Viewing file:  sm_afsk1200.c (7.75 KB) -rw-r--r--
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/*****************************************************************************/
/*
* sm_afsk1200.c -- soundcard radio modem driver, 1200 baud AFSK modem
*
* Copyright (C) 1996 Thomas Sailer (sailer@ife.ee.ethz.ch)
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*
* Please note that the GPL allows you to use the driver, NOT the radio.
* In order to use the radio, you need a license from the communications
* authority of your country.
*
*/
#include "sm.h"
#include "sm_tbl_afsk1200.h"
/* --------------------------------------------------------------------- */
struct demod_state_afsk12 {
unsigned int shreg;
unsigned int bit_pll;
unsigned char last_sample;
unsigned int dcd_shreg;
int dcd_sum0, dcd_sum1, dcd_sum2;
unsigned int dcd_time;
unsigned char last_rxbit;
};
struct mod_state_afsk12 {
unsigned int shreg;
unsigned char tx_bit;
unsigned int bit_pll;
unsigned int dds_inc;
unsigned int txphase;
};
/* --------------------------------------------------------------------- */
static const int dds_inc[2] = {
AFSK12_TX_FREQ_LO*0x10000/AFSK12_SAMPLE_RATE,
AFSK12_TX_FREQ_HI*0x10000/AFSK12_SAMPLE_RATE
};
static void modulator_1200_u8(struct sm_state *sm, unsigned char *buf,
unsigned int buflen)
{
struct mod_state_afsk12 *st = (struct mod_state_afsk12 *)(&sm->m);
for (; buflen > 0; buflen--) {
if (!((st->txphase++) & 7)) {
if (st->shreg <= 1)
st->shreg = hdlcdrv_getbits(&sm->hdrv) | 0x10000;
st->tx_bit = (st->tx_bit ^ (!(st->shreg & 1))) & 1;
st->shreg >>= 1;
}
st->dds_inc = dds_inc[st->tx_bit & 1];
*buf++ = OFFSCOS(st->bit_pll);
st->bit_pll += st->dds_inc;
}
}
/* --------------------------------------------------------------------- */
static void modulator_1200_s16(struct sm_state *sm, short *buf, unsigned int buflen)
{
struct mod_state_afsk12 *st = (struct mod_state_afsk12 *)(&sm->m);
for (; buflen > 0; buflen--) {
if (!((st->txphase++) & 7)) {
if (st->shreg <= 1)
st->shreg = hdlcdrv_getbits(&sm->hdrv) | 0x10000;
st->tx_bit = (st->tx_bit ^ (!(st->shreg & 1))) & 1;
st->shreg >>= 1;
}
st->dds_inc = dds_inc[st->tx_bit & 1];
*buf++ = COS(st->bit_pll);
st->bit_pll += st->dds_inc;
}
}
/* --------------------------------------------------------------------- */
extern __inline__ int convolution8_u8(const unsigned char *st, const int *coeff, int csum)
{
int sum = -0x80 * csum;
sum += (st[0] * coeff[0]);
sum += (st[-1] * coeff[1]);
sum += (st[-2] * coeff[2]);
sum += (st[-3] * coeff[3]);
sum += (st[-4] * coeff[4]);
sum += (st[-5] * coeff[5]);
sum += (st[-6] * coeff[6]);
sum += (st[-7] * coeff[7]);
sum >>= 7;
return sum * sum;
}
extern __inline__ int convolution8_s16(const short *st, const int *coeff, int csum)
{
int sum = 0;
sum += (st[0] * coeff[0]);
sum += (st[-1] * coeff[1]);
sum += (st[-2] * coeff[2]);
sum += (st[-3] * coeff[3]);
sum += (st[-4] * coeff[4]);
sum += (st[-5] * coeff[5]);
sum += (st[-6] * coeff[6]);
sum += (st[-7] * coeff[7]);
sum >>= 15;
return sum * sum;
}
extern __inline__ int do_filter_1200_u8(const unsigned char *buf)
{
int sum = convolution8_u8(buf, afsk12_tx_lo_i, SUM_AFSK12_TX_LO_I);
sum += convolution8_u8(buf, afsk12_tx_lo_q, SUM_AFSK12_TX_LO_Q);
sum -= convolution8_u8(buf, afsk12_tx_hi_i, SUM_AFSK12_TX_HI_I);
sum -= convolution8_u8(buf, afsk12_tx_hi_q, SUM_AFSK12_TX_HI_Q);
return sum;
}
extern __inline__ int do_filter_1200_s16(const short *buf)
{
int sum = convolution8_s16(buf, afsk12_tx_lo_i, SUM_AFSK12_TX_LO_I);
sum += convolution8_s16(buf, afsk12_tx_lo_q, SUM_AFSK12_TX_LO_Q);
sum -= convolution8_s16(buf, afsk12_tx_hi_i, SUM_AFSK12_TX_HI_I);
sum -= convolution8_s16(buf, afsk12_tx_hi_q, SUM_AFSK12_TX_HI_Q);
return sum;
}
/* --------------------------------------------------------------------- */
static const int pll_corr[2] = { -0x1000, 0x1000 };
static void demodulator_1200_u8(struct sm_state *sm, const unsigned char *buf, unsigned int buflen)
{
struct demod_state_afsk12 *st = (struct demod_state_afsk12 *)(&sm->d);
int j;
int sum;
unsigned char newsample;
for (; buflen > 0; buflen--, buf++) {
sum = do_filter_1200_u8(buf);
st->dcd_shreg <<= 1;
st->bit_pll += 0x2000;
newsample = (sum > 0);
if (st->last_sample ^ newsample) {
st->last_sample = newsample;
st->dcd_shreg |= 1;
st->bit_pll += pll_corr
[st->bit_pll < 0x9000];
j = 4 * hweight8(st->dcd_shreg & 0x38)
- hweight16(st->dcd_shreg & 0x7c0);
st->dcd_sum0 += j;
}
hdlcdrv_channelbit(&sm->hdrv, st->last_sample);
if ((--st->dcd_time) <= 0) {
hdlcdrv_setdcd(&sm->hdrv, (st->dcd_sum0 +
st->dcd_sum1 +
st->dcd_sum2) < 0);
st->dcd_sum2 = st->dcd_sum1;
st->dcd_sum1 = st->dcd_sum0;
st->dcd_sum0 = 2; /* slight bias */
st->dcd_time = 120;
}
if (st->bit_pll >= 0x10000) {
st->bit_pll &= 0xffff;
st->shreg >>= 1;
st->shreg |= (!(st->last_rxbit ^
st->last_sample)) << 16;
st->last_rxbit = st->last_sample;
diag_trigger(sm);
if (st->shreg & 1) {
hdlcdrv_putbits(&sm->hdrv, st->shreg >> 1);
st->shreg = 0x10000;
}
}
diag_add(sm, (((int)*buf)-0x80) << 8, sum);
}
}
/* --------------------------------------------------------------------- */
static void demodulator_1200_s16(struct sm_state *sm, const short *buf, unsigned int buflen)
{
struct demod_state_afsk12 *st = (struct demod_state_afsk12 *)(&sm->d);
int j;
int sum;
unsigned char newsample;
for (; buflen > 0; buflen--, buf++) {
sum = do_filter_1200_s16(buf);
st->dcd_shreg <<= 1;
st->bit_pll += 0x2000;
newsample = (sum > 0);
if (st->last_sample ^ newsample) {
st->last_sample = newsample;
st->dcd_shreg |= 1;
st->bit_pll += pll_corr
[st->bit_pll < 0x9000];
j = 4 * hweight8(st->dcd_shreg & 0x38)
- hweight16(st->dcd_shreg & 0x7c0);
st->dcd_sum0 += j;
}
hdlcdrv_channelbit(&sm->hdrv, st->last_sample);
if ((--st->dcd_time) <= 0) {
hdlcdrv_setdcd(&sm->hdrv, (st->dcd_sum0 +
st->dcd_sum1 +
st->dcd_sum2) < 0);
st->dcd_sum2 = st->dcd_sum1;
st->dcd_sum1 = st->dcd_sum0;
st->dcd_sum0 = 2; /* slight bias */
st->dcd_time = 120;
}
if (st->bit_pll >= 0x10000) {
st->bit_pll &= 0xffff;
st->shreg >>= 1;
st->shreg |= (!(st->last_rxbit ^
st->last_sample)) << 16;
st->last_rxbit = st->last_sample;
diag_trigger(sm);
if (st->shreg & 1) {
hdlcdrv_putbits(&sm->hdrv, st->shreg >> 1);
st->shreg = 0x10000;
}
}
diag_add(sm, *buf, sum);
}
}
/* --------------------------------------------------------------------- */
static void demod_init_1200(struct sm_state *sm)
{
struct demod_state_afsk12 *st = (struct demod_state_afsk12 *)(&sm->d);
st->dcd_time = 120;
st->dcd_sum0 = 2;
}
/* --------------------------------------------------------------------- */
const struct modem_tx_info sm_afsk1200_tx = {
"afsk1200", sizeof(struct mod_state_afsk12),
AFSK12_SAMPLE_RATE, 1200, modulator_1200_u8, modulator_1200_s16, NULL
};
const struct modem_rx_info sm_afsk1200_rx = {
"afsk1200", sizeof(struct demod_state_afsk12),
AFSK12_SAMPLE_RATE, 1200, 8, AFSK12_SAMPLE_RATE/1200,
demodulator_1200_u8, demodulator_1200_s16, demod_init_1200
};
/* --------------------------------------------------------------------- */
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