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/Compiler.h" 17 #include "llvm/Support/DataTypes.h" 18 19 namespace llvm { 20 template <typename T> class ArrayRef; 21 22 // Compute the CRC-32 of Data. 23 LLVM_ABI uint32_t crc32(ArrayRef<uint8_t> Data); 24 25 // Compute the running CRC-32 of Data, with CRC being the previous value of the 26 // checksum. 27 LLVM_ABI uint32_t crc32(uint32_t CRC, ArrayRef<uint8_t> Data); 28 29 // Class for computing the JamCRC. 30 // 31 // We will use the "Rocksoft^tm Model CRC Algorithm" to describe the properties 32 // of this CRC: 33 // Width : 32 34 // Poly : 04C11DB7 35 // Init : FFFFFFFF 36 // RefIn : True 37 // RefOut : True 38 // XorOut : 00000000 39 // Check : 340BC6D9 (result of CRC for "123456789") 40 // 41 // In other words, this is the same as CRC-32, except that XorOut is 0 instead 42 // of FFFFFFFF. 43 // 44 // N.B. We permit flexibility of the "Init" value. Some consumers of this need 45 // it to be zero. 46 class JamCRC { 47 public: CRC(Init)48 JamCRC(uint32_t Init = 0xFFFFFFFFU) : CRC(Init) {} 49 50 // Update the CRC calculation with Data. 51 LLVM_ABI void update(ArrayRef<uint8_t> Data); 52 getCRC()53 uint32_t getCRC() const { return CRC; } 54 55 private: 56 uint32_t CRC; 57 }; 58 59 } // end namespace llvm 60 61 #endif 62