text: //  Copyright (c) 2021, Qualcomm Innovation Center, Inc. All rights reserved.
  //
  //  Redistribution and use in source and binary forms, with or without
  //  modification, are permitted provided that the following conditions are met:
  //
  //  1. Redistributions of source code must retain the above copyright notice,
  //     this list of conditions and the following disclaimer.
  //
  //  2. Redistributions in binary form must reproduce the above copyright notice,
  //     this list of conditions and the following disclaimer in the documentation
  //     and/or other materials provided with the distribution.
  //
  //  3. Neither the name of the copyright holder nor the names of its contributors
  //     may be used to endorse or promote products derived from this software
  //     without specific prior written permission.
  //
  //  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  //  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  //  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  //  ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
  //  LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  //  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  //  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  //  INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  //  CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  //  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  //  POSSIBILITY OF SUCH DAMAGE.
  //
  //  SPDX-License-Identifier: BSD-3-Clause
  
  #ifndef VDDS_DATA_HPP
  #define VDDS_DATA_HPP
  
  #define _GNU_SOURCE 1
  
  #include <stdint.h>
  #include <memory>
  #include <array>
  
  namespace vdds {
  
  /// Base data type for PubSub operations.
  /// User-defined types shall be derived from this type.
  /// Sized to be exactly 256 bytes (4 cachelines on most CPUs).
  struct data {
  	/// Generic shared data type used with std::shared_ptr
  	struct shared_t {
  		virtual ~shared_t() { };
  	};
  
  	using shared_p = std::shared_ptr<shared_t>;
  	using seqno_t  = uint64_t;
  	using timestamp_t = uint64_t;
  
  	// Generic plain data type used for small payload
  	using plain_t = std::array<uint8_t, 256 - sizeof(seqno_t) - sizeof(timestamp_t) - sizeof(shared_p)>;
  
  	seqno_t     seqno;     ///< Sequence number set by vDDS publish operation.
  	timestamp_t timestamp; ///< Timestamp in nanoseconds (userdefined timebase).
  	shared_p    shared;    ///< Shared data. Used by derived types for shared payload.
  	plain_t     plain;     ///< Plain data. Used by derived types for plain payload.
  };
  
  } // namespace vdds
  
  #endif // VDDS_DATA_HPP
  