base.h

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/* Copyright (c) 2008-2022 the MRtrix3 contributors.
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 *
 * Covered Software is provided under this License on an "as is"
 * basis, without warranty of any kind, either expressed, implied, or
 * statutory, including, without limitation, warranties that the
 * Covered Software is free of defects, merchantable, fit for a
 * particular purpose or non-infringing.
 * See the Mozilla Public License v. 2.0 for more details.
 *
 * For more details, see http://www.mrtrix.org/.
 */
 
#ifndef __image_io_base_h__
#define __image_io_base_h__
 
#include <cassert>
#include <cstdint>
#include <unistd.h>
 
#include "memory.h"
#include "mrtrix.h"
#include "types.h"
#include "file/entry.h"
 
#define MAX_FILES_PER_IMAGE 256U
 
namespace MR
{
 
  class Header;
 
 
  namespace ImageIO
  {
 
    class Base
    { NOMEMALIGN
      public:
        Base (const Header& header);
        Base (Base&&) noexcept = default;
        Base (const Base&) = delete;
        Base& operator=(const Base&) = delete;
 
        virtual ~Base ();
 
        virtual bool is_file_backed () const;
 
        // buffer_size is only used for scratch data; it is ignored in all
        // other (file-backed) handlers, where the buffer size is determined
        // from the information in the header
        void open (const Header& header, size_t buffer_size = 0);
        void close (const Header& header);
 
        bool is_image_new () const { return is_new; }
        bool is_image_readwrite () const { return writable; }
 
        void set_readwrite (bool readwrite) {
          writable = readwrite;
        }
        void set_image_is_new (bool image_is_new) {
          is_new = image_is_new;
        }
        void set_readwrite_if_existing (bool readwrite) {
          if (!is_new) 
            writable = readwrite;
        }
 
        uint8_t* segment (size_t n) const {
          assert (n < addresses.size());
          return addresses[n].get();
        }
        size_t nsegments () const {
          return addresses.size();
        }
        size_t segment_size () const {
          check();
          return segsize;
        }
 
        vector<File::Entry> files;
 
        void merge (const Base& B) {
          assert (addresses.empty());
          for (size_t n = 0; n < B.files.size(); ++n) 
            files.push_back (B.files[n]);
          segsize += B.segsize;
        }
 
        friend std::ostream& operator<< (std::ostream& stream, const Base& B) {
          stream << str (B.files.size()) << " files, segsize " << str(B.segsize)
            << ", is " << (B.is_new ? "" : "NOT ") << "new, " << (B.writable ? "read/write" : "read-only");
          return stream;
        }
 
      protected:
        size_t segsize;
        vector<std::unique_ptr<uint8_t[]>> addresses;
        bool is_new, writable;
 
        void check () const {
          assert (addresses.size());
        }
        virtual void load (const Header& header, size_t buffer_size) = 0;
        virtual void unload (const Header& header) = 0;
    };
 
  }
 
}
 
#endif