portapack-mayhem/firmware/baseband/stream_input.cpp

/*
 * Copyright (C) 2016 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 "stream_input.hpp"

#include "lpc43xx_cpp.hpp"
using namespace lpc43xx;

StreamInput::StreamInput(CaptureConfig* const config)
    : fifo_buffers_empty{buffers_empty.data(), buffer_count_max_log2},
      fifo_buffers_full{buffers_full.data(), buffer_count_max_log2},
      config{config},
      data{std::make_unique<uint8_t[]>(config->write_size * config->buffer_count)} {
    config->fifo_buffers_empty = &fifo_buffers_empty;
    config->fifo_buffers_full = &fifo_buffers_full;

    for (size_t i = 0; i < config->buffer_count; i++) {
        buffers[i] = {&(data.get()[i * config->write_size]), config->write_size};
        fifo_buffers_empty.in(&buffers[i]);
    }
}

size_t StreamInput::write(const void* const data, const size_t length) {
    const uint8_t* p = static_cast<const uint8_t*>(data);
    size_t written = 0;

    while (written < length) {
        if (!active_buffer) {
            // We need an empty buffer...
            if (!fifo_buffers_empty.out(active_buffer)) {
                // ...but none are available. Samples were dropped.
                break;
            }
        }

        const auto remaining = length - written;
        written += active_buffer->write(&p[written], remaining);

        if (active_buffer->is_full()) {
            if (!fifo_buffers_full.in(active_buffer)) {
                // FIFO is full of buffers, there's no place for this one.
                // Bail out of the loop, and try submitting the buffer in the
                // next pass.
                // This should never happen if the number of buffers is less
                // than the capacity of the FIFO.
                break;
            }
            active_buffer = nullptr;
            creg::m4txevent::assert_event();
        }
    }

    config->baseband_bytes_received += length;
    config->baseband_bytes_dropped += (length - written);

    return written;
}