www.pudn.com > soundmodem.rar > sm_psk4800.c
/*****************************************************************************/
/*
* sm_psk4800.c -- soundcard radio modem driver, 4800 baud 8PSK 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_psk4800.h"
/* --------------------------------------------------------------------- */
#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 */
#define SCRAM_SHIFT 17
/* --------------------------------------------------------------------- */
struct demod_state_psk48 {
/*
* input mixer and lowpass
*/
short infi[PSK48_RXF_LEN/2], infq[PSK48_RXF_LEN/2];
unsigned int downmixer;
int ovrphase;
short magi, magq;
/*
* sampling instant recovery
*/
int pwrhist[5];
unsigned int s_phase;
int cur_sync;
/*
* phase recovery
*/
short cur_phase_dev;
short last_ph_err;
unsigned short pskph;
unsigned int phase;
unsigned short last_pskph;
unsigned char cur_raw, last_raw, rawbits;
/*
* decoding
*/
unsigned int shreg;
unsigned long descram;
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_psk48 {
unsigned char txbits[PSK48_TXF_NUMSAMPLES];
unsigned short txphase;
unsigned int shreg;
unsigned long scram;
const short *tbl;
unsigned int txseq;
};
/* --------------------------------------------------------------------- */
static void modulator_4800_u8(struct sm_state *sm, unsigned char *buf, unsigned int buflen)
{
struct mod_state_psk48 *st = (struct mod_state_psk48 *)(&sm->m);
int i, j;
int si, sq;
for (; buflen > 0; buflen--, buf++) {
if (!st->txseq++) {
memmove(st->txbits+1, st->txbits,
sizeof(st->txbits)-sizeof(st->txbits[0]));
for (i = 0; i < 3; i++) {
if (st->shreg <= 1)
st->shreg = hdlcdrv_getbits(&sm->hdrv) | 0x10000;
st->scram = (st->scram << 1) |
(st->shreg & 1);
st->shreg >>= 1;
if (st->scram & SCRAM_TAP1)
st->scram ^= SCRAM_TAPN;
}
j = (st->scram >> (SCRAM_SHIFT+3)) & 7;
st->txbits[0] -= (j ^ (j >> 1));
st->txbits[0] &= 7;
st->tbl = psk48_tx_table;
}
if (st->txseq >= PSK48_TXF_OVERSAMPLING)
st->txseq = 0;
for (j = si = sq = 0; j < PSK48_TXF_NUMSAMPLES; j++, st->tbl += 16) {
si += st->tbl[st->txbits[j]];
sq += st->tbl[st->txbits[j]+8];
}
*buf = ((si*COS(st->txphase)+ sq*SIN(st->txphase)) >> 23) + 0x80;
st->txphase = (st->txphase + PSK48_PHASEINC) & 0xffffu;
}
}
/* --------------------------------------------------------------------- */
static void modulator_4800_s16(struct sm_state *sm, short *buf, unsigned int buflen)
{
struct mod_state_psk48 *st = (struct mod_state_psk48 *)(&sm->m);
int i, j;
int si, sq;
for (; buflen > 0; buflen--, buf++) {
if (!st->txseq++) {
memmove(st->txbits+1, st->txbits,
sizeof(st->txbits)-sizeof(st->txbits[0]));
for (i = 0; i < 3; i++) {
if (st->shreg <= 1)
st->shreg = hdlcdrv_getbits(&sm->hdrv) | 0x10000;
st->scram = (st->scram << 1) |
(st->shreg & 1);
st->shreg >>= 1;
if (st->scram & SCRAM_TAP1)
st->scram ^= SCRAM_TAPN;
}
j = (st->scram >> (SCRAM_SHIFT+3)) & 7;
st->txbits[0] -= (j ^ (j >> 1));
st->txbits[0] &= 7;
st->tbl = psk48_tx_table;
}
if (st->txseq >= PSK48_TXF_OVERSAMPLING)
st->txseq = 0;
for (j = si = sq = 0; j < PSK48_TXF_NUMSAMPLES; j++, st->tbl += 16) {
si += st->tbl[st->txbits[j]];
sq += st->tbl[st->txbits[j]+8];
}
*buf = (si*COS(st->txphase)+ sq*SIN(st->txphase)) >> 15;
st->txphase = (st->txphase + PSK48_PHASEINC) & 0xffffu;
}
}
/* --------------------------------------------------------------------- */
static __inline__ unsigned short tbl_atan(short q, short i)
{
short tmp;
unsigned short argoffs = 0;
if (i == 0 && q == 0)
return 0;
switch (((q < 0) << 1) | (i < 0)) {
case 0:
break;
case 1:
tmp = q;
q = -i;
i = tmp;
argoffs = 0x4000;
break;
case 3:
q = -q;
i = -i;
argoffs = 0x8000;
break;
case 2:
tmp = -q;
q = i;
i = tmp;
argoffs = 0xc000;
break;
}
if (q > i) {
tmp = i / q * ATAN_TABLEN;
return (argoffs+0x4000-atan_tab[((i<<15)/q*ATAN_TABLEN>>15)])
&0xffffu;
}
return (argoffs+atan_tab[((q<<15)/i*ATAN_TABLEN)>>15])&0xffffu;
}
#define ATAN(q,i) tbl_atan(q, i)
/* --------------------------------------------------------------------- */
static void demod_psk48_baseband(struct sm_state *sm, struct demod_state_psk48 *st,
short vali, short valq)
{
int i, j;
st->magi = vali;
st->magq = valq;
memmove(st->pwrhist+1, st->pwrhist,
sizeof(st->pwrhist)-sizeof(st->pwrhist[0]));
st->pwrhist[0] = st->magi * st->magi +
st->magq * st->magq;
st->cur_sync = ((st->pwrhist[4] >> 2) > st->pwrhist[2] &&
(st->pwrhist[0] >> 2) > st->pwrhist[2] &&
st-> pwrhist[3] > st->pwrhist[2] &&
st->pwrhist[1] > st->pwrhist[2]);
st->s_phase &= 0xffff;
st->s_phase += PSK48_SPHASEINC;
st->dcd_shreg <<= 1;
if (st->cur_sync) {
if (st->s_phase >= (0x8000 + 5*PSK48_SPHASEINC/2))
st->s_phase -= PSK48_SPHASEINC/6;
else
st->s_phase += PSK48_SPHASEINC/6;
st->dcd_sum0 = 4*hweight8(st->dcd_shreg & 0xf8)-
hweight16(st->dcd_shreg & 0x1f00);
}
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 = 240;
}
if (st->s_phase < 0x10000)
return;
/*
* sample one constellation
*/
st->last_pskph = st->pskph;
st->pskph = (ATAN(st->magq, st->magi)-
st->phase) & 0xffffu;
st->last_ph_err = (st->pskph & 0x1fffu) - 0x1000;
st->phase += st->last_ph_err/16;
st->last_raw = st->cur_raw;
st->cur_raw = ((st->pskph >> 13) & 7);
i = (st->cur_raw - st->last_raw) & 7;
st->rawbits = i ^ (i >> 1) ^ (i >> 2);
st->descram = (st->descram << 3) | (st->rawbits);
hdlcdrv_channelbit(&sm->hdrv, st->descram & 4);
hdlcdrv_channelbit(&sm->hdrv, st->descram & 2);
hdlcdrv_channelbit(&sm->hdrv, st->descram & 1);
i = (((st->descram >> DESCRAM_TAPSH1) & 7) ^
((st->descram >> DESCRAM_TAPSH2) & 7) ^
((st->descram >> DESCRAM_TAPSH3) & 7));
for (j = 4; j; j >>= 1) {
st->shreg >>= 1;
st->shreg |= (!!(i & j)) << 16;
if (st->shreg & 1) {
hdlcdrv_putbits(&sm->hdrv, st->shreg >> 1);
st->shreg = 0x10000;
}
}
#if 0
st->dcd_shreg <<= 1;
st->bit_pll += 0x4000;
curbit = (*buf >= 0x80);
if (st->last_sample ^ curbit) {
st->dcd_shreg |= 1;
st->bit_pll += pll_corr
[st->bit_pll < 0xa000];
st->dcd_sum0 += 8 *
hweight8(st->dcd_shreg & 0x0c) -
!!(st->dcd_shreg & 0x10);
}
st->last_sample = curbit;
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 = 240;
}
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);
}
diag_add_one(sm, ((short)(*buf - 0x80)) << 8);
#endif
diag_trigger(sm);
diag_add_constellation(sm, (vali*COS(st->phase)+ valq*SIN(st->phase)) >> 13,
(valq*COS(st->phase) - vali*SIN(st->phase)) >> 13);
}
/* --------------------------------------------------------------------- */
static void demodulator_4800_u8(struct sm_state *sm, const unsigned char *buf, unsigned int buflen)
{
struct demod_state_psk48 *st = (struct demod_state_psk48 *)(&sm->d);
int i, si, sq;
const short *coeff;
for (; buflen > 0; buflen--, buf++) {
memmove(st->infi+1, st->infi,
sizeof(st->infi)-sizeof(st->infi[0]));
memmove(st->infq+1, st->infq,
sizeof(st->infq)-sizeof(st->infq[0]));
si = *buf;
si &= 0xff;
si -= 128;
diag_add_one(sm, si << 8);
st->infi[0] = (si * COS(st->downmixer))>>7;
st->infq[0] = (si * SIN(st->downmixer))>>7;
st->downmixer = (st->downmixer-PSK48_PHASEINC)&0xffffu;
for (i = si = sq = 0, coeff = psk48_rx_coeff; i < (PSK48_RXF_LEN/2);
i++, coeff += 2) {
si += st->infi[i] * (*coeff);
sq += st->infq[i] * (*coeff);
}
demod_psk48_baseband(sm, st, si >> 15, sq >> 15);
for (i = si = sq = 0, coeff = psk48_rx_coeff + 1; i < (PSK48_RXF_LEN/2);
i++, coeff += 2) {
si += st->infi[i] * (*coeff);
sq += st->infq[i] * (*coeff);
}
demod_psk48_baseband(sm, st, si >> 15, sq >> 15);
}
}
/* --------------------------------------------------------------------- */
static void demodulator_4800_s16(struct sm_state *sm, const short *buf, unsigned int buflen)
{
struct demod_state_psk48 *st = (struct demod_state_psk48 *)(&sm->d);
int i, si, sq;
const short *coeff;
for (; buflen > 0; buflen--, buf++) {
memmove(st->infi+1, st->infi,
sizeof(st->infi)-sizeof(st->infi[0]));
memmove(st->infq+1, st->infq,
sizeof(st->infq)-sizeof(st->infq[0]));
si = *buf;
diag_add_one(sm, si);
st->infi[0] = (si * COS(st->downmixer))>>15;
st->infq[0] = (si * SIN(st->downmixer))>>15;
st->downmixer = (st->downmixer-PSK48_PHASEINC)&0xffffu;
for (i = si = sq = 0, coeff = psk48_rx_coeff; i < (PSK48_RXF_LEN/2);
i++, coeff += 2) {
si += st->infi[i] * (*coeff);
sq += st->infq[i] * (*coeff);
}
demod_psk48_baseband(sm, st, si >> 15, sq >> 15);
for (i = si = sq = 0, coeff = psk48_rx_coeff + 1; i < (PSK48_RXF_LEN/2);
i++, coeff += 2) {
si += st->infi[i] * (*coeff);
sq += st->infq[i] * (*coeff);
}
demod_psk48_baseband(sm, st, si >> 15, sq >> 15);
}
}
/* --------------------------------------------------------------------- */
static void mod_init_4800(struct sm_state *sm)
{
struct mod_state_psk48 *st = (struct mod_state_psk48 *)(&sm->m);
st->scram = 1;
}
/* --------------------------------------------------------------------- */
static void demod_init_4800(struct sm_state *sm)
{
struct demod_state_psk48 *st = (struct demod_state_psk48 *)(&sm->d);
st->dcd_time = 120;
st->dcd_sum0 = 2;
}
/* --------------------------------------------------------------------- */
const struct modem_tx_info sm_psk4800_tx = {
"psk4800", sizeof(struct mod_state_psk48),
PSK48_SAMPLERATE, 4800,
modulator_4800_u8, modulator_4800_s16, mod_init_4800
};
const struct modem_rx_info sm_psk4800_rx = {
"psk4800", sizeof(struct demod_state_psk48),
PSK48_SAMPLERATE, 4800, 1, PSK48_TXF_OVERSAMPLING,
demodulator_4800_u8, demodulator_4800_s16, demod_init_4800
};
/* --------------------------------------------------------------------- */