From 3e81d1eb64eb4af9eee86475d77caef722018359 Mon Sep 17 00:00:00 2001
From: Andy CA6JAU <juribeparada@gmail.com>
Date: Sun, 23 Sep 2018 11:11:44 -0300
Subject: [PATCH] Extend preamble length for network CSBK preamble

---
 DMRCSBK.cpp | 13 +++++++++++++
 DMRCSBK.h   |  2 ++
 DMRSlot.cpp | 24 +++++++++++++++++++++++-
 3 files changed, 38 insertions(+), 1 deletion(-)

diff --git a/DMRCSBK.cpp b/DMRCSBK.cpp
index 8496ecd..de7320d 100644
--- a/DMRCSBK.cpp
+++ b/DMRCSBK.cpp
@@ -127,6 +127,14 @@ void CDMRCSBK::get(unsigned char* bytes) const
 {
 	assert(bytes != NULL);
 
+	m_data[10U] ^= CSBK_CRC_MASK[0U];
+	m_data[11U] ^= CSBK_CRC_MASK[1U];
+
+	CCRC::addCCITT162(m_data, 12U);
+
+	m_data[10U] ^= CSBK_CRC_MASK[0U];
+	m_data[11U] ^= CSBK_CRC_MASK[1U];
+
 	CBPTC19696 bptc;
 	bptc.encode(m_data, bytes);
 }
@@ -170,3 +178,8 @@ unsigned char CDMRCSBK::getCBF() const
 {
 	return m_CBF;
 }
+
+void CDMRCSBK::setCBF(unsigned char cbf)
+{
+	m_CBF = m_data[3U] = cbf;
+}
diff --git a/DMRCSBK.h b/DMRCSBK.h
index 69942b4..5dc62a0 100644
--- a/DMRCSBK.h
+++ b/DMRCSBK.h
@@ -57,6 +57,8 @@ public:
 	bool          getDataContent() const;
 	unsigned char getCBF() const;
 
+	void          setCBF(unsigned char cbf);
+
 private:
 	unsigned char* m_data;
 	CSBKO          m_CSBKO;
diff --git a/DMRSlot.cpp b/DMRSlot.cpp
index 0e536d9..65c6dd8 100644
--- a/DMRSlot.cpp
+++ b/DMRSlot.cpp
@@ -66,6 +66,7 @@ const unsigned char TALKER_ID_BLOCK3 = 0x08U;
 
 const unsigned int NO_HEADERS_SIMPLEX = 8U;
 const unsigned int NO_HEADERS_DUPLEX  = 3U;
+const unsigned int NO_PREAMBLE_CSBK   = 15U;
 
 // #define	DUMP_DMR
 
@@ -1565,7 +1566,28 @@ void CDMRSlot::writeNetwork(const CDMRData& dmrData)
 		data[0U] = TAG_DATA;
 		data[1U] = 0x00U;
 
-		writeQueueNet(data);
+		if (csbko == CSBKO_PRECCSBK && csbk.getDataContent()) {
+			unsigned int cbf = NO_PREAMBLE_CSBK + csbk.getCBF() - 1U;
+			for (unsigned int i = 0U; i < NO_PREAMBLE_CSBK; i++, cbf--) {
+				// Change blocks to follow
+				csbk.setCBF(cbf);
+
+				// Regenerate the CSBK data
+				csbk.get(data + 2U);
+
+				// Regenerate the Slot Type
+				CDMRSlotType slotType;
+				slotType.putData(data + 2U);
+				slotType.setColorCode(m_colorCode);
+				slotType.getData(data + 2U);
+
+				// Convert the Data Sync to be from the BS or MS as needed
+				CSync::addDMRDataSync(data + 2U, m_duplex);
+
+				writeQueueNet(data);
+			}
+		} else
+			writeQueueNet(data);
 
 #if defined(DUMP_DMR)
 		openFile();