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◆ main openmsx / src / utils / DeltaBlock.hh
1.9 KiB · C++ · last changed chore(): initial commit 1 month ago source blame history raw
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#ifndef DELTA_BLOCK_HH
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#define DELTA_BLOCK_HH
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#define STATISTICS 0
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#include "MemBuffer.hh"
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#include <cstdint>
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#include <memory>
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#include <span>
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#include <vector>
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#ifdef DEBUG
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#include "sha1.hh"
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#endif
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namespace openmsx {
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class DeltaBlock
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{
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public:
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#if STATISTICS
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	virtual ~DeltaBlock();
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#else
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	virtual ~DeltaBlock() = default;
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#endif
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	virtual void apply(std::span<uint8_t> dst) const = 0;
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protected:
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	DeltaBlock() = default;
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#ifdef DEBUG
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public:
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	Sha1Sum sha1;
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#endif
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#if STATISTICS
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protected:
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	static inline size_t globalAllocSize = 0;
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	size_t allocSize;
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#endif
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};
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class DeltaBlockCopy final : public DeltaBlock
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{
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public:
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	explicit DeltaBlockCopy(std::span<const uint8_t> data);
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	void apply(std::span<uint8_t> dst) const override;
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	void compress(size_t size);
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	[[nodiscard]] const uint8_t* getData();
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private:
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	[[nodiscard]] bool compressed() const { return compressedSize != 0; }
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	MemBuffer<uint8_t> block;
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	size_t compressedSize = 0;
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};
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class DeltaBlockDiff final : public DeltaBlock
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{
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public:
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	DeltaBlockDiff(std::shared_ptr<DeltaBlockCopy> prev_,
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	               std::span<const uint8_t> data);
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	void apply(std::span<uint8_t> dst) const override;
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	[[nodiscard]] size_t getDeltaSize() const;
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private:
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	const std::shared_ptr<DeltaBlockCopy> prev;
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	const std::vector<uint8_t> delta; // TODO could be tweaked to use OutputBuffer
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};
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class LastDeltaBlocks
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{
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public:
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	[[nodiscard]] std::shared_ptr<DeltaBlock> createNew(
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		const void* id, std::span<const uint8_t> data);
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	[[nodiscard]] std::shared_ptr<DeltaBlock> createNullDiff(
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		const void* id, std::span<const uint8_t> data);
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	void clear();
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private:
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	struct Info {
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		Info(const void* id_, size_t size_)
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			: id(id_), size(size_) {}
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		const void* id;
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		size_t size;
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		std::weak_ptr<DeltaBlockCopy> ref;
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		std::weak_ptr<DeltaBlock> last;
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		size_t accSize = 0;
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	};
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	std::vector<Info> infos;
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};
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} // namespace openmsx
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#endif