mayhem-firmware/firmware/baseband/proc_ook.cpp

/*
 * Copyright (C) 2014 Jared Boone, ShareBrained Technology, Inc.
 * Copyright (C) 2016 Furrtek
 *
 * 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_ook.hpp"
#include "portapack_shared_memory.hpp"
#include "sine_table_int8.hpp"
#include "event_m4.hpp"

#include <cstdint>

inline void OOKProcessor::write_sample(const buffer_c8_t& buffer, uint8_t bit_value, size_t i) {
	int8_t re, im;

	if (bit_value) {
		phase = (phase + 200);			// What ?
		sphase = phase + (64 << 18);

		re = (sine_table_i8[(sphase & 0x03FC0000) >> 18]);
		im = (sine_table_i8[(phase & 0x03FC0000) >> 18]);
	} else {
		re = 0;
		im = 0;
	}

	buffer.p[i] = {re, im};
}

bool OOKProcessor::scan_init(unsigned int order) {
	if (order > MAX_DE_BRUIJN_ORDER)
		return false;

	scan_done = false;
	scan_progress = 0;

	k = 0;
	idx = 1;

	duval_symbols = 2; // 2 for binary, 3 for ternary encoders
	duval_length = 0;
	duval_bit = 0;
	duval_sample_bit = 0;
	duval_symbol = 0;

	memset(v, 0, sizeof(v));
	return true;
}

bool OOKProcessor::scan_encode(const buffer_c8_t& buffer, size_t& buf_ptr) {
	// encode data: 0 = 1000, 1 = 1110
	// @TODO: make this user-configurable
	const uint8_t sym[] = { 0b0001, 0b0111 };
	constexpr auto symbol_length = 4;

	// iterate over every symbol in the sequence and convert it to bits with required bitrate
	for (; duval_bit < duval_length; duval_bit++) {
		auto val = v_tmp[duval_bit];
		for (; duval_symbol < symbol_length; duval_symbol++) {
			auto s = sym[val] & (1 << duval_symbol);
			for (; duval_sample_bit < samples_per_bit; duval_sample_bit++) {
				if (buf_ptr >= buffer.count) {
					// buffer is full - continue next time
					txprogress_message.done = false;
					txprogress_message.progress = scan_progress++;
					shared_memory.application_queue.push(txprogress_message);
					return false;
				}
				write_sample(buffer, s, buf_ptr++);
			}
			duval_sample_bit = 0;
		}
		duval_symbol = 0;
	}
	duval_bit = 0;
	return true;
}

inline size_t OOKProcessor::duval_algo_step() {
	size_t buf_ptr = 0;
	const unsigned int w = de_bruijn_length;

	// Duval's algorithm for generating de Bruijn sequence
	while (idx) {
		if (w % idx == 0) {
			for (unsigned int k = 0; k < idx; k++)
				v_tmp[buf_ptr++] = v[k];
			k = 0;
		}

		for (unsigned int j = 0; j < w - idx; j++)
			v[idx + j] = v[j];

		for (idx = w; (idx > 0) && (v[idx - 1] >= duval_symbols - 1); idx--) ;

		if (idx)
			v[idx - 1]++;

		if (buf_ptr) {
			// we fill at most de_bruijn_length number of elements
			return buf_ptr;
		}
	}

	return 0;
}

void OOKProcessor::scan_process(const buffer_c8_t& buffer) {
	size_t buf_ptr = 0;

	// transmit any leftover bits from previous step
	if (!scan_encode(buffer, buf_ptr))
		return;

	while (1) {
		// calculate next chunk of deBruijn sequence
		duval_length = duval_algo_step();

		if (duval_length == 0) {
			// last chunk - done
			if (!scan_done) {
				txprogress_message.done = true;
				shared_memory.application_queue.push(txprogress_message);
			}
			scan_done = 1;

			// clear the remaining buffer in case we have any bytes left
			for (size_t i = buf_ptr; i < buffer.count; i++)
				buffer.p[i] = { 0, 0 };

			break;
		}

		duval_bit = 0;
		duval_sample_bit = 0;
		duval_symbol = 0;

		// encode the sequence into required format
		if (!scan_encode(buffer, buf_ptr))
			break;
	}
}

void OOKProcessor::execute(const buffer_c8_t& buffer) {
	// This is called at 2.28M/2048 = 1113Hz

	if (!configured) return;

	if (de_bruijn_length) {
		scan_process(buffer);
		return;
	}

	for (size_t i = 0; i < buffer.count; i++) {

		// Synthesis at 2.28M/10 = 228kHz
		if (!s) {
			s = 10 - 1;
			if (sample_count >= samples_per_bit) {
				if (configured) {
					if (bit_pos >= length) {
						// End of data
						if (pause_counter == 0) {
							pause_counter = pause;
							cur_bit = 0;
						} else if (pause_counter == 1) {
							if (repeat_counter < repeat) {
								// Repeat
								cur_bit = shared_memory.bb_data.data[0] & 0x80;
								txprogress_message.progress = repeat_counter + 1;
								txprogress_message.done = false;
								shared_memory.application_queue.push(txprogress_message);
								bit_pos = 1;
								repeat_counter++;
							} else {
								// Stop
								cur_bit = 0;
								txprogress_message.done = true;
								shared_memory.application_queue.push(txprogress_message);
								configured = false;
							}
							pause_counter = 0;
						} else {
							pause_counter--;
						}
					} else {
						cur_bit = (shared_memory.bb_data.data[bit_pos >> 3] << (bit_pos & 7)) & 0x80;
						bit_pos++;
					}
				}

				sample_count = 0;
			} else {
				sample_count++;
			}
		} else {
			s--;
		}

		write_sample(buffer, cur_bit, i);
	}
}

void OOKProcessor::on_message(const Message* const p) {
	const auto message = *reinterpret_cast<const OOKConfigureMessage*>(p);

	if (message.id == Message::ID::OOKConfigure) {
		configured = false;

		repeat = message.repeat - 1;
		length = message.stream_length;
		pause = message.pause_symbols + 1;
		de_bruijn_length = message.de_bruijn_length;
		samples_per_bit = message.samples_per_bit;

		if (!length && !samples_per_bit) {
			// shutdown
			return;
		}

		if (de_bruijn_length) {
			if (!scan_init(de_bruijn_length))
				return;
		} else {
			samples_per_bit /= 10;
		}

		pause_counter = 0;
		s = 0;
		sample_count = samples_per_bit;
		repeat_counter = 0;
		bit_pos = 0;
		cur_bit = 0;
		txprogress_message.progress = 0;
		txprogress_message.done = false;
		configured = true;
	}
}

int main() {
	EventDispatcher event_dispatcher { std::make_unique<OOKProcessor>() };
	event_dispatcher.run();
	return 0;
}