From 2797ca0d1b9c2656a1f1c12c3dc39ff56eee34a3 Mon Sep 17 00:00:00 2001
From: Harald Barth <haba@kth.se>
Date: Mon, 7 Jul 2025 22:12:18 +0200
Subject: [PATCH] Make sniffer more robust against loop() not keeping up.
 Eliminate fetch flag as the list size does say it all

---
 Sniffer.cpp | 18 ++++++++++++------
 Sniffer.h   |  4 ----
 2 files changed, 12 insertions(+), 10 deletions(-)

diff --git a/Sniffer.cpp b/Sniffer.cpp
index 77d1464..2a57afe 100644
--- a/Sniffer.cpp
+++ b/Sniffer.cpp
@@ -196,19 +196,25 @@ void IRAM_ATTR Sniffer::processInterrupt(int32_t capticks, bool posedge) {
 	    inpacket = false;
 	    dcclen = currentbyte+1;
 	    debugfield = bitfield;
-	    // put it into the out packet
-	    if (fetchflag) {
-	      // not good, should have been fetched
-              // blink_diag(1);
-	      packeterror(); // or better?
+	    // We have something we want to give to the outpacket queue
+	    // Check length of outpacket queue
+	    if (outpacket.size() > 3) {
+	      // not good, these should have been fetched
+	      // the arbitraty number to check is THREE (see the holy grail)
+              // blink_diag(1); DO NOT DO THIS HERE -> will crash
+	      packeterror(); // or what to do better?
+	      // take emergency action:
+	      while (!outpacket.empty()) {
+		outpacket.pop_front();
+	      }
 	    }
 	    lastendofpacket = millis();
 	    DCCPacket temppacket(dccbytes, dcclen);
 	    if (!(temppacket == prevpacket)) {
 	      // we have something new to offer to the fetch routine
+	      // put it into the outpacket queue
 	      outpacket.push_back(temppacket);
 	      prevpacket = temppacket;
-	      fetchflag = true;
 	    }
 	    return;
 	  }
diff --git a/Sniffer.h b/Sniffer.h
index 5994c79..10064d7 100644
--- a/Sniffer.h
+++ b/Sniffer.h
@@ -51,9 +51,6 @@ public:
       p = outpacket.front();
       outpacket.pop_front();
     }
-    if (fetchflag) {
-      fetchflag = false; // (data has been fetched)
-    }
     interrupts();
     return p;
   };
@@ -71,7 +68,6 @@ private:
   bool inpacket = false;
   // these vars are used as interface to other parts of sniffer
   byte halfbitcounter = 0;
-  bool fetchflag = false;
   std::list<DCCPacket> outpacket;
   DCCPacket prevpacket;
   volatile unsigned long lastendofpacket = 0; // timestamp millis