portapack-mayhem/firmware/baseband/proc_sstvtx.cpp

/*
 * Copyright (C) 2015 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_sstvtx.hpp"
#include "sine_table_int8.hpp"
#include "event_m4.hpp"

#include <cstdint>

// This is called at 3072000/2048 = 1500Hz
void SSTVTXProcessor::execute(const buffer_c8_t& buffer) {
    if (!configured) return;

    for (size_t i = 0; i < buffer.count; i++) {
        if (!sample_count) {
            // This FSM is a mess. It seems to do a lot where it shouldn't (I/Q loop),
            // but it actually doesn't do much. Used for sequencing the different parts
            // of the scanline. Todo: simplify !

            if (state == STATE_CALIBRATION) {
                // Once per picture
                tone_delta = calibration_sequence[substep].first;
                sample_count = calibration_sequence[substep].second;
                if (substep == 2) {
                    substep = 0;
                    state = STATE_VIS;
                } else
                    substep++;
            } else if (state == STATE_VIS) {
                // Once per picture
                if (substep == 10) {
                    current_scanline = &scanline_buffer[buffer_flip];
                    buffer_flip ^= 1;
                    // Ask application for a new scanline
                    shared_memory.application_queue.push(sig_message);
                    // Do we have to transmit a start tone ?
                    if (current_scanline->start_tone.duration) {
                        state = STATE_SYNC;
                        tone_delta = current_scanline->start_tone.frequency;
                        sample_count = current_scanline->start_tone.duration;
                    } else {
                        state = STATE_PIXELS;
                        tone_delta = current_scanline->gap_tone.frequency;
                        sample_count = current_scanline->gap_tone.duration;
                    }
                } else {
                    tone_delta = vis_code_sequence[substep];
                    sample_count = SSTV_MS2S(30);  // A VIS code bit is 30ms
                    substep++;
                }
            } else if (state == STATE_SYNC) {
                // Once per scanline, optional
                state = STATE_PIXELS;
                tone_delta = current_scanline->gap_tone.frequency;
                sample_count = current_scanline->gap_tone.duration;
            } else if (state == STATE_PIXELS) {
                // Many times per scanline
                tone_delta = SSTV_F2D(1500 + ((current_scanline->luma[pixel_index] * 800) / 256));
                sample_count = pixel_duration;
                pixel_index++;

                if (pixel_index >= 320) {
                    // Scanline done, (dirty) state jump
                    pixel_index = 0;
                    state = STATE_VIS;
                    substep = 10;
                }
            }
        } else {
            sample_count--;
        }

        // Tone synth
        tone_sample = (sine_table_i8[(tone_phase & 0xFF000000U) >> 24]);
        tone_phase += tone_delta;

        // FM
        delta = tone_sample * fm_delta;

        phase += delta;
        sphase = phase + (64 << 24);

        re = (sine_table_i8[(sphase & 0xFF000000U) >> 24]);
        im = (sine_table_i8[(phase & 0xFF000000U) >> 24]);

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

void SSTVTXProcessor::on_message(const Message* const msg) {
    const auto message = *reinterpret_cast<const SSTVConfigureMessage*>(msg);
    uint8_t vis_code;

    switch (msg->id) {
        case Message::ID::SSTVConfigure:
            pixel_duration = message.pixel_duration;

            if (!pixel_duration) {
                configured = false;  // Shutdown
                return;
            }

            vis_code = message.vis_code;

            // VIS code:
            // 1200, (0=1300, 1=1100), 1200
            vis_code_sequence[0] = SSTV_VIS_SS;
            for (uint32_t c = 0; c < 8; c++)
                vis_code_sequence[c + 1] = ((vis_code >> c) & 1) ? SSTV_VIS_ONE : SSTV_VIS_ZERO;
            vis_code_sequence[9] = SSTV_VIS_SS;

            fm_delta = 9000 * (0xFFFFFFULL / 3072000);  // Fixed bw for now

            pixel_index = 0;
            sample_count = 0;
            tone_phase = 0;
            state = STATE_CALIBRATION;
            substep = 0;

            configured = true;
            break;

        case Message::ID::FIFOData:
            memcpy(&scanline_buffer[buffer_flip], static_cast<const FIFODataMessage*>(msg)->data, sizeof(sstv_scanline));
            break;

        default:
            break;
    }
}

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