From 5f0df4d943e54b0aff95812c11eeecd095aef8d4 Mon Sep 17 00:00:00 2001
From: Bryan Biedenkapp <gatekeep@gmail.com>
Date: Tue, 7 Mar 2023 17:21:11 -0500
Subject: [PATCH] some corrections for NXDN CC;

---
 edac/CRC.cpp          | 5 +++--
 edac/CRC.h            | 4 ++--
 nxdn/channel/CAC.cpp  | 9 +++------
 nxdn/packet/Trunk.cpp | 4 ++--
 4 files changed, 10 insertions(+), 12 deletions(-)

diff --git a/edac/CRC.cpp b/edac/CRC.cpp
index e0acf7ff..6883052d 100644
--- a/edac/CRC.cpp
+++ b/edac/CRC.cpp
@@ -690,8 +690,9 @@ bool CRC::checkCRC16(const uint8_t* in, uint32_t bitLength)
 /// </summary>
 /// <param name="in">Input byte array.</param>
 /// <param name="bitLength">Length of byte array in bits.</param>
+/// <param name="offset">Offset in bits to write CRC.</param>
 /// <returns>16-bit CRC.</returns>
-uint16_t CRC::addCRC16(uint8_t* in, uint32_t bitLength)
+uint16_t CRC::addCRC16(uint8_t* in, uint32_t bitLength, uint32_t offset)
 {
     assert(in != nullptr);
 
@@ -704,7 +705,7 @@ uint16_t CRC::addCRC16(uint8_t* in, uint32_t bitLength)
     uint32_t n = bitLength;
     for (uint32_t i = 0U; i < 16U; i++, n++) {
         bool b = READ_BIT(temp, i);
-        WRITE_BIT(in, n, b);
+        WRITE_BIT(in, n + offset, b);
     }
 
 #if DEBUG_CRC
diff --git a/edac/CRC.h b/edac/CRC.h
index a15a0d75..2c598f24 100644
--- a/edac/CRC.h
+++ b/edac/CRC.h
@@ -85,8 +85,8 @@ namespace edac
 
         /// <summary>Check 16-bit CRC-CCITT.</summary>
         static bool checkCRC16(const uint8_t* in, uint32_t bitLength);
-        /// <summary>Encode 15-bit CRC.</summary>
-        static uint16_t addCRC16(uint8_t* in, uint32_t bitLength);
+        /// <summary>Encode 16-bit CRC.</summary>
+        static uint16_t addCRC16(uint8_t* in, uint32_t bitLength, uint32_t offset = 0);
 
     private:
         /// <summary></summary>
diff --git a/nxdn/channel/CAC.cpp b/nxdn/channel/CAC.cpp
index 807d27eb..ea8fd348 100644
--- a/nxdn/channel/CAC.cpp
+++ b/nxdn/channel/CAC.cpp
@@ -261,11 +261,8 @@ void CAC::encode(uint8_t* data) const
 {
     assert(data != nullptr);
 
-    m_data[0U] &= 0xC0U;
-    m_data[0U] |= m_ran;
-
-    m_data[0U] &= 0x3FU;
-    m_data[0U] |= (m_structure << 6) & 0xC0U;
+    m_data[0U] = m_ran;
+    m_data[0U] |= ((m_structure << 6) & 0xC0U);
 
     uint8_t buffer[NXDN_CAC_FEC_LENGTH_BYTES];
     ::memset(buffer, 0x00U, NXDN_CAC_FEC_LENGTH_BYTES);
@@ -275,7 +272,7 @@ void CAC::encode(uint8_t* data) const
         WRITE_BIT(buffer, i, b);
     }
 
-    uint16_t crc = CRC::addCRC16(buffer, NXDN_CAC_LENGTH_BITS);
+    uint16_t crc = CRC::addCRC16(buffer, NXDN_CAC_LENGTH_BITS, 5U);
 
 #if DEBUG_NXDN_CAC
     Utils::dump(2U, "Encoded CAC", buffer, NXDN_CAC_FEC_LENGTH_BYTES);
diff --git a/nxdn/packet/Trunk.cpp b/nxdn/packet/Trunk.cpp
index dc12b020..e89f2e8e 100644
--- a/nxdn/packet/Trunk.cpp
+++ b/nxdn/packet/Trunk.cpp
@@ -758,12 +758,12 @@ void Trunk::writeRF_CC_Message_Service_Info()
 
     std::unique_ptr<rcch::MESSAGE_TYPE_SRV_INFO> rcch = new_unique(rcch::MESSAGE_TYPE_SRV_INFO);
     rcch->encode(buffer, NXDN_RCCH_LC_LENGTH_BITS / 2U);
-    rcch->encode(buffer, NXDN_RCCH_LC_LENGTH_BITS / 2U, NXDN_RCCH_LC_LENGTH_BITS / 2U);
+    //rcch->encode(buffer, NXDN_RCCH_LC_LENGTH_BITS / 2U, NXDN_RCCH_LC_LENGTH_BITS / 2U);
 
     // generate the CAC
     channel::CAC cac;
     cac.setRAN(m_nxdn->m_ran);
-    cac.setStructure(NXDN_SR_RCCH_DUAL);
+    cac.setStructure(NXDN_SR_RCCH_SINGLE);
     cac.setData(buffer);
     cac.encode(data + 2U);