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‎.gitignore‎

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‎LICENSE‎

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Copyright (c) 2016, S&K Software Development Ltd
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All rights reserved.
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions are met:
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* Redistributions of source code must retain the above copyright
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notice, this list of conditions and the following disclaimer.
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* Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions and the following disclaimer in the
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documentation and/or other materials provided with the distribution.
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* Neither the name of the S&K Software Development Ltd nor the
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names of its contributors may be used to endorse or promote products
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derived from this software without specific prior written permission.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
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ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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DISCLAIMED. IN NO EVENT SHALL <COPYRIGHT HOLDER> BE LIABLE FOR ANY
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DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

‎README.md‎

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This package implements generic CRC calculations up to 64 bits wide.
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It aims to be fairly fast and fairly complete, allowing users to match pretty much
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any CRC algorithm used in the wild by choosing appropriate Parameters. This obviously
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includes all popular CRC algorithms, such as CRC64-ISO, CRC64-ECMA, CRC32, CRC32C, CRC16, CCITT, XMODEM and many others.
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See http://reveng.sourceforge.net/crc-catalogue/ for a good list of CRC algorithms and their parameters.
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This package has been largely inspired by Ross Williams' 1993 paper "A Painless Guide to CRC Error Detection Algorithms".
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## Usage
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Using src is easy. Here is an example of calculating CCITT crc.
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```java
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import com.github.snksoft.crc.CRC;
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public class Example
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{
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public static void main(String [] args) {
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String data = "123456789";
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long ccittCrc = CRC.calculateCRC(CRC.Parameters.CCITT, data.getBytes());
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System.out.printf("CRC is 0x%04X\n", ccittCrc); // prints "CRC is 0x29B1"
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}
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}
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```
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For larger data, table driven implementation is faster. Here is how to use it.
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```java
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import com.github.snksoft.crc.CRC;
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public class Example
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{
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public static void main(String [] args) {
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String data = "123456789";
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CRC tableDriven = new CRC(CRC.Parameters.XMODEM);
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long xmodemCrc = tableDriven.calculateCRC(data.getBytes());
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System.out.printf("CRC is 0x%04X\n", xmodemCrc); // prints "CRC is 0x31C3"
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// You can also reuse CRC object instance for another crc calculation.
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// Given that the only state for a CRC calculation is the "intermediate value"
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// and it is stored in your code, you can even use same CRC instance to calculate CRC
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// of multiple data sets in parallel.
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// And if data is too big, you may feed it in chunks
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long curValue = tableDriven.init(); // initialize intermediate value
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curValue = tableDriven.update(curValue, "123456789".getBytes()); // feed first chunk
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curValue = tableDriven.update(curValue, "01234567890".getBytes()); // feed next chunk
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long xmodemCrc2 = tableDriven.finalCRC(curValue); // gets CRC of whole data ("12345678901234567890")
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System.out.printf("CRC is 0x%04X\n", xmodemCrc2); // prints "CRC is 0x2C89"
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}
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}
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```

‎pom.xml‎

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<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
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xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
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<modelVersion>4.0.0</modelVersion>
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<groupId>com.github.snksoft</groupId>
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<artifactId>java-crc</artifactId>
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<version>1.0-SNAPSHOT</version>
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<packaging>jar</packaging>
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<name>Generic CRC implementation for java</name>
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<url>https://github.com/snksoft/java-crc</url>
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<properties>
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<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
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<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
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</properties>
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<build>
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<plugins>
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<!-- Mandatory plugins for using Spock -->
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<plugin>
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<!-- The gmavenplus plugin is used to compile Groovy code. To learn more about this plugin,
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visit https://github.com/groovy/GMavenPlus/wiki -->
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<groupId>org.codehaus.gmavenplus</groupId>
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<artifactId>gmavenplus-plugin</artifactId>
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<version>1.4</version>
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<executions>
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<execution>
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<goals>
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<goal>compile</goal>
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<goal>testCompile</goal>
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</goals>
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</execution>
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</executions>
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</plugin>
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<!-- Optional plugins for using Spock -->
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<!-- Only required if names of spec classes don't match default Surefire patterns (`*Example` etc.) -->
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<plugin>
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<artifactId>maven-surefire-plugin</artifactId>
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<version>2.6</version>
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<configuration>
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<useFile>false</useFile>
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<includes>
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<include>**/*Spec.java</include>
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</includes>
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</configuration>
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</plugin>
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<!-- Only required for spock-example build -->
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<plugin>
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<artifactId>maven-deploy-plugin</artifactId>
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<version>2.5</version>
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<configuration>
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<skip>true</skip>
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</configuration>
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</plugin>
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</plugins>
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</build>
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<dependencies>
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<dependency>
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<groupId>org.codehaus.groovy</groupId>
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<artifactId>groovy-all</artifactId>
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<version>2.4.1</version>
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<scope>compile</scope>
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</dependency>
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<dependency>
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<groupId>org.spockframework</groupId>
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<artifactId>spock-core</artifactId>
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<version>1.0-groovy-2.4</version>
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<scope>compile</scope>
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</dependency>
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</dependencies>
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</project>
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