portapack-mayhem/firmware/application/hw/spi_arbiter.hpp

/*
 * Copyright (C) 2014 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 __SPI_ARBITER_H__
#define __SPI_ARBITER_H__

#include <cstddef>

#include "spi_pp.hpp"

namespace spi {
namespace arbiter {

class Arbiter {
   public:
    constexpr Arbiter(
        SPI& bus)
        : _bus(bus),
          _config(nullptr) {
    }

    void transfer(const SPIConfig* const config, void* const data, const size_t count) {
        if (config != _config) {
            _bus.stop();
            _bus.start(*config);
            _config = config;
        }
        _bus.transfer(data, count);
    }

   private:
    SPI& _bus;
    const SPIConfig* _config;
};

class Target {
   public:
    constexpr Target(
        Arbiter& arbiter,
        const SPIConfig& config)
        : _arbiter(arbiter),
          _config(config) {
    }

    void transfer(void* const data, const size_t count) {
        _arbiter.transfer(&_config, data, count);
    }

   private:
    Arbiter& _arbiter;
    const SPIConfig _config;
};

}  // namespace arbiter
}  // namespace spi

#endif /*__SPI_ARBITER_H__*/