Refactor the Golay 24,12,8 code and its uses.

g4klx · Apr 7, 2021 · ffb4bdb · ffb4bdb
1 parent 8dc54ed
commit ffb4bdb
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Showing 6 changed files with 43 additions and 32 deletions.
diff --git a/AMBEFEC.cpp b/AMBEFEC.cpp
@@ -793,22 +793,25 @@ unsigned int CAMBEFEC::regenerateIMBE(unsigned char* bytes) const
 
 unsigned int CAMBEFEC::regenerateDStar(unsigned int& a, unsigned int& b) const
 {
-	bool valid;
-
 	unsigned int orig_a = a;
 	unsigned int orig_b = b;
 
-	unsigned int data = CGolay24128::decode24128(a, valid);
-
-	a = CGolay24128::encode24128(data);
+	unsigned int data;
+	bool valid1 = CGolay24128::decode24128(a, data);
+	if (!valid1)
+		return 10U;
 
 	// The PRNG
 	unsigned int p = PRNG_TABLE[data];
 
 	b ^= p;
 
-	unsigned int datb = CGolay24128::decode24128(b, valid);
+	unsigned int datb;
+	bool valid2 = CGolay24128::decode24128(b, datb);
+	if (!valid2)
+		return 10U;
 
+	a = CGolay24128::encode24128(data);
 	b = CGolay24128::encode24128(datb);
 
 	b ^= p;
@@ -824,12 +827,17 @@ unsigned int CAMBEFEC::regenerateDStar(unsigned int& a, unsigned int& b) const
 
 unsigned int CAMBEFEC::regenerateDMR(unsigned int& a, unsigned int& b, unsigned int& c) const
 {
-	bool valid;
-
 	unsigned int orig_a = a;
 	unsigned int orig_b = b;
 
-	unsigned int data = CGolay24128::decode24128(a, valid);
+	unsigned int data;
+	bool valid = CGolay24128::decode24128(a, data);
+	if (!valid) {
+		a = 0xF00292U;
+		b = 0x0E0B20U;
+		c = 0x000000U;
+		return 10U;		// An invalid A block gives an error count of 10
+	}
 
 	a = CGolay24128::encode24128(data);
 

diff --git a/Golay24128.cpp b/Golay24128.cpp
@@ -1090,23 +1090,25 @@ unsigned int CGolay24128::decode23127(unsigned int code)
 	return code >> 11;
 }
 
-unsigned int CGolay24128::decode24128(unsigned int input, bool& valid)
+bool CGolay24128::decode24128(unsigned int in, unsigned int& out)
 {
-	unsigned int syndrome = ::get_syndrome_23127(input >> 1);
+	unsigned int syndrome = ::get_syndrome_23127(in >> 1);
 	unsigned int error_pattern = DECODING_TABLE_23127[syndrome] << 1;
 
-	unsigned int output = input ^ error_pattern;
+	out = in ^ error_pattern;
 
-	valid = (CUtils::countBits(syndrome) < 3U) || !(CUtils::countBits(output) & 1);
+	bool valid = (CUtils::countBits(syndrome) < 3U) || !(CUtils::countBits(out) & 1);
 
-	return output >> 12;
+	out >>= 12;
+
+	return valid;
 }
 
-unsigned int CGolay24128::decode24128(unsigned char* bytes, bool& valid)
+bool CGolay24128::decode24128(unsigned char* in, unsigned int& out)
 {
-	assert(bytes != NULL);
+	assert(in != NULL);
 
-	unsigned int code = (bytes[0U] << 16) | (bytes[1U] << 8) | (bytes[2U] << 0);
+	unsigned int code = (in[0U] << 16) | (in[1U] << 8) | (in[2U] << 0);
 
-	return decode24128(code, valid);
+	return decode24128(code, out);
 }
diff --git a/Golay24128.h b/Golay24128.h
@@ -25,8 +25,9 @@ class CGolay24128 {
 	static unsigned int encode24128(unsigned int data);
 
 	static unsigned int decode23127(unsigned int code);
-	static unsigned int decode24128(unsigned int code, bool& valid);
-	static unsigned int decode24128(unsigned char* bytes, bool& valid);
+
+	static bool decode24128(unsigned int in, unsigned int& out);
+	static bool decode24128(unsigned char* in, unsigned int& out);
 };
 
 #endif
diff --git a/M17Control.cpp b/M17Control.cpp
@@ -212,11 +212,11 @@ bool CM17Control::writeModem(unsigned char* data, unsigned int len)
 	}
 
 	if (m_rfState == RS_RF_LATE_ENTRY && data[0U] == TAG_DATA1) {
-		bool valid1, valid2, valid3, valid4;
-		unsigned int lich1 = CGolay24128::decode24128(data + 2U + M17_SYNC_LENGTH_BYTES + 0U, valid1);
-		unsigned int lich2 = CGolay24128::decode24128(data + 2U + M17_SYNC_LENGTH_BYTES + 3U, valid2);
-		unsigned int lich3 = CGolay24128::decode24128(data + 2U + M17_SYNC_LENGTH_BYTES + 6U, valid3);
-		unsigned int lich4 = CGolay24128::decode24128(data + 2U + M17_SYNC_LENGTH_BYTES + 9U, valid4);
+		unsigned int lich1, lich2, lich3, lich4;
+		bool valid1 = CGolay24128::decode24128(data + 2U + M17_SYNC_LENGTH_BYTES + 0U, lich1);
+		bool valid2 = CGolay24128::decode24128(data + 2U + M17_SYNC_LENGTH_BYTES + 3U, lich2);
+		bool valid3 = CGolay24128::decode24128(data + 2U + M17_SYNC_LENGTH_BYTES + 6U, lich3);
+		bool valid4 = CGolay24128::decode24128(data + 2U + M17_SYNC_LENGTH_BYTES + 9U, lich4);
 
 		if (!valid1 || !valid2 || !valid3 || !valid4)
 			return false;

diff --git a/Version.h b/Version.h
@@ -19,6 +19,6 @@
 #if !defined(VERSION_H)
 #define	VERSION_H
 
-const char* VERSION = "20210329";
+const char* VERSION = "20210407";
 
 #endif
diff --git a/YSFFICH.cpp b/YSFFICH.cpp
@@ -99,13 +99,13 @@ bool CYSFFICH::decode(const unsigned char* bytes)
 	unsigned char output[13U];
 	viterbi.chainback(output, 96U);
 
-	bool valid1, valid2, valid3, valid4;
-	unsigned int b0 = CGolay24128::decode24128(output + 0U, valid1);
-	unsigned int b1 = CGolay24128::decode24128(output + 3U, valid2);
-	unsigned int b2 = CGolay24128::decode24128(output + 6U, valid3);
-	unsigned int b3 = CGolay24128::decode24128(output + 9U, valid4);
+	unsigned int b0, b1, b2, b3;
+	bool valid0 = CGolay24128::decode24128(output + 0U, b0);
+	bool valid1 = CGolay24128::decode24128(output + 3U, b1);
+	bool valid2 = CGolay24128::decode24128(output + 6U, b2);
+	bool valid3 = CGolay24128::decode24128(output + 9U, b3);
 
-	if (!valid1 || !valid2 || !valid3 || !valid4)
+	if (!valid0 || !valid1 || !valid2 || !valid3)
 		return false;
 
 	m_fich[0U] = (b0 >> 4) & 0xFFU;