// Copyright 2022 The Abseil Authors

//

// Licensed under the Apache License, Version 2.0 (the "License");

// you may not use this file except in compliance with the License.

// You may obtain a copy of the License at

//

//     https://www.apache.org/licenses/LICENSE-2.0

//

// Unless required by applicable law or agreed to in writing, software

// distributed under the License is distributed on an "AS IS" BASIS,

// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

// See the License for the specific language governing permissions and

// limitations under the License.

#ifndef ABSL_CRC_INTERNAL_CRC_MEMCPY_H_

#define ABSL_CRC_INTERNAL_CRC_MEMCPY_H_

#include <cstddef>

#include <memory>

#include "absl/base/config.h"

#include "absl/crc/crc32c.h"

#include "absl/crc/internal/crc32_x86_arm_combined_simd.h"

// Defined if the class AcceleratedCrcMemcpyEngine exists.

// TODO(b/299127771): Consider relaxing the pclmul requirement once the other

// intrinsics are conditionally compiled without it.

#if defined(ABSL_CRC_INTERNAL_HAVE_X86_SIMD)

#define ABSL_INTERNAL_HAVE_X86_64_ACCELERATED_CRC_MEMCPY_ENGINE 1

#elif defined(ABSL_CRC_INTERNAL_HAVE_ARM_SIMD)

#define ABSL_INTERNAL_HAVE_ARM_ACCELERATED_CRC_MEMCPY_ENGINE 1

#endif

namespace absl {

ABSL_NAMESPACE_BEGIN

namespace crc_internal {

class CrcMemcpyEngine {

 public:

  virtual ~CrcMemcpyEngine() = default;

  virtual crc32c_t Compute(void* __restrict dst, const void* __restrict src,

                           std::size_t length, crc32c_t initial_crc) const = 0;

 protected:

  CrcMemcpyEngine() = default;

};

class CrcMemcpy {

 public:

  static crc32c_t CrcAndCopy(void* __restrict dst, const void* __restrict src,

                             std::size_t length,

                             crc32c_t initial_crc = crc32c_t{0},

                             bool non_temporal = false) {

    static const ArchSpecificEngines engines = GetArchSpecificEngines();

    auto* engine = non_temporal ? engines.non_temporal : engines.temporal;

    return engine->Compute(dst, src, length, initial_crc);

  }

  // For testing only: get an architecture-specific engine for tests.

  static std::unique_ptr<CrcMemcpyEngine> GetTestEngine(int vector,

                                                        int integer);

 private:

  struct ArchSpecificEngines {

    CrcMemcpyEngine* temporal;

    CrcMemcpyEngine* non_temporal;

  };

  static ArchSpecificEngines GetArchSpecificEngines();

};

// Fallback CRC-memcpy engine.

class FallbackCrcMemcpyEngine : public CrcMemcpyEngine {

 public:

  FallbackCrcMemcpyEngine() = default;

  FallbackCrcMemcpyEngine(const FallbackCrcMemcpyEngine&) = delete;

  FallbackCrcMemcpyEngine operator=(const FallbackCrcMemcpyEngine&) = delete;

  crc32c_t Compute(void* __restrict dst, const void* __restrict src,

                   std::size_t length, crc32c_t initial_crc) const override;

};

// CRC Non-Temporal-Memcpy engine.

class CrcNonTemporalMemcpyEngine : public CrcMemcpyEngine {

 public:

  CrcNonTemporalMemcpyEngine() = default;

  CrcNonTemporalMemcpyEngine(const CrcNonTemporalMemcpyEngine&) = delete;

  CrcNonTemporalMemcpyEngine operator=(const CrcNonTemporalMemcpyEngine&) =

      delete;

  crc32c_t Compute(void* __restrict dst, const void* __restrict src,

                   std::size_t length, crc32c_t initial_crc) const override;

};

// CRC Non-Temporal-Memcpy AVX engine.

class CrcNonTemporalMemcpyAVXEngine : public CrcMemcpyEngine {

 public:

  CrcNonTemporalMemcpyAVXEngine() = default;

  CrcNonTemporalMemcpyAVXEngine(const CrcNonTemporalMemcpyAVXEngine&) = delete;

  CrcNonTemporalMemcpyAVXEngine operator=(

      const CrcNonTemporalMemcpyAVXEngine&) = delete;

  crc32c_t Compute(void* __restrict dst, const void* __restrict src,

                   std::size_t length, crc32c_t initial_crc) const override;

};

// Copy source to destination and return the CRC32C of the data copied.  If an

// accelerated version is available, use the accelerated version, otherwise use

// the generic fallback version.

inline crc32c_t Crc32CAndCopy(void* __restrict dst, const void* __restrict src,

                              std::size_t length,

                              crc32c_t initial_crc = crc32c_t{0},

                              bool non_temporal = false) {

  return CrcMemcpy::CrcAndCopy(dst, src, length, initial_crc, non_temporal);

}

}  // namespace crc_internal

ABSL_NAMESPACE_END

}  // namespace absl

#endif  // ABSL_CRC_INTERNAL_CRC_MEMCPY_H_