1 | //===-- llvm/Support/CRC.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 implementations of CRC functions. |
10 | // |
11 | //===----------------------------------------------------------------------===// |
12 | |
13 | #ifndef LLVM_SUPPORT_CRC_H |
14 | #define LLVM_SUPPORT_CRC_H |
15 | |
16 | #include "llvm/Support/DataTypes.h" |
17 | |
18 | namespace llvm { |
19 | template <typename T> class ArrayRef; |
20 | |
21 | // Compute the CRC-32 of Data. |
22 | uint32_t crc32(ArrayRef<uint8_t> Data); |
23 | |
24 | // Compute the running CRC-32 of Data, with CRC being the previous value of the |
25 | // checksum. |
26 | uint32_t crc32(uint32_t CRC, ArrayRef<uint8_t> Data); |
27 | |
28 | // Class for computing the JamCRC. |
29 | // |
30 | // We will use the "Rocksoft^tm Model CRC Algorithm" to describe the properties |
31 | // of this CRC: |
32 | // Width : 32 |
33 | // Poly : 04C11DB7 |
34 | // Init : FFFFFFFF |
35 | // RefIn : True |
36 | // RefOut : True |
37 | // XorOut : 00000000 |
38 | // Check : 340BC6D9 (result of CRC for "123456789") |
39 | // |
40 | // In other words, this is the same as CRC-32, except that XorOut is 0 instead |
41 | // of FFFFFFFF. |
42 | // |
43 | // N.B. We permit flexibility of the "Init" value. Some consumers of this need |
44 | // it to be zero. |
45 | class JamCRC { |
46 | public: |
47 | JamCRC(uint32_t Init = 0xFFFFFFFFU) : CRC(Init) {} |
48 | |
49 | // Update the CRC calculation with Data. |
50 | void update(ArrayRef<uint8_t> Data); |
51 | |
52 | uint32_t getCRC() const { return CRC; } |
53 | |
54 | private: |
55 | uint32_t CRC; |
56 | }; |
57 | |
58 | } // end namespace llvm |
59 | |
60 | #endif |
61 | |