LLVM  10.0.0svn
JamCRC.h
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1 //===-- llvm/Support/JamCRC.h - Cyclic Redundancy Check ---------*- C++ -*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file contains an implementation of JamCRC.
10 //
11 // We will use the "Rocksoft^tm Model CRC Algorithm" to describe the properties
12 // of this CRC:
13 // Width : 32
14 // Poly : 04C11DB7
15 // Init : FFFFFFFF
16 // RefIn : True
17 // RefOut : True
18 // XorOut : 00000000
19 // Check : 340BC6D9 (result of CRC for "123456789")
20 //
21 // N.B. We permit flexibility of the "Init" value. Some consumers of this need
22 // it to be zero.
23 //
24 //===----------------------------------------------------------------------===//
25 
26 #ifndef LLVM_SUPPORT_JAMCRC_H
27 #define LLVM_SUPPORT_JAMCRC_H
28 
29 #include "llvm/Support/DataTypes.h"
30 
31 namespace llvm {
32 template <typename T> class ArrayRef;
33 
34 class JamCRC {
35 public:
36  JamCRC(uint32_t Init = 0xFFFFFFFFU) : CRC(Init) {}
37 
38  // Update the CRC calculation with Data.
40 
41  uint32_t getCRC() const { return CRC; }
42 
43 private:
44  uint32_t CRC;
45 };
46 } // End of namespace llvm
47 
48 #endif
uint32_t getCRC() const
Definition: JamCRC.h:41
JamCRC(uint32_t Init=0xFFFFFFFFU)
Definition: JamCRC.h:36
This class represents lattice values for constants.
Definition: AllocatorList.h:23
ArrayRef - Represent a constant reference to an array (0 or more elements consecutively in memory)...
Definition: APInt.h:32
void update(ArrayRef< char > Data)
Definition: JamCRC.cpp:91