xls-r-300m-sv-robust / kenlm /lm /binary_format.hh

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	#ifndef LM_BINARY_FORMAT_H
	#define LM_BINARY_FORMAT_H

	#include "config.hh"
	#include "model_type.hh"
	#include "read_arpa.hh"

	#include "../util/file_piece.hh"
	#include "../util/mmap.hh"
	#include "../util/scoped.hh"

	#include <cstddef>
	#include <vector>

	#include <stdint.h>

	namespace lm {
	namespace ngram {

	extern const char *kModelNames[6];

	/*Inspect a file to determine if it is a binary lm. If not, return false.
	* If so, return true and set recognized to the type. This is the only API in
	* this header designed for use by decoder authors.
	*/
	bool RecognizeBinary(const char *file, ModelType &recognized);

	struct FixedWidthParameters {
	unsigned char order;
	float probing_multiplier;
	// What type of model is this?
	ModelType model_type;
	// Does the end of the file have the actual strings in the vocabulary?
	bool has_vocabulary;
	unsigned int search_version;
	};

	// This is a macro instead of an inline function so constants can be assigned using it.
	#define ALIGN8(a) ((std::ptrdiff_t(((a)-1)/8)+1)*8)

	// Parameters stored in the header of a binary file.
	struct Parameters {
	FixedWidthParameters fixed;
	std::vector<uint64_t> counts;
	};

	class BinaryFormat {
	public:
	explicit BinaryFormat(const Config &config);

	// Reading a binary file:
	// Takes ownership of fd
	void InitializeBinary(int fd, ModelType model_type, unsigned int search_version, Parameters &params);
	// Used to read parts of the file to update the config object before figuring out full size.
	void ReadForConfig(void *to, std::size_t amount, uint64_t offset_excluding_header) const;
	// Actually load the binary file and return a pointer to the beginning of the search area.
	void *LoadBinary(std::size_t size);

	uint64_t VocabStringReadingOffset() const {
	assert(vocab_string_offset_ != kInvalidOffset);
	return vocab_string_offset_;
	}

	// Writing a binary file or initializing in RAM from ARPA:
	// Size for vocabulary.
	void *SetupJustVocab(std::size_t memory_size, uint8_t order);
	// Warning: can change the vocaulary base pointer.
	void GrowForSearch(std::size_t memory_size, std::size_t vocab_pad, void &vocab_base);
	// Warning: can change vocabulary and search base addresses.
	void WriteVocabWords(const std::string &buffer, void &vocab_base, void &search_base);
	// Write the header at the beginning of the file.
	void FinishFile(const Config &config, ModelType model_type, unsigned int search_version, const std::vector<uint64_t> &counts);

	private:
	void MapFile(void &vocab_base, void &search_base);

	// Copied from configuration.
	const Config::WriteMethod write_method_;
	const char *write_mmap_;
	util::LoadMethod load_method_;

	// File behind memory, if any.
	util::scoped_fd file_;

	// If there is a file involved, a single mapping.
	util::scoped_memory mapping_;

	// If the data is only in memory, separately allocate each because the trie
	// knows vocab's size before it knows search's size (because SRILM might
	// have pruned).
	util::scoped_memory memory_vocab_, memory_search_;

	// Memory ranges. Note that these may not be contiguous and may not all
	// exist.
	std::size_t header_size_, vocab_size_, vocab_pad_;
	// aka end of search.
	uint64_t vocab_string_offset_;

	static const uint64_t kInvalidOffset = (uint64_t)-1;
	};

	bool IsBinaryFormat(int fd);

	} // namespace ngram
	} // namespace lm
	#endif // LM_BINARY_FORMAT_H