Remove the CRC4 processing.

g4klx · Mar 28, 2021 · 389bd3b · 389bd3b
1 parent 6ac672e
commit 389bd3b
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Showing 4 changed files with 1 addition and 74 deletions.
diff --git a/M17CRC.cpp b/M17CRC.cpp
@@ -46,24 +46,6 @@ const uint16_t CRC16_TABLE[] = {0x0000U, 0x5935U, 0xB26AU, 0xEB5FU, 0x3DE1U, 0x6
 			       0xAC02U, 0xF537U, 0x2389U, 0x7ABCU, 0x91E3U, 0xC8D6U, 0x65AAU, 0x3C9FU, 0xD7C0U, 0x8EF5U, 0x584BU,
 			       0x017EU, 0xEA21U, 0xB314U};
 
-const uint8_t CRC4_TABLE[] = {
-					0x0, 0x7, 0xe, 0x9, 0x5, 0x2, 0xb, 0xc, 0xa, 0xd, 0x4, 0x3, 0xf, 0x8, 0x1, 0x6,
-					0xd, 0xa, 0x3, 0x4, 0x8, 0xf, 0x6, 0x1, 0x7, 0x0, 0x9, 0xe, 0x2, 0x5, 0xc, 0xb,
-					0x3, 0x4, 0xd, 0xa, 0x6, 0x1, 0x8, 0xf, 0x9, 0xe, 0x7, 0x0, 0xc, 0xb, 0x2, 0x5,
-					0xe, 0x9, 0x0, 0x7, 0xb, 0xc, 0x5, 0x2, 0x4, 0x3, 0xa, 0xd, 0x1, 0x6, 0xf, 0x8,
-					0x6, 0x1, 0x8, 0xf, 0x3, 0x4, 0xd, 0xa, 0xc, 0xb, 0x2, 0x5, 0x9, 0xe, 0x7, 0x0,
-					0xb, 0xc, 0x5, 0x2, 0xe, 0x9, 0x0, 0x7, 0x1, 0x6, 0xf, 0x8, 0x4, 0x3, 0xa, 0xd,
-					0x5, 0x2, 0xb, 0xc, 0x0, 0x7, 0xe, 0x9, 0xf, 0x8, 0x1, 0x6, 0xa, 0xd, 0x4, 0x3,
-					0x8, 0xf, 0x6, 0x1, 0xd, 0xa, 0x3, 0x4, 0x2, 0x5, 0xc, 0xb, 0x7, 0x0, 0x9, 0xe,
-					0xc, 0xb, 0x2, 0x5, 0x9, 0xe, 0x7, 0x0, 0x6, 0x1, 0x8, 0xf, 0x3, 0x4, 0xd, 0xa,
-					0x1, 0x6, 0xf, 0x8, 0x4, 0x3, 0xa, 0xd, 0xb, 0xc, 0x5, 0x2, 0xe, 0x9, 0x0, 0x7,
-					0xf, 0x8, 0x1, 0x6, 0xa, 0xd, 0x4, 0x3, 0x5, 0x2, 0xb, 0xc, 0x0, 0x7, 0xe, 0x9,
-					0x2, 0x5, 0xc, 0xb, 0x7, 0x0, 0x9, 0xe, 0x8, 0xf, 0x6, 0x1, 0xd, 0xa, 0x3, 0x4,
-					0xa, 0xd, 0x4, 0x3, 0xf, 0x8, 0x1, 0x6, 0x0, 0x7, 0xe, 0x9, 0x5, 0x2, 0xb, 0xc,
-					0x7, 0x0, 0x9, 0xe, 0x2, 0x5, 0xc, 0xb, 0xd, 0xa, 0x3, 0x4, 0x8, 0xf, 0x6, 0x1,
-					0x9, 0xe, 0x7, 0x0, 0xc, 0xb, 0x2, 0x5, 0x3, 0x4, 0xd, 0xa, 0x6, 0x1, 0x8, 0xf,
-					0x4, 0x3, 0xa, 0xd, 0x1, 0x6, 0xf, 0x8, 0xe, 0x9, 0x0, 0x7, 0xb, 0xc, 0x5, 0x2};
-
 bool CM17CRC::checkCRC16(const unsigned char* in, unsigned int nBytes)
 {
 	assert(in != NULL);
@@ -100,45 +82,3 @@ uint16_t CM17CRC::createCRC16(const unsigned char* in, unsigned int nBytes)
 
 	return crc;
 }
-
-bool CM17CRC::checkCRC4(unsigned char* in, unsigned int nBytes)
-{
-	assert(in != NULL);
-	assert(nBytes > 1U);
-
-	uint8_t save = in[nBytes - 1U] & 0x0FU;
-
-	// Mask out the 4-bit CRC location
-	in[nBytes - 1U] &= 0xF0U;
-
-	uint8_t crc = createCRC4(in, nBytes);
-
-	// Restore the original CRC
-	in[nBytes - 1U] |= save;
-
-	return save == crc;
-}
-
-void CM17CRC::encodeCRC4(unsigned char* in, unsigned int nBytes)
-{
-	assert(in != NULL);
-	assert(nBytes > 1U);
-
-	in[nBytes - 1U] &= 0xF0U;
-
-	uint8_t crc = createCRC4(in, nBytes);
-
-	in[nBytes - 1U] |= crc & 0x0FU;
-}
-
-uint8_t CM17CRC::createCRC4(const unsigned char* in, unsigned int nBytes)
-{
-	assert(in != NULL);
-
-	uint8_t crc = 0x0FU;
-
-	for (unsigned int i = 0U; i < nBytes; i++)
-		crc = CRC4_TABLE[crc ^ in[i]];
-
-	return crc;
-}
diff --git a/M17CRC.h b/M17CRC.h
@@ -27,12 +27,8 @@ class CM17CRC
 	static bool checkCRC16(const unsigned char* in, unsigned int nBytes);
 	static void encodeCRC16(unsigned char* in, unsigned int nBytes);
 
-	static bool checkCRC4(unsigned char* in, unsigned int nBytes);
-	static void encodeCRC4(unsigned char* in, unsigned int nBytes);
-
 private:
 	static uint16_t createCRC16(const unsigned char* in, unsigned int nBytes);
-	static uint8_t  createCRC4(const unsigned char* in, unsigned int nBytes);
 };
 
 #endif
diff --git a/M17Control.cpp b/M17Control.cpp
@@ -218,9 +218,6 @@ bool CM17Control::writeModem(unsigned char* data, unsigned int len)
 		unsigned char lich[M17_LICH_FRAGMENT_LENGTH_BYTES];
 		CM17Utils::combineFragmentLICH(lich1, lich2, lich3, lich4, lich);
 
-		// if (!CM17CRC::checkCRC4(lich, M17_LICH_FRAGMENT_LENGTH_BYTES))
-		//	return false;
-
 		m_rfLSFn = (lich4 >> 5) & 0x07U;
 		m_rfLSF.setFragment(lich, m_rfLSFn);
 
@@ -286,9 +283,6 @@ bool CM17Control::writeModem(unsigned char* data, unsigned int len)
 		// Add the fragment number
 		lich[5U] = (m_rfLSFn & 0x07U) << 5;
 
-		// Add the CRC
-		// CM17CRC::encodeCRC4(lich, M17_LICH_FRAGMENT_LENGTH_BYTES);
-
 		unsigned int frag1, frag2, frag3, frag4;
 		CM17Utils::splitFragmentLICH(lich, frag1, frag2, frag3, frag4);
 
@@ -508,9 +502,6 @@ void CM17Control::writeNetwork()
 		// Add the fragment number
 		lich[5U] = (m_netLSFn & 0x07U) << 5;
 
-		// Add the CRC
-		// CM17CRC::encodeCRC4(lich, M17_LICH_FRAGMENT_LENGTH_BYTES);
-
 		unsigned int frag1, frag2, frag3, frag4;
 		CM17Utils::splitFragmentLICH(lich, frag1, frag2, frag3, frag4);
 

diff --git a/Version.h b/Version.h
@@ -19,6 +19,6 @@
 #if !defined(VERSION_H)
 #define	VERSION_H
 
-const char* VERSION = "20210327";
+const char* VERSION = "20210328";
 
 #endif