// SPDX-License-Identifier: Apache-2.0

// SPDX-FileCopyrightText: Copyright The WasmEdge Authors

//===-- wasmedge/runtime/instance/data.h - Data Instance definition -------===//

//

// Part of the WasmEdge Project.

//

//===----------------------------------------------------------------------===//

///

/// \file

/// This file contains the data instance definition in store manager.

///

//===----------------------------------------------------------------------===//

#pragma once

#include "common/span.h"

#include "common/types.h"

#include <vector>

namespace WasmEdge {

namespace Runtime {

namespace Instance {

class DataInstance {

public:

  DataInstance() = delete;

  DataInstance(const uint64_t Offset, Span<const Byte> Init) noexcept

      : Off(Offset), Data(Init.begin(), Init.end()) {}

  /// Get offset in data instance.

  uint64_t getOffset() const noexcept { return Off; }

  /// Get data in data instance.

  Span<const Byte> getData() const noexcept { return Data; }

  /// Load bytes to value.

  ValVariant loadValue(const uint64_t Offset, const uint32_t N) const noexcept {

    assuming(N <= 16);

    // Due to applying the Memory64 proposal, we should avoid the overflow issue

    // of the following code.

    // Check the data boundary.

    if (unlikely(std::numeric_limits<uint64_t>::max() - Offset < N ||

                 Offset + N > Data.size())) {

      return 0;

    }

    // Load the data to the value.

    EndianValue<uint128_t> Value;

    std::memcpy(&Value.raw(), &Data[Offset], N);

    if constexpr (Endian::native == Endian::big) {

      Value.raw() >>= (128 - N * 8);

    }

    return Value.le();

  }

  /// Clear data in data instance.

  void clear() noexcept { Data.clear(); }

private:

  /// \name Data of data instance.

  /// @{

  const uint64_t Off;

  std::vector<Byte> Data;

  /// @}

};

} // namespace Instance

} // namespace Runtime

} // namespace WasmEdge