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CLK/Storage/Disk/DiskImage/DiskImage.hpp

98 lines
3.1 KiB
C++

//
// DiskImage.hpp
// Clock Signal
//
// Created by Thomas Harte on 21/09/2017.
// Copyright © 2017 Thomas Harte. All rights reserved.
//
#ifndef DiskImage_hpp
#define DiskImage_hpp
#include <map>
#include <memory>
#include "../Disk.hpp"
#include "../Track/Track.hpp"
namespace Storage {
namespace Disk {
/*!
Models a disk image as a collection of tracks, plus a range of possible track positions.
The intention is not that tracks necessarily be evenly spaced; a head_position_count of 3 wih track
A appearing in positions 0 and 1, and track B appearing in position 2 is an appropriate use of this API
if it matches the media.
*/
class DiskImage {
public:
virtual ~DiskImage() {}
/*!
@returns the number of discrete positions that this disk uses to model its complete surface area.
This is not necessarily a track count. There is no implicit guarantee that every position will
return a distinct track, or — e.g. if the media is holeless — will return any track at all.
*/
virtual unsigned int get_head_position_count() = 0;
/*!
@returns the number of heads (and, therefore, impliedly surfaces) available on this disk.
*/
virtual unsigned int get_head_count() { return 1; }
/*!
@returns the @c Track at @c position underneath @c head if there are any detectable events there;
returns @c nullptr otherwise.
*/
virtual std::shared_ptr<Track> get_track_at_position(unsigned int head, unsigned int position) = 0;
/*!
Replaces the Track at position @c position underneath @c head with @c track. Ignored if this disk is read-only.
Subclasses that are not read-only should use the protected methods @c get_is_modified and, optionally,
@c get_modified_track_at_position to query for changes when closing.
*/
virtual void set_track_at_position(unsigned int head, unsigned int position, const std::shared_ptr<Track> &track) {}
/*!
@returns whether the disk image is read only. Defaults to @c true if not overridden.
*/
virtual bool get_is_read_only() { return true; }
};
class DiskImageHolderBase: public Disk {
protected:
int get_id_for_track_at_position(unsigned int head, unsigned int position);
std::map<int, std::shared_ptr<Track>> cached_tracks_;
std::unique_ptr<Concurrency::AsyncTaskQueue> update_queue_;
};
/*!
Provides a wrapper that wraps a DiskImage to make it into a Disk, providing caching and,
thereby, an intermediate store for modified tracks so that mutable disk images can either
update on the fly or perform a block update on closure, as appropriate.
*/
template <typename T> class DiskImageHolder: public DiskImageHolderBase {
public:
template <typename... Ts> DiskImageHolder(Ts&&... args) :
disk_image_(args...) {}
~DiskImageHolder();
unsigned int get_head_position_count();
unsigned int get_head_count();
std::shared_ptr<Track> get_track_at_position(unsigned int head, unsigned int position);
void set_track_at_position(unsigned int head, unsigned int position, const std::shared_ptr<Track> &track);
bool get_is_read_only();
private:
T disk_image_;
};
#include "DiskImageImplementation.hpp"
}
}
#endif /* DiskImage_hpp */