Implementation of M17 code puncturing scheme

openrtx/include/protocols/M17/M17Callsign.h

@@ -18,8 +18,8 @@
  *   along with this program; if not, see <http://www.gnu.org/licenses/>   *
  ***************************************************************************/
 
-#ifndef M17CALLSIGN_H
+#ifndef M17_CALLSIGN_H
-#define M17CALLSIGN_H
+#define M17_CALLSIGN_H
 
 #ifndef __cplusplus
 #error This header is C++ only!
@@ -52,4 +52,4 @@ bool encode_callsign(const std::string& callsign, call_t& encodedCall,
  */
 std::string decode_callsign(const call_t& encodedCall);
 
-#endif /* M17CALLSIGN_H */
+#endif /* M17_CALLSIGN_H */

openrtx/include/protocols/M17/M17CodePuncturing.h

@@ -0,0 +1,90 @@
+/***************************************************************************
+ *   Copyright (C) 2021 by Federico Amedeo Izzo IU2NUO,                    *
+ *                         Niccolò Izzo IU2KIN                             *
+ *                         Frederik Saraci IU2NRO                          *
+ *                         Silvano Seva IU2KWO                             *
+ *                                                                         *
+ *   Adapted from original code written by Rob Riggs, Mobilinkd LLC        *
+ *                                                                         *
+ *   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 3 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, see <http://www.gnu.org/licenses/>   *
+ ***************************************************************************/
+
+#ifndef M17_CODE_PUNCTURING_H
+#define M17_CODE_PUNCTURING_H
+
+#ifndef __cplusplus
+#error This header is C++ only!
+#endif
+
+#include <experimental/array>
+#include "M17Utils.h"
+
+
+/**
+ * Puncture matrix for linx setup frame.
+ */
+static constexpr auto LSF_puncture = std::experimental::make_array< uint8_t >
+(
+    1, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 1, 1, 1, 1, 0,
+    1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 1, 1, 1, 1, 0, 1, 1, 0, 1, 1, 0,
+    1, 1, 0, 1, 1, 1, 1, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 1, 1, 1, 1,
+    0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 1, 1, 1, 1, 0, 1, 1, 0, 1, 1,
+    0, 1, 1, 0, 1, 1, 1, 1, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1,
+    1, 1, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 1
+);
+
+
+/**
+ *  Puncture matrix for audio frames.
+ */
+static constexpr auto Audio_puncture = std::experimental::make_array< uint8_t >
+(
+    1, 1, 1, 1, 1, 1,
+    1, 1, 1, 1, 1, 0
+);
+
+
+/**
+ * Apply a given puncturing scheme to a byte array.
+ *
+ * \param input: input byte array.
+ * \param output: output byte array, containing puntured data.
+ * \param puncture: puncturing matrix, stored as an array of 8 bit values.
+ * \return resulting bit count after punturing.
+ */
+template < size_t IN, size_t OUT, size_t P >
+size_t puncture(const std::array< uint8_t, IN  >& input,
+                      std::array< uint8_t, OUT >& output,
+                const std::array< uint8_t, P   >& puncture)
+{
+    size_t outIndex   = 0;
+    size_t punctIndex = 0;
+    size_t bit_count  = 0;
+
+    for(size_t i = 0; i < 8*IN && outIndex < 8*OUT; i++)
+    {
+        if(puncture[punctIndex++])
+        {
+            setBit(output, outIndex++, getBit(input, i));
+            bit_count++;
+        }
+
+        if(punctIndex == P) punctIndex = 0;
+    }
+
+    return bit_count;
+}
+
+
+#endif /* M17_CODE_PUNCTURING_H */

openrtx/include/protocols/M17/M17ConvolutionalEncoder.h

@@ -20,8 +20,8 @@
  *   along with this program; if not, see <http://www.gnu.org/licenses/>   *
  ***************************************************************************/
 
-#ifndef M17CONVOLUTIONALENCODER_H
+#ifndef M17_CONVOLUTIONAL_ENCODER_H
-#define M17CONVOLUTIONALENCODER_H
+#define M17_CONVOLUTIONAL_ENCODER_H
 
 #ifndef __cplusplus
 #error This header is C++ only!
@@ -111,4 +111,4 @@ private:
     uint8_t memory = 0;    ///< Convolutional encoder memory.
 };
 
-#endif /* M17CONVOLUTIONALENCODER_H */
+#endif /* M17_CONVOLUTIONAL_ENCODER_H */

openrtx/include/protocols/M17/M17Datatypes.h

@@ -18,8 +18,8 @@
  *   along with this program; if not, see <http://www.gnu.org/licenses/>   *
  ***************************************************************************/
 
-#ifndef M17DATATYPES_H
+#ifndef M17_DATATYPES_H
-#define M17DATATYPES_H
+#define M17_DATATYPES_H
 
 #include <cstdint>
 #include <array>
@@ -75,4 +75,4 @@ typedef struct
 }
 __attribute__((packed)) dataFrame_t;
 
-#endif /* M17DATATYPES_H */
+#endif /* M17_DATATYPES_H */

openrtx/include/protocols/M17/M17Frame.h

@@ -18,8 +18,8 @@
  *   along with this program; if not, see <http://www.gnu.org/licenses/>   *
  ***************************************************************************/
 
-#ifndef M17FRAME_H
+#ifndef M17_FRAME_H
-#define M17FRAME_H
+#define M17_FRAME_H
 
 #ifndef __cplusplus
 #error This header is C++ only!
@@ -115,4 +115,4 @@ private:
     dataFrame_t data;   ///< Underlying frame data.
 };
 
-#endif /* M17FRAME_H */
+#endif /* M17_FRAME_H */

openrtx/include/protocols/M17/M17LinkSetupFrame.h

@@ -18,8 +18,8 @@
  *   along with this program; if not, see <http://www.gnu.org/licenses/>   *
  ***************************************************************************/
 
-#ifndef M17LINKSETUPFRAME_H
+#ifndef M17_LINKSETUPFRAME_H
-#define M17LINKSETUPFRAME_H
+#define M17_LINKSETUPFRAME_H
 
 #ifndef __cplusplus
 #error This header is C++ only!
@@ -125,4 +125,4 @@ private:
     lsf_t data;    ///< Underlying frame data.
 };
 
-#endif /* M17LINKSETUPFRAME_H */
+#endif /* M17_LINKSETUPFRAME_H */

openrtx/include/protocols/M17/M17Utils.h

@@ -0,0 +1,70 @@
+/***************************************************************************
+ *   Copyright (C) 2021 by Federico Amedeo Izzo IU2NUO,                    *
+ *                         Niccolò Izzo IU2KIN                             *
+ *                         Frederik Saraci IU2NRO                          *
+ *                         Silvano Seva IU2KWO                             *
+ *                                                                         *
+ *                                                                         *
+ *   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 3 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, see <http://www.gnu.org/licenses/>   *
+ ***************************************************************************/
+
+#ifndef M17_UTILS_H
+#define M17_UTILS_H
+
+#ifndef __cplusplus
+#error This header is C++ only!
+#endif
+
+#include <array>
+
+
+/**
+ * Utility function allowing to retrieve the value of a single bit from an array
+ * of bytes. Bits are counted scanning from left to right, thus bit number zero
+ * is the leftmost bit of array[0].
+ *
+ * \param array: byte array.
+ * \param pos: bit position inside the array.
+ * \return value of the indexed bit, as boolean variable.
+ */
+template < size_t N >
+inline bool getBit(const std::array< uint8_t, N >& array, const size_t pos)
+{
+    size_t i = pos / 8;
+    size_t j = pos % 8;
+    return (array[i] >> (7 - j)) & 0x01;
+}
+
+
+/**
+ * Utility function allowing to set the value of a single bit from an array
+ * of bytes. Bits are counted scanning from left to right, thus bit number zero
+ * is the leftmost bit of array[0].
+ *
+ * \param array: byte array.
+ * \param pos: bit position inside the array.
+ * \param bit: bit value to be set.
+ */
+template < size_t N >
+inline void setBit(std::array< uint8_t, N >& array, const size_t pos,
+                   const bool bit)
+{
+    size_t i     = pos / 8;
+    size_t j     = pos % 8;
+    uint8_t mask = 1 << (7 - j);
+    array[i] = (array[i] & ~mask) |
+               (bit ? mask : 0x00);
+}
+
+#endif /* M17_UTILS_H */