From e1d1ac4a4d2483bde003e356b6cae202d03a7a2c Mon Sep 17 00:00:00 2001
From: Jonathan Naylor <naylorjs@yahoo.com>
Date: Wed, 10 Jun 2020 12:07:04 +0100
Subject: [PATCH] More work on adding AX.25 decoding.

---
 AX25Demodulator.cpp | 16 +++++++++++++---
 AX25Demodulator.h   | 14 +++++++++++---
 AX25RX.cpp          | 38 ++++++++++++++++++++++++++++++--------
 AX25RX.h            |  1 +
 4 files changed, 55 insertions(+), 14 deletions(-)

diff --git a/AX25Demodulator.cpp b/AX25Demodulator.cpp
index b1a9d84..8df7833 100644
--- a/AX25Demodulator.cpp
+++ b/AX25Demodulator.cpp
@@ -20,12 +20,22 @@
 #include "Globals.h"
 #include "AX25Demodulator.h"
 
-CAX25Demodulator::CAX25Demodulator(uint16_t n) :
-m_n(n)
+CAX25Demodulator::CAX25Demodulator() :
+m_nrziState(false)
 {
 }
 
-void CAX25Demodulator::process(q15_t sample)
+bool CAX25Demodulator::process(const q15_t* samples, uint8_t length, AX25Frame& frame)
 {
+  return false;
+}
+
+bool CAX25Demodulator::NRZI(bool b)
+{
+  bool result = (b == m_nrziState);
+
+  m_nrziState = b;
+
+  return result;
 }
 
diff --git a/AX25Demodulator.h b/AX25Demodulator.h
index d26aa32..16abc7e 100644
--- a/AX25Demodulator.h
+++ b/AX25Demodulator.h
@@ -21,14 +21,22 @@
 
 #include "Config.h"
 
+struct AX25Frame {
+  uint8_t  m_data[300U];
+  uint16_t m_length;
+  uint16_t m_fcs;
+};
+
 class CAX25Demodulator {
 public:
-  CAX25Demodulator(uint16_t n);
+  CAX25Demodulator();
 
-  void process(q15_t sample);
+  bool process(const q15_t* samples, uint8_t length, AX25Frame& frame);
 
 private:
-  uint16_t m_n;
+  bool m_nrziState;
+
+  bool NRZI(bool b);
 };
 
 #endif
diff --git a/AX25RX.cpp b/AX25RX.cpp
index 260d549..2fea46e 100644
--- a/AX25RX.cpp
+++ b/AX25RX.cpp
@@ -21,20 +21,42 @@
 #include "AX25RX.h"
 
 CAX25RX::CAX25RX() :
-m_demod1(1U),
-m_demod2(2U),
-m_demod3(3U)
+m_demod1(),
+m_demod2(),
+m_demod3(),
+m_lastFCS(0U)
 {
 }
 
 void CAX25RX::samples(const q15_t* samples, uint8_t length)
 {
-  for (uint8_t i = 0U; i < length; i++) {
-    q15_t sample = samples[i];
+  AX25Frame frame;
 
-    m_demod1.process(sample);
-    m_demod2.process(sample);
-    m_demod3.process(sample);
+  bool ret = m_demod1.process(samples, length, frame);
+  if (ret) {
+    if (m_lastFCS != frame.m_fcs) {
+      DEBUG1("Decoder 1 reported");
+      m_lastFCS = frame.m_fcs;
+      serial.writeAX25Data(frame.m_data, frame.m_length);
+    }
+  }
+
+  ret = m_demod2.process(samples, length, frame);
+  if (ret) {
+    if (m_lastFCS != frame.m_fcs) {
+      DEBUG1("Decoder 2 reported");
+      m_lastFCS = frame.m_fcs;
+      serial.writeAX25Data(frame.m_data, frame.m_length);
+    }
+  }
+
+  ret = m_demod3.process(samples, length, frame);
+  if (ret) {
+    if (m_lastFCS != frame.m_fcs) {
+      DEBUG1("Decoder 3 reported");
+      m_lastFCS = frame.m_fcs;
+      serial.writeAX25Data(frame.m_data, frame.m_length);
+    }
   }
 }
 
diff --git a/AX25RX.h b/AX25RX.h
index feab90a..68f3532 100644
--- a/AX25RX.h
+++ b/AX25RX.h
@@ -33,6 +33,7 @@ private:
   CAX25Demodulator m_demod1;
   CAX25Demodulator m_demod2;
   CAX25Demodulator m_demod3;
+  uint16_t         m_lastFCS;
 };
 
 #endif