/*****************************************************************************/
/*
* sm_afsk2666.c -- soundcard radio modem driver, 2666 baud AFSK modem
*
* Copyright (C) 1997 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_afsk2666.h"
/* --------------------------------------------------------------------- */
struct demod_state_afsk26 {
unsigned int shreg;
unsigned long descram;
int dem_sum[8];
int dem_sum_mean;
int dem_cnt;
unsigned int bit_pll;
unsigned char last_sample;
unsigned int dcd_shreg;
int dcd_sum0, dcd_sum1, dcd_sum2;
unsigned int dcd_time;
};
struct mod_state_afsk26 {
unsigned int shreg;
unsigned long scram;
unsigned int bit_pll;
unsigned int phinc;
unsigned int tx_seq;
};
/* --------------------------------------------------------------------- */
#define DESCRAM_TAP1 0x20000
#define DESCRAM_TAP2 0x01000
#define DESCRAM_TAP3 0x00001
#define DESCRAM_TAPSH1 17
#define DESCRAM_TAPSH2 12
#define DESCRAM_TAPSH3 0
#define SCRAM_TAP1 0x20000 /* X^17 */
#define SCRAM_TAPN 0x00021 /* X^0+X^5 */
/* --------------------------------------------------------------------- */
static void modulator_2666_u8(struct sm_state *sm, unsigned char *buf, unsigned int buflen)
{
struct mod_state_afsk26 *st = (struct mod_state_afsk26 *)(&sm->m);
for (; buflen > 0; buflen--, buf++) {
if (!st->tx_seq++) {
if (st->shreg <= 1)
st->shreg = hdlcdrv_getbits(&sm->hdrv) | 0x10000;
st->scram = ((st->scram << 1) | (st->scram & 1));
st->scram ^= (!(st->shreg & 1));
st->shreg >>= 1;
if (st->scram & (SCRAM_TAP1 << 1))
st->scram ^= SCRAM_TAPN << 1;
st->phinc = afsk26_carfreq[!(st->scram & (SCRAM_TAP1 << 2))];
}
if (st->tx_seq >= 6)
st->tx_seq = 0;
*buf = OFFSCOS(st->bit_pll);
st->bit_pll += st->phinc;
}
}
/* --------------------------------------------------------------------- */
static void modulator_2666_s16(struct sm_state *sm, short *buf, unsigned int buflen)
{
struct mod_state_afsk26 *st = (struct mod_state_afsk26 *)(&sm->m);
for (; buflen > 0; buflen--, buf++) {
if (!st->tx_seq++) {
if (st->shreg <= 1)
st->shreg = hdlcdrv_getbits(&sm->hdrv) | 0x10000;
st->scram = ((st->scram << 1) | (st->scram & 1));
st->scram ^= (!(st->shreg & 1));
st->shreg >>= 1;
if (st->scram & (SCRAM_TAP1 << 1))
st->scram ^= SCRAM_TAPN << 1;
st->phinc = afsk26_carfreq[!(st->scram & (SCRAM_TAP1 << 2))];
}
if (st->tx_seq >= 6)
st->tx_seq = 0;
*buf = COS(st->bit_pll);
st->bit_pll += st->phinc;
}
}
/* --------------------------------------------------------------------- */
static inline int convolution12_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 += (st[-8] * coeff[8]);
sum += (st[-9] * coeff[9]);
sum += (st[-10] * coeff[10]);
sum += (st[-11] * coeff[11]);
return sum;
}
static inline int convolution12_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 += (st[-8] * coeff[8]);
sum += (st[-9] * coeff[9]);
sum += (st[-10] * coeff[10]);
sum += (st[-11] * coeff[11]);
sum >>= 8;
return sum;
}
/* ---------------------------------------------------------------------- */
#if 0
static int binexp(unsigned int i)
{
int ret = 31;
if (!i)
return 0;
if (i < 0x10000LU) {
i <<= 16;
ret -= 16;
}
if (i < 0x1000000LU) {
i <<= 8;
ret -= 8;
}
if (i < 0x10000000LU) {
i <<= 4;
ret -= 4;
}
if (i < 0x40000000LU) {
i <<= 2;
ret -= 2;
}
if (i < 0x80000000LU)
ret -= 1;
return ret;
}
static const sqrt_tab[16] = {
00000, 16384, 23170, 28378, 32768, 36636, 40132, 43348,
46341, 49152, 51811, 54340, 56756, 59073, 61303, 63455
};
static unsigned int int_sqrt_approx(unsigned int i)
{
unsigned int j;
if (i < 16)
return sqrt_tab[i] >> 14;
j = binexp(i) >> 1;
i >>= (j * 2 - 2);
return (sqrt_tab[i & 0xf] << j) >> 15;
}
#endif
/* --------------------------------------------------------------------- */
extern unsigned int est_pwr(int i, int q)
{
unsigned int ui = abs(i);
unsigned int uq = abs(q);
if (uq > ui) {
unsigned int tmp;
tmp = ui;
ui = uq;
uq = tmp;
}
if (uq > (ui >> 1))
return 7*(ui>>3) + 9*(uq>>4);
else
return ui + (uq>>2);
}
/* --------------------------------------------------------------------- */
static void demod_one_sample(struct sm_state *sm, struct demod_state_afsk26 *st, int curval,
int loi, int loq, int hii, int hiq)
{
static const int pll_corr[2] = { -0xa00, 0xa00 };
unsigned char curbit;
unsigned int descx;
int val;
/*
* estimate power
*/
val = est_pwr(hii, hiq) - est_pwr(loi, loq);
/*
* estimate center value
*/
st->dem_sum[0] += val >> 8;
if ((++st->dem_cnt) >= 256) {
st->dem_cnt = 0;
st->dem_sum_mean = (st->dem_sum[0]+st->dem_sum[1]+
st->dem_sum[2]+st->dem_sum[3]+
st->dem_sum[4]+st->dem_sum[5]+
st->dem_sum[6]+st->dem_sum[7]) >> 3;
memmove(st->dem_sum+1, st->dem_sum,
sizeof(st->dem_sum)-sizeof(st->dem_sum[0]));
st->dem_sum[0] = 0;
}
/*
* decision and bit clock regen
*/
val -= st->dem_sum_mean;
diag_add(sm, curval, val);
st->dcd_shreg <<= 1;
st->bit_pll += 0x1555;
curbit = (val > 0);
if (st->last_sample ^ curbit) {
st->dcd_shreg |= 1;
st->bit_pll += pll_corr[st->bit_pll < (0x8000+0x1555)];
st->dcd_sum0 += 4*hweight8(st->dcd_shreg & 0x1e) -
hweight16(st->dcd_shreg & 0xfe00);
}
st->last_sample = curbit;
hdlcdrv_channelbit(&sm->hdrv, curbit);
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 = 400;
}
if (st->bit_pll >= 0x10000) {
st->bit_pll &= 0xffffu;
st->descram = (st->descram << 1) | curbit;
descx = st->descram ^ (st->descram >> 1);
descx ^= ((descx >> DESCRAM_TAPSH1) ^
(descx >> DESCRAM_TAPSH2));
st->shreg >>= 1;
st->shreg |= (!(descx & 1)) << 16;
if (st->shreg & 1) {
hdlcdrv_putbits(&sm->hdrv, st->shreg >> 1);
st->shreg = 0x10000;
}
diag_trigger(sm);
}
}
/* --------------------------------------------------------------------- */
static void demodulator_2666_u8(struct sm_state *sm, const unsigned char *buf, unsigned int buflen)
{
struct demod_state_afsk26 *st = (struct demod_state_afsk26 *)(&sm->d);
for (; buflen > 0; buflen--, buf++) {
demod_one_sample(sm, st, (*buf-0x80)<<8,
convolution12_u8(buf, afsk26_dem_tables[0][0].i, AFSK26_DEM_SUM_I_0_0),
convolution12_u8(buf, afsk26_dem_tables[0][0].q, AFSK26_DEM_SUM_Q_0_0),
convolution12_u8(buf, afsk26_dem_tables[0][1].i, AFSK26_DEM_SUM_I_0_1),
convolution12_u8(buf, afsk26_dem_tables[0][1].q, AFSK26_DEM_SUM_Q_0_1));
demod_one_sample(sm, st, (*buf-0x80)<<8,
convolution12_u8(buf, afsk26_dem_tables[1][0].i, AFSK26_DEM_SUM_I_1_0),
convolution12_u8(buf, afsk26_dem_tables[1][0].q, AFSK26_DEM_SUM_Q_1_0),
convolution12_u8(buf, afsk26_dem_tables[1][1].i, AFSK26_DEM_SUM_I_1_1),
convolution12_u8(buf, afsk26_dem_tables[1][1].q, AFSK26_DEM_SUM_Q_1_1));
}
}
/* --------------------------------------------------------------------- */
static void demodulator_2666_s16(struct sm_state *sm, const short *buf, unsigned int buflen)
{
struct demod_state_afsk26 *st = (struct demod_state_afsk26 *)(&sm->d);
for (; buflen > 0; buflen--, buf++) {
demod_one_sample(sm, st, *buf,
convolution12_s16(buf, afsk26_dem_tables[0][0].i, AFSK26_DEM_SUM_I_0_0),
convolution12_s16(buf, afsk26_dem_tables[0][0].q, AFSK26_DEM_SUM_Q_0_0),
convolution12_s16(buf, afsk26_dem_tables[0][1].i, AFSK26_DEM_SUM_I_0_1),
convolution12_s16(buf, afsk26_dem_tables[0][1].q, AFSK26_DEM_SUM_Q_0_1));
demod_one_sample(sm, st, *buf,
convolution12_s16(buf, afsk26_dem_tables[1][0].i, AFSK26_DEM_SUM_I_1_0),
convolution12_s16(buf, afsk26_dem_tables[1][0].q, AFSK26_DEM_SUM_Q_1_0),
convolution12_s16(buf, afsk26_dem_tables[1][1].i, AFSK26_DEM_SUM_I_1_1),
convolution12_s16(buf, afsk26_dem_tables[1][1].q, AFSK26_DEM_SUM_Q_1_1));
}
}
/* --------------------------------------------------------------------- */
static void demod_init_2666(struct sm_state *sm)
{
struct demod_state_afsk26 *st = (struct demod_state_afsk26 *)(&sm->d);
st->dcd_time = 400;
st->dcd_sum0 = 2;
}
/* --------------------------------------------------------------------- */
const struct modem_tx_info sm_afsk2666_tx = {
"afsk2666", sizeof(struct mod_state_afsk26), AFSK26_SAMPLERATE, 2666,
modulator_2666_u8, modulator_2666_s16, NULL
};
const struct modem_rx_info sm_afsk2666_rx = {
"afsk2666", sizeof(struct demod_state_afsk26), AFSK26_SAMPLERATE, 2666, 12, 6,
demodulator_2666_u8, demodulator_2666_s16, demod_init_2666
};
/* --------------------------------------------------------------------- */
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