Merge pull request #1 from saurabhb17/develop

Added main functions

1 files changed, 870 insertions, 0 deletions

diff --git a/pcbnew/router/pns_diff_pair.cpp b/pcbnew/router/pns_diff_pair.cpp
new file mode 100644
index 0000000..771928b
--- /dev/null
+++ b/pcbnew/router/pns_diff_pair.cpp
@@ -0,0 +1,870 @@
+/*
+ * KiRouter - a push-and-(sometimes-)shove PCB router
+ *
+ * Copyright (C) 2013-2015 CERN
+ * Author: Tomasz Wlostowski <tomasz.wlostowski@cern.ch>
+ *
+ * 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 <boost/foreach.hpp>
+
+#include <cstdio>
+#include <cstdlib>
+#include <limits>
+
+#include <geometry/shape.h>
+#include <geometry/shape_rect.h>
+#include <geometry/shape_circle.h>
+#include <geometry/shape_segment.h>
+
+#include "direction.h"
+
+#include "pns_diff_pair.h"
+#include "pns_router.h"
+#include "pns_solid.h"
+#include "pns_utils.h"
+
+
+class PNS_LINE;
+
+PNS_DP_PRIMITIVE_PAIR::PNS_DP_PRIMITIVE_PAIR( PNS_ITEM* aPrimP, PNS_ITEM* aPrimN )
+{
+    m_primP = aPrimP->Clone();
+    m_primN = aPrimN->Clone();
+
+    m_anchorP = m_primP->Anchor( 0 );
+    m_anchorN = m_primN->Anchor( 0 );
+}
+
+
+void PNS_DP_PRIMITIVE_PAIR::SetAnchors( const VECTOR2I& aAnchorP, const VECTOR2I& aAnchorN )
+{
+    m_anchorP = aAnchorP;
+    m_anchorN = aAnchorN;
+}
+
+
+PNS_DP_PRIMITIVE_PAIR::PNS_DP_PRIMITIVE_PAIR( const VECTOR2I& aAnchorP, const VECTOR2I& aAnchorN )
+{
+    m_anchorP = aAnchorP;
+    m_anchorN = aAnchorN;
+    m_primP = m_primN = NULL;
+}
+
+
+PNS_DP_PRIMITIVE_PAIR::PNS_DP_PRIMITIVE_PAIR( const PNS_DP_PRIMITIVE_PAIR& aOther )
+{
+    m_primP = m_primN = NULL;
+
+    if( aOther.m_primP )
+        m_primP = aOther.m_primP->Clone();
+
+    if( aOther.m_primN )
+        m_primN = aOther.m_primN->Clone();
+
+    m_anchorP = aOther.m_anchorP;
+    m_anchorN = aOther.m_anchorN;
+}
+
+
+PNS_DP_PRIMITIVE_PAIR& PNS_DP_PRIMITIVE_PAIR::operator=( const PNS_DP_PRIMITIVE_PAIR& aOther )
+{
+    if( aOther.m_primP )
+        m_primP = aOther.m_primP->Clone();
+    if( aOther.m_primN )
+        m_primN = aOther.m_primN->Clone();
+
+    m_anchorP = aOther.m_anchorP;
+    m_anchorN = aOther.m_anchorN;
+
+    return *this;
+}
+
+
+PNS_DP_PRIMITIVE_PAIR::~PNS_DP_PRIMITIVE_PAIR()
+{
+    delete m_primP;
+    delete m_primN;
+}
+
+
+bool PNS_DP_PRIMITIVE_PAIR::Directional() const
+{
+    if( !m_primP )
+        return false;
+
+    return m_primP->OfKind( PNS_ITEM::SEGMENT );
+}
+
+
+DIRECTION_45 PNS_DP_PRIMITIVE_PAIR::anchorDirection( PNS_ITEM* aItem, const VECTOR2I& aP ) const
+{
+    if( !aItem->OfKind ( PNS_ITEM::SEGMENT ) )
+        return DIRECTION_45();
+
+    PNS_SEGMENT* s = static_cast<PNS_SEGMENT*>( aItem );
+
+    if( s->Seg().A == aP )
+        return DIRECTION_45( s->Seg().A - s->Seg().B );
+    else
+        return DIRECTION_45( s->Seg().B - s->Seg().A );
+}
+
+
+DIRECTION_45 PNS_DP_PRIMITIVE_PAIR::DirP() const
+{
+    return anchorDirection( m_primP, m_anchorP );
+}
+
+
+DIRECTION_45 PNS_DP_PRIMITIVE_PAIR::DirN() const
+{
+    return anchorDirection( m_primN, m_anchorN );
+}
+
+
+static void drawGw( VECTOR2I p, int color )
+{
+    SHAPE_LINE_CHAIN l;
+
+    l.Append( p - VECTOR2I( -50000, -50000 ) );
+    l.Append( p + VECTOR2I( -50000, -50000 ) );
+
+    l.Clear();
+    l.Append( p - VECTOR2I( 50000, -50000 ) );
+    l.Append( p + VECTOR2I( 50000, -50000 ) );
+}
+
+
+static DIRECTION_45::AngleType angle( const VECTOR2I &a, const VECTOR2I &b )
+{
+    DIRECTION_45 dir_a( a );
+    DIRECTION_45 dir_b( b );
+
+    return dir_a.Angle( dir_b );
+}
+
+
+static bool checkGap( const SHAPE_LINE_CHAIN &p, const SHAPE_LINE_CHAIN &n, int gap )
+{
+    int i, j;
+
+    for( i = 0; i < p.SegmentCount(); i++ )
+    {
+        for( j = 0; j < n.SegmentCount() ; j++ )
+        {
+            int dist = p.CSegment( i ).Distance( n.CSegment( j ) );
+
+            if( dist  < gap - 100 )
+                return false;
+        }
+    }
+
+    return true;
+}
+
+
+void PNS_DP_GATEWAY::Reverse()
+{
+    m_entryN = m_entryN.Reverse();
+    m_entryP = m_entryP.Reverse();
+}
+
+
+bool PNS_DIFF_PAIR::BuildInitial( PNS_DP_GATEWAY& aEntry, PNS_DP_GATEWAY &aTarget, bool aPrefDiagonal )
+{
+    SHAPE_LINE_CHAIN p = DIRECTION_45().BuildInitialTrace ( aEntry.AnchorP(), aTarget.AnchorP(), aPrefDiagonal );
+    SHAPE_LINE_CHAIN n = DIRECTION_45().BuildInitialTrace ( aEntry.AnchorN(), aTarget.AnchorN(), aPrefDiagonal );
+
+    int mask = aEntry.AllowedAngles() | DIRECTION_45::ANG_STRAIGHT | DIRECTION_45::ANG_OBTUSE;
+
+    SHAPE_LINE_CHAIN sum_n, sum_p;
+    m_p = p;
+    m_n = n;
+
+    if( aEntry.HasEntryLines() )
+    {
+        if( !aEntry.Entry().CheckConnectionAngle( *this, mask ) )
+            return false;
+
+        sum_p = aEntry.Entry().CP();
+        sum_n = aEntry.Entry().CN();
+        sum_p.Append( p );
+        sum_n.Append( n );
+    }
+    else
+    {
+        sum_p = p;
+        sum_n = n;
+    }
+
+    mask = aTarget.AllowedAngles() | DIRECTION_45::ANG_STRAIGHT | DIRECTION_45::ANG_OBTUSE;
+
+    m_p = sum_p;
+    m_n = sum_n;
+
+    if( aTarget.HasEntryLines() )
+    {
+        PNS_DP_GATEWAY t(aTarget) ;
+        t.Reverse();
+
+        if( !CheckConnectionAngle( t.Entry(), mask ) )
+            return false;
+
+        sum_p.Append( t.Entry().CP() );
+        sum_n.Append( t.Entry().CN() );
+    }
+
+    m_p = sum_p;
+    m_n = sum_n;
+
+    if( !checkGap ( p, n, m_gapConstraint ) )
+        return false;
+
+    if( p.SelfIntersecting() || n.SelfIntersecting() )
+        return false;
+
+    if( p.Intersects( n ) )
+        return false;
+
+    return true;
+}
+
+
+bool PNS_DIFF_PAIR::CheckConnectionAngle( const PNS_DIFF_PAIR& aOther, int aAllowedAngles ) const
+{
+    bool checkP, checkN;
+
+    if( m_p.SegmentCount() == 0 || aOther.m_p.SegmentCount() == 0 )
+        checkP = true;
+    else
+    {
+        DIRECTION_45 p0( m_p.CSegment( -1 ) );
+        DIRECTION_45 p1( aOther.m_p.CSegment( 0 ) );
+
+        checkP = ( p0.Angle( p1 ) & aAllowedAngles ) != 0;
+    }
+
+    if( m_n.SegmentCount() == 0 || aOther.m_n.SegmentCount() == 0 )
+        checkN = true;
+    else
+    {
+        DIRECTION_45 n0( m_n.CSegment( -1 ) );
+        DIRECTION_45 n1( aOther.m_n.CSegment( 0 ) );
+
+        checkN = ( n0.Angle( n1 ) & aAllowedAngles ) != 0;
+    }
+
+    return checkP && checkN;
+}
+
+
+const PNS_DIFF_PAIR PNS_DP_GATEWAY::Entry() const
+{
+    return PNS_DIFF_PAIR( m_entryP, m_entryN, 0 );
+}
+
+
+void PNS_DP_GATEWAYS::BuildOrthoProjections( PNS_DP_GATEWAYS& aEntries,
+        const VECTOR2I& aCursorPos, int aOrthoScore )
+{
+    BOOST_FOREACH( PNS_DP_GATEWAY g, aEntries.Gateways() )
+    {
+        VECTOR2I midpoint( ( g.AnchorP() + g.AnchorN() ) / 2 );
+        SEG guide_s( midpoint, midpoint + VECTOR2I( 1, 0 ) );
+        SEG guide_d( midpoint, midpoint + VECTOR2I( 1, 1 ) );
+
+        VECTOR2I proj_s = guide_s.LineProject( aCursorPos );
+        VECTOR2I proj_d = guide_d.LineProject( aCursorPos );
+
+        int dist_s = ( proj_s - aCursorPos ).EuclideanNorm();
+        int dist_d = ( proj_d - aCursorPos ).EuclideanNorm();
+
+
+        VECTOR2I proj = ( dist_s < dist_d ? proj_s : proj_d );
+
+        PNS_DP_GATEWAYS targets( m_gap );
+
+        targets.m_viaGap = m_viaGap;
+        targets.m_viaDiameter = m_viaDiameter;
+        targets.m_fitVias = m_fitVias;
+
+        targets.BuildForCursor( proj );
+
+        BOOST_FOREACH( PNS_DP_GATEWAY t, targets.Gateways() )
+        {
+            t.SetPriority( aOrthoScore );
+            m_gateways.push_back( t );
+        }
+    }
+}
+
+
+bool PNS_DP_GATEWAYS::FitGateways( PNS_DP_GATEWAYS& aEntry, PNS_DP_GATEWAYS& aTarget,
+        bool aPrefDiagonal, PNS_DIFF_PAIR& aDp )
+{
+    std::vector<DP_CANDIDATE> candidates;
+
+    BOOST_FOREACH( PNS_DP_GATEWAY g_entry, aEntry.Gateways() )
+    {
+        BOOST_FOREACH( PNS_DP_GATEWAY g_target, aTarget.Gateways() )
+        {
+            for( int attempt = 0; attempt < 2; attempt++ )
+            {
+                PNS_DIFF_PAIR l( m_gap );
+
+                if( l.BuildInitial( g_entry, g_target, aPrefDiagonal ^ ( attempt ? true : false ) ) )
+                {
+                    int score = ( attempt == 1 ? -3 : 0 );
+                    score +=g_entry.Priority();
+                    score +=g_target.Priority();
+
+                    DP_CANDIDATE c;
+                    c.score = score;
+                    c.p = l.CP();
+                    c.n = l.CN();
+                    candidates.push_back( c );
+                }
+            }
+        }
+    }
+
+    int bestScore = -1000;
+    DP_CANDIDATE best;
+    bool found = false;
+
+    BOOST_FOREACH( DP_CANDIDATE c, candidates )
+    {
+        if( c.score > bestScore )
+        {
+            bestScore = c.score;
+            best = c;
+            found = true;
+        }
+    }
+
+    if( found )
+    {
+        aDp.SetGap( m_gap );
+        aDp.SetShape( best.p, best.n );
+        return true;
+    }
+
+    return false;
+}
+
+
+bool PNS_DP_GATEWAYS::checkDiagonalAlignment( const VECTOR2I& a, const VECTOR2I& b ) const
+{
+    VECTOR2I dir ( std::abs (a.x - b.x), std::abs ( a.y - b.y ));
+
+    return (dir.x == 0 && dir.y != 0) || (dir.x == dir.y) || (dir.y == 0 && dir.x != 0);
+}
+
+
+void PNS_DP_GATEWAYS::BuildFromPrimitivePair( PNS_DP_PRIMITIVE_PAIR aPair, bool aPreferDiagonal )
+{
+    VECTOR2I majorDirection;
+    VECTOR2I p0_p, p0_n;
+    int orthoFanDistance;
+    int diagFanDistance;
+    const SHAPE* shP = NULL;
+
+    if( aPair.PrimP() == NULL )
+    {
+        BuildGeneric( aPair.AnchorP(), aPair.AnchorN(), true );
+        return;
+    }
+
+    const int pvMask = PNS_ITEM::SOLID | PNS_ITEM::VIA;
+
+    if( aPair.PrimP()->OfKind( pvMask ) && aPair.PrimN()->OfKind(  pvMask ) )
+    {
+        p0_p = aPair.AnchorP();
+        p0_n = aPair.AnchorN();
+
+        shP = aPair.PrimP()->Shape();
+    }
+    else if( aPair.PrimP()->OfKind( PNS_ITEM::SEGMENT ) && aPair.PrimN()->OfKind( PNS_ITEM::SEGMENT ) )
+    {
+        buildDpContinuation( aPair, aPreferDiagonal );
+
+        return;
+    }
+
+    majorDirection = ( p0_p - p0_n ).Perpendicular();
+
+    if( shP == NULL )
+        return;
+
+    switch( shP->Type() )
+    {
+    case SH_RECT:
+    {
+        int w = static_cast<const SHAPE_RECT*>( shP )->GetWidth();
+        int h = static_cast<const SHAPE_RECT*>( shP )->GetHeight();
+
+        if( w < h )
+            std::swap( w, h );
+
+        orthoFanDistance = w * 3/4;
+        diagFanDistance = ( w - h ) / 2;
+        break;
+    }
+
+    case SH_SEGMENT:
+    {
+        int w = static_cast<const SHAPE_SEGMENT*>( shP )->GetWidth();
+        SEG s = static_cast<const SHAPE_SEGMENT*>( shP )->GetSeg();
+
+        orthoFanDistance = w + ( s.B - s.A ).EuclideanNorm() / 2;
+        diagFanDistance = ( s.B - s.A ).EuclideanNorm() / 2;
+        break;
+    }
+
+    default:
+        BuildGeneric ( p0_p, p0_n, true );
+        return;
+    }
+
+    if( checkDiagonalAlignment( p0_p, p0_n ) )
+    {
+        int padDist = ( p0_p - p0_n ).EuclideanNorm();
+
+        for( int k = 0; k < 2; k++ )
+        {
+            VECTOR2I dir, dp, dv;
+
+            if( k == 0 )
+            {
+                dir = majorDirection.Resize( orthoFanDistance );
+                int d = ( padDist - m_gap ) / 2;
+
+                dp = dir.Resize( d );
+                dv = ( p0_n - p0_p ).Resize( d );
+            }
+            else
+            {
+                dir = majorDirection.Resize( diagFanDistance );
+                int d = ( padDist - m_gap ) / 2;
+                dp = dir.Resize( d );
+                dv = ( p0_n - p0_p ).Resize( d );
+            }
+
+            for( int i = 0; i < 2; i++ )
+            {
+                int sign = i ? -1 : 1;
+
+                VECTOR2I gw_p( p0_p + sign * ( dir + dp ) + dv );
+                VECTOR2I gw_n( p0_n + sign * ( dir + dp ) - dv );
+
+                SHAPE_LINE_CHAIN entryP( p0_p, p0_p + sign * dir, gw_p );
+                SHAPE_LINE_CHAIN entryN( p0_n, p0_n + sign * dir, gw_n );
+
+                PNS_DP_GATEWAY gw( gw_p, gw_n, false );
+
+                gw.SetEntryLines( entryP, entryN );
+                gw.SetPriority( 100 - k );
+                m_gateways.push_back( gw );
+            }
+        }
+    }
+
+    BuildGeneric( p0_p, p0_n, true );
+}
+
+
+void PNS_DP_GATEWAYS::BuildForCursor( const VECTOR2I& aCursorPos )
+{
+    int gap = m_fitVias ? m_viaGap + m_viaDiameter : m_gap;
+
+    for( int attempt = 0; attempt < 2; attempt++ )
+    {
+        for( int i = 0; i < 4; i++ )
+        {
+            VECTOR2I dir;
+
+            if( !attempt )
+            {
+                dir = VECTOR2I( gap, gap ).Resize( gap / 2 );
+
+                if( i % 2 == 0 )
+                    dir.x = -dir.x;
+
+                if( i / 2 == 0 )
+                    dir.y = -dir.y;
+            }
+            else
+            {
+                if( i /2 == 0 )
+                    dir = VECTOR2I( gap / 2 * ( ( i % 2 ) ? -1 : 1 ), 0 );
+                else
+                    dir = VECTOR2I( 0, gap / 2 * ( ( i % 2 ) ? -1 : 1) );
+            }
+
+            if( m_fitVias )
+                BuildGeneric( aCursorPos + dir, aCursorPos - dir, true, true );
+            else
+                m_gateways.push_back( PNS_DP_GATEWAY( aCursorPos + dir,
+                                      aCursorPos - dir, attempt ? true : false ) );
+
+            drawGw ( aCursorPos + dir, 2 );
+            drawGw ( aCursorPos - dir, 3 );
+        }
+    }
+}
+
+
+void PNS_DP_GATEWAYS::buildEntries( const VECTOR2I& p0_p, const VECTOR2I& p0_n )
+{
+    BOOST_FOREACH( PNS_DP_GATEWAY &g, m_gateways )
+    {
+        if( !g.HasEntryLines() )
+        {
+            SHAPE_LINE_CHAIN lead_p = DIRECTION_45().BuildInitialTrace ( g.AnchorP(), p0_p, g.IsDiagonal() ).Reverse();
+            SHAPE_LINE_CHAIN lead_n = DIRECTION_45().BuildInitialTrace ( g.AnchorN(), p0_n, g.IsDiagonal() ).Reverse();
+            g.SetEntryLines( lead_p, lead_n );
+        }
+    }
+}
+
+
+void PNS_DP_GATEWAYS::buildDpContinuation( PNS_DP_PRIMITIVE_PAIR aPair, bool aIsDiagonal )
+{
+    PNS_DP_GATEWAY gw( aPair.AnchorP(), aPair.AnchorN(), aIsDiagonal );
+    gw.SetPriority( 100 );
+    m_gateways.push_back( gw );
+
+    if( !aPair.Directional() )
+        return;
+
+    DIRECTION_45 dP = aPair.DirP();
+    DIRECTION_45 dN = aPair.DirN();
+
+    int gap = ( aPair.AnchorP() - aPair.AnchorN() ).EuclideanNorm();
+
+    VECTOR2I vdP = aPair.AnchorP() + dP.Left().ToVector();
+    VECTOR2I vdN = aPair.AnchorN() + dN.Left().ToVector();
+
+    PNS_SEGMENT* sP = static_cast<PNS_SEGMENT*>( aPair.PrimP() );
+
+    VECTOR2I t1, t2;
+
+    if( sP->Seg().Side( vdP ) == sP->Seg().Side( vdN ) )
+    {
+        t1 = aPair.AnchorP() + dP.Left().ToVector().Resize( gap );
+        t2 = aPair.AnchorN() + dP.Right().ToVector().Resize( gap );
+    }
+    else
+    {
+        t1 = aPair.AnchorP() + dP.Right().ToVector().Resize( gap );
+        t2 = aPair.AnchorN() + dP.Left().ToVector().Resize( gap );
+    }
+
+    PNS_DP_GATEWAY gwL( t2, aPair.AnchorN(), !aIsDiagonal );
+    SHAPE_LINE_CHAIN ep = dP.BuildInitialTrace( aPair.AnchorP(), t2, !aIsDiagonal );
+
+    gwL.SetPriority( 10 );
+    gwL.SetEntryLines( ep , SHAPE_LINE_CHAIN() );
+
+    m_gateways.push_back( gwL );
+
+    PNS_DP_GATEWAY gwR( aPair.AnchorP(), t1, !aIsDiagonal );
+    SHAPE_LINE_CHAIN en = dP.BuildInitialTrace( aPair.AnchorN(), t1, !aIsDiagonal );
+    gwR.SetPriority( 10) ;
+    gwR.SetEntryLines( SHAPE_LINE_CHAIN(), en );
+
+    m_gateways.push_back( gwR );
+}
+
+
+void PNS_DP_GATEWAYS::BuildGeneric( const VECTOR2I& p0_p, const VECTOR2I& p0_n, bool aBuildEntries, bool aViaMode )
+{
+    SEG st_p[2], st_n[2];
+    SEG d_n[2], d_p[2];
+
+    const int padToGapThreshold = 3;
+    int padDist = ( p0_p - p0_p ).EuclideanNorm();
+
+    st_p[0] = SEG(p0_p + VECTOR2I( -100, 0 ), p0_p + VECTOR2I( 100, 0 ) );
+    st_n[0] = SEG(p0_n + VECTOR2I( -100, 0 ), p0_n + VECTOR2I( 100, 0 ) );
+    st_p[1] = SEG(p0_p + VECTOR2I( 0, -100 ), p0_p + VECTOR2I( 0, 100 ) );
+    st_n[1] = SEG(p0_n + VECTOR2I( 0, -100 ), p0_n + VECTOR2I( 0, 100 ) );
+    d_p[0] = SEG( p0_p + VECTOR2I( -100, -100 ), p0_p + VECTOR2I( 100, 100 ) );
+    d_p[1] = SEG( p0_p + VECTOR2I( 100, -100 ), p0_p + VECTOR2I( -100, 100 ) );
+    d_n[0] = SEG( p0_n + VECTOR2I( -100, -100 ), p0_n + VECTOR2I( 100, 100 ) );
+    d_n[1] = SEG( p0_n + VECTOR2I( 100, -100 ), p0_n + VECTOR2I( -100, 100 ) );
+
+    // midpoint exit & side-by exits
+    for( int i = 0; i < 2; i++ )
+    {
+        bool straightColl = st_p[i].Collinear( st_n[i] );
+        bool diagColl = d_p[i].Collinear( d_n[i] );
+
+        if( straightColl || diagColl )
+        {
+            VECTOR2I dir = ( p0_n - p0_p ).Resize( m_gap / 2 );
+            VECTOR2I m = ( p0_p + p0_n ) / 2;
+            int prio = ( padDist > padToGapThreshold * m_gap ? 2 : 1);
+
+            if( !aViaMode )
+            {
+                m_gateways.push_back( PNS_DP_GATEWAY( m - dir, m + dir, diagColl, DIRECTION_45::ANG_RIGHT, prio ) );
+
+                dir = ( p0_n - p0_p ).Resize( m_gap );
+                m_gateways.push_back( PNS_DP_GATEWAY( p0_p - dir, p0_p - dir + dir.Perpendicular(), diagColl ) );
+                m_gateways.push_back( PNS_DP_GATEWAY( p0_p - dir, p0_p - dir - dir.Perpendicular(), diagColl ) );
+                m_gateways.push_back( PNS_DP_GATEWAY( p0_n + dir + dir.Perpendicular(), p0_n + dir, diagColl ) );
+                m_gateways.push_back( PNS_DP_GATEWAY( p0_n + dir - dir.Perpendicular(), p0_n + dir, diagColl ) );
+            }
+        }
+    }
+
+    for( int i = 0; i < 2; i++ )
+    {
+        for( int j = 0; j < 2; j++ )
+        {
+            OPT_VECTOR2I ips[2];
+
+            ips[0] = d_n[i].IntersectLines( d_p[j] );
+            ips[1] = st_p[i].IntersectLines( st_n[j] );
+
+            if( d_n[i].Collinear( d_p[j] ) )
+                ips[0] = boost::none;
+            if( st_p[i].Collinear( st_p[j] ) )
+                ips[1] = boost::none;
+
+            // diagonal-diagonal and straight-straight cases - the most typical case if the pads
+            // are on the same straight/diagonal line
+            for( int k = 0; k < 2; k++ )
+            {
+                if( ips[k] )
+                {
+                    const VECTOR2I m( *ips[k] );
+
+                    if( m != p0_p && m != p0_n )
+                    {
+                        int prio = ( padDist > padToGapThreshold * m_gap ? 10 : 20 );
+                        VECTOR2I g_p( ( p0_p - m ).Resize( (double) m_gap * M_SQRT1_2 ) );
+                        VECTOR2I g_n( ( p0_n - m ).Resize( (double) m_gap * M_SQRT1_2 ) );
+
+                        m_gateways.push_back( PNS_DP_GATEWAY( m + g_p, m + g_n, k == 0 ? true : false, DIRECTION_45::ANG_OBTUSE, prio ) );
+                    }
+                }
+            }
+
+            ips[0] = st_n[i].IntersectLines( d_p[j] );
+            ips[1] = st_p[i].IntersectLines( d_n[j] );
+
+//          diagonal-straight cases: 8 possibilities of "weirder" exists
+            for( int k = 0; k < 2; k++ )
+            {
+                if( ips[k] )
+                {
+                    const VECTOR2I m( *ips[k] );
+
+                    if( !aViaMode && m != p0_p && m != p0_n )
+                    {
+                        VECTOR2I g_p, g_n;
+
+                        g_p = ( p0_p - m ).Resize( (double) m_gap * M_SQRT2 );
+                        g_n = ( p0_n - m ).Resize( (double) m_gap );
+
+                        if( angle( g_p, g_n ) != DIRECTION_45::ANG_ACUTE )
+                            m_gateways.push_back( PNS_DP_GATEWAY( m + g_p, m + g_n, true ) );
+
+                        g_p = ( p0_p - m ).Resize( m_gap );
+                        g_n = ( p0_n - m ).Resize( (double) m_gap * M_SQRT2 );
+
+                        if( angle( g_p, g_n ) != DIRECTION_45::ANG_ACUTE )
+                            m_gateways.push_back( PNS_DP_GATEWAY( m + g_p, m + g_n, true ) );
+                    }
+                }
+            }
+        }
+    }
+
+    if( aBuildEntries )
+        buildEntries( p0_p, p0_n );
+}
+
+
+PNS_DP_PRIMITIVE_PAIR PNS_DIFF_PAIR::EndingPrimitives()
+{
+    if( m_hasVias )
+        return PNS_DP_PRIMITIVE_PAIR( &m_via_p, &m_via_n );
+    else
+    {
+        const PNS_LINE lP( PLine() );
+        const PNS_LINE lN( NLine() );
+
+        PNS_SEGMENT sP( lP, lP.CSegment( -1 ) );
+        PNS_SEGMENT sN( lN, lN.CSegment( -1 ) );
+
+        PNS_DP_PRIMITIVE_PAIR dpair( &sP, &sN );
+        dpair.SetAnchors( sP.Seg().B, sN.Seg().B );
+
+        return dpair;
+    }
+}
+
+
+bool commonParallelProjection( SEG n, SEG p, 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;
+}
+
+
+double PNS_DIFF_PAIR::Skew() const
+{
+    return m_p.Length() - m_n.Length();
+}
+
+
+void PNS_DIFF_PAIR::CoupledSegmentPairs( COUPLED_SEGMENTS_VEC& aPairs ) const
+{
+    SHAPE_LINE_CHAIN p( m_p );
+    SHAPE_LINE_CHAIN n( m_n );
+
+    p.Simplify();
+    n.Simplify();
+
+    for( int i = 0; i < p.SegmentCount(); i++ )
+    {
+        for( int j = 0; j < n.SegmentCount(); j++ )
+        {
+            SEG sp = p.CSegment( i );
+            SEG sn = n.CSegment( j );
+
+            SEG p_clip, n_clip;
+
+            int64_t dist = std::abs( sp.Distance( sn ) - m_width );
+
+            if( sp.ApproxParallel( sn ) && m_gapConstraint.Matches( dist ) && commonParallelProjection( sp, sn, p_clip, n_clip ) )
+            {
+                const COUPLED_SEGMENTS spair( p_clip, sp, i, n_clip, sn, j );
+                aPairs.push_back( spair );
+            }
+        }
+    }
+}
+
+
+int64_t PNS_DIFF_PAIR::CoupledLength( const SHAPE_LINE_CHAIN& aP, const SHAPE_LINE_CHAIN& aN ) const
+{
+    int64_t total = 0;
+
+    for( int i = 0; i < aP.SegmentCount(); i++ )
+    {
+        for( int j = 0; j < aN.SegmentCount(); j++ )
+        {
+            SEG sp = aP.CSegment( i );
+            SEG sn = aN.CSegment( j );
+
+            SEG p_clip, n_clip;
+
+            int64_t dist = std::abs( sp.Distance(sn) - m_width );
+
+            if( sp.ApproxParallel( sn ) && m_gapConstraint.Matches( dist ) &&
+                    commonParallelProjection( sp, sn, p_clip, n_clip ) )
+                total += p_clip.Length();
+        }
+    }
+
+    return total;
+}
+
+
+double PNS_DIFF_PAIR::CoupledLength() const
+{
+    COUPLED_SEGMENTS_VEC pairs;
+
+    CoupledSegmentPairs( pairs );
+
+    double l = 0.0;
+    for( unsigned int i = 0; i < pairs.size(); i++ )
+        l += pairs[i].coupledP.Length();
+
+    return l;
+}
+
+
+double PNS_DIFF_PAIR::CoupledLengthFactor() const
+{
+    double t = TotalLength();
+
+    if( t == 0.0 )
+        return 0.0;
+
+    return CoupledLength() / t;
+}
+
+
+double PNS_DIFF_PAIR::TotalLength() const
+{
+    double lenP = m_p.Length();
+    double lenN = m_n.Length();
+
+    return (lenN + lenP ) / 2.0;
+}
+
+
+int PNS_DIFF_PAIR::CoupledLength ( const SEG& aP, const SEG& aN ) const
+{
+    SEG p_clip, n_clip;
+    int64_t dist = std::abs( aP.Distance( aN ) - m_width );
+
+    if( aP.ApproxParallel( aN ) && m_gapConstraint.Matches( dist ) &&
+            commonParallelProjection ( aP, aN, p_clip, n_clip ) )
+        return p_clip.Length();
+
+    return 0;
+}