90 lines
2.3 KiB
C
90 lines
2.3 KiB
C
/* V27 Modem
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*
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* (C) 2020 by Andreas Eversberg <jolly@eversberg.eu>
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* All Rights Reserved
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <stdio.h>
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#include <stdint.h>
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#include <string.h>
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#include "../liblogging/logging.h"
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#include "../libsample/sample.h"
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#include "modem.h"
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static int psk_send_bit(void *inst)
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{
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v27modem_t *modem = (v27modem_t *)inst;
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uint8_t bit;
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bit = modem->send_bit(modem->inst);
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bit = v27_scrambler_bit(&modem->scrambler, bit);
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return bit;
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}
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static void psk_receive_bit(void *inst, int bit)
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{
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v27modem_t *modem = (v27modem_t *)inst;
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bit = v27_scrambler_bit(&modem->descrambler, bit);
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modem->receive_bit(modem->inst, bit);
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}
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/* init psk */
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int v27_modem_init(v27modem_t *modem, void *inst, int (*send_bit)(void *inst), void (*receive_bit)(void *inst, int bit), int samplerate, int bis)
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{
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int rc = 0;
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memset(modem, 0, sizeof(*modem));
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modem->send_bit = send_bit;
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modem->receive_bit = receive_bit;
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modem->inst = inst;
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/* V.27bis/ter with 4800 bps */
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rc = psk_mod_init(&modem->psk_mod, modem, psk_send_bit, samplerate, 1600.0);
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if (rc)
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goto error;
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rc = psk_demod_init(&modem->psk_demod, modem, psk_receive_bit, samplerate, 1600.0);
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if (rc)
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goto error;
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v27_scrambler_init(&modem->scrambler, bis, 0);
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v27_scrambler_init(&modem->descrambler, bis, 1);
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return 0;
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error:
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v27_modem_exit(modem);
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return rc;
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}
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void v27_modem_exit(v27modem_t *modem)
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{
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psk_mod_exit(&modem->psk_mod);
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psk_demod_exit(&modem->psk_demod);
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}
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void v27_modem_send(v27modem_t *modem, sample_t *sample, int length)
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{
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psk_mod(&modem->psk_mod, sample, length);
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}
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void v27_modem_receive(v27modem_t *modem, sample_t *sample, int length)
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{
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psk_demod(&modem->psk_demod, sample, length);
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}
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