From 9c2091c060579a1cfbe66218d515aa8d9b67c78d Mon Sep 17 00:00:00 2001
From: Silvano Seva <silseva@fastwebnet.it>
Date: Thu, 21 Jul 2022 22:14:55 +0200
Subject: [PATCH] Changed M17 RX behaviour so that received stream data is
 forwarded to codec2 decode only when a full valid LSF is received.

---
 openrtx/include/protocols/M17/M17LinkSetupFrame.hpp | 4 ++--
 openrtx/src/protocols/M17/M17LinkSetupFrame.cpp     | 4 ++--
 openrtx/src/rtx/OpMode_M17.cpp                      | 3 ++-
 3 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/openrtx/include/protocols/M17/M17LinkSetupFrame.hpp b/openrtx/include/protocols/M17/M17LinkSetupFrame.hpp
index d8848130..82601a51 100644
--- a/openrtx/include/protocols/M17/M17LinkSetupFrame.hpp
+++ b/openrtx/include/protocols/M17/M17LinkSetupFrame.hpp
@@ -122,7 +122,7 @@ public:
      * @return true if CRC of LSF data matches the one stored in the LSF itself,
      * false otherwise.
      */
-    bool valid();
+    bool valid() const;
 
     /**
      * Get underlying data.
@@ -150,7 +150,7 @@ private:
      * \param len: lenght of the data block, in bytes.
      * \return computed CRC16 over the data block.
      */
-    uint16_t crc16(const void *data, const size_t len);
+    uint16_t crc16(const void *data, const size_t len) const;
 
 
     struct __attribute__((packed))
diff --git a/openrtx/src/protocols/M17/M17LinkSetupFrame.cpp b/openrtx/src/protocols/M17/M17LinkSetupFrame.cpp
index f096e546..4bdc849b 100644
--- a/openrtx/src/protocols/M17/M17LinkSetupFrame.cpp
+++ b/openrtx/src/protocols/M17/M17LinkSetupFrame.cpp
@@ -88,7 +88,7 @@ void M17LinkSetupFrame::updateCrc()
     data.crc     = __builtin_bswap16(crc);
 }
 
-bool M17LinkSetupFrame::valid()
+bool M17LinkSetupFrame::valid() const
 {
     uint16_t crc = crc16(&data, 28);
     if(data.crc == __builtin_bswap16(crc)) return true;
@@ -138,7 +138,7 @@ lich_t M17LinkSetupFrame::generateLichSegment(const uint8_t segmentNum)
     return result;
 }
 
-uint16_t M17LinkSetupFrame::crc16(const void *data, const size_t len)
+uint16_t M17LinkSetupFrame::crc16(const void *data, const size_t len) const
 {
     const uint8_t *ptr = reinterpret_cast< const uint8_t *>(data);
     uint16_t crc = 0xFFFF;
diff --git a/openrtx/src/rtx/OpMode_M17.cpp b/openrtx/src/rtx/OpMode_M17.cpp
index 11f65e5c..74c065f1 100644
--- a/openrtx/src/rtx/OpMode_M17.cpp
+++ b/openrtx/src/rtx/OpMode_M17.cpp
@@ -163,8 +163,9 @@ void OpMode_M17::rxState(rtxStatus_t *const status)
     {
         auto& frame = demodulator.getFrame();
         auto type   = decoder.decodeFrame(frame);
+        bool lsfOk  = decoder.getLsf().valid();
 
-        if(type == M17FrameType::STREAM)
+        if((type == M17FrameType::STREAM) && (lsfOk == true))
         {
             M17StreamFrame sf = decoder.getStreamFrame();
             codec_pushFrame(sf.payload().data(),     false);