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: CRC(Init)47 JamCRC(uint32_t Init = 0xFFFFFFFFU) : CRC(Init) {} 48 49 // Update the CRC calculation with Data. 50 void update(ArrayRef<uint8_t> Data); 51 getCRC()52 uint32_t getCRC() const { return CRC; } 53 54 private: 55 uint32_t CRC; 56 }; 57 58 } // end namespace llvm 59 60 #endif 61