portapack-mayhem/firmware/baseband/proc_fsk.cpp

128 lines
3.6 KiB
C++

/*
* Copyright (C) 2014 Jared Boone, ShareBrained Technology, Inc.
*
* This file is part of PortaPack.
*
* 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, 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; see the file COPYING. If not, write to
* the Free Software Foundation, Inc., 51 Franklin Street,
* Boston, MA 02110-1301, USA.
*/
#include "proc_fsk.hpp"
#include "portapack_shared_memory.hpp"
#include "i2s.hpp"
using namespace lpc43xx;
FSKProcessor::FSKProcessor(
MessageHandlerMap& message_handlers
) : message_handlers(message_handlers)
{
message_handlers.register_handler(Message::ID::FSKConfiguration,
[this](const Message* const p) {
auto m = reinterpret_cast<const FSKConfigurationMessage*>(p);
this->configure(m->configuration);
}
);
}
FSKProcessor::~FSKProcessor() {
message_handlers.unregister_handler(Message::ID::FSKConfiguration);
}
void FSKProcessor::configure(const FSKConfiguration new_configuration) {
demod.configure(sampling_rate, 2 * new_configuration.symbol_rate);
clock_recovery.configure(sampling_rate / 4, new_configuration.symbol_rate);
access_code_correlator.configure(
new_configuration.access_code,
new_configuration.access_code_length,
new_configuration.access_code_tolerance
);
packet_builder.configure(new_configuration.packet_length);
}
void FSKProcessor::execute(buffer_c8_t buffer) {
/* 2.4576MHz, 2048 samples */
auto decimator_out = decimator.execute(buffer);
/* 153.6kHz, 128 samples */
const buffer_c16_t work_baseband_buffer {
(complex16_t*)decimator_out.p,
decimator_out.count
};
/* 153.6kHz complex<int16_t>[128]
* -> FIR filter, <?kHz (?fs) pass, gain 1.0
* -> 76.8kHz int16_t[64] */
auto channel = channel_filter.execute(decimator_out, work_baseband_buffer);
/* 76.8kHz, 64 samples */
feed_channel_stats(channel);
feed_channel_spectrum(
channel,
decimator_out.sampling_rate * channel_filter_taps.pass_frequency_normalized,
decimator_out.sampling_rate * channel_filter_taps.stop_frequency_normalized
);
// 76.8k
const buffer_s16_t work_demod_buffer {
(int16_t*)decimator_out.p,
decimator_out.count * sizeof(*decimator_out.p) / sizeof(int16_t)
};
auto demodulated = demod.execute(channel, work_demod_buffer);
// TODO: Factor out this hidden decimation magic.
for(size_t i=0; i<demodulated.count; i+=4) {
clock_recovery(demodulated.p[i] / 32768.0f);
}
i2s::i2s0::tx_mute();
}
void FSKProcessor::consume_symbol(
const float raw_symbol
) {
const auto payload_handler_fn = [this](
const std::bitset<256>& payload,
const size_t bits_received
) {
this->payload_handler(payload, bits_received);
};
const uint_fast8_t sliced_symbol = (raw_symbol >= 0.0f) ? 1 : 0;
const auto decoded_symbol = nrzi_decode(sliced_symbol);
const bool access_code_found = access_code_correlator(decoded_symbol);
packet_builder.execute(
decoded_symbol,
access_code_found,
payload_handler_fn
);
}
void FSKProcessor::payload_handler(
const std::bitset<256>& payload,
const size_t bits_received
) {
FSKPacketMessage message;
message.packet.payload = payload;
message.packet.bits_received = bits_received;
shared_memory.application_queue.push(message);
}