Add the possibility not to decode large clusters as such

It is useful for offline studies to remove the treatment of large clusters (e.g. to study saturation effects). This Gaudi::Property allows just that (left: normal decoding, right: edited decoding)

@bleverin @luwitola @ppais

FT/FTDAQ/src/FTRawBankDecoder.cpp

@@ -56,6 +56,8 @@ public:
 private:
   // Force decoding of v5 as v4 for testing of v5 encoding; expert use only
   Gaudi::Property<bool> m_decodeV5AsV4{this, "DecodeV5AsV4", false, "Decode v5 as v4"};
+  // Force not doing anything with large clusters to study saturation effects
+  Gaudi::Property<bool> m_ignoreLarge{this, "IgnoreLarge", false, "IgnoreLarge"};
 
   ConditionAccessor<DeFT> m_det{this, DeFTDetectorLocation::Default};
 
@@ -582,30 +584,40 @@ FTLiteClusters FTRawBankDecoder::decode( const EventContext& evtCtx, LHCb::RawBa
       };
 
       // Make clusters between two channels
-      auto make_clusters = [&]( unsigned firstChannel, short int c, short int c2 ) {
-        unsigned int widthClus = ( cell( c2 ) - cell( c ) + 2 ); // lastCh-firstCh+4/2
-
-        // fragmented clusters, size > 2*max size
-        // only edges were saved, add middles now
-        if ( widthClus > 2 * LHCb::Detector::FT::RawBank::maxClusterWidth ) {
-          // add the first edge cluster, and then the middle clusters
-          unsigned int i = 0;
-          for ( ; i < widthClus - LHCb::Detector::FT::RawBank::maxClusterWidth;
-                i += LHCb::Detector::FT::RawBank::maxClusterWidth ) {
-            // all middle clusters will have same size as the first cluster,
-            // for max size 4, fractions is always 1
-            make_cluster( firstChannel + i, 1, 0 );
-          }
+      std::function<void( unsigned, short int, short int )> make_clusters;
+      if ( m_ignoreLarge ) {
+        make_clusters = [&]( unsigned, short int c, short int c2 ) {
+          unsigned int widthClus = ( cell( c2 ) - cell( c ) + 2 ); // lastCh-firstCh+4/2
+          unsigned int size      = ( widthClus > 2 * LHCb::Detector::FT::RawBank::maxClusterWidth ) ? 0 : widthClus;
+          make_cluster( cell( c ), 1, size );
+          make_cluster( cell( c2 ), 1, size );
+        }; // End lambda make_clusters
+      } else {
+        make_clusters = [&]( unsigned firstChannel, short int c, short int c2 ) {
+          unsigned int widthClus = ( cell( c2 ) - cell( c ) + 2 ); // lastCh-firstCh+4/2
+
+          // fragmented clusters, size > 2*max size
+          // only edges were saved, add middles now
+          if ( widthClus > 2 * LHCb::Detector::FT::RawBank::maxClusterWidth ) {
+            // add the first edge cluster, and then the middle clusters
+            unsigned int i = 0;
+            for ( ; i < widthClus - LHCb::Detector::FT::RawBank::maxClusterWidth;
+                  i += LHCb::Detector::FT::RawBank::maxClusterWidth ) {
+              // all middle clusters will have same size as the first cluster,
+              // for max size 4, fractions is always 1
+              make_cluster( firstChannel + i, 1, 0 );
+            }
 
-          // add the last edge
-          unsigned int lastChannel = firstChannel + i + std::floor( ( widthClus - i - 1 ) / 2 ) - 1;
-          make_cluster( lastChannel, ( widthClus - 1 ) % 2, 0 );
-        } else { // big cluster size upto size 8
+            // add the last edge
+            unsigned int lastChannel = firstChannel + i + std::floor( ( widthClus - i - 1 ) / 2 ) - 1;
+            make_cluster( lastChannel, ( widthClus - 1 ) % 2, 0 );
+          } else { // big cluster size upto size 8
 
-          make_cluster( firstChannel + ( widthClus - 1 ) / 2 - 1, ( widthClus - 1 ) % 2, widthClus );
+            make_cluster( firstChannel + ( widthClus - 1 ) / 2 - 1, ( widthClus - 1 ) % 2, widthClus );
 
-        } // end if adjacent clusters
-      };  // End lambda make_clusters
+          } // end if adjacent clusters
+        };  // End lambda make_clusters
+      }
 
       clusters = clusters.subspan( 2 ); // skip first 32b of header
       if ( !clusters.empty() && clusters.back() == 0 )