Crc - calculator

A C++ library designed for Python, enabling efficient CRC (Cyclic Redundancy Check) calculations based on provided bit strings. This library serves as a vital tool for developers needing reliable error-detection mechanisms in their Python applications.

Key Features

• CRC Calculation: The core functionality of the library is to compute CRC values from input bit strings. This implementation ensures accuracy and reliability, providing a crucial tool for data integrity verification.

• Extensibility: One of the standout features of this library is its modular design. Adding new CRC algorithms is straightforward, allowing developers to extend the library's functionality with minimal effort. This design facilitates quick adaptation to various CRC standards without the need for extensive modifications.

• Ease of Integration: The library is designed for seamless integration with Python projects. Comprehensive documentation and examples are provided to help developers quickly incorporate CRC calculations into their workflows.

Technical Details

• Language: Implemented in C++ and exposed to Python through bindings.
• Modularity: Designed with a clear separation of core functionality and algorithm-specific implementations, making the addition of new CRC variants a simple process.
• Compatibility: Works with Python 3.x and is compatible with major operating systems, ensuring broad applicability.

Installation

To install the library, follow these steps:

1. Clone the repository:

git clone https://github.com/gruszczrob/Crc-calculator.git

2. Navigate to the created directory and clone the pybind11 repository:

cd Crc-calculator
git clone https://github.com/pybind/pybind11.git

3. Follow the instructions for your operating system:

---

• Windows:

1. Download and install Microsoft Visual Studio.
2. Open the Crc-calculator directory in Visual Studio.
3. Build the project by selecting "Build" and then "Build All" or by pressing Ctrl+Shift+B.
4. If the build completes without errors, the library will be located in the ./out/build/ directory. This directory will have a platform-specific name, but inside it, you will find the file Crc_Cal_Module.[Your OS specialization].pyd.
5. Copy this .pyd file to the same directory as your Python script.
6. Import Crc_Cal_Module in python file

---

• Linux:

1. Create build folder and inside it release folder

mkdir build
cd build
mkdir release
cd release

2. Use cmake and make

cmake ../..
make

3. If the build compiles without errors, the library will be located in release folder. It should be named: Crc_Cal_Module.[Your OS specialization].so
4. Copy this .os file to same directory as your Python script.
5. Import Crc_Cal_Module in python file

How to add new Crc

Many crc models are presented on this web page

In places where anything is in those brackets /*[]*/ fill it with custom info

1. In Crc directory add Folder named [Crc_Name]
2. In folder create 3 files:
   • [Crc_Name].cpp
   • [Crc_Name].h
   • CMakeLists.txt
3. Fill those files with templates:

• [Crc_Name].cpp

#include "/*[Crc_Name]*/.h"

uint64_t /*[Crc_Name]*/::computeDec(const std::string& input) {
    return computeCRC(input, LENGTH, INITIAL_VALUE, POLYNOMIAL, FINAL_XOR_VALUE, REFIN, REFOUT);
}

std::string /*[Crc_Name]*/::computeHex(const std::string& input) {
    std::stringstream stream;
    stream << "CRC: 0x" << std::hex << std::uppercase << computeDec(input);
    return stream.str();
}

• [Crc_Name].h

#ifndef /*[Crc_Name with capital letters]*/_H
#define /*[Crc_Name with capital letters]*/_H

#include <Functions.h>

class /*[Crc_Name]*/ {
	// Parameters
	private:
		static const uint64_t POLYNOMIAL = 0xc599;
		static const uint64_t INITIAL_VALUE = 0x0000;
		static const uint64_t FINAL_XOR_VALUE = 0x000;
		static const uint8_t LENGTH = 15;
		static const bool REFIN = false;
		static const bool REFOUT = false;

	// Functions
	public:
		static uint64_t computeDec(const std::string& input);
		static std::string computeHex(const std::string& input);
};
#endif

• CMakeLists.txt

cmake_minimum_required(VERSION 3.12)

project(/*[Crc_Name]*/)

add_library(/*[Crc_Name]*/ STATIC /*[Crc_Name]*/.cpp)

target_link_libraries(/*[Crc_Name]*/ PRIVATE Functions)

target_include_directories(/*[Crc_Name]*/ PUBLIC ${CMAKE_CURRENT_SOURCE_DIR})

4. In main folder add to CMakeLists.txt new lines at the end of file:

add_subdirectory(Crc//*[Crc_Name]*/)
target_link_libraries(Crc_Cal_App PRIVATE /*[Crc_Name]*/)
target_link_libraries(Crc_Cal_Module PRIVATE /*[Crc_Name]*/)

5. In main folder add to module.cpp new lines inside this function: PYBIND11_MODULE(Crc_Cal_Module, m) {}

    m.def("[/*Function name for your crc for dec*/]", &/*[Crc_Name]*/::computeDec, "A function that compute /*[Crc_Name]*/ and return uint64_t");
    m.def("[/*Function name for your crc for hex*/]", &/*[Crc_Name]*/::computeHex, "A function that compute /*[Crc_Name]*/ and return string");

also in the same file at the top of the file add this:

#include </*[Crc_Name]*/.h>

6. Optional If you want to be able to test this crc in main.cpp at the to of the file add this:

#include </*[Crc_Name]*/.h>

7. Important: Atfer previous operations, you need to build project again to be able to use your crc in python. And you need to place new library file in python project instead of the old one.

Crc build-in functions in library

In library by default there are few crc implementation, if you don't want them you should remove everything that is in how to add new crc tutorial. This crc are:

• Crc 8
• Crc 15 CAN
• Crc 16 DECT R
• Crc 17 CAN FD
• Crc 21 CAN FD
• Crc 32
• Crc 64 ECMA

Functions connected to them in python are:

• compute8Dec(BINARY STRING) - A function that compute CRC 8 and return decimal value in uint64_t
• compute8Hex(BINARY STRING) - A function that compute CRC 8 and return hexadecimal value in string
• compute15Dec(BINARY STRING) - A function that compute CAN CRC 15 and return decimal value in uint64_t
• compute15Hex(BINARY STRING) - A function that compute CAN CRC 15 and return hexadecimal value in string
• compute16DectRDec(BINARY STRING) - A function that compute CRC DECT R 16 and return decimal value in uint64_t
• compute16DectRHex(BINARY STRING) - A function that compute CRC DECT R 16 and return hexadecimal value in string
• compute17Dec(BINARY STRING) - A function that compute CAN CRC 17 and return decimal value in uint64_t
• compute17Hex(BINARY STRING) - A function that compute CAN CRC 17 and return hexadecimal value in string
• compute21Dec(BINARY STRING) - A function that compute CAN CRC 21 and return decimal value in uint64_t
• compute21Hex(BINARY STRING) - A function that compute CAN CRC 21 and return hexadecimal value in string
• compute32Dec(BINARY STRING) - A function that compute CRC 32 and return decimal value in uint64_t
• compute32Hex(BINARY STRING) - A function that compute CRC 32 and return hexadecimal value in string
• compute64ECMADec(BINARY STRING) - A function that compute CRC 64 ECMA and return decimal value in uint64_t
• compute64ECMAHex(BINARY STRING) - A function that compute CRC 64 ECMA and return hexadecimal value in string

If you want to print all avaliable crc function in python use:

import Crc_Cal_Module # type: ignore
print(dir(Crc_Cal_Module))

Examples of usage

• In this case we want to compute Crc 64 ECMA for 1000010000001101100100010000101000101111110110010100101011100111101110110101001111110100011010010110 and get result in hexadecimal number stored in string.

import Crc_Cal_Module # type: ignore
print(Crc_Cal_Module.compute64ECMAHex("1000010000001101100100010000101000101111110110010100101011100111101110110101001111110100011010010110"))

Output: CRC: 0xDC110E6C2CFA806C

• In this case we want to commpute Crc 32 for 000010001101100011110010101110000101110000 and get result in decimal number stored in uint64_t

import Crc_Cal_Module # type: ignore
print(Crc_Cal_Module.compute32Dec("000010001101100011110010101110000101110000"))

Output: 2506624157

Author

• @gruszczrob

Feedback

If you have any feedback, please reach out to me at gruszczrobert@proton.me