Line data    Source code

       1             : #include "ConvCode.h"
       2             : #include <string.h>
       3             : 
       4             : // each 32-bit word stores 8 values, one per each nibble
       5             : static const uint32_t ConvCodeTable1_3[16] = {
       6             :   0x07347043, 0x61521625, 0x16256152, 0x70430734,
       7             :   0x43703407, 0x25165261, 0x52612516, 0x34074370,
       8             :   0x70430734, 0x16256152, 0x61521625, 0x07347043,
       9             :   0x34074370, 0x52612516, 0x25165261, 0x43703407,
      10             : };
      11             : 
      12             : static const uint32_t ConvCodeTable1_2[4] = { 
      13             :   0x03122130, 0x21300312, 0x30211203, 0x12033021,
      14             : };
      15             : 
      16           1 : RadioLibConvCode::RadioLibConvCode() {
      17             : 
      18           1 : }
      19             : 
      20           0 : void RadioLibConvCode::begin(uint8_t rt) {
      21           0 :   this->enc_state = 0;
      22           0 :   this->rate = rt;
      23           0 : }
      24             : 
      25           0 : int16_t RadioLibConvCode::encode(const uint8_t* in, size_t in_bits, uint8_t* out, size_t* out_bits) {
      26           0 :   if(!in || !out) {
      27           0 :     return(RADIOLIB_ERR_UNKNOWN);
      28             :   }
      29             : 
      30             :   size_t ind_bit;
      31           0 :   uint16_t data_out_bitcount = 0;
      32           0 :   uint32_t bin_out_word = 0;
      33             : 
      34             :   // iterate over the provided bits
      35           0 :   for(ind_bit = 0; ind_bit < in_bits; ind_bit++) {
      36           0 :     uint8_t cur_bit = GET_BIT_IN_ARRAY_LSB(in, ind_bit);
      37           0 :     const uint32_t* lut_ptr = (this->rate == 2) ? ConvCodeTable1_2 : ConvCodeTable1_3;
      38           0 :     uint8_t word_pos = this->enc_state / 4;
      39           0 :     uint8_t byte_pos = (3 - (this->enc_state % 4)) * 8;
      40           0 :     uint8_t nibble_pos = (1 - cur_bit) * 4;
      41           0 :     uint8_t g1g0 = (lut_ptr[word_pos] >> (byte_pos + nibble_pos)) & 0x0F;
      42             : 
      43           0 :     uint8_t mod = this->rate == 2 ? 16 : 64;
      44           0 :     this->enc_state = (this->enc_state * 2 + cur_bit) % mod;
      45           0 :     bin_out_word |= (g1g0 << ((7 - (ind_bit % 8)) * this->rate));
      46           0 :     if(ind_bit % 8 == 7) {
      47           0 :       if(this->rate == 3) {
      48           0 :         *out++ = (uint8_t)(bin_out_word >> 16);
      49             :       }
      50           0 :       *out++ = (uint8_t)(bin_out_word >> 8);
      51           0 :       *out++ = (uint8_t)bin_out_word;
      52           0 :       bin_out_word  = 0;
      53             :     }
      54           0 :     data_out_bitcount += this->rate;
      55             :   }
      56             : 
      57           0 :   if(ind_bit % 8) {
      58           0 :     if(this->rate == 3) {
      59           0 :       *out++ = (uint8_t)(bin_out_word >> 16);
      60             :     }
      61           0 :     *out++ = (uint8_t)(bin_out_word >> 8);
      62           0 :     *out++ = (uint8_t)bin_out_word;
      63             :   }
      64             : 
      65           0 :   if(out_bits) { *out_bits = data_out_bitcount; }
      66             : 
      67           0 :   return(RADIOLIB_ERR_NONE);
      68             : }