pcbnew: Set dp clearance based on netclass

Minimum differential pair clearance should be limited to the netclass
differential pair spacing.  This also cleans up some unused code that
was left over from previous work on differential pair clearances.

Fixes: lp:1673632
* https://bugs.launchpad.net/kicad/+bug/1673632

pcbnew/router/pns_diff_pair_placer.cpp

@@ -164,9 +164,6 @@ bool DIFF_PAIR_PLACER::attemptWalk( NODE* aNode, DIFF_PAIR* aCurrent,
     WALKAROUND walkaround( aNode, Router() );
     WALKAROUND::WALKAROUND_STATUS wf1;
 
-    Router()->GetRuleResolver()->OverrideClearance( true,
-            aCurrent->NetP(), aCurrent->NetN(), aCurrent->Gap() );
-
     walkaround.SetSolidsOnly( aSolidsOnly );
     walkaround.SetIterationLimit( Settings().WalkaroundIterationLimit() );
 
@@ -233,7 +230,6 @@ bool DIFF_PAIR_PLACER::attemptWalk( NODE* aNode, DIFF_PAIR* aCurrent,
         return false;
 
     aWalk.SetShape( cur.CP(), cur.CN() );
-    Router()->GetRuleResolver()->OverrideClearance( false );
 
     return true;
 }

pcbnew/router/pns_kicad_iface.cpp

@@ -71,8 +71,6 @@ public:
 
     virtual int Clearance( const PNS::ITEM* aA, const PNS::ITEM* aB ) const override;
     virtual int Clearance( int aNetCode ) const override;
-    virtual void OverrideClearance( bool aEnable, int aNetA = 0, int aNetB = 0, int aClearance = 0 ) override;
-    virtual void UseDpGap( bool aUseDpGap ) override { m_useDpGap = aUseDpGap; }
     virtual int DpCoupledNet( int aNet ) override;
     virtual int DpNetPolarity( int aNet ) override;
     virtual bool DpNetPair( PNS::ITEM* aItem, int& aNetP, int& aNetN ) override;
@@ -82,6 +80,7 @@ private:
     struct CLEARANCE_ENT
     {
         int coupledNet;
+        int dpClearance;
         int clearance;
     };
 
@@ -94,10 +93,6 @@ private:
     std::vector<CLEARANCE_ENT> m_netClearanceCache;
     std::unordered_map<const D_PAD*, int> m_localClearanceCache;
     int m_defaultClearance;
-    bool m_overrideEnabled;
-    int m_overrideNetA, m_overrideNetB;
-    int m_overrideClearance;
-    bool m_useDpGap;
 };
 
 
@@ -126,9 +121,11 @@ PNS_PCBNEW_RULE_RESOLVER::PNS_PCBNEW_RULE_RESOLVER( BOARD* aBoard, PNS::ROUTER*
 
         int clearance = nc->GetClearance();
         ent.clearance = clearance;
+        ent.dpClearance = nc->GetDiffPairGap();
         m_netClearanceCache[i] = ent;
 
-        wxLogTrace( "PNS", "Add net %u netclass %s clearance %d", i, netClassName.mb_str(), clearance );
+        wxLogTrace( "PNS", "Add net %u netclass %s clearance %d Diff Pair clearance %d",
+                i, netClassName.mb_str(), clearance, ent.dpClearance );
     }
 
     // Build clearance cache for pads
@@ -148,8 +145,6 @@ PNS_PCBNEW_RULE_RESOLVER::PNS_PCBNEW_RULE_RESOLVER( BOARD* aBoard, PNS::ROUTER*
         }
     }
 
-    m_overrideEnabled = false;
-
     auto defaultRule = m_board->GetDesignSettings().m_NetClasses.Find ("Default");
 
     if( defaultRule )
@@ -160,11 +155,6 @@ PNS_PCBNEW_RULE_RESOLVER::PNS_PCBNEW_RULE_RESOLVER( BOARD* aBoard, PNS::ROUTER*
     {
         m_defaultClearance = Millimeter2iu(0.254);
     }
-
-    m_overrideNetA = 0;
-    m_overrideNetB = 0;
-    m_overrideClearance = 0;
-    m_useDpGap = false;
 }
 
 
@@ -196,17 +186,14 @@ int PNS_PCBNEW_RULE_RESOLVER::Clearance( const PNS::ITEM* aA, const PNS::ITEM* a
     int net_b = aB->Net();
     int cl_b = ( net_b >= 0 ? m_netClearanceCache[net_b].clearance : m_defaultClearance );
 
-    bool linesOnly = aA->OfKind( PNS::ITEM::SEGMENT_T | PNS::ITEM::LINE_T )
+    // Clearance in differential pairs can only happen when there is a specific net
-                  && aB->OfKind( PNS::ITEM::SEGMENT_T | PNS::ITEM::LINE_T );
-
     if( net_a >= 0 && net_b >= 0 && m_netClearanceCache[net_a].coupledNet == net_b )
     {
-        if( linesOnly )
+        cl_a = m_netClearanceCache[net_a].dpClearance;
-            cl_a = cl_b = m_router->Sizes().DiffPairGap() - 2 * PNS_HULL_MARGIN;
+        cl_b = m_netClearanceCache[net_b].dpClearance;
-        else
-            cl_a = cl_b = m_router->Sizes().DiffPairViaGap() - 2 * PNS_HULL_MARGIN;
     }
 
+    // Pad clearance is 0 if the ITEM* is not a pad
     int pad_a = localPadClearance( aA );
     int pad_b = localPadClearance( aB );
 
@@ -229,16 +216,6 @@ int PNS_PCBNEW_RULE_RESOLVER::Clearance( int aNetCode ) const
 }
 
 
-// fixme: ugly hack to make the optimizer respect gap width for currently routed differential pair.
-void PNS_PCBNEW_RULE_RESOLVER::OverrideClearance( bool aEnable, int aNetA, int aNetB , int aClearance )
-{
-    m_overrideEnabled = aEnable;
-    m_overrideNetA = aNetA;
-    m_overrideNetB = aNetB;
-    m_overrideClearance = aClearance;
-}
-
-
 int PNS_PCBNEW_RULE_RESOLVER::matchDpSuffix( wxString aNetName, wxString& aComplementNet, wxString& aBaseDpName )
 {
     int rv = 0;

pcbnew/router/pns_node.h

@@ -60,8 +60,6 @@ public:
 
     virtual int Clearance( const ITEM* aA, const ITEM* aB ) const = 0;
     virtual int Clearance( int aNetCode ) const = 0;
-    virtual void OverrideClearance( bool aEnable, int aNetA = 0, int aNetB = 0, int aClearance = 0 ) = 0;
-    virtual void UseDpGap( bool aUseDpGap ) = 0;
     virtual int DpCoupledNet( int aNet ) = 0;
     virtual int DpNetPolarity( int aNet ) = 0;
     virtual bool DpNetPair( ITEM* aItem, int& aNetP, int& aNetN ) = 0;