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//===-- llvm/Support/CRC.h - Cyclic Redundancy Check-------------*- C++ -*-===//

//

// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.

// See https://llvm.org/LICENSE.txt for license information.

// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception

//

//===----------------------------------------------------------------------===//

//

// This file contains implementations of CRC functions.

//

//===----------------------------------------------------------------------===//

#ifndef LLVM_SUPPORT_CRC_H

#define LLVM_SUPPORT_CRC_H

#include "llvm/Support/DataTypes.h"

namespace llvm {

template <typename T> class ArrayRef;

// Compute the CRC-32 of Data.

uint32_t crc32(ArrayRef<uint8_t> Data);

// Compute the running CRC-32 of Data, with CRC being the previous value of the

// checksum.

uint32_t crc32(uint32_t CRC, ArrayRef<uint8_t> Data);

// Class for computing the JamCRC.

//

// We will use the "Rocksoft^tm Model CRC Algorithm" to describe the properties

// of this CRC:

//   Width  : 32

//   Poly   : 04C11DB7

//   Init   : FFFFFFFF

//   RefIn  : True

//   RefOut : True

//   XorOut : 00000000

//   Check  : 340BC6D9 (result of CRC for "123456789")

//

// In other words, this is the same as CRC-32, except that XorOut is 0 instead

// of FFFFFFFF.

//

// N.B.  We permit flexibility of the "Init" value.  Some consumers of this need

//       it to be zero.

class JamCRC {

public:

  JamCRC(uint32_t Init = 0xFFFFFFFFU) : CRC(Init) {}

  // Update the CRC calculation with Data.

  void update(ArrayRef<uint8_t> Data);

  uint32_t getCRC() const { return CRC; }

private:

  uint32_t CRC;

};

} // end namespace llvm

#endif