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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
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