Repo created

libs/coding/mmap_reader.hpp

@@ -0,0 +1,43 @@
+#pragma once
+
+#include "coding/reader.hpp"
+
+#include <cstddef>
+#include <cstdint>
+#include <memory>
+#include <string>
+
+/// @TODO Add Windows support
+class MmapReader : public ModelReader
+{
+public:
+  enum class Advice
+  {
+    Normal,
+    Random,
+    Sequential
+  };
+
+  explicit MmapReader(std::string const & fileName, Advice advice = Advice::Normal);
+
+  uint64_t Size() const override;
+  void Read(uint64_t pos, void * p, size_t size) const override;
+  std::unique_ptr<Reader> CreateSubReader(uint64_t pos, uint64_t size) const override;
+
+  /// Direct file/memory access
+  uint8_t * Data() const;
+
+protected:
+  // Used in special derived readers.
+  void SetOffsetAndSize(uint64_t offset, uint64_t size);
+
+private:
+  using base_type = ModelReader;
+  class MmapData;
+
+  MmapReader(MmapReader const & reader, uint64_t offset, uint64_t size);
+
+  std::shared_ptr<MmapData> m_data;
+  uint64_t m_offset;
+  uint64_t m_size;
+};