Add parameter to limit the printing of the payload to X values (#508)

* Add parameter to limit the printing of the paylaod to X values

* Update readout.json

* Update readout.json

* Update readout.json

* format

* Update DaqTask.cxx

Author: Barthelemy

Framework/readout.json

@@ -39,6 +39,7 @@
           "": "All the printing options might significantly slow down your QC",
           "printInputHeader": "false",        "": "set to true to print all headers",
           "printInputPayload": "false",       "": "hex or bin (anything else means no)",
+          "printInputPayloadLimit": "-1",     "": "only print the X first words (-1 means no limit)",
           "printPageInfo": "false",           "": "set to true to print information about pages",
           "printRDH": "false",                "": "set to true to print the RDHs"
         }

Modules/Daq/src/DaqTask.cxx

@@ -147,6 +147,10 @@ void DaqTask::printInputPayload(const header::DataHeader* header, const char* pa
   } else if (mCustomParameters["printInputPayload"] == "bin") {
     representation = getBinRepresentation((unsigned char*)payload, header->payloadSize);
   }
+  size_t limit = std::numeric_limits<size_t>::max();
+  if (mCustomParameters.count("printInputPayloadLimit") > 0) {
+    limit = std::stoi(mCustomParameters["printInputPayloadLimit"]);
+  }
 
   for (size_t i = 0; i < representation.size();) {
     ILOG(Info, Ops) << std::setw(4) << i << " : ";
@@ -162,6 +166,10 @@ void DaqTask::printInputPayload(const header::DataHeader* header, const char* pa
     }
     ILOG(Info, Ops) << ENDM;
     i = i + 8;
+    // limit output but we don't troncate the lines.
+    if (i > limit) {
+      return;
+    }
   }
 }