wenet/tx/ldpc_enc.c

111 wiersze
2.4 KiB
C
Czysty Zwykły widok Historia

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/*
LDPC Encoder, using a 'RA' encoder written by Bill Cowley VK5DSP in March 2016.
Compile with:
gcc -fPIC -shared -o ldpc_enc.so ldpc_enc.c
*/
#include<stdio.h>
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#include<string.h>
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#include<stdlib.h>
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/*
LDPC Encoder Functions
*/
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#define Nibits 2064
#define Npbits 516
#define Nwt 12
unsigned short hrows[] = {
// read from file created via make_Hrows_txt.m
// use the new code of March 2016
#include "Hrow2064.txt"
};
void encode(unsigned char *ibits, unsigned char *pbits) {
unsigned int p, i, tmp, par, prev=0;
char c;
for (p=0; p<Npbits; p++) {
par =0;
for (i=0; i<Nwt; i++)
par = par + ibits[hrows[p*Nwt+i]-1];
// -1 as matlab arrays start from 1, C from 0
tmp = par + prev;
//printf(" p ind %d, parity %d \n", p, tmp);
//c = getchar();
tmp &= 1; // only retain the lsb
prev = tmp;
pbits[p] =tmp;
}
}
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/*
Diagonal Interleaver Functions
From fldigi
Copyright (C) 2006
Dave Freese, W1HKJ
*/
#define INTERLEAVE_FWD 0
#define INTERLEAVE_REV 1
#define PUNCTURE 0
#define INTERLEAVER_SIZE 256
#define INTERLEAVER_DEPTH 10
int len, interleaver_direction = 0;
unsigned char interleaver_table[INTERLEAVER_SIZE*INTERLEAVER_SIZE*INTERLEAVER_DEPTH];
// Helper function for accessing interleaver table.
unsigned char *tab(int i, int j, int k) {
return &interleaver_table[(INTERLEAVER_SIZE * INTERLEAVER_SIZE * i) + (INTERLEAVER_SIZE * j) + k];
}
void interleaver_flush(void)
{
// Fill entire RX interleaver with punctures or 0 depending on whether
// Rx or Tx
if (interleaver_direction == INTERLEAVE_REV)
memset(interleaver_table, 0, len);
else
memset(interleaver_table, PUNCTURE, len);
}
void interleave_symbols(unsigned char *psyms)
{
int i, j, k;
for (k = 0; k < INTERLEAVER_DEPTH; k++) {
for (i = 0; i < INTERLEAVER_SIZE; i++)
for (j = 0; j < INTERLEAVER_SIZE - 1; j++)
*tab(k, i, j) = *tab(k, i, j + 1);
for (i = 0; i < INTERLEAVER_SIZE; i++)
*tab(k, i, INTERLEAVER_SIZE - 1) = psyms[i];
for (i = 0; i < INTERLEAVER_SIZE; i++) {
if (interleaver_direction == INTERLEAVE_FWD)
psyms[i] = *tab(k, i, INTERLEAVER_SIZE - i - 1);
else
psyms[i] = *tab(k, i, i);
}
}
}
void init_interleaver(int direction){
len = INTERLEAVER_SIZE*INTERLEAVER_SIZE*INTERLEAVER_DEPTH;
interleaver_direction = direction;
interleaver_flush();
}