// Licensed to the Apache Software Foundation (ASF) under one

// or more contributor license agreements.  See the NOTICE file

// distributed with this work for additional information

// regarding copyright ownership.  The ASF licenses this file

// to you 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.

#pragma once

#include <crc32c/crc32c.h>

#include <cstddef>

#include <cstdint>

#include "storage/index/snii/common/slice.h"

namespace doris::snii {

// CRC32C (Castagnoli, polynomial 0x1EDC6F41). Used to checksum the tail of each

// format block. Thin inline adapter over Doris's bundled Google crc32c thirdparty

// (crc32c::Extend / crc32c::Crc32c). That library computes the same canonical

// CRC32C (same reflected polynomial, same standard pre/post inversion), so every

// on-disk checksum stays byte-identical to the previous in-tree slice-by-8 /

// SSE4.2 implementation -- this is an implementation swap, not a format change.

// The leading :: keeps the crc32c namespace distinct from crc32c() below.

inline uint32_t crc32c_extend(uint32_t crc, Slice data) {

    return ::crc32c::Extend(crc, data.data(), data.size());

}

inline uint32_t crc32c(Slice data) {

    return ::crc32c::Crc32c(data.data(), data.size());

}

#ifdef BE_TEST

// T21 test seam. The production crc32c()/crc32c_extend() above delegate to the

// bundled Google crc32c thirdparty (see commit d0416bb4129), which already runs a

// runtime-dispatched, hardware-accelerated and interleaved CRC32C -- so T21's

// "hardware interleaved CRC" goal is already met (and exceeded: that library adds

// a PCLMULQDQ fold a hand-rolled 3-way _mm_crc32_u64 lacks). Rather than regress

// that reuse, the reference sub-paths below let unit tests prove, byte-for-byte

// across all sizes/alignments, that the production path equals the canonical

// CRC32C and that the hardware path is engaged:

//   * crc32c_slice8_extend    -- portable software slice-by-8 (always available);

//   * crc32c_hw_serial_extend -- serial SSE4.2 _mm_crc32 hardware path;

//   * crc32c_hw3_extend       -- 3-way interleaved SSE4.2 hardware path with a

//                                GF(2) shift-combine and a 1024-byte fall-back to

//                                the serial path (the algorithm T21 specifies).

// hw_serial/hw3 fall back to slice8 when SSE4.2 is absent. Each *_extend applies

// the standard ~crc pre/post inversion, so *_extend(0, d) == crc32c(d). The whole

// seam plus its static slice-by-8 table and startup CPUID probe are compiled out

// of release builds by this BE_TEST gate, so production carries no extra code.

// Pure functions with no shared mutable state (CONCURRENCY: N/A).

namespace detail {

uint32_t crc32c_slice8_extend(uint32_t crc, Slice data);

uint32_t crc32c_hw_serial_extend(uint32_t crc, Slice data);

uint32_t crc32c_hw3_extend(uint32_t crc, Slice data);

size_t crc32c_interleave_threshold();

bool crc32c_has_hw();

} // namespace detail

#endif // BE_TEST

} // namespace doris::snii