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Add CodingLoopBase abstract class.

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Natalia Portillo
2019-02-11 01:38:32 +00:00
parent be7e3bad5b
commit 367d9579aa
2 changed files with 65 additions and 0 deletions
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1
Claunia.ReedSolomon/Claunia.ReedSolomon.csproj
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@@ -38,6 +38,7 @@
<Reference Include="System.Xml" />
</ItemGroup>
<ItemGroup>
<Compile Include="CodingLoopBase.cs" />
<Compile Include="Galois.cs" />
<Compile Include="ICodingLoop.cs" />
<Compile Include="Matrix.cs" />

64
Claunia.ReedSolomon/CodingLoopBase.cs Normal file
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/**
* Common implementations for coding loops.
*
* Copyright 2015, Backblaze, Inc. All rights reserved.
* Copyright © 2019 Natalia Portillo
*/
using System.Diagnostics.CodeAnalysis;
namespace Claunia.ReedSolomon
{
public abstract class CodingLoopBase : ICodingLoop
{
/// <summary>
/// All of the available coding loop algorithms. The different choices nest the three loops in different orders,
/// and either use the log/exponents tables, or use the multiplication table. The naming of the three loops is (with
/// number of loops in benchmark): "byte" - Index of byte within shard. (200,000 bytes in each shard) "input" -
/// Which input shard is being read. (17 data shards) "output" - Which output shard is being computed. (3 parity
/// shards) And the naming for multiplication method is: "table" - Use the multiplication table. "exp" - Use the
/// logarithm/exponent table. The ReedSolomonBenchmark class compares the performance of the different loops, which
/// will depend on the specific processor you're running on. This is the inner loop. It needs to be fast. Be careful
/// if you change it. I have tried inlining Galois.multiply(), but it doesn't make things any faster. The JIT compiler
/// is known to inline methods, so it's probably already doing so.
/// </summary>
[SuppressMessage("ReSharper", "InconsistentNaming")]
public static readonly ICodingLoop[] ALL_CODING_LOOPS =
{
/*new ByteInputOutputExpCodingLoop(), new ByteInputOutputTableCodingLoop(),
new ByteOutputInputExpCodingLoop(), new ByteOutputInputTableCodingLoop(),
new InputByteOutputExpCodingLoop(), new InputByteOutputTableCodingLoop(),
new InputOutputByteExpCodingLoop(), new InputOutputByteTableCodingLoop(),
new OutputByteInputExpCodingLoop(), new OutputByteInputTableCodingLoop(),
new OutputInputByteExpCodingLoop(), new OutputInputByteTableCodingLoop()*/
};
public abstract void CodeSomeShards(byte[][] matrixRows, byte[][] inputs, int inputCount, byte[][] outputs,
int outputCount, int offset, int byteCount);
public virtual bool CheckSomeShards(byte[][] matrixRows, byte[][] inputs, int inputCount, byte[][] toCheck,
int checkCount, int offset, int byteCount, byte[] tempBuffer)
{
// This is the loop structure for ByteOutputInput, which does not
// require temporary buffers for checking.
byte[][] table = Galois.MULTIPLICATION_TABLE;
for(int iByte = offset; iByte < offset + byteCount; iByte++)
{
for(int iOutput = 0; iOutput < checkCount; iOutput++)
{
byte[] matrixRow = matrixRows[iOutput];
int value = 0;
for(int iInput = 0; iInput < inputCount; iInput++)
value ^= table[matrixRow[iInput] & 0xFF][inputs[iInput][iByte] & 0xFF];
if(toCheck[iOutput][iByte] != (byte)value)
return false;
}
}
return true;
}
}
}