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/*
FILE...: ldpc_enc.c
AUTHOR.: Bill Cowley, David Rowe
CREATED: Sep 2016
RA LDPC encoder program. Using the elegant back substitution of RA
LDPC codes.
*/
#include <errno.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "ldpc_codes.h"
#include "mpdecode_core.h"
#include "ofdm_internal.h"
int opt_exists(char *argv[], int argc, char opt[]) {
int i;
for (i = 0; i < argc; i++) {
if (strcmp(argv[i], opt) == 0) {
return i;
}
}
return 0;
}
int main(int argc, char *argv[]) {
FILE *fin, *fout;
int arg, sd, i, frames, codename, testframes, Nframes, data_bits_per_frame,
parity_bits_per_frame;
struct LDPC ldpc;
int unused_data_bits;
if (argc < 2) {
fprintf(stderr, "\n");
fprintf(stderr,
"usage: %s InputOneBytePerBit OutputFile [--sd] [--code CodeName] "
"[--testframes Nframes] [--unused numUnusedDataBits]\n",
argv[0]);
fprintf(stderr, "\n");
fprintf(stderr, "usage: %s --listcodes\n\n", argv[0]);
fprintf(stderr,
" List supported codes (more can be added via using Octave ldpc "
"scripts)\n");
fprintf(stderr, "\n");
exit(0);
}
/* todo: put this in a function file to share with ldpc_dec.c */
if ((codename = opt_exists(argv, argc, "--listcodes")) != 0) {
ldpc_codes_list();
exit(0);
}
/* set up LDPC code */
int code_index = 0;
if ((codename = opt_exists(argv, argc, "--code")) != 0)
code_index = ldpc_codes_find(argv[codename + 1]);
memcpy(&ldpc, &ldpc_codes[code_index], sizeof(struct LDPC));
fprintf(stderr, "Using: %s\n", ldpc.name);
data_bits_per_frame = ldpc.NumberRowsHcols;
parity_bits_per_frame = ldpc.NumberParityBits;
unsigned char ibits[data_bits_per_frame];
unsigned char pbits[parity_bits_per_frame];
float sdout[data_bits_per_frame + parity_bits_per_frame];
if (strcmp(argv[1], "-") == 0)
fin = stdin;
else if ((fin = fopen(argv[1], "rb")) == NULL) {
fprintf(stderr, "Error opening input bit file: %s: %s.\n", argv[1],
strerror(errno));
exit(1);
}
if (strcmp(argv[2], "-") == 0)
fout = stdout;
else if ((fout = fopen(argv[2], "wb")) == NULL) {
fprintf(stderr, "Error opening output bit file: %s: %s.\n", argv[2],
strerror(errno));
exit(1);
}
sd = 0;
if (opt_exists(argv, argc, "--sd")) {
sd = 1;
}
unused_data_bits = 0;
if ((arg = opt_exists(argv, argc, "--unused"))) {
unused_data_bits = atoi(argv[arg + 1]);
}
testframes = Nframes = 0;
if ((arg = (opt_exists(argv, argc, "--testframes")))) {
testframes = 1;
Nframes = atoi(argv[arg + 1]);
fprintf(stderr, "Nframes: %d\n", Nframes);
}
frames = 0;
int written = 0;
while (fread(ibits, sizeof(char), data_bits_per_frame, fin) ==
data_bits_per_frame) {
if (testframes) {
uint16_t r[data_bits_per_frame];
ofdm_rand(r, data_bits_per_frame);
for (i = 0; i < data_bits_per_frame - unused_data_bits; i++) {
ibits[i] = r[i] > 16384;
}
for (i = data_bits_per_frame - unused_data_bits; i < data_bits_per_frame;
i++) {
ibits[i] = 1;
}
}
encode(&ldpc, ibits, pbits);
if (sd) {
/* map to BPSK symbols */
for (i = 0; i < data_bits_per_frame - unused_data_bits; i++)
sdout[i] = 1.0 - 2.0 * ibits[i];
for (i = 0; i < parity_bits_per_frame; i++)
sdout[i + data_bits_per_frame - unused_data_bits] =
1.0 - 2.0 * pbits[i];
written += fwrite(
sdout, sizeof(float),
data_bits_per_frame - unused_data_bits + parity_bits_per_frame, fout);
} else {
written += fwrite(ibits, sizeof(char), data_bits_per_frame, fout);
written += fwrite(pbits, sizeof(char), parity_bits_per_frame, fout);
}
frames++;
if (testframes && (frames >= Nframes)) {
goto finished;
}
}
finished:
fprintf(stderr, "written: %d\n", written);
fclose(fin);
fclose(fout);
return 1;
}
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