FEC.h

#if !defined(_RADIOLIB_FEC_H)
#define _RADIOLIB_FEC_H
 
#include "../TypeDef.h"
#include "../Module.h"
#if defined(RADIOLIB_BUILD_ARDUINO)
#include "../ArduinoHal.h"
#endif
 
// BCH(31, 21) code constants
#define RADIOLIB_PAGER_BCH_N                                    (31)
#define RADIOLIB_PAGER_BCH_K                                    (21)
#define RADIOLIB_PAGER_BCH_PRIMITIVE_POLY                       (0x25)
 
#if RADIOLIB_STATIC_ONLY
#define RADIOLIB_BCH_MAX_N                                      (63)
#define RADIOLIB_BCH_MAX_K                                      (31)
#endif
 
class RadioLibBCH {
  public:
    RadioLibBCH();
 
    ~RadioLibBCH();
 
    void begin(uint8_t n, uint8_t k, uint32_t poly);
 
    uint32_t encode(uint32_t dataword);
 
  private:
    uint8_t n = 0;
    uint8_t k = 0;
    uint32_t poly = 0;
    uint8_t m = 0;
    
    #if RADIOLIB_STATIC_ONLY
      int32_t alphaTo[RADIOLIB_BCH_MAX_N + 1] = { 0 };
      int32_t indexOf[RADIOLIB_BCH_MAX_N + 1] = { 0 };
      int32_t generator[RADIOLIB_BCH_MAX_N - RADIOLIB_BCH_MAX_K + 1] = { 0 };
    #else
      int32_t* alphaTo = nullptr;
      int32_t* indexOf = nullptr;
      int32_t* generator = nullptr;
    #endif
};
 
// the global singleton
extern RadioLibBCH RadioLibBCHInstance;
 
// macros to access bits in byte array, from http://www.mathcs.emory.edu/~cheung/Courses/255/Syllabus/1-C-intro/bit-array.html
#define SET_BIT_IN_ARRAY_MSB(A, k)                              ( A[((k)/8)] |= (1 << ((k)%8)) )
#define CLEAR_BIT_IN_ARRAY_MSB(A, k)                            ( A[((k)/8)] &= ~(1 << ((k)%8)) )
#define TEST_BIT_IN_ARRAY_MSB(A, k)                             ( A[((k)/8)] & (1 << ((k)%8)) )
#define GET_BIT_IN_ARRAY_MSB(A, k)                              ( (A[((k)/8)] & (1 << ((k)%8))) ? 1 : 0 )
#define SET_BIT_IN_ARRAY_LSB(A, k)                              ( A[((k)/8)] |= (1 << (7 - ((k)%8))) )
#define CLEAR_BIT_IN_ARRAY_LSB(A, k)                            ( A[((k)/8)] &= ~(1 << (7 - ((k)%8))) )
#define TEST_BIT_IN_ARRAY_LSB(A, k)                             ( A[((k)/8)] & (1 << (7 - ((k)%8))) )
#define GET_BIT_IN_ARRAY_LSB(A, k)                              ( (A[((k)/8)] & (1 << (7 - ((k)%8)))) ? 1 : 0 )
 
class RadioLibConvCode {
  public:
    RadioLibConvCode();
 
    void begin(uint8_t rt);
 
    int16_t encode(const uint8_t* in, size_t in_bits, uint8_t* out, size_t* out_bits = NULL);
 
  private:
    uint8_t enc_state = 0;
    uint8_t rate = 0;
};
 
// each 32-bit word stores 8 values, one per each nibble
static const uint32_t ConvCodeTable1_3[16] = {
  0x07347043, 0x61521625, 0x16256152, 0x70430734,
  0x43703407, 0x25165261, 0x52612516, 0x34074370,
  0x70430734, 0x16256152, 0x61521625, 0x07347043,
  0x34074370, 0x52612516, 0x25165261, 0x43703407,
};
 
static const uint32_t ConvCodeTable1_2[4] = { 
  0x03122130, 0x21300312, 0x30211203, 0x12033021,
};
 
extern RadioLibConvCode RadioLibConvCodeInstance;
 
#endif