src/lib/FEC/FEC.cpp

   1 #include "FEC.h"
   2
   3 void FECEncode(uint8_t *incomingData, uint8_t *FECBuffer)
   4 {
   5     // Encode Hamming(7,4)
   6     uint8_t encodedBuffer[8 * 2] = {0};
   7     for (uint8_t i = 0; i < 8; i++)
   8     {
   9         encodedBuffer[i * 2 + 0] = HammingTableEncode(incomingData[i] & 0x0F);  // LSB nibble
  10         encodedBuffer[i * 2 + 1] = HammingTableEncode(incomingData[i] >> 4);    // MSB nibble
  11     }
  12
  13     // Interleaving
  14     for (uint8_t i = 0; i < (14 / 2); i++)
  15     {
  16         for (uint8_t j = 0; j < 8; j++)
  17         {
  18             FECBuffer[i * 2 + 0] |= ((encodedBuffer[j + 0] >> i) & 0x01) << j;
  19             FECBuffer[i * 2 + 1] |= ((encodedBuffer[j + 8] >> i) & 0x01) << j;
  20         }
  21     }
  22 }
  23
  24 void FECDecode(uint8_t *incomingFECBuffer, uint8_t *outgoingData)
  25 {
  26     // Interleaving
  27     uint8_t encodedBuffer[16] = {0};
  28     for (uint8_t i = 0; i < 8; i++)
  29     {
  30         for (uint8_t j = 0; j < 7; j++)
  31         {
  32             encodedBuffer[i + 0] |= ((incomingFECBuffer[j * 2 + 0] >> i) & 0x01) << j;
  33             encodedBuffer[i + 8] |= ((incomingFECBuffer[j * 2 + 1] >> i) & 0x01) << j;
  34         }
  35     }
  36
  37     // Decode Hamming(7,4)
  38     for (uint8_t i = 0; i < 8; i++)
  39     {
  40         outgoingData[i] =  HammingTableDecode(encodedBuffer[i * 2 + 0]);         // LSB nibble
  41         outgoingData[i] |= HammingTableDecode(encodedBuffer[i * 2 + 1]) << 4;    // MSB nibble
  42     }
  43 }