Add the P25 NID BCH encoder.

BCH.cpp

@@ -0,0 +1,145 @@
+/*
+* File:    bch3.c
+* Title:   Encoder/decoder for binary BCH codes in C (Version 3.1)
+* Author:  Robert Morelos-Zaragoza
+* Date:    August 1994
+* Revised: June 13, 1997
+*
+* ===============  Encoder/Decoder for binary BCH codes in C =================
+*
+* Version 1:   Original program. The user provides the generator polynomial
+*              of the code (cumbersome!).
+* Version 2:   Computes the generator polynomial of the code.
+* Version 3:   No need to input the coefficients of a primitive polynomial of
+*              degree m, used to construct the Galois Field GF(2**m). The
+*              program now works for any binary BCH code of length such that:
+*              2**(m-1) - 1 < length <= 2**m - 1
+*
+* Note:        You may have to change the size of the arrays to make it work.
+*
+* The encoding and decoding methods used in this program are based on the
+* book "Error Control Coding: Fundamentals and Applications", by Lin and
+* Costello, Prentice Hall, 1983.
+*
+* Thanks to Patrick Boyle (pboyle@era.com) for his observation that 'bch2.c'
+* did not work for lengths other than 2**m-1 which led to this new version.
+* Portions of this program are from 'rs.c', a Reed-Solomon encoder/decoder
+* in C, written by Simon Rockliff (simon@augean.ua.oz.au) on 21/9/89. The
+* previous version of the BCH encoder/decoder in C, 'bch2.c', was written by
+* Robert Morelos-Zaragoza (robert@spectra.eng.hawaii.edu) on 5/19/92.
+*
+* NOTE:
+*          The author is not responsible for any malfunctioning of
+*          this program, nor for any damage caused by it. Please include the
+*          original program along with these comments in any redistribution.
+*
+*  For more information, suggestions, or other ideas on implementing error
+*  correcting codes, please contact me at:
+*
+*                           Robert Morelos-Zaragoza
+*                           5120 Woodway, Suite 7036
+*                           Houston, Texas 77056
+*
+*                    email: r.morelos-zaragoza@ieee.org
+*
+* COPYRIGHT NOTICE: This computer program is free for non-commercial purposes.
+* You may implement this program for any non-commercial application. You may
+* also implement this program for commercial purposes, provided that you
+* obtain my written permission. Any modification of this program is covered
+* by this copyright.
+*
+* == Copyright (c) 1994-7,  Robert Morelos-Zaragoza. All rights reserved.  ==
+*
+* m = order of the Galois field GF(2**m)
+* n = 2**m - 1 = size of the multiplicative group of GF(2**m)
+* length = length of the BCH code
+* t = error correcting capability (max. no. of errors the code corrects)
+* d = 2*t + 1 = designed min. distance = no. of consecutive roots of g(x) + 1
+* k = n - deg(g(x)) = dimension (no. of information bits/codeword) of the code
+* p[] = coefficients of a primitive polynomial used to generate GF(2**m)
+* g[] = coefficients of the generator polynomial, g(x)
+* alpha_to [] = log table of GF(2**m)
+* index_of[] = antilog table of GF(2**m)
+* data[] = information bits = coefficients of data polynomial, i(x)
+* bb[] = coefficients of redundancy polynomial x^(length-k) i(x) modulo g(x)
+* numerr = number of errors
+* errpos[] = error positions
+* recd[] = coefficients of the received polynomial
+* decerror = number of decoding errors (in _message_ positions)
+*
+*/
+
+#include "BCH.h"
+#include "Utils.h"
+#include "Log.h"
+
+#include <cmath>
+#include <cstdio>
+#include <cassert>
+
+const unsigned char BIT_MASK_TABLE[] = { 0x80U, 0x40U, 0x20U, 0x10U, 0x08U, 0x04U, 0x02U, 0x01U };
+
+#define WRITE_BIT(p,i,b) p[(i)>>3] = (b) ? (p[(i)>>3] | BIT_MASK_TABLE[(i)&7]) : (p[(i)>>3] & ~BIT_MASK_TABLE[(i)&7])
+#define READ_BIT(p,i)    (p[(i)>>3] & BIT_MASK_TABLE[(i)&7])
+
+const int length = 63;
+const int k = 16;
+
+const int g[] = {1, 1, 0,  0, 1, 1,  0, 1, 1,  0, 0, 1,  0, 0, 1,  1, 0, 0,  0, 0, 1,  0, 1, 1,
+				 1, 1, 0,  1, 1, 1,  0, 1, 0,  0, 1, 1,  1, 0, 1,  1, 0, 0,  1, 0, 1,  0, 1, 1};
+
+CBCH::CBCH()
+{
+}
+
+CBCH::~CBCH()
+{
+}
+
+void CBCH::encode(const int* data, int* bb)
+/*
+* Compute redundacy bb[], the coefficients of b(x). The redundancy
+* polynomial b(x) is the remainder after dividing x^(length-k)*data(x)
+* by the generator polynomial g(x).
+*/
+{
+	for (int i = 0; i < length - k; i++)
+		bb[i] = 0;
+
+	for (int i = k - 1; i >= 0; i--) {
+		int feedback = data[i] ^ bb[length - k - 1];
+		if (feedback != 0) {
+			for (int j = length - k - 1; j > 0; j--)
+				if (g[j] != 0)
+					bb[j] = bb[j - 1] ^ feedback;
+				else
+					bb[j] = bb[j - 1];
+			bb[0] = g[0] && feedback;
+		} else {
+			for (int j = length - k - 1; j > 0; j--)
+				bb[j] = bb[j - 1];
+			bb[0] = 0;
+		}
+	}
+}
+
+void CBCH::encode(unsigned char* nid)
+{
+	assert(nid != NULL);
+
+	CUtils::dump(1U, "data", nid, 2U);
+
+	int data[16];
+	for (int i = 0; i < 16; i++)
+		data[i] = READ_BIT(nid, i) ? 1 : 0;
+
+	int bb[63];
+	encode(data, bb);
+
+	for (int i = 0; i < (length - k); i++) {
+		bool b = bb[i] == 1;
+		WRITE_BIT(nid, i + 16U, b);
+	}
+
+	CUtils::dump(1U, "out", nid, 8U);
+}

BCH.h

@@ -0,0 +1,33 @@
+/*
+*   Copyright (C) 2016 by Jonathan Naylor G4KLX
+*
+*   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.
+*/
+
+#if !defined(BCH_H)
+#define	BCH_H
+
+class CBCH {
+public:
+	CBCH();
+	~CBCH();
+
+	void encode(unsigned char* data);
+
+private:
+	void encode(const int* data, int* bb);
+};
+
+#endif

MMDVMHost.vcxproj

@@ -147,6 +147,7 @@
   </ItemDefinitionGroup>
   <ItemGroup>
     <ClInclude Include="AMBEFEC.h" />
+    <ClInclude Include="BCH.h" />
     <ClInclude Include="BPTC19696.h" />
     <ClInclude Include="Conf.h" />
     <ClInclude Include="CRC.h" />
@@ -212,6 +213,7 @@
   </ItemGroup>
   <ItemGroup>
     <ClCompile Include="AMBEFEC.cpp" />
+    <ClCompile Include="BCH.cpp" />
     <ClCompile Include="BPTC19696.cpp" />
     <ClCompile Include="Conf.cpp" />
     <ClCompile Include="CRC.cpp" />

MMDVMHost.vcxproj.filters

@@ -200,6 +200,9 @@
     <ClInclude Include="RS.h">
       <Filter>Header Files</Filter>
     </ClInclude>
+    <ClInclude Include="BCH.h">
+      <Filter>Header Files</Filter>
+    </ClInclude>
   </ItemGroup>
   <ItemGroup>
     <ClCompile Include="BPTC19696.cpp">
@@ -370,5 +373,8 @@
     <ClCompile Include="RS.cpp">
       <Filter>Source Files</Filter>
     </ClCompile>
+    <ClCompile Include="BCH.cpp">
+      <Filter>Source Files</Filter>
+    </ClCompile>
   </ItemGroup>
 </Project>

Makefile

@@ -7,7 +7,7 @@ LIBS    = -lpthread
 LDFLAGS = -g
 
 OBJECTS = \
-		AMBEFEC.o BPTC19696.o Conf.o CRC.o Display.o DMRControl.o DMRCSBK.o DMRData.o DMRDataHeader.o DMREMB.o DMREmbeddedLC.o DMRFullLC.o DMRLookup.o DMRLC.o \
+		AMBEFEC.o BCH.o BPTC19696.o Conf.o CRC.o Display.o DMRControl.o DMRCSBK.o DMRData.o DMRDataHeader.o DMREMB.o DMREmbeddedLC.o DMRFullLC.o DMRLookup.o DMRLC.o \
 		DMRNetwork.o DMRShortLC.o DMRSlot.o DMRSlotType.o DMRAccessControl.o DMRTrellis.o DStarControl.o DStarHeader.o DStarNetwork.o DStarSlowData.o Golay2087.o \
 		Golay24128.o Hamming.o Log.o MMDVMHost.o Modem.o Nextion.o NullDisplay.o P25Audio.o P25Control.o P25Data.o P25LowSpeedData.o P25Network.o P25NID.o P25Utils.o \
 		QR1676.o RS.o RS129.o SerialController.o SHA256.o StopWatch.o Sync.o TFTSerial.o Thread.o Timer.o UDPSocket.o Utils.o YSFControl.o YSFConvolution.o YSFFICH.o \

Makefile.Pi.Adafruit

@@ -7,7 +7,7 @@ LIBS    = -lwiringPi -lwiringPiDev -lpthread
 LDFLAGS = -g -L/usr/local/lib
 
 OBJECTS = \
-		AMBEFEC.o BPTC19696.o Conf.o CRC.o Display.o DMRControl.o DMRCSBK.o DMRData.o DMRDataHeader.o DMREMB.o DMREmbeddedLC.o DMRFullLC.o DMRLookup.o DMRLC.o \
+		AMBEFEC.o BCH.o BPTC19696.o Conf.o CRC.o Display.o DMRControl.o DMRCSBK.o DMRData.o DMRDataHeader.o DMREMB.o DMREmbeddedLC.o DMRFullLC.o DMRLookup.o DMRLC.o \
 		DMRNetwork.o DMRShortLC.o DMRSlot.o DMRSlotType.o DMRAccessControl.o DMRTrellis.o DStarControl.o DStarHeader.o DStarNetwork.o DStarSlowData.o Golay2087.o \
 		Golay24128.o Hamming.o HD44780.o Log.o MMDVMHost.o Modem.o Nextion.o NullDisplay.o P25Audio.o P25Control.o P25Data.o P25LowSpeedData.o P25Network.o P25NID.o \
 		P25Utils.o QR1676.o RS.o RS129.o SerialController.o SHA256.o StopWatch.o Sync.o TFTSerial.o Thread.o Timer.o UDPSocket.o Utils.o YSFControl.o YSFConvolution.o \

Makefile.Pi.HD44780

@@ -7,7 +7,7 @@ LIBS    = -lwiringPi -lwiringPiDev -lpthread
 LDFLAGS = -g -L/usr/local/lib
 
 OBJECTS = \
-		AMBEFEC.o BPTC19696.o Conf.o CRC.o Display.o DMRControl.o DMRCSBK.o DMRData.o DMRDataHeader.o DMREMB.o DMREmbeddedLC.o DMRFullLC.o DMRLookup.o DMRLC.o \
+		AMBEFEC.o BCH.o BPTC19696.o Conf.o CRC.o Display.o DMRControl.o DMRCSBK.o DMRData.o DMRDataHeader.o DMREMB.o DMREmbeddedLC.o DMRFullLC.o DMRLookup.o DMRLC.o \
 		DMRNetwork.o DMRShortLC.o DMRSlot.o DMRSlotType.o DMRAccessControl.o DMRTrellis.o DStarControl.o DStarHeader.o DStarNetwork.o DStarSlowData.o Golay2087.o \
 		Golay24128.o Hamming.o HD44780.o Log.o MMDVMHost.o Modem.o Nextion.o NullDisplay.o P25Audio.o P25Control.o P25Data.o P25LowSpeedData.o P25Network.o P25NID.o \
 		P25Utils.o QR1676.o RS.o RS129.o SerialController.o SHA256.o StopWatch.o Sync.o TFTSerial.o Thread.o Timer.o UDPSocket.o Utils.o YSFControl.o YSFConvolution.o \

Makefile.Pi.OLED

@@ -7,7 +7,7 @@ LIBS    = -lArduiPi_OLED -lpthread
 LDFLAGS = -g -L/usr/local/lib
 
 OBJECTS = \
-		AMBEFEC.o BPTC19696.o Conf.o CRC.o Display.o DMRControl.o DMRCSBK.o DMRData.o DMRDataHeader.o DMREMB.o DMREmbeddedLC.o DMRFullLC.o DMRLookup.o DMRLC.o \
+		AMBEFEC.o BCH.o BPTC19696.o Conf.o CRC.o Display.o DMRControl.o DMRCSBK.o DMRData.o DMRDataHeader.o DMREMB.o DMREmbeddedLC.o DMRFullLC.o DMRLookup.o DMRLC.o \
 		DMRNetwork.o DMRShortLC.o DMRSlot.o DMRSlotType.o DMRAccessControl.o DMRTrellis.o DStarControl.o DStarHeader.o DStarNetwork.o DStarSlowData.o Golay2087.o \
 		Golay24128.o Hamming.o OLED.o Log.o MMDVMHost.o Modem.o Nextion.o NullDisplay.o P25Audio.o P25Control.o P25Data.o P25LowSpeedData.o P25Network.o P25NID.o \
 		P25Utils.o QR1676.o RS.o RS129.o SerialController.o SHA256.o StopWatch.o Sync.o TFTSerial.o Thread.o Timer.o UDPSocket.o Utils.o YSFControl.o YSFConvolution.o \

Makefile.Pi.PCF8574

@@ -7,7 +7,7 @@ LIBS    = -lwiringPi -lwiringPiDev -lpthread
 LDFLAGS = -g -L/usr/local/lib
 
 OBJECTS = \
-		AMBEFEC.o BPTC19696.o Conf.o CRC.o Display.o DMRControl.o DMRCSBK.o DMRData.o DMRDataHeader.o DMREMB.o DMREmbeddedLC.o DMRFullLC.o DMRLookup.o DMRLC.o \
+		AMBEFEC.o BCH.o BPTC19696.o Conf.o CRC.o Display.o DMRControl.o DMRCSBK.o DMRData.o DMRDataHeader.o DMREMB.o DMREmbeddedLC.o DMRFullLC.o DMRLookup.o DMRLC.o \
 		DMRNetwork.o DMRShortLC.o DMRSlot.o DMRSlotType.o DMRAccessControl.o DMRTrellis.o DStarControl.o DStarHeader.o DStarNetwork.o DStarSlowData.o Golay2087.o \
 		Golay24128.o Hamming.o HD44780.o Log.o MMDVMHost.o Modem.o Nextion.o NullDisplay.o P25Audio.o P25Control.o P25Data.o P25LowSpeedData.o P25Network.o P25NID.o \
 		P25Utils.o QR1676.o RS.o RS129.o SerialController.o SHA256.o StopWatch.o Sync.o TFTSerial.o Thread.o Timer.o UDPSocket.o Utils.o YSFControl.o YSFConvolution.o \

Makefile.Solaris

@@ -7,7 +7,7 @@ LIBS    = -lpthread -lsocket
 LDFLAGS = -g
 
 OBJECTS = \
-		AMBEFEC.o BPTC19696.o Conf.o CRC.o Display.o DMRControl.o DMRCSBK.o DMRData.o DMRDataHeader.o DMREMB.o DMREmbeddedLC.o DMRFullLC.o DMRLookup.o DMRLC.o \
+		AMBEFEC.o BCH.o BPTC19696.o Conf.o CRC.o Display.o DMRControl.o DMRCSBK.o DMRData.o DMRDataHeader.o DMREMB.o DMREmbeddedLC.o DMRFullLC.o DMRLookup.o DMRLC.o \
 		DMRNetwork.o DMRShortLC.o DMRSlot.o DMRSlotType.o DMRAccessControl.o DMRTrellis.o DStarControl.o DStarHeader.o DStarNetwork.o DStarSlowData.o Golay2087.o \
 		Golay24128.o Hamming.o Log.o MMDVMHost.o Modem.o Nextion.o NullDisplay.o P25Audio.o P25Control.o P25Data.o P25LowSpeedData.o P25Network.o P25NID.o P25Utils.o \
 		QR1676.o RS.o RS129.o SerialController.o SHA256.o StopWatch.o Sync.o TFTSerial.o Thread.o Timer.o UDPSocket.o Utils.o YSFControl.o YSFConvolution.o YSFFICH.o \

P25Control.cpp

@@ -54,7 +54,7 @@ m_netFrames(0U),
 m_netBits(0U),
 m_netErrs(0U),
 m_netLost(0U),
-m_nid(),
+m_nid(nac),
 m_audio(),
 m_rfData(),
 m_netData()
@@ -82,6 +82,7 @@ bool CP25Control::writeModem(unsigned char* data, unsigned int len)
 		LogMessage("P25, transmission lost, %.1f seconds, BER: %.1f%%", float(m_rfFrames) / 5.56F, float(m_rfErrs * 100U) / float(m_rfBits));
 		if (m_netState == RS_NET_IDLE)
 			m_display->clearP25();
+		writeNetwork(data + 2U, P25_DUID_TERM);
 		m_rfState = RS_RF_LISTENING;
 		m_rfTimeout.stop();
 		m_rfData.reset();

P25NID.cpp

@@ -19,21 +19,68 @@
 #include "P25NID.h"
 #include "P25Defines.h"
 #include "P25Utils.h"
+#include "BCH.h"
 
 #include <cstdio>
 #include <cassert>
 
-CP25NID::CP25NID() :
+CP25NID::CP25NID(unsigned int nac) :
 m_duid(0U),
-m_nac(0U)
+m_nac(0U),
+m_hdr(NULL),
+m_ldu1(NULL),
+m_ldu2(NULL),
+m_termlc(NULL),
+m_term(NULL)
 {
+	CBCH bch;
+
+	m_hdr = new unsigned char[P25_NID_LENGTH_BYTES];
+	m_hdr[0U]  = (nac >> 4) & 0xFFU;
+	m_hdr[1U]  = (nac << 4) & 0xF0U;
+	m_hdr[1U] |= P25_DUID_HEADER;
+	bch.encode(m_hdr);
+	m_hdr[7U] &= 0xFEU;		// Clear the parity bit
+
+	m_ldu1 = new unsigned char[P25_NID_LENGTH_BYTES];
+	m_ldu1[0U]  = (nac >> 4) & 0xFFU;
+	m_ldu1[1U]  = (nac << 4) & 0xF0U;
+	m_ldu1[1U] |= P25_DUID_LDU1;
+	bch.encode(m_ldu1);
+	m_ldu1[7U] |= 0x01U;	// Set the parity bit
+
+	m_ldu2 = new unsigned char[P25_NID_LENGTH_BYTES];
+	m_ldu2[0U]  = (nac >> 4) & 0xFFU;
+	m_ldu2[1U]  = (nac << 4) & 0xF0U;
+	m_ldu2[1U] |= P25_DUID_LDU2;
+	bch.encode(m_ldu2);
+	m_ldu2[7U] |= 0x01U;	// Set the parity bit
+
+	m_termlc = new unsigned char[P25_NID_LENGTH_BYTES];
+	m_termlc[0U]  = (nac >> 4) & 0xFFU;
+	m_termlc[1U]  = (nac << 4) & 0xF0U;
+	m_termlc[1U] |= P25_DUID_TERM_LC;
+	bch.encode(m_termlc);
+	m_termlc[7U] &= 0xFEU;		// Clear the parity bit
+
+	m_term = new unsigned char[P25_NID_LENGTH_BYTES];
+	m_term[0U]  = (nac >> 4) & 0xFFU;
+	m_term[1U]  = (nac << 4) & 0xF0U;
+	m_term[1U] |= P25_DUID_TERM;
+	bch.encode(m_term);
+	m_term[7U] &= 0xFEU;		// Clear the parity bit
 }
 
 CP25NID::~CP25NID()
 {
+	delete[] m_hdr;
+	delete[] m_ldu1;
+	delete[] m_ldu2;
+	delete[] m_termlc;
+	delete[] m_term;
 }
 
-void CP25NID::process(unsigned char* data)
+bool CP25NID::process(unsigned char* data)
 {
 	assert(data != NULL);
 
@@ -41,14 +88,14 @@ void CP25NID::process(unsigned char* data)
 
 	CP25Utils::decode(data, nid, 48U, 114U);
 
-	// XXX Process FEC here
-
 	m_duid = nid[1U] & 0x0FU;
 
 	m_nac  = (nid[0U] << 4) & 0xFF0U;
 	m_nac |= (nid[1U] >> 4) & 0x00FU;
 
 	CP25Utils::encode(nid, data, 48U, 114U);
+
+	return true;
 }
 
 unsigned char CP25NID::getDUID() const

P25NID.h

@@ -21,17 +21,22 @@
 
 class CP25NID {
 public:
-	CP25NID();
+	CP25NID(unsigned int nac);
 	~CP25NID();
 
-	void process(unsigned char* data);
+	bool process(unsigned char* data);
 
 	unsigned char getDUID() const;
 	unsigned int  getNAC() const;
 
 private:
-	unsigned char m_duid;
-	unsigned int  m_nac;
+	unsigned char  m_duid;
+	unsigned int   m_nac;
+	unsigned char* m_hdr;
+	unsigned char* m_ldu1;
+	unsigned char* m_ldu2;
+	unsigned char* m_termlc;
+	unsigned char* m_term;
 };
 
 #endif