| //===-- 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 |