Reed-Solomon Algorithm Implementation

This project is a C# implementation of the Reed-Solomon error correction algorithm, based on Backblaze's original Java implementation. The library provides robust error correction capabilities and includes comprehensive unit tests.

Description

This implementation simplifies integration of Reed-Solomon error correction into your applications.

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Installation

To install the Reed-Solomon library, simply add it to your project using NuGet Package Manager:

Install-Package Witteborn.ReedSolomon

Usage

Using the Reed-Solomon library is straightforward. Here's a simple example of how to encode and decode data:

Managed Example: Byte

Console.WriteLine("Managed Example Byte");
Console.WriteLine("--------------------");
const int dataShardCount = 4;
const int parityShardCount = 2;

// Initialize Reed-Solomon with data shards and parity shards
ReedSolomon rs = new ReedSolomon(dataShardCount, parityShardCount);

// Example data to encode
byte[] data = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 };
Console.WriteLine("Data:");
Console.WriteLine(string.Join(" ", data));

// Encode the data using ManagedEncode to produce shards
var shards = rs.ManagedEncode(data, dataShardCount, parityShardCount);

Console.WriteLine("Encoded Data:");
foreach (var shard in shards)
{
    Console.WriteLine(string.Join(" ", shard));
}

// Simulate loss of one shard 
shards[1] = null;

Console.WriteLine("Encoded with missing Data:");
foreach (var shard in shards)
{
    if (shard == null)
    {
        Console.WriteLine("null");
    }
    else
    {
        Console.WriteLine(string.Join(" ", shard));
    }
}

// Decode the remaining shards using ManagedDecode to recover original data
var decodedData = rs.ManagedDecode(shards, dataShardCount, parityShardCount);

Console.WriteLine("Decoded data:");
Console.WriteLine(string.Join(" ", decodedData));

Managed Example: SByte

Console.WriteLine("Managed Example SByte");
Console.WriteLine("---------------------");
const int dataShardCount = 4;
const int parityShardCount = 2;

// Initialize Reed-Solomon with data shards and parity shards
ReedSolomon rs = new ReedSolomon(dataShardCount, parityShardCount);

// Example data to encode
sbyte[] data = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 };
Console.WriteLine("Data:");
Console.WriteLine(string.Join(" ", data));

// Encode the data using ManagedEncode to produce shards
var shards = rs.ManagedEncode(data, dataShardCount, parityShardCount);

Console.WriteLine("Encoded Data:");

foreach (var shard in shards)
{
    Console.WriteLine(string.Join(" ", shard));
}

// Simulate loss of one shard 
shards[1] = null;

Console.WriteLine("Encoded with missing Data:");
foreach (var shard in shards)
{
    if (shard == null)
    {
        Console.WriteLine("null");
    }
    else
    {
        Console.WriteLine(string.Join(" ", shard));
    }
}

// Decode the remaining shards using ManagedDecode to recover original data
var decodedData = rs.ManagedDecode(shards, dataShardCount, parityShardCount);

Console.WriteLine("Decoded data:");
Console.WriteLine(string.Join(" ", decodedData));

Manual Example: SByte

Console.WriteLine("Example SByte");
Console.WriteLine("-------------");

const int dataShardCount = 4;
const int parityShardCount = 2;
const int shardSize = 4;

// Create the shards array with data and empty parity shards
sbyte[][] shards =
{
    new sbyte[] { 0, 1, 2, 3 },
    new sbyte[] { 4, 5, 6, 7 },
    new sbyte[] { 8, 9, 10, 11 },
    new sbyte[] { 12, 13, 14, 15 },
    new sbyte[shardSize], // Parity shard 1
    new sbyte[shardSize]  // Parity shard 2
};

Console.WriteLine("Shards:");
foreach (var shard in shards)
{
    Console.WriteLine(string.Join(" ", shard));
}

// Initialize Reed-Solomon with data shards and parity shards
ReedSolomon rs = new ReedSolomon(dataShardCount, parityShardCount);

// Encode the data with Reed-Solomon to generate parity shards
rs.EncodeParity(shards, 0, shardSize);

Console.WriteLine("Encoded data:");
foreach (var shard in shards)
{
    Console.WriteLine(string.Join(" ", shard));
}

// Simulate loss of one shard (e.g., network transmission loss)
shards[1] = null; // Simulating the shard is lost

Console.WriteLine("Encoded with missing Data:");
foreach (var shard in shards)
{
    if (shard == null)
    {
        Console.WriteLine("null");
    }
    else
    {
        Console.WriteLine(string.join(" ", shard));
    }
}

bool[] shardPresent = shards.Select(shard => shard != null).ToArray();

//Manual null fix
for (int i = 0; i < shards.Length; i++)
{
    if (shards[i] == null)
    {
        shards[i] = new sbyte[shardSize];
    }
}

// Decode the remaining shards to recover original data
rs.DecodeMissing(shards, shardPresent, 0, shardSize);

// Print the decoded data (should match original data)
Console.WriteLine("Decoded data:");
foreach (var shard in shards.Where(s => s != null))
{
    Console.WriteLine(string.Join(" ", shard));
}

Contribution

Contributions via pull requests are welcome. Please open an issue first and review our Contribution Guidelines and Code of Conduct.

Support

For assistance, refer to our Support file.

Security

To report security issues or vulnerabilities, refer to our Security file.

Acknowledgments

Backblaze for the original Java implementation that inspired this project.

And a big Thank You to all contributors, issue reporters, and supporters who have helped make this project possible.

Witteborn/ReedSolomon