From a06dbf9d552f0f6003d8d13a4e0ba072ff95eeee Mon Sep 17 00:00:00 2001
From: Bryan Biedenkapp <gatekeep@gmail.com>
Date: Mon, 12 Nov 2018 13:22:18 -0500
Subject: [PATCH] implement logic to reuse the last properly decoded LC's
 instead of dropping the entire LDU; add undecodable LC counter;

---
 P25Control.cpp | 66 ++++++++++++++++++++++++++++++++------------------
 P25Control.h   |  5 +++-
 2 files changed, 47 insertions(+), 24 deletions(-)

diff --git a/P25Control.cpp b/P25Control.cpp
index bceff05..f1fd7a8 100644
--- a/P25Control.cpp
+++ b/P25Control.cpp
@@ -57,6 +57,7 @@ m_networkWatchdog(1000U, 0U, 1500U),
 m_rfFrames(0U),
 m_rfBits(0U),
 m_rfErrs(0U),
+m_rfUndecodableLC(0U),
 m_netFrames(0U),
 m_netLost(0U),
 m_rfDataFrames(0U),
@@ -64,6 +65,8 @@ m_nid(nac),
 m_lastDUID(P25_DUID_TERM),
 m_audio(),
 m_rfData(),
+m_rfLastLDU1(),
+m_rfLastLDU2(),
 m_netData(),
 m_rfLSD(),
 m_netLSD(),
@@ -123,6 +126,8 @@ bool CP25Control::writeModem(unsigned char* data, unsigned int len)
 		else
 			LogMessage("P25, transmission lost, %.1f seconds, BER: %.1f%%", float(m_rfFrames) / 5.56F, float(m_rfErrs * 100U) / float(m_rfBits));
 
+        LogMessage("P25, total frames: %d, bits: %d, undecodable LC: %d, errors: %d, BER: %.4f%%", m_rfFrames, m_rfBits, m_rfUndecodableLC, m_rfErrs, float(m_rfErrs * 100U) / float(m_rfBits));
+
 		if (m_netState == RS_NET_IDLE)
 			m_display->clearP25();
 
@@ -208,24 +213,24 @@ bool CP25Control::writeModem(unsigned char* data, unsigned int len)
 		m_rssiCount++;
 	}
 
-	if (duid == P25_DUID_HEADER) {
-		if (m_rfState == RS_RF_LISTENING) {
+    if (duid == P25_DUID_HEADER) {
+        if (m_rfState == RS_RF_LISTENING) {
+            m_rfData.reset();
+            bool ret = m_rfData.decodeHeader(data + 2U);
+            if (!ret) {
+                m_lastDUID = duid;
+                return false;
+            }
+
+            LogMessage("P25, received RF header");
+
+            m_lastDUID = duid;
+            return true;
+        }
+    }
+    else if (duid == P25_DUID_LDU1) {
+        if (m_rfState == RS_RF_LISTENING) {
 			m_rfData.reset();
-			bool ret = m_rfData.decodeHeader(data + 2U);
-			if (!ret) {
-				m_lastDUID = duid;
-				return false;
-			}
-
-			LogMessage("P25, received RF header");
-
-			m_lastDUID = duid;
-			return true;
-		}
-	}
-	else if (duid == P25_DUID_LDU1) {
-		if (m_rfState == RS_RF_LISTENING) {
-			//m_rfData.reset();
 			bool ret = m_rfData.decodeLDU1(data + 2U);
 			if (!ret) {
 				m_lastDUID = duid;
@@ -278,9 +283,14 @@ bool CP25Control::writeModem(unsigned char* data, unsigned int len)
 
 		if (m_rfState == RS_RF_AUDIO) {
 			bool ret = m_rfData.decodeLDU1(data + 2U);
-			if (!ret) {
-				return false;
-			}
+            if (!ret) {
+                LogWarning("P25, LDU1 undecodable LC, using last LDU1 LC");
+                m_rfData = m_rfLastLDU1;
+                m_rfUndecodableLC++;
+            }
+            else {
+                m_rfLastLDU1 = m_rfData;
+            }
 
 			// Regenerate Sync
 			CSync::addP25Sync(data + 2U);
@@ -327,9 +337,14 @@ bool CP25Control::writeModem(unsigned char* data, unsigned int len)
 	} else if (duid == P25_DUID_LDU2) {
 		if (m_rfState == RS_RF_AUDIO) {
 			bool ret = m_rfData.decodeLDU2(data + 2U);
-			if (!ret) {
-				return false;
-			}
+            if (!ret) {
+                LogWarning("P25, LDU2 undecodable LC, using last LDU2 LC");
+                m_rfData = m_rfLastLDU2;
+                m_rfUndecodableLC++;
+            }
+            else {
+                m_rfLastLDU2 = m_rfData;
+            }
 
 			writeNetwork(m_rfLDU, m_lastDUID, false);
 
@@ -479,6 +494,8 @@ bool CP25Control::writeModem(unsigned char* data, unsigned int len)
 			else
 				LogMessage("P25, received RF end of voice transmission, %.1f seconds, BER: %.1f%%", float(m_rfFrames) / 5.56F, float(m_rfErrs * 100U) / float(m_rfBits));
 
+            LogMessage("P25, total frames: %d, bits: %d, undecodable LC: %d, errors: %d, BER: %.4f%%", m_rfFrames, m_rfBits, m_rfUndecodableLC, m_rfErrs, float(m_rfErrs * 100U) / float(m_rfBits));
+
 			m_display->clearP25();
 
 #if defined(DUMP_P25)
@@ -936,6 +953,9 @@ void CP25Control::createRFHeader()
 
 	m_rfFrames = 0U;
 	m_rfErrs = 0U;
+    m_rfUndecodableLC = 0U;
+    m_rfLastLDU1.reset();
+    m_rfLastLDU2.reset();
 	m_rfBits = 1U;
 	m_rfTimeout.start();
 	m_lastDUID = P25_DUID_HEADER;
diff --git a/P25Control.h b/P25Control.h
index fa069d3..988ed44 100644
--- a/P25Control.h
+++ b/P25Control.h
@@ -65,6 +65,7 @@ private:
 	unsigned int               m_rfFrames;
 	unsigned int               m_rfBits;
 	unsigned int               m_rfErrs;
+    unsigned int               m_rfUndecodableLC;
 	unsigned int               m_netFrames;
 	unsigned int               m_netLost;
 	unsigned int               m_rfDataFrames;
@@ -72,7 +73,9 @@ private:
 	unsigned char              m_lastDUID;
 	CP25Audio                  m_audio;
 	CP25Data                   m_rfData;
-	CP25Data                   m_netData;
+    CP25Data                   m_rfLastLDU1;
+    CP25Data                   m_rfLastLDU2;
+    CP25Data                   m_netData;
 	CP25LowSpeedData           m_rfLSD;
 	CP25LowSpeedData           m_netLSD;
 	unsigned char*             m_netLDU1;