drc_test_provider_diff_pair_coupling.cpp

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/*
 * This program source code file is part of KiCad, a free EDA CAD application.
 *
 * Copyright (C) 2004-2022 KiCad Developers.
 *
 * 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 <common.h>
#include <board.h>
#include <pcb_track.h>

#include <drc/drc_engine.h>
#include <drc/drc_item.h>
#include <drc/drc_rule.h>
#include <drc/drc_test_provider.h>
#include <drc/drc_length_report.h>
#include <drc/drc_rtree.h>

#include <geometry/shape_segment.h>

#include <connectivity/connectivity_data.h>
#include <connectivity/from_to_cache.h>

#include <view/view_overlay.h>

/*
 Differential pair gap/coupling test.
 Errors generated:
 - DRCE_DIFF_PAIR_GAP_OUT_OF_RANGE
 - DRCE_DIFF_PAIR_UNCOUPLED_LENGTH_TOO_LONG
 - DRCE_TOO_MANY_VIAS
 Todo:
 - arc support.
 - improve recognition of coupled segments (now anything that's parallel is considered
 coupled, causing DRC errors on meanders)
*/

namespace test {

class DRC_TEST_PROVIDER_DIFF_PAIR_COUPLING : public DRC_TEST_PROVIDER
{
public:
 DRC_TEST_PROVIDER_DIFF_PAIR_COUPLING () :
 m_board( nullptr )
 {
 }

 virtual ~DRC_TEST_PROVIDER_DIFF_PAIR_COUPLING()
 {
 }

 virtual bool Run() override;

 virtual const wxString GetName() const override
 {
 return wxT( "diff_pair_coupling" );
 };

 virtual const wxString GetDescription() const override
 {
 return wxT( "Tests differential pair coupling" );
 }

 virtual int GetNumPhases() const override
 {
 return 1;
 }

 virtual std::set<DRC_CONSTRAINT_T> GetConstraintTypes() const override;

private:

 BOARD* m_board;
};

};


static bool commonParallelProjection( SEG p, SEG n, SEG &pClip, SEG& nClip )
{
 SEG n_proj_p( p.LineProject( n.A ), p.LineProject( n.B ) );

 int64_t t_a = 0;
 int64_t t_b = p.TCoef( p.B );

 int64_t tproj_a = p.TCoef( n_proj_p.A );
 int64_t tproj_b = p.TCoef( n_proj_p.B );

 if( t_b < t_a )
 std::swap( t_b, t_a );

 if( tproj_b < tproj_a )
 std::swap( tproj_b, tproj_a );

 if( t_b <= tproj_a )
 return false;

 if( t_a >= tproj_b )
 return false;

 int64_t t[4] = { 0, p.TCoef( p.B ), p.TCoef( n_proj_p.A ), p.TCoef( n_proj_p.B ) };
 std::vector<int64_t> tv( t, t + 4 );
 std::sort( tv.begin(), tv.end() ); // fixme: awful and disgusting way of finding 2 midpoints

 int64_t pLenSq = p.SquaredLength();

 VECTOR2I dp = p.B - p.A;
 pClip.A.x = p.A.x + rescale( (int64_t)dp.x, tv[1], pLenSq );
  pClip.A.y = p.A.y + rescale( (int64_t)dp.y, tv[1], pLenSq );

 pClip.B.x = p.A.x + rescale( (int64_t)dp.x, tv[2], pLenSq );
 pClip.B.y = p.A.y + rescale( (int64_t)dp.y, tv[2], pLenSq );

 nClip.A = n.LineProject( pClip.A );
 nClip.B = n.LineProject( pClip.B );

 return true;
}


struct DIFF_PAIR_KEY
{
 bool operator<( const DIFF_PAIR_KEY& b ) const
 {
  if( netP < b.netP )
 {
 return true;
 }
 else if( netP > b.netP )
 {
 return false;
 }
 else // netP == b.netP
 {
 if( netN < b.netN )
 return true;
 else if( netN > b.netN )
 return false;
 else
 return parentRule < b.parentRule;
 }
 }

 int netP, netN;
 DRC_RULE* parentRule;
};

struct DIFF_PAIR_COUPLED_SEGMENTS
{
 SEG coupledN;
 SEG coupledP;
 PCB_TRACK* parentN;
 PCB_TRACK* parentP;
 int computedGap;
 PCB_LAYER_ID layer;
 bool couplingOK;

 DIFF_PAIR_COUPLED_SEGMENTS() :
 parentN( nullptr ),
 parentP( nullptr ),
 computedGap( 0 ),
 layer( UNDEFINED_LAYER ),
 couplingOK( false )
 {}
};

struct DIFF_PAIR_ITEMS
{
 std::set<BOARD_CONNECTED_ITEM*> itemsP, itemsN;
 std::vector<DIFF_PAIR_COUPLED_SEGMENTS> coupled;
 int totalCoupled;
 int totalLengthN;
 int totalLengthP;
};

static void extractDiffPairCoupledItems( DIFF_PAIR_ITEMS& aDp, DRC_RTREE& aTree )
{
 for( BOARD_CONNECTED_ITEM* itemP : aDp.itemsP )
 {
 PCB_TRACK* sp = dyn_cast<PCB_TRACK*>( itemP );
 OPT<DIFF_PAIR_COUPLED_SEGMENTS> bestCoupled;
 int bestGap = std::numeric_limits<int>::max();

 if( !sp )
 continue;

 for ( BOARD_CONNECTED_ITEM* itemN : aDp.itemsN )
 {
 PCB_TRACK* sn = dyn_cast<PCB_TRACK*> ( itemN );

 if( !sn )
 continue;

 if( ( sn->GetLayerSet() & sp->GetLayerSet() ).none() )
 continue;

 SEG ssp ( sp->GetStart(), sp->GetEnd() );
 SEG ssn ( sn->GetStart(), sn->GetEnd() );

 // Segments that are ~ 1 IU in length per side are approximately parallel (tolerance is 1 IU)
 // with everything and their parallel projection is < 1 IU, leading to bad distance calculations
 if( ssp.SquaredLength() > 2 && ssn.SquaredLength() > 2 && ssp.ApproxParallel(ssn) )
 {
 DIFF_PAIR_COUPLED_SEGMENTS cpair;
 bool coupled = commonParallelProjection( ssp, ssn, cpair.coupledP, cpair.coupledN );

 if( coupled )
 {
 cpair.parentP = sp;
 cpair.parentN = sn;
 cpair.layer = sp->GetLayer();

 int gap = (cpair.coupledP.A - cpair.coupledN.A).EuclideanNorm();
 if( gap < bestGap )
 {
 bestGap = gap;
 bestCoupled = cpair;
 }
 }

 }
 }

 if( bestCoupled )
 {
 auto excludeSelf =
 [&] ( BOARD_ITEM *aItem )
 {
 if( aItem == bestCoupled->parentN || aItem == bestCoupled->parentP )
 {
 return false;
 }

 if( aItem->Type() == PCB_TRACE_T || aItem->Type() == PCB_VIA_T )
 {
 auto bci = static_cast<BOARD_CONNECTED_ITEM*>( aItem );

 if( bci->GetNetCode() == bestCoupled->parentN->GetNetCode()
 || bci->GetNetCode() == bestCoupled->parentP->GetNetCode() )
 return false;
 }

 return true;
 };

 SHAPE_SEGMENT checkSegStart( bestCoupled->coupledP.A, bestCoupled->coupledN.A );
 SHAPE_SEGMENT checkSegEnd( bestCoupled->coupledP.B, bestCoupled->coupledN.B );

 // check if there's anything in between the segments suspected to be coupled. If
 // there's nothing, assume they are really coupled.

  if( !aTree.CheckColliding( &checkSegStart, sp->GetLayer(), 0, excludeSelf )
 && !aTree.CheckColliding( &checkSegEnd, sp->GetLayer(), 0, excludeSelf ) )
 {
 aDp.coupled.push_back( *bestCoupled );
 }
 }
 }
}



bool test::DRC_TEST_PROVIDER_DIFF_PAIR_COUPLING::Run()
{
 m_board = m_drcEngine->GetBoard();



 std::map<DIFF_PAIR_KEY, DIFF_PAIR_ITEMS> dpRuleMatches;

 auto evaluateDpConstraints =
 [&]( BOARD_ITEM *item ) -> bool
 {
 DIFF_PAIR_KEY key;
 BOARD_CONNECTED_ITEM* citem = static_cast<BOARD_CONNECTED_ITEM*>( item );
 NETINFO_ITEM* refNet = citem->GetNet();

 if( refNet && DRC_ENGINE::IsNetADiffPair( m_board, refNet, key.netP, key.netN ) )
 {
 drc_dbg( 10, wxT( "eval dp %p\n" ), item );

 const DRC_CONSTRAINT_T constraintsToCheck[] = {
 DIFF_PAIR_GAP_CONSTRAINT,
 DIFF_PAIR_MAX_UNCOUPLED_CONSTRAINT
 };

 for( int i = 0; i < 2; i++ )
 {
 auto constraint = m_drcEngine->EvalRules( constraintsToCheck[ i ], item,
 nullptr, item->GetLayer() );

 if( constraint.IsNull() )
 continue;

 drc_dbg( 10, wxT( "cns %d item %p\n" ), constraintsToCheck[i], item );

 key.parentRule = constraint.GetParentRule();

 if( refNet->GetNetCode() == key.netN )
 dpRuleMatches[key].itemsN.insert( citem );
 else
 dpRuleMatches[key].itemsP.insert( citem );
 }
 }

 return true;
 };

 m_board->GetConnectivity()->GetFromToCache()->Rebuild( m_board );

 forEachGeometryItem( { PCB_TRACE_T, PCB_VIA_T, PCB_ARC_T },
 LSET::AllCuMask(), evaluateDpConstraints );

 drc_dbg( 10, wxT( "dp rule matches %d\n" ), (int) dpRuleMatches.size() );


 DRC_RTREE copperTree;

 auto addToTree =
 [&copperTree]( BOARD_ITEM *item ) -> bool
 {
 for( PCB_LAYER_ID layer : item->GetLayerSet().Seq() )
 {
 if( IsCopperLayer( layer ) )
 copperTree.Insert( item, layer );
 }

 return true;
 };

 forEachGeometryItem( { PCB_TRACE_T, PCB_VIA_T, PCB_PAD_T, PCB_ZONE_T, PCB_ARC_T },
 LSET::AllCuMask(), addToTree );


 reportAux( wxString::Format( _("DPs evaluated:") ) );

 for( auto& it : dpRuleMatches )
 {
 NETINFO_ITEM *niP = m_board->GetNetInfo().GetNetItem( it.first.netP );
 NETINFO_ITEM *niN = m_board->GetNetInfo().GetNetItem( it.first.netN );

 assert( niP );
 assert( niN );

 wxString nameP = niP->GetNetname();
 wxString nameN = niN->GetNetname();

 reportAux( wxString::Format( wxT( "Rule '%s', DP: (+) %s - (-) %s" ),
 it.first.parentRule->m_Name,
 nameP,
 nameN ) );

 extractDiffPairCoupledItems( it.second, copperTree );

 it.second.totalCoupled = 0;
 it.second.totalLengthN = 0;
 it.second.totalLengthP = 0;

 drc_dbg(10, wxT( " coupled prims : %d\n" ), (int) it.second.coupled.size() );

 OPT<DRC_CONSTRAINT> gapConstraint =
 it.first.parentRule->FindConstraint( DIFF_PAIR_GAP_CONSTRAINT );
 OPT<DRC_CONSTRAINT> maxUncoupledConstraint =
 it.first.parentRule->FindConstraint( DIFF_PAIR_MAX_UNCOUPLED_CONSTRAINT );

 for( BOARD_CONNECTED_ITEM* item : it.second.itemsN )
 {
 // fixme: include vias
 if( PCB_TRACK* track = dyn_cast<PCB_TRACK*>( item ) )
 it.second.totalLengthN += track->GetLength();
 }

 for( BOARD_CONNECTED_ITEM* item : it.second.itemsP )
 {
 // fixme: include vias
 if( PCB_TRACK* track = dyn_cast<PCB_TRACK*>( item ) )
 it.second.totalLengthP += track->GetLength();
 }

 for( auto& cpair : it.second.coupled )
 {
 int length = cpair.coupledN.Length();
 int gap = cpair.coupledN.Distance( cpair.coupledP );

 gap -= cpair.parentN->GetWidth() / 2;
 gap -= cpair.parentP->GetWidth() / 2;

 cpair.computedGap = gap;

 auto overlay = m_drcEngine->GetDebugOverlay();

 if( overlay )
 {
 overlay->SetIsFill(false);
 overlay->SetIsStroke(true);
 overlay->SetStrokeColor( RED );
 overlay->SetLineWidth( 100000 );
 overlay->Line( cpair.coupledP );
 overlay->SetStrokeColor( BLUE );
 overlay->Line( cpair.coupledN );
 }

 drc_dbg( 10, wxT( " len %d gap %d l %d\n" ),
 length,
 gap,
 cpair.parentP->GetLayer() );

 if( gapConstraint )
 {
 auto val = gapConstraint->GetValue();
 bool insideRange = true;

 if( val.HasMin() && gap < val.Min() )
 insideRange = false;

 if( val.HasMax() && gap > val.Max() )
 insideRange = false;

// if(val.HasMin() && val.HasMax() )
 // drc_dbg(10, "Vmin %d vmax %d\n", val.Min(), val.Max() );

 cpair.couplingOK = insideRange;
 }
 else
 {
 cpair.couplingOK = true;
 }

 if( cpair.couplingOK )
 it.second.totalCoupled += length;
 }

 int totalLen = std::max( it.second.totalLengthN, it.second.totalLengthP );
 reportAux( wxString::Format( wxT( " - coupled length: %s, total length: %s" ),
 MessageTextFromValue( userUnits(), it.second.totalCoupled ),
 MessageTextFromValue( userUnits(), totalLen ) ) );

 int totalUncoupled = totalLen - it.second.totalCoupled;

 bool uncoupledViolation = false;

 if( maxUncoupledConstraint )
 {
 auto val = maxUncoupledConstraint->GetValue();

 if ( val.HasMax() && totalUncoupled > val.Max() )
 {
 auto drce = DRC_ITEM::Create( DRCE_DIFF_PAIR_UNCOUPLED_LENGTH_TOO_LONG );

 m_msg = wxString::Format( _( "(%s maximum uncoupled length: %s; actual: %s)" ),
 maxUncoupledConstraint->GetParentRule()->m_Name,
 MessageTextFromValue( userUnits(), val.Max() ),
 MessageTextFromValue( userUnits(), totalUncoupled ) );

 drce->SetErrorMessage( drce->GetErrorText() + wxS( " " ) + m_msg );

 auto pit = it.second.itemsP.begin();
 auto nit = it.second.itemsN.begin();

 drce->AddItem( *pit );
 drce->AddItem( *nit );

 for( pit++; pit != it.second.itemsP.end(); pit++ )
 drce->AddItem( *pit );

 for( nit++; nit != it.second.itemsN.end(); nit++ )
 drce->AddItem( *nit );

 uncoupledViolation = true;

 drce->SetViolatingRule( maxUncoupledConstraint->GetParentRule() );

 reportViolation( drce, ( *it.second.itemsP.begin() )->GetPosition() );
 }
 }

 if ( gapConstraint && ( uncoupledViolation || !maxUncoupledConstraint ) )
 {
 for( auto& cpair : it.second.coupled )
 {
 if( !cpair.couplingOK )
 {
 auto val = gapConstraint->GetValue();
 auto drcItem = DRC_ITEM::Create( DRCE_DIFF_PAIR_GAP_OUT_OF_RANGE );

 m_msg = drcItem->GetErrorText() + wxT( " (" ) +
 gapConstraint->GetParentRule()->m_Name + wxS( " " );

 if( val.HasMin() )
 m_msg += wxString::Format( _( "minimum gap: %s; " ),
 MessageTextFromValue( userUnits(), val.Min() ) );

 if( val.HasMax() )
 m_msg += wxString::Format( _( "maximum gap: %s; " ),
 MessageTextFromValue( userUnits(), val.Max() ) );

 m_msg += wxString::Format( _( "actual: %s)" ),
 MessageTextFromValue( userUnits(), cpair.computedGap ) );

 drcItem->SetErrorMessage( m_msg );

 drcItem->AddItem( cpair.parentP );
 drcItem->AddItem( cpair.parentN );

 drcItem->SetViolatingRule( gapConstraint->GetParentRule() );

 reportViolation( drcItem, cpair.parentP->GetPosition() );
 }
 }
 }
 }

 reportRuleStatistics();

 return true;
}


std::set<DRC_CONSTRAINT_T> test::DRC_TEST_PROVIDER_DIFF_PAIR_COUPLING::GetConstraintTypes() const
{
 return { DIFF_PAIR_GAP_CONSTRAINT, DIFF_PAIR_MAX_UNCOUPLED_CONSTRAINT };
}


namespace detail
{
 static DRC_REGISTER_TEST_PROVIDER<test::DRC_TEST_PROVIDER_DIFF_PAIR_COUPLING> dummy;
}