// 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_CRC32C_INLINE_H_

#define ABSL_CRC_INTERNAL_CRC32C_INLINE_H_

#include <cstddef>

#include <cstdint>

#include "absl/base/config.h"

#include "absl/base/internal/endian.h"

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

namespace absl {

ABSL_NAMESPACE_BEGIN

namespace crc_internal {

// CRC32C implementation optimized for small inputs.

// Either computes crc and return true, or if there is

// no hardware support does nothing and returns false.

inline bool ExtendCrc32cInline(uint32_t* crc, const char* p, size_t n) {

#if defined(ABSL_CRC_INTERNAL_HAVE_ARM_SIMD) || \

    defined(ABSL_CRC_INTERNAL_HAVE_X86_SIMD)

  constexpr uint32_t kCrc32Xor = 0xffffffffU;

  *crc ^= kCrc32Xor;

  if (n & 1) {

    *crc = CRC32_u8(*crc, static_cast<uint8_t>(*p));

    n--;

    p++;

  }

  if (n & 2) {

    *crc = CRC32_u16(*crc, absl::little_endian::Load16(p));

    n -= 2;

    p += 2;

  }

  if (n & 4) {

    *crc = CRC32_u32(*crc, absl::little_endian::Load32(p));

    n -= 4;

    p += 4;

  }

  while (n) {

    *crc = CRC32_u64(*crc, absl::little_endian::Load64(p));

    n -= 8;

    p += 8;

  }

  *crc ^= kCrc32Xor;

  return true;

#else

  // No hardware support, signal the need to fallback.

  static_cast<void>(crc);

  static_cast<void>(p);

  static_cast<void>(n);

  return false;

#endif  // defined(ABSL_CRC_INTERNAL_HAVE_ARM_SIMD) ||

        // defined(ABSL_CRC_INTERNAL_HAVE_X86_SIMD)

}

}  // namespace crc_internal

ABSL_NAMESPACE_END

}  // namespace absl

#endif  // ABSL_CRC_INTERNAL_CRC32C_INLINE_H_