M17_Implementations/SP5WWP/m17-coder/m17-coder-sym.c

#include <stdio.h>
#include <string.h>
#include <stdint.h>
#include <unistd.h>

#include "../inc/m17.h"
#include "golay.h"

struct LSF
{
	uint8_t dst[6];
	uint8_t src[6];
	uint8_t type[2];
	uint8_t meta[112/8];
	uint8_t crc[2];
} lsf;

uint8_t lich[6];                    //48 bits packed raw, unencoded LICH
uint8_t lich_encoded[12];           //96 bits packed, encoded LICH
uint8_t enc_bits[SYM_PER_PLD*2];    //type-2 bits, unpacked
uint8_t rf_bits[SYM_PER_PLD*2];     //type-4 bits, unpacked

uint8_t data[16];                   //raw payload, packed bits
uint16_t fn=0;                      //16-bit Frame Number (for the stream mode)
uint8_t lich_cnt=0;                 //0..5 LICH counter, derived from the Frame Number
uint8_t got_lsf=0;                  //have we filled the LSF struct yet?

void send_Preamble(const uint8_t type)
{
    float symb;

    if(type) //pre-BERT
    {
        for(uint16_t i=0; i<192/2; i++) //40ms * 4800 = 192
        {
            symb=-3.0;
            write(STDOUT_FILENO, (uint8_t*)&symb,  sizeof(float));
            symb=+3.0;
            write(STDOUT_FILENO, (uint8_t*)&symb,  sizeof(float));
        }
    }
    else //pre-LSF
    {
        for(uint16_t i=0; i<192/2; i++) //40ms * 4800 = 192
        {
            symb=+3.0;
            write(STDOUT_FILENO, (uint8_t*)&symb,  sizeof(float));
            symb=-3.0;
            write(STDOUT_FILENO, (uint8_t*)&symb,  sizeof(float));
        }
    }
}

void send_Syncword(const uint16_t sword)
{
    float symb;

    for(uint8_t i=0; i<16; i+=2)
    {
        symb=symbol_map[(sword>>(14-i))&3];
        write(STDOUT_FILENO, (uint8_t*)&symb,  sizeof(float));
    }
}

//main routine
int main(void)
{
    //debug
    //printf("%06X\n", golay24_encode(1)); //golay encoder codeword test
    //printf("%d -> %d -> %d\n", 1, intrl_seq[1], intrl_seq[intrl_seq[1]]); //interleaver bijective reciprocality test, f(f(x))=x
    //return 0;

    while(1)
    {
        if(got_lsf) //stream frames
        {
            //we could discard the data we already have
            while(read(STDIN_FILENO, &(lsf.dst), 6)<6);
            while(read(STDIN_FILENO, &(lsf.src), 6)<6);
            while(read(STDIN_FILENO, &(lsf.type), 2)<2);
            while(read(STDIN_FILENO, &(lsf.meta), 14)<14);
            while(read(STDIN_FILENO, data, 16)<16);

            //send stream frame syncword
            send_Syncword(SYNC_STR);

            //derive the LICH_CNT from the Frame Number
            lich_cnt=fn%6;

            //extract LICH from the whole LSF
            switch(lich_cnt)
            {
                case 0:
                    lich[0]=lsf.dst[0];
                    lich[1]=lsf.dst[1];
                    lich[2]=lsf.dst[2];
                    lich[3]=lsf.dst[3];
                    lich[4]=lsf.dst[4];
                break;

                case 1:
                    lich[0]=lsf.dst[5];
                    lich[1]=lsf.src[0];
                    lich[2]=lsf.src[1];
                    lich[3]=lsf.src[2];
                    lich[4]=lsf.src[3];
                break;

                case 2:
                    lich[0]=lsf.src[4];
                    lich[1]=lsf.src[5];
                    lich[2]=lsf.type[0];
                    lich[3]=lsf.type[1];
                    lich[4]=lsf.meta[0];
                break;

                case 3:
                    lich[0]=lsf.meta[1];
                    lich[1]=lsf.meta[2];
                    lich[2]=lsf.meta[3];
                    lich[3]=lsf.meta[4];
                    lich[4]=lsf.meta[5];
                break;

                case 4:
                    lich[0]=lsf.meta[6];
                    lich[1]=lsf.meta[7];
                    lich[2]=lsf.meta[8];
                    lich[3]=lsf.meta[9];
                    lich[4]=lsf.meta[10];
                break;

                case 5:
                    lich[0]=lsf.meta[11];
                    lich[1]=lsf.meta[12];
                    lich[2]=lsf.meta[13];
                    lich[3]=lsf.crc[0];
                    lich[4]=lsf.crc[1];
                break;

                default:
                    ;
                break;
            }
            lich[5]=lich_cnt<<5;

            //encode the LICH
            uint32_t val;

            val=golay24_encode((lich[0]<<4)|(lich[1]>>4));
            lich_encoded[0]=(val>>16)&0xFF;
            lich_encoded[1]=(val>>8)&0xFF;
            lich_encoded[2]=(val>>0)&0xFF;
            val=golay24_encode(((lich[1]&0x0F)<<8)|lich[2]);
            lich_encoded[3]=(val>>16)&0xFF;
            lich_encoded[4]=(val>>8)&0xFF;
            lich_encoded[5]=(val>>0)&0xFF;
            val=golay24_encode((lich[3]<<4)|(lich[4]>>4));
            lich_encoded[6]=(val>>16)&0xFF;
            lich_encoded[7]=(val>>8)&0xFF;
            lich_encoded[8]=(val>>0)&0xFF;
            val=golay24_encode(((lich[4]&0x0F)<<8)|lich[5]);
            lich_encoded[9]=(val>>16)&0xFF;
            lich_encoded[10]=(val>>8)&0xFF;
            lich_encoded[11]=(val>>0)&0xFF;

            //unpack LICH (12 bytes)
            memset(enc_bits, 0, SYM_PER_PLD*2);
            for(uint8_t i=0; i<12; i++)
            {
                for(uint8_t j=0; j<8; j++)
                    enc_bits[i*8+j]=(lich_encoded[i]>>(7-j))&1;
            }

            //reorder bits
            for(uint16_t i=0; i<SYM_PER_PLD*2; i++)
                rf_bits[i]=enc_bits[intrl_seq[i]];

            //randomize
            for(uint16_t i=0; i<SYM_PER_PLD*2; i++)
            {
                if((rand_seq[i/8]>>(7-(i%8)))&1) //flip bit if '1'
                {
                    if(rf_bits[i])
                        rf_bits[i]=0;
                    else
                        rf_bits[i]=1;
                }
            }

            //send dummy symbols (debug)
            /*float s=0.0;
            for(uint8_t i=0; i<SYM_PER_PLD; i++) //40ms * 4800 - 8 (syncword)
                write(STDOUT_FILENO, (uint8_t*)&s, sizeof(float));*/

            float s;
            for(uint16_t i=0; i<SYM_PER_PLD; i++) //40ms * 4800 - 8 (syncword)
            {
                s=symbol_map[rf_bits[2*i]*2+rf_bits[2*i+1]];
                write(STDOUT_FILENO, (uint8_t*)&s, sizeof(float));
            }

            /*printf("\tDATA: ");
            for(uint8_t i=0; i<16; i++)
                printf("%02X", data[i]);
            printf("\n");*/

            //increment the Frame Number
            fn++;

            //debug-only
            if(fn==6)
                return 0;
        }
        else //LSF
        {
            while(read(STDIN_FILENO, &(lsf.dst), 6)<6);
            while(read(STDIN_FILENO, &(lsf.src), 6)<6);
            while(read(STDIN_FILENO, &(lsf.type), 2)<2);
            while(read(STDIN_FILENO, &(lsf.meta), 14)<14);
            while(read(STDIN_FILENO, data, 16)<16);

            got_lsf=1;

            //send out the preamble and LSF
            send_Preamble(0); //0 - LSF preamble, as opposed to 1 - BERT preamble

            //send LSF syncword
            send_Syncword(SYNC_LSF);

            //send dummy symbols (debug)
            float s=0.0;
            for(uint8_t i=0; i<184; i++) //40ms * 4800 - 8 (syncword)
                write(STDOUT_FILENO, (uint8_t*)&s, sizeof(float));

            /*printf("DST: ");
            for(uint8_t i=0; i<6; i++)
                printf("%02X", lsf.dst[i]);
            printf(" SRC: ");
            for(uint8_t i=0; i<6; i++)
                printf("%02X", lsf.src[i]);
            printf(" TYPE: ");
            for(uint8_t i=0; i<2; i++)
                printf("%02X", lsf.type[i]);
            printf(" META: ");
            for(uint8_t i=0; i<14; i++)
                printf("%02X", lsf.meta[i]);
            printf("\n");*/
        }
    }

	return 0;
}