First commit

2026-04-05 22:35:26 +00:00 · 2017-02-01 01:33:31 -03:00 · 2017-02-01 01:33:31 -03:00 · 587fe63a47
commit 587fe63a47
46 changed files with 6893 additions and 0 deletions
--- a/P25RX.cpp
+++ b/P25RX.cpp
@ -0,0 +1,143 @@
+/*
+ *   Copyright (C) 2016,2017 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.
+ */
+
+// #define  WANT_DEBUG
+
+#include "Config.h"
+#include "Globals.h"
+#include "P25RX.h"
+#include "Utils.h"
+
+const uint8_t SYNC_BIT_START_ERRS = 2U;
+const uint8_t SYNC_BIT_RUN_ERRS   = 4U;
+
+const unsigned int MAX_SYNC_FRAMES = 3U + 1U;
+
+const uint8_t BIT_MASK_TABLE[] = {0x80U, 0x40U, 0x20U, 0x10U, 0x08U, 0x04U, 0x02U, 0x01U};
+
+#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])
+
+CP25RX::CP25RX() :
+m_prev(false),
+m_state(P25RXS_NONE),
+m_bitBuffer(0x00U),
+m_outBuffer(),
+m_buffer(NULL),
+m_bufferPtr(0U),
+m_lostCount(0U)
+{
+  m_buffer = m_outBuffer + 1U;
+}
+
+void CP25RX::reset()
+{
+  m_prev      = false;
+  m_state     = P25RXS_NONE;
+  m_bitBuffer = 0x00U;
+  m_bufferPtr = 0U;
+  m_lostCount = 0U;
+}
+
+void CP25RX::databit(bool bit)
+{
+  if (m_state == P25RXS_NONE)
+    processNone(bit);
+  else
+    processData(bit);
+}
+
+void CP25RX::processNone(bool bit)
+{
+  m_bitBuffer <<= 1;
+  if (bit)
+    m_bitBuffer |= 0x01U;
+
+  // Fuzzy matching of the data sync bit sequence
+  if (countBits64((m_bitBuffer & P25_SYNC_BITS_MASK) ^ P25_SYNC_BITS) <= SYNC_BIT_START_ERRS) {
+    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;
+    
+    io.setDecode(true);
+  }
+}
+
+void CP25RX::processData(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);
+
+      // 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];
+
+      m_lostCount = MAX_SYNC_FRAMES;
+      m_bufferPtr = P25_SYNC_LENGTH_BITS;
+    }
+  }
+
+  // Only search for a sync in the right place +-2 symbols
+  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);
+      m_lostCount = MAX_SYNC_FRAMES;
+      m_bufferPtr = P25_SYNC_LENGTH_BITS;
+    }
+  }
+
+  // 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--;
+    if (m_lostCount == 0U) {
+      DEBUG1("P25RX: sync timed out, lost lock");
+      io.setDecode(false);
+      
+      serial.writeP25Lost();
+
+      m_state = P25RXS_NONE;
+    } else {
+      m_outBuffer[0U] = m_lostCount == (MAX_SYNC_FRAMES - 1U) ? 0x01U : 0x00U;
+
+      serial.writeP25Ldu(m_outBuffer, P25_LDU_FRAME_LENGTH_BYTES + 1U);
+
+      // Start the next frame
+      ::memset(m_outBuffer, 0x00U, P25_LDU_FRAME_LENGTH_BYTES + 3U);
+      m_bufferPtr = 0U;
+    }
+  }
+}
+