/* CONVOLUTIONAL ENCODER */
/* Copyright (c) 1999, Spectrum Applications, Derwood, MD, USA */
/* All rights reserved */
/* Version 2.0 Last Modified 1999.02.17 */
//#include <alloc.h>
//#include <conio.h>
#include <stdio.h>
#include <stdlib.h>
#include "vdsim.h"
void cnv_encd(int g[2][K], short input_len, short *in_array, short *out_array) {
int m; /* K - 1 */
int t, tt; /* bit time, symbol time */
int j, k; /* loop variables */
//short *unencoded_data; /* pointer to data array */
int shift_reg[K]; /* the encoder shift register */
int sr_head; /* index to the first elt in the sr */
int p, q; /* the upper and lower xor gate outputs */
.
.
.
/* Now start the encoding process */
/* compute the upper and lower mod-two adder outputs, one bit at a time */
for (t = 0; t < input_len + m; t++) {
shift_reg[sr_head] = *( unencoded_data + t );
p = 0;
q = 0;
for (j = 0; j < K; j++) {
k = (j + sr_head) % K;
p ^= shift_reg[k] & g[0][j];
q ^= shift_reg[k] & g[1][j];
}
/* write the upper and lower xor gate outputs as channel symbols */
*(out_array + tt) = p;
tt = tt + 1;
*(out_array + tt) = q;
tt = tt + 1;
.
.
.
}
