chromium/third_party/leveldatabase/src/util/crc32c.h

// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.

#ifndef STORAGE_LEVELDB_UTIL_CRC32C_H_
#define STORAGE_LEVELDB_UTIL_CRC32C_H_

#include <cstddef>
#include <cstdint>

namespace leveldb {
namespace crc32c {

// Return the crc32c of concat(A, data[0,n-1]) where init_crc is the
// crc32c of some string A.  Extend() is often used to maintain the
// crc32c of a stream of data.
uint32_t Extend(uint32_t init_crc, const char* data, size_t n);

// Return the crc32c of data[0,n-1]
inline uint32_t Value(const char* data, size_t n) { … }

static const uint32_t kMaskDelta = …;

// Return a masked representation of crc.
//
// Motivation: it is problematic to compute the CRC of a string that
// contains embedded CRCs.  Therefore we recommend that CRCs stored
// somewhere (e.g., in files) should be masked before being stored.
inline uint32_t Mask(uint32_t crc) { … }

// Return the crc whose masked representation is masked_crc.
inline uint32_t Unmask(uint32_t masked_crc) { … }

}  // namespace crc32c
}  // namespace leveldb

#endif  // STORAGE_LEVELDB_UTIL_CRC32C_H_