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P25 RX logic rewrite (including some updates from MMDVM)
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@juribeparada
juribeparada committed Oct 28, 2018
1 parent 8d55079 commit 3284a72
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Showing 4 changed files with 137 additions and 57 deletions.
33 changes: 18 additions & 15 deletions P25Defines.h
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Original file line number Diff line number Diff line change
@@ -1,5 +1,6 @@
/*
* Copyright (C) 2016 by Jonathan Naylor G4KLX
* Copyright (C) 2018 by Andy Uribe CA6JAU
*
* 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
Expand All @@ -21,38 +22,40 @@

const unsigned int P25_HDR_FRAME_LENGTH_BYTES = 99U;
const unsigned int P25_HDR_FRAME_LENGTH_BITS = P25_HDR_FRAME_LENGTH_BYTES * 8U;
const unsigned int P25_HDR_FRAME_LENGTH_SYMBOLS = P25_HDR_FRAME_LENGTH_BYTES * 4U;

const unsigned int P25_LDU_FRAME_LENGTH_BYTES = 216U;
const unsigned int P25_LDU_FRAME_LENGTH_BITS = P25_LDU_FRAME_LENGTH_BYTES * 8U;
const unsigned int P25_LDU_FRAME_LENGTH_SYMBOLS = P25_LDU_FRAME_LENGTH_BYTES * 4U;

const unsigned int P25_TERMLC_FRAME_LENGTH_BYTES = 54U;
const unsigned int P25_TERMLC_FRAME_LENGTH_BITS = P25_TERMLC_FRAME_LENGTH_BYTES * 8U;
const unsigned int P25_TERMLC_FRAME_LENGTH_SYMBOLS = P25_TERMLC_FRAME_LENGTH_BYTES * 4U;

const unsigned int P25_TERM_FRAME_LENGTH_BYTES = 18U;
const unsigned int P25_TERM_FRAME_LENGTH_BITS = P25_TERM_FRAME_LENGTH_BYTES * 8U;
const unsigned int P25_TERM_FRAME_LENGTH_SYMBOLS = P25_TERM_FRAME_LENGTH_BYTES * 4U;

const unsigned int P25_SYNC_LENGTH_BYTES = 6U;
const unsigned int P25_SYNC_LENGTH_BITS = P25_SYNC_LENGTH_BYTES * 8U;
const unsigned int P25_SYNC_LENGTH_SYMBOLS = P25_SYNC_LENGTH_BYTES * 4U;
const unsigned int P25_TSDU_FRAME_LENGTH_BYTES = 45U;
const unsigned int P25_TSDU_FRAME_LENGTH_BITS = P25_TSDU_FRAME_LENGTH_BYTES * 8U;

const unsigned int P25_NID_LENGTH_BITS = 64U;
const unsigned int P25_NID_LENGTH_SYMBOLS = 32U;
const unsigned int P25_PDU_HDR_FRAME_LENGTH_BYTES = 45U;
const unsigned int P25_PDU_HDR_FRAME_LENGTH_BITS = P25_PDU_HDR_FRAME_LENGTH_BYTES * 8U;

const unsigned int P25_SYNC_LENGTH_BYTES = 6U;
const unsigned int P25_SYNC_LENGTH_BITS = P25_SYNC_LENGTH_BYTES * 8U;

const unsigned int P25_NID_LENGTH_BYTES = 8U;
const unsigned int P25_NID_LENGTH_BITS = P25_NID_LENGTH_BYTES * 8U;

const uint8_t P25_SYNC_BYTES[] = {0x55U, 0x75U, 0xF5U, 0xFFU, 0x77U, 0xFFU};
const uint8_t P25_SYNC_BYTES_LENGTH = 6U;

const uint64_t P25_SYNC_BITS = 0x00005575F5FF77FFU;
const uint64_t P25_SYNC_BITS_MASK = 0x0000FFFFFFFFFFFFU;

// 5 5 7 5 F 5 F F 7 7 F F
// 01 01 01 01 01 11 01 01 11 11 01 01 11 11 11 11 01 11 01 11 11 11 11 11
// +3 +3 +3 +3 +3 -3 +3 +3 -3 -3 +3 +3 -3 -3 -3 -3 +3 -3 +3 -3 -3 -3 -3 -3

const uint32_t P25_SYNC_SYMBOLS = 0x00FB30A0U;
const uint32_t P25_SYNC_SYMBOLS_MASK = 0x00FFFFFFU;
const uint8_t P25_DUID_HDU = 0x00U; // Header Data Unit
const uint8_t P25_DUID_TDU = 0x03U; // Simple Terminator Data Unit
const uint8_t P25_DUID_LDU1 = 0x05U; // Logical Link Data Unit 1
const uint8_t P25_DUID_TSDU = 0x07U; // Trunking System Data Unit
const uint8_t P25_DUID_LDU2 = 0x0AU; // Logical Link Data Unit 2
const uint8_t P25_DUID_PDU = 0x0CU; // Packet Data Unit
const uint8_t P25_DUID_TDULC = 0x0FU; // Terminator Data Unit with Link Control

#endif
145 changes: 109 additions & 36 deletions P25RX.cpp
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Original file line number Diff line number Diff line change
@@ -1,6 +1,6 @@
/*
* Copyright (C) 2016,2017 by Jonathan Naylor G4KLX
* Copyright (C) 2016,2017 by Andy Uribe CA6JAU
* Copyright (C) 2016,2017,2018 by Andy Uribe CA6JAU
*
* 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
Expand Down Expand Up @@ -31,33 +31,44 @@ const uint8_t BIT_MASK_TABLE[] = {0x80U, 0x40U, 0x20U, 0x10U, 0x08U, 0x04U, 0x02

#define WRITE_BIT1(p,i,b) p[(i)>>3] = (b) ? (p[(i)>>3] | BIT_MASK_TABLE[(i)&7]) : (p[(i)>>3] & ~BIT_MASK_TABLE[(i)&7])

const uint16_t NOENDPTR = 9999U;

CP25RX::CP25RX() :
m_prev(false),
m_state(P25RXS_NONE),
m_bitBuffer(0x00U),
m_outBuffer(),
m_buffer(NULL),
m_bufferPtr(0U),
m_lostCount(0U)
m_endPtr(NOENDPTR),
m_lostCount(0U),
m_duid(0U)
{
m_buffer = m_outBuffer + 1U;
}

void CP25RX::reset()
{
m_prev = false;
m_state = P25RXS_NONE;
m_bitBuffer = 0x00U;
m_bufferPtr = 0U;
m_endPtr = NOENDPTR;
m_lostCount = 0U;
m_duid = 0U;
}

void CP25RX::databit(bool bit)
{
if (m_state == P25RXS_NONE)
processNone(bit);
else
processData(bit);
switch (m_state) {
case P25RXS_HDR:
processHdr(bit);
break;
case P25RXS_LDU:
processLdu(bit);
break;
default:
processNone(bit);
break;
}
}

void CP25RX::processNone(bool bit)
Expand All @@ -71,87 +82,149 @@ void CP25RX::processNone(bool bit)
DEBUG1("P25RX: sync found in None");
for (uint8_t i = 0U; i < P25_SYNC_LENGTH_BYTES; i++)
m_buffer[i] = P25_SYNC_BYTES[i];

m_lostCount = MAX_SYNC_FRAMES;
m_bufferPtr = P25_SYNC_LENGTH_BITS;
m_state = P25RXS_DATA;
m_state = P25RXS_HDR;

io.setDecode(true);
}
}

void CP25RX::processData(bool bit)
void CP25RX::processHdr(bool bit)
{
m_bitBuffer <<= 1;
if (bit)
m_bitBuffer |= 0x01U;

WRITE_BIT1(m_buffer, m_bufferPtr, bit);
m_bufferPtr++;

// Search for an early sync to indicate an LDU following a header
if (m_bufferPtr >= (P25_HDR_FRAME_LENGTH_BITS + P25_SYNC_LENGTH_BITS - 1U) && m_bufferPtr <= (P25_HDR_FRAME_LENGTH_BITS + P25_SYNC_LENGTH_BITS + 1U)) {
// Fuzzy matching of the data sync bit sequence
if (countBits64((m_bitBuffer & P25_SYNC_BITS_MASK) ^ P25_SYNC_BITS) <= SYNC_BIT_RUN_ERRS) {
DEBUG2("P25RX: found LDU sync in Data, pos", m_bufferPtr - P25_SYNC_LENGTH_BITS);

m_outBuffer[0U] = 0x01U;
serial.writeP25Hdr(m_outBuffer, P25_HDR_FRAME_LENGTH_BYTES + 1U);
m_bufferPtr++;
if (m_bufferPtr > P25_LDU_FRAME_LENGTH_BITS)
reset();

// Restore the sync that's now in the wrong place
for (uint8_t i = 0U; i < P25_SYNC_LENGTH_BYTES; i++)
m_buffer[i] = P25_SYNC_BYTES[i];
if (m_bufferPtr == P25_SYNC_LENGTH_BITS + 16U) {
// FIXME: we should check and correct for errors in NID first!
m_duid = m_buffer[7U] & 0x0F;

if (m_duid != P25_DUID_HDU && m_duid != P25_DUID_TSDU &&
m_duid != P25_DUID_TDU && m_duid != P25_DUID_TDULC) {
m_lostCount = MAX_SYNC_FRAMES;
m_bufferPtr = P25_SYNC_LENGTH_BITS;
m_state = P25RXS_LDU;
return;
}

setEndPtr();
DEBUG2("P25RX: DUID", m_duid);
}

// Search for end of header frame
if (m_bufferPtr == m_endPtr) {
m_outBuffer[0U] = 0x01U;
serial.writeP25Hdr(m_outBuffer, (m_endPtr / 8U) + 1U);

m_lostCount = MAX_SYNC_FRAMES;
m_bufferPtr = 0U;
m_state = P25RXS_LDU;
}
}

void CP25RX::processLdu(bool bit)
{
m_bitBuffer <<= 1;
if (bit)
m_bitBuffer |= 0x01U;

WRITE_BIT1(m_buffer, m_bufferPtr, bit);

m_bufferPtr++;
if (m_bufferPtr > P25_LDU_FRAME_LENGTH_BITS)
reset();

// Only search for a sync in the right place +-2 symbols
// Only search for a sync in the right place +-2 bits
if (m_bufferPtr >= (P25_SYNC_LENGTH_BITS - 2U) && m_bufferPtr <= (P25_SYNC_LENGTH_BITS + 2U)) {
// Fuzzy matching of the data sync bit sequence
if (countBits64((m_bitBuffer & P25_SYNC_BITS_MASK) ^ P25_SYNC_BITS) <= SYNC_BIT_RUN_ERRS) {
DEBUG2("P25RX: found sync in Data, pos", m_bufferPtr - P25_SYNC_LENGTH_BITS);
DEBUG1("P25RX: found sync in LDU");
m_lostCount = MAX_SYNC_FRAMES;
m_bufferPtr = P25_SYNC_LENGTH_BITS;
}
}

if (m_bufferPtr == P25_SYNC_LENGTH_BITS + 16U) {
// We use DUID here only to detect TDU for EOT
// FIXME: we should check and correct for errors in NID first!
m_duid = m_buffer[7U] & 0x0F;
setEndPtr();
DEBUG2("P25RX: DUID", m_duid);
}

// Send a data frame to the host if the required number of bits have been received
if (m_bufferPtr == P25_LDU_FRAME_LENGTH_BITS) {
// We've not seen a data sync for too long, signal RXLOST and change to RX_NONE
m_lostCount--;
// We've not seen a data sync for too long, signal RXLOST and change to RX_NONE
if (m_lostCount == 0U) {
DEBUG1("P25RX: sync timed out, lost lock");
io.setDecode(false);

serial.writeP25Lost();

m_state = P25RXS_NONE;
reset();
} else {
// Write data to host
m_outBuffer[0U] = m_lostCount == (MAX_SYNC_FRAMES - 1U) ? 0x01U : 0x00U;

writeRSSILdu(m_outBuffer);

// Start the next frame
::memset(m_outBuffer, 0x00U, P25_LDU_FRAME_LENGTH_BYTES + 3U);
m_bufferPtr = 0U;
}

// Check if we found a TDU to avoid a false "lost lock"
if (m_duid == P25_DUID_TDU || m_duid == P25_DUID_TDULC) {
reset();
}
}
}

void CP25RX::writeRSSILdu(uint8_t* ldu)
{
#if defined(SEND_RSSI_DATA)
uint16_t rssi = io.readRSSI();

ldu[217U] = (rssi >> 8) & 0xFFU;
ldu[218U] = (rssi >> 0) & 0xFFU;

serial.writeP25Ldu(ldu, P25_LDU_FRAME_LENGTH_BYTES + 3U);
#else
serial.writeP25Ldu(ldu, P25_LDU_FRAME_LENGTH_BYTES + 1U);
#endif
}


void CP25RX::setEndPtr()
{
switch (m_duid) {
case P25_DUID_HDU:
DEBUG1("P25RX: sync found in HDU");
m_endPtr = P25_HDR_FRAME_LENGTH_BITS;
break;
case P25_DUID_TDU:
DEBUG1("P25RX: sync found in TDU");
m_endPtr = P25_TERM_FRAME_LENGTH_BITS;
break;
case P25_DUID_TSDU:
DEBUG1("P25RX: sync found in TSDU");
m_endPtr = P25_TSDU_FRAME_LENGTH_BITS;
break;
case P25_DUID_PDU:
// FIXME: not sure about PDU lengths since they have arbitrary length...
DEBUG1("P25RX: sync found in PDU");
m_endPtr = P25_PDU_HDR_FRAME_LENGTH_BITS;
break;
case P25_DUID_TDULC:
DEBUG1("P25RX: sync found in TDULC");
m_endPtr = P25_TERMLC_FRAME_LENGTH_BITS;
break;
default:
m_endPtr = P25_LDU_FRAME_LENGTH_BITS;
break;
}
}
12 changes: 8 additions & 4 deletions P25RX.h
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Original file line number Diff line number Diff line change
@@ -1,6 +1,6 @@
/*
* Copyright (C) 2015,2016,2017 by Jonathan Naylor G4KLX
* Copyright (C) 2016,2017 by Andy Uribe CA6JAU
* Copyright (C) 2016,2017,2018 by Andy Uribe CA6JAU
*
* 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
Expand All @@ -24,7 +24,8 @@

enum P25RX_STATE {
P25RXS_NONE,
P25RXS_DATA
P25RXS_HDR,
P25RXS_LDU
};

class CP25RX {
Expand All @@ -36,17 +37,20 @@ class CP25RX {
void reset();

private:
bool m_prev;
P25RX_STATE m_state;
uint64_t m_bitBuffer;
uint8_t m_outBuffer[P25_LDU_FRAME_LENGTH_BYTES + 3U];
uint8_t* m_buffer;
uint16_t m_bufferPtr;
uint16_t m_endPtr;
uint16_t m_lostCount;
uint8_t m_duid;

void processNone(bool bit);
void processData(bool bit);
void processHdr(bool bit);
void processLdu(bool bit);
void writeRSSILdu(uint8_t* data);
void setEndPtr();
};

#endif
Expand Down
4 changes: 2 additions & 2 deletions version.h
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Original file line number Diff line number Diff line change
Expand Up @@ -24,8 +24,8 @@

#define VER_MAJOR "1"
#define VER_MINOR "4"
#define VER_REV "10"
#define VERSION_DATE "20181008"
#define VER_REV "11"
#define VERSION_DATE "20181028"

#if defined(ZUMSPOT_ADF7021)
#define BOARD_INFO "ZUMspot"
Expand Down

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