#23 detect CRC header in calc CRC, add test

.vscode/launch.json

@@ -109,7 +109,7 @@
             "type": "cppdbg",
             "request": "launch",
             "program": "${workspaceFolder}/DGWVoiceTransmit/dgwvoicetransmit",
-            "args": ["F4FXL  B", "${workspaceFolder}/Sandbox/Announce_F5ZEE__B.dvtool", "-text", "www.F5KAV.fr"],
+            "args": ["F4FXL  B", "${workspaceFolder}/Sandbox/Announce_F5ZEE__B.dvtool", "-text", "www.F5KAV.fr", "-dprs", "!4858.72ND00736.91E&RNG0037/A=000098 440 Voice 439.80000MHz -9.4000MHz"],
             "stopAtEntry": false,
             "cwd": "${workspaceFolder}",
             "environment": [],

APRS/APRSUtils.cpp

@@ -37,8 +37,12 @@ unsigned int CAPRSUtils::calcGPSAIcomCRC(const std::string& gpsa)
 {
 	unsigned int icomcrc = 0xFFFFU;
 
+	unsigned int dataBegin = 0U;
+	if(boost::starts_with(gpsa, "$$CRC") && gpsa.length() >= 10 && gpsa[9] == ',')
+		dataBegin = 10U;
+
     auto length = gpsa.length();
-	for (unsigned int j = 10U; j < length; j++) {
+	for (unsigned int j = dataBegin; j < length; j++) {
 		unsigned char ch = (unsigned char)gpsa[j];
 
 		for (unsigned int i = 0U; i < 8U; i++) {

Tests/APRSUtils/calcGPSAIcomCRC.cpp

@@ -0,0 +1,41 @@
+/*
+ *   Copyright (c) 2021-2022 by Geoffrey Merck F4FXL / KC3FRA
+ *
+ *   This program is free software; you can redistribute it and/or modify
+ *   it under the terms of the GNU General Public License as published by
+ *   the Free Software Foundation; either version 2 of the License, or
+ *   (at your option) any later version.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *   GNU General Public License for more details.
+ *
+ *   You should have received a copy of the GNU General Public License
+ *   along with this program; if not, write to the Free Software
+ *   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include <gtest/gtest.h>
+
+#include "APRSUtils.h"
+
+namespace APRStoDPRSTests
+{
+    class APRSUtils_calcGPSAIcomCRC : public ::testing::Test { 
+    };
+
+    TEST_F(APRSUtils_calcGPSAIcomCRC, withCRCHeader)
+    {
+        auto crc = CAPRSUtils::calcGPSAIcomCRC("$$CRC6F5E,ABCDEF");
+
+        EXPECT_EQ(crc, 0x6f5e) << "CRC shall be valid";
+    }
+
+    TEST_F(APRSUtils_calcGPSAIcomCRC, withoutCRCHeader)
+    {
+        auto crc = CAPRSUtils::calcGPSAIcomCRC("ABCDEF");
+
+        EXPECT_EQ(crc, 0x6f5e) << "CRC shall be valid";
+    }
+}