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/*****************************************************************************/

/*

 *      sm_afsk2400_8.c  -- soundcard radio modem driver, 2400 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.

 *

 */

/*

 * This driver is intended to be compatible with TCM3105 modems

 * overclocked to 8MHz. The mark and space frequencies therefore

 * lie at 3970 and 2165 Hz.

 * Note that I do _not_ recommend the building of such links, I provide

 * this only for the users who live in the coverage area of such

 * a "legacy" link.

 */

#include "sm.h"

#include "sm_tbl_afsk2400_8.h"

/* --------------------------------------------------------------------- */

struct demod_state_afsk24 {

        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_afsk24 {

        unsigned int shreg;

        unsigned char tx_bit;

        unsigned int bit_pll;

        unsigned int tx_seq;

        unsigned int phinc;

};

/* --------------------------------------------------------------------- */

static const int dds_inc[2] = { AFSK24_TX_FREQ_LO*0x10000/AFSK24_SAMPLERATE,

                                AFSK24_TX_FREQ_HI*0x10000/AFSK24_SAMPLERATE };

static void modulator_2400_u8(struct sm_state *sm, unsigned char *buf, unsigned int buflen)

{

        struct mod_state_afsk24 *st = (struct mod_state_afsk24 *)(&sm->m);

        for (; buflen > 0; buflen--, buf++) {

                if (st->tx_seq < 0x5555) {

                        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->phinc = dds_inc[st->tx_bit & 1];

                }

                st->tx_seq += 0x5555;

                st->tx_seq &= 0xffff;

                *buf = OFFSCOS(st->bit_pll);

                st->bit_pll += st->phinc;

        }

}

/* --------------------------------------------------------------------- */

static void modulator_2400_s16(struct sm_state *sm, short *buf, unsigned int buflen)

{

        struct mod_state_afsk24 *st = (struct mod_state_afsk24 *)(&sm->m);

        for (; buflen > 0; buflen--, buf++) {

                if (st->tx_seq < 0x5555) {

                        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->phinc = dds_inc[st->tx_bit & 1];

                }

                st->tx_seq += 0x5555;

                st->tx_seq &= 0xffff;

                *buf = COS(st->bit_pll);

                st->bit_pll += st->phinc;

        }

}

/* --------------------------------------------------------------------- */

extern __inline__ int convolution14_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]);

        sum += (st[-12] * coeff[12]);

        sum += (st[-13] * coeff[13]);

        sum >>= 7;

        return sum * sum;

}

extern __inline__ int convolution14_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 += (st[-12] * coeff[12]);

        sum += (st[-13] * coeff[13]);

        sum >>= 15;

        return sum * sum;

}

extern __inline__ int do_filter_2400_u8(const unsigned char *buf)

{

        int sum = convolution14_u8(buf, afsk24_tx_lo_i, SUM_AFSK24_TX_LO_I);

        sum += convolution14_u8(buf, afsk24_tx_lo_q, SUM_AFSK24_TX_LO_Q);

        sum -= convolution14_u8(buf, afsk24_tx_hi_i, SUM_AFSK24_TX_HI_I);

        sum -= convolution14_u8(buf, afsk24_tx_hi_q, SUM_AFSK24_TX_HI_Q);

        return sum;

}

extern __inline__ int do_filter_2400_s16(const short *buf)

{

        int sum = convolution14_s16(buf, afsk24_tx_lo_i, SUM_AFSK24_TX_LO_I);

        sum += convolution14_s16(buf, afsk24_tx_lo_q, SUM_AFSK24_TX_LO_Q);

        sum -= convolution14_s16(buf, afsk24_tx_hi_i, SUM_AFSK24_TX_HI_I);

        sum -= convolution14_s16(buf, afsk24_tx_hi_q, SUM_AFSK24_TX_HI_Q);

        return sum;

}

/* --------------------------------------------------------------------- */

static void demodulator_2400_u8(struct sm_state *sm, const unsigned char *buf, unsigned int buflen)

{

        struct demod_state_afsk24 *st = (struct demod_state_afsk24 *)(&sm->d);

        int j;

        int sum;

        unsigned char newsample;

        for (; buflen > 0; buflen--, buf++) {

                sum = do_filter_2400_u8(buf);

                st->dcd_shreg <<= 1;

                st->bit_pll += AFSK24_BITPLL_INC;

                newsample = (sum > 0);

                if (st->last_sample ^ newsample) {

                        st->last_sample = newsample;

                        st->dcd_shreg |= 1;

                        if (st->bit_pll < (0x8000+AFSK24_BITPLL_INC/2))

                                st->bit_pll += AFSK24_BITPLL_INC/2;

                        else

                                st->bit_pll -= AFSK24_BITPLL_INC/2;

                        j = /* 2 * */ hweight8(st->dcd_shreg & 0x1c)

                                - hweight16(st->dcd_shreg & 0x1e0);

                        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_2400_s16(struct sm_state *sm, const short *buf, unsigned int buflen)

{

        struct demod_state_afsk24 *st = (struct demod_state_afsk24 *)(&sm->d);

        int j;

        int sum;

        unsigned char newsample;

        for (; buflen > 0; buflen--, buf++) {

                sum = do_filter_2400_s16(buf);

                st->dcd_shreg <<= 1;

                st->bit_pll += AFSK24_BITPLL_INC;

                newsample = (sum > 0);

                if (st->last_sample ^ newsample) {

                        st->last_sample = newsample;

                        st->dcd_shreg |= 1;

                        if (st->bit_pll < (0x8000+AFSK24_BITPLL_INC/2))

                                st->bit_pll += AFSK24_BITPLL_INC/2;

                        else

                                st->bit_pll -= AFSK24_BITPLL_INC/2;

                        j = /* 2 * */ hweight8(st->dcd_shreg & 0x1c)

                                - hweight16(st->dcd_shreg & 0x1e0);

                        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_2400(struct sm_state *sm)

{

        struct demod_state_afsk24 *st = (struct demod_state_afsk24 *)(&sm->d);

        st->dcd_time = 120;

        st->dcd_sum0 = 2;

}

/* --------------------------------------------------------------------- */

const struct modem_tx_info sm_afsk2400_8_tx = {

        "afsk2400_8", sizeof(struct mod_state_afsk24), AFSK24_SAMPLERATE, 2400,

        modulator_2400_u8, modulator_2400_s16, NULL

};

const struct modem_rx_info sm_afsk2400_8_rx = {

        "afsk2400_8", sizeof(struct demod_state_afsk24),

        AFSK24_SAMPLERATE, 2400, 14, AFSK24_SAMPLERATE/2400,

        demodulator_2400_u8, demodulator_2400_s16, demod_init_2400

};

/* --------------------------------------------------------------------- */