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;
}