Reorganised M17LinkSetupframe and M17Frame classes, encapsulating structs defining their internal data structure

openrtx/include/protocols/M17/M17Datatypes.h

@@ -35,6 +35,10 @@ using payload_t = std::array< uint8_t, 16 >;   // Data type for frame payload fi
 using lich_t    = std::array< uint8_t, 12 >;   // Data type for Golay(24,12) encoded LICH data
 
 
+static constexpr std::array<uint8_t, 2> LSF_SYNC_WORD  = {0x55, 0xF7};  // LSF sync word
+static constexpr std::array<uint8_t, 2> DATA_SYNC_WORD = {0xFF, 0x5D};  // Stream data sync word
+
+
 /**
  * This structure provides bit field definitions for the "TYPE" field
  * contained in an M17 Link Setup Frame.
@@ -49,35 +53,11 @@ typedef union
         uint16_t encSubType : 2;    //< Encryption subtype
         uint16_t CAN        : 4;    //< Channel Access Number
         uint16_t            : 4;    //< Reserved, padding to 16 bit
-    };
+    }
+    fields;
 
     uint16_t value;
 }
 streamType_t;
 
-
-/**
- * Data structure corresponding to a full M17 Link Setup Frame.
- */
-typedef struct
-{
-    call_t       dst;    //< Destination callsign
-    call_t       src;    //< Source callsign
-    streamType_t type;   //< Stream type information
-    meta_t       meta;   //< Metadata
-    uint16_t     crc;    //< CRC
-}
-__attribute__((packed)) lsf_t;
-
-
-/**
- * Data structure corresponding to a full M17 data frame.
- */
-typedef struct
-{
-    uint16_t   frameNum;  //< Frame number
-    payload_t  payload;   //< Payload data
-}
-__attribute__((packed)) dataFrame_t;
-
 #endif /* M17_DATATYPES_H */

openrtx/include/protocols/M17/M17Frame.h

@@ -89,30 +89,28 @@ public:
     }
 
     /**
-     * Get underlying data structure.
+     * Get underlying data.
      *
-     * @return a reference to the underlying dataFrame_t data structure.
+     * @return a pointer to const uint8_t allowing direct access to frame data.
      */
-    dataFrame_t& getData()
+    const uint8_t *getData()
     {
-        return data;
+        return reinterpret_cast < const uint8_t * > (&data);
-    }
-
-    /**
-     * Dump the frame content to a std::array.
-     *
-     * \return std::array containing the content of the frame.
-     */
-    std::array< uint8_t, sizeof(dataFrame_t) > toArray()
-    {
-        std::array< uint8_t, sizeof(dataFrame_t) > frame;
-        memcpy(frame.data(), &data, frame.size());
-        return frame;
     }
 
 private:
 
-    dataFrame_t data;   ///< Underlying frame data.
+    /**
+     * Data structure corresponding to a full M17 data frame.
+     */
+    typedef struct
+    {
+        uint16_t   frameNum;  ///< Frame number
+        payload_t  payload;   ///< Payload data
+    }
+    __attribute__((packed)) dataFrame_t;
+
+    dataFrame_t data;         ///< Underlying frame data.
 };
 
 #endif /* M17_FRAME_H */

openrtx/include/protocols/M17/M17LinkSetupFrame.h

@@ -61,6 +61,13 @@ public:
      */
     void setSource(const std::string& callsign);
 
+    /**
+     * Get source callsign.
+     *
+     * @return: string containing the source callsign.
+     */
+    std::string getSource();
+
     /**
      * Set destination callsign.
      *
@@ -68,6 +75,13 @@ public:
      */
     void setDestination(const std::string& callsign);
 
+    /**
+     * Get destination callsign.
+     *
+     * @return: string containing the destination callsign.
+     */
+    std::string getDestination();
+
     /**
      * Get stream type field.
      *
@@ -97,11 +111,20 @@ public:
     void updateCrc();
 
     /**
-     * Get underlying data structure.
+     * Check if frame data is valid that is, if the CRC computed over the LSF
+     * fields matches the one carried by the LSF itself.
      *
-     * @return a reference to the underlying dataFrame_t data structure.
+     * @return true if CRC of LSF data matches the one stored in the LSF itself,
+     * false otherwise.
      */
-    lsf_t& getData();
+    bool valid();
+
+    /**
+     * Get underlying data.
+     *
+     * @return a pointer to const uint8_t allowing direct access to LSF data.
+     */
+    const uint8_t *getData();
 
     /**
      * Generate one of the six possible LSF chunks for embedding in data frame's
@@ -112,13 +135,6 @@ public:
      */
     lich_t generateLichSegment(const uint8_t segmentNum);
 
-    /**
-     * Dump the frame content to a std::array.
-     *
-     * \return std::array containing the content of the frame.
-     */
-    std::array< uint8_t, sizeof(lsf_t) > toArray();
-
 private:
 
     /**
@@ -131,7 +147,20 @@ private:
      */
     uint16_t crc16(const void *data, const size_t len);
 
-    lsf_t data;    ///< Underlying frame data.
+    /**
+     * Data structure corresponding to a full M17 Link Setup Frame.
+     */
+    typedef struct
+    {
+        call_t       dst;    ///< Destination callsign
+        call_t       src;    ///< Source callsign
+        streamType_t type;   ///< Stream type information
+        meta_t       meta;   ///< Metadata
+        uint16_t     crc;    ///< CRC
+    }
+    __attribute__((packed)) lsf_t;
+
+    lsf_t data;              ///< Underlying frame data.
 };
 
 #endif /* M17_LINKSETUPFRAME_H */

openrtx/src/protocols/M17/M17LinkSetupFrame.cpp

@@ -45,11 +45,21 @@ void M17LinkSetupFrame::setSource(const std::string& callsign)
     encode_callsign(callsign, data.src);
 }
 
+std::string M17LinkSetupFrame::getSource()
+{
+    return decode_callsign(data.src);
+}
+
 void M17LinkSetupFrame::setDestination(const std::string& callsign)
 {
     encode_callsign(callsign, data.dst);
 }
 
+std::string M17LinkSetupFrame::getDestination()
+{
+    return decode_callsign(data.dst);
+}
+
 streamType_t M17LinkSetupFrame::getType()
 {
     // NOTE: M17 fields are big-endian, we need to swap bytes
@@ -77,9 +87,17 @@ void M17LinkSetupFrame::updateCrc()
     data.crc     = __builtin_bswap16(crc);
 }
 
-lsf_t& M17LinkSetupFrame::getData()
+bool M17LinkSetupFrame::valid()
 {
-    return data;
+    uint16_t crc = crc16(&data, 28);
+    if(data.crc == __builtin_bswap16(crc)) return true;
+
+    return false;
+}
+
+const uint8_t * M17LinkSetupFrame::getData()
+{
+    return reinterpret_cast < const uint8_t * >(&data);
 }
 
 lich_t M17LinkSetupFrame::generateLichSegment(const uint8_t segmentNum)
@@ -119,13 +137,6 @@ lich_t M17LinkSetupFrame::generateLichSegment(const uint8_t segmentNum)
     return result;
 }
 
-std::array< uint8_t, sizeof(lsf_t) > M17LinkSetupFrame::toArray()
-{
-    std::array< uint8_t, sizeof(lsf_t) > frame;
-    memcpy(frame.data(), &data, frame.size());
-    return frame;
-}
-
 uint16_t M17LinkSetupFrame::crc16(const void *data, const size_t len)
 {
     const uint8_t *ptr = reinterpret_cast< const uint8_t *>(data);

openrtx/src/protocols/M17/M17Transmitter.cpp

@@ -26,9 +26,6 @@
 namespace M17
 {
 
-static constexpr std::array<uint8_t, 2> LSF_SYNC_WORD  = {0x55, 0xF7};
-static constexpr std::array<uint8_t, 2> DATA_SYNC_WORD = {0xFF, 0x5D};
-
 M17Transmitter::M17Transmitter(M17Modulator& modulator) : modulator(modulator),
                                                 currentLich(0), frameNumber(0)
 {
@@ -59,9 +56,9 @@ void M17Transmitter::start(const std::string& src, const std::string& dst)
     if(!dst.empty()) lsf.setDestination(dst);
 
     streamType_t type;
-    type.stream   = 1;    // Stream
+    type.fields.stream   = 1;    // Stream
-    type.dataType = 2;    // Voice data
+    type.fields.dataType = 2;    // Voice data
-    type.CAN      = 0;  // Channel access number
+    type.fields.CAN      = 0;  // Channel access number
 
     lsf.setType(type);
     lsf.updateCrc();
@@ -75,7 +72,7 @@ void M17Transmitter::start(const std::string& src, const std::string& dst)
     // Encode the LSF, then puncture and decorrelate its data
     std::array<uint8_t, 61> encoded;
     encoder.reset();
-    encoder.encode(&lsf.getData(), encoded.data(), sizeof(lsf_t));
+    encoder.encode(lsf.getData(), encoded.data(), sizeof(M17LinkSetupFrame));
     encoded[60] = encoder.flush();
 
     std::array<uint8_t, 46> punctured;
@@ -105,7 +102,7 @@ void M17Transmitter::send(const payload_t& payload, const bool isLast)
     // Encode frame
     std::array<uint8_t, 37> encoded;
     encoder.reset();
-    encoder.encode(&dataFrame.getData(), encoded.data(), sizeof(dataFrame_t));
+    encoder.encode(dataFrame.getData(), encoded.data(), sizeof(M17Frame));
     encoded[36] = encoder.flush();
 
     std::array<uint8_t, 34> punctured;