portapack-mayhem/firmware/common/message_queue.hpp

/*
 * Copyright (C) 2015 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.
 */

#ifndef __MESSAGE_QUEUE_H__
#define __MESSAGE_QUEUE_H__

#include <cstdint>

#include "message.hpp"
#include "fifo.hpp"

#include <ch.h>

class MessageQueue {
   public:
    MessageQueue() = delete;
    MessageQueue(const MessageQueue&) = delete;
    MessageQueue(MessageQueue&&) = delete;

    MessageQueue(
        uint8_t* const data,
        size_t k)
        : fifo{data, k} {
        chMtxInit(&mutex_write);
    }

    template <typename T>
    bool push(const T& message) {
        static_assert(sizeof(T) <= Message::MAX_SIZE, "Message::MAX_SIZE too small for message type");
        static_assert(std::is_base_of<Message, T>::value, "type is not based on Message");

        return push(&message, sizeof(message));
    }

    template <typename T>
    bool push_and_wait(const T& message) {
        const bool result = push(message);
        if (result) {
            // TODO: More graceful method of waiting for empty? Maybe sleep for a bit?
            while (!is_empty())
                ;
        }
        return result;
    }

    template <typename HandlerFn>
    void handle(HandlerFn handler) {
        std::array<uint8_t, Message::MAX_SIZE> message_buffer;
        while (Message* const message = peek(message_buffer)) {
            handler(message);
            skip();
        }
    }

    bool is_empty() const {
        return fifo.is_empty();
    }

    void reset() {
        fifo.reset();
    }

   private:
    FIFO<uint8_t> fifo;
    Mutex mutex_write{};

    Message* peek(std::array<uint8_t, Message::MAX_SIZE>& buf) {
        Message* const p = reinterpret_cast<Message*>(buf.data());
        return fifo.peek_r(buf.data(), buf.size()) ? p : nullptr;
    }

    bool skip() {
        return fifo.skip();
    }

    Message* pop(std::array<uint8_t, Message::MAX_SIZE>& buf) {
        Message* const p = reinterpret_cast<Message*>(buf.data());
        return fifo.out_r(buf.data(), buf.size()) ? p : nullptr;
    }

    size_t len() const {
        return fifo.len();
    }

    bool push(const void* const buf, const size_t len) {
        bool lock_success = chMtxTryLock(&mutex_write);
        if (!lock_success) {
            return false;
        }

        const auto result = fifo.in_r(buf, len);
        chMtxUnlock();

        const bool success = (result == len);
        if (success) {
            signal();
        }
        return success;
    }

    void signal();
};

#endif /*__MESSAGE_QUEUE_H__*/