src/libs/decoders/mp3_seek_table.h

/*
 * DOSBox-X MP3 Seek Table Handler
 * -------------------------------
 * See mp3_seek_table.cpp for more documentation.
 *
 * The seek table handler makes use of the following single-header
 * public libraries:
 *   - dr_mp3: http://mackron.github.io/dr_mp3.html, by David Reid
 *   - archive: https://github.com/voidah/archive, by Arthur Ouellet
 *   - xxHash: http://cyan4973.github.io/xxHash, by Yann Collet
 *
 *  Copyright (C) 2020       The DOSBox-X Team
 *  Copyright (C) 2018-2019  Kevin R. Croft <krcroft@gmail.com>
 *
 *  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 of the License, 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; if not, write to the Free Software Foundation, Inc.,
 *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 */

#include <vector>    // provides: vector
#include <SDL.h>     // provides: SDL_RWops
#include "archive.h" // provides: archive

// Ensure we only get the API
#ifdef DR_MP3_IMPLEMENTATION
#  undef DR_MP3_IMPLEMENTATION
#endif
#include "dr_mp3.h" // provides: drmp3

// Note: this C++ struct must match (in binary-form) the "drmp3_seek_point" struct
//       defined in dr_mp3.h.  If that changes, then update this to match, along
//       with adjusting the Serialize() template function that union's the values.
//
struct drmp3_seek_point_serial {
    drmp3_uint64 seekPosInBytes;      // Points to the first byte of an MP3 frame.
    drmp3_uint64 pcmFrameIndex;       // The index of the PCM frame this seek point targets.
    drmp3_uint16 mp3FramesToDiscard;  // The number of whole MP3 frames to be discarded before pcmFramesToDiscard.
    drmp3_uint16 pcmFramesToDiscard;
    template <class T> void Serialize(T& archive) {
            archive & seekPosInBytes & pcmFrameIndex & mp3FramesToDiscard & pcmFramesToDiscard;
    }
};

// Our private-decoder structure where we hold:
//   - a pointer to the working dr_mp3 instance
//   - a template vector of seek_points (the serializeable form)
struct mp3_t {
    drmp3* p_dr = nullptr;    // the actual drmp3 instance we open, read, and seek within
    std::vector<drmp3_seek_point_serial> seek_points_vector = {};
};

uint64_t populate_seek_points(struct SDL_RWops* const context,
                              mp3_t* p_mp3,
                              const char* seektable_filename,
                              bool &result);