "tuned-path-skew-n" ) );
 
            m_router->GetInterface()->DisplayPathLine( l->CLine(), isPositive ? 0 : 1 );
        }
    }
 
    // Convert the user-facing skew target (active total minus coupled total) into a meander-only
    // doMove target. m_coupledLength already includes the chain-extras aggregate captured at
    // Start(); the chain extras and any unmeasured stub on the active net are absorbed by the
    // chain rather than by the meander, so subtract them here. Without this, the meander
    // over-corrects by exactly chainNarrowingOffset() whenever the diff pair belongs to a chain.
    const long long offset = chainNarrowingOffset();
 
    return doMove( aP, aEndItem, m_coupledLength + m_settings.m_targetSkew.Opt() - offset,
                   m_coupledLength + m_settings.m_targetSkew.Min() - offset,
                   m_coupledLength + m_settings.m_targetSkew.Max() - offset );
}
 
 
long long int MEANDER_SKEW_PLACER::TuningLengthResult() const
{
    return m_lastLength - m_coupledLength;
}
 
 
int64_t MEANDER_SKEW_PLACER::TuningDelayResult() const
{
    return m_lastDelay - m_coupledDelay;
}
 
 
void MEANDER_SKEW_PLACER::calculateTimeDomainTargets()
{
    auto calculateTargetSkew = [this]( const int64_t targetSkewDelay )
    {
        const int64_t curSkewDelay = m_lastDelay - m_coupledDelay;
        const int64_t skewDelayDifference = targetSkewDelay - curSkewDelay;
 
        int64_t skewLengthDiff = m_router->GetInterface()->CalculateLengthForDelay(
                std::abs( skewDelayDifference ), m_originPair.Width(), true, m_originPair.Gap(),
                m_router->GetCurrentLayer(), m_netClass );
 
        const int64_t curSkew = CurrentSkew();
        skewLengthDiff = skewDelayDifference > 0 ? skewLengthDiff : -skewLengthDiff;
 
        return static_cast<int>( curSkew + skewLengthDiff );
    };
 
    if( m_settings.m_isTimeDomain )
    {
        const int minSkew = calculateTargetSkew( m_settings.m_targetSkewDelay.Min() );
        m_settings.m_targetSkew.SetMin( static_cast<int>( minSkew ) );
 
        const int optSkew = calculateTargetSkew( m_settings.m_targetSkewDelay.Opt() );
        m_settings.m_targetSkew.SetOpt( static_cast<int>( optSkew ) );
 
        const int maxSkew = calculateTargetSkew( m_settings.m_targetSkewDelay.Max() );
        m_settings.m_targetSkew.SetMax( static_cast<int>( maxSkew ) );
    }
}
}