folly/folly/hash/Checksum.cpp

/*
 * Copyright (c) Meta Platforms, Inc. and affiliates.
 *
 * 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
 *
 *     http://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.
 */

#include <folly/hash/Checksum.h>

#include <algorithm>
#include <stdexcept>

#include <boost/crc.hpp>

#include <folly/CpuId.h>
#include <folly/detail/TrapOnAvx512.h>
#include <folly/external/fast-crc32/avx512_crc32c_v8s3x4.h> // @manual
#include <folly/external/fast-crc32/sse_crc32c_v8s3x3.h> // @manual
#include <folly/hash/detail/ChecksumDetail.h>

#if FOLLY_SSE_PREREQ(4, 2)
#include <emmintrin.h>
#include <nmmintrin.h>
#endif

namespace folly {

namespace detail {

uint32_t crc32c_sw(
    const uint8_t* data, size_t nbytes, uint32_t startingChecksum);
#if FOLLY_SSE_PREREQ(4, 2)

uint32_t crc32_sw(
    const uint8_t* data, size_t nbytes, uint32_t startingChecksum);

// Fast SIMD implementation of CRC-32 for x86 with pclmul
uint32_t crc32_hw(
    const uint8_t* data, size_t nbytes, uint32_t startingChecksum) {
  uint32_t sum = startingChecksum;
  size_t offset = 0;

  // Process unaligned bytes
  if ((uintptr_t)data & 15) {
    size_t limit = std::min(nbytes, -(uintptr_t)data & 15);
    sum = crc32_sw(data, limit, sum);
    offset += limit;
    nbytes -= limit;
  }

  if (nbytes >= 16) {
    sum = crc32_hw_aligned(sum, (const __m128i*)(data + offset), nbytes / 16);
    offset += nbytes & ~15;
    nbytes &= 15;
  }

  // Remaining unaligned bytes
  if (nbytes == 0) {
    return sum;
  }
  return crc32_sw(data + offset, nbytes, sum);
}

bool crc32c_hw_supported() {
  static folly::CpuId id;
  return id.sse42();
}

bool crc32c_hw_supported_avx512() {
  static folly::CpuId id;
  static bool supported = id.avx512vl() && !detail::hasTrapOnAvx512();
  return supported;
}

bool crc32_hw_supported() {
  static folly::CpuId id;
  return id.sse42();
}

#else

uint32_t crc32_hw(
    const uint8_t* /* data */,
    size_t /* nbytes */,
    uint32_t /* startingChecksum */) { … }

bool crc32c_hw_supported() { … }

bool crc32c_hw_supported_avx512() { … }

bool crc32_hw_supported() { … }
#endif

template <uint32_t CRC_POLYNOMIAL>
uint32_t crc_sw(const uint8_t* data, size_t nbytes, uint32_t startingChecksum) { … }

uint32_t crc32c_sw(
    const uint8_t* data, size_t nbytes, uint32_t startingChecksum) { … }

uint32_t crc32_sw(
    const uint8_t* data, size_t nbytes, uint32_t startingChecksum) { … }

} // namespace detail

uint32_t crc32c(const uint8_t* data, size_t nbytes, uint32_t startingChecksum) { … }

uint32_t crc32(const uint8_t* data, size_t nbytes, uint32_t startingChecksum) { … }

uint32_t crc32_type(
    const uint8_t* data, size_t nbytes, uint32_t startingChecksum) { … }

uint32_t crc32_combine(uint32_t crc1, uint32_t crc2, size_t crc2len) { … }

uint32_t crc32c_combine(uint32_t crc1, uint32_t crc2, size_t crc2len) { … }

} // namespace folly