61 lines
1.6 KiB
C
61 lines
1.6 KiB
C
|
//===-- 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
|