From 8ddaf58a3af627a1d97113eb8f8b2454493f77e0 Mon Sep 17 00:00:00 2001
From: Natalia Portillo <claunia@claunia.com>
Date: Mon, 11 Feb 2019 01:43:47 +0000
Subject: [PATCH] Add OutputInputByteTableCodingLoop class.

---
 .../Claunia.ReedSolomon.csproj                |  1 +
 Claunia.ReedSolomon/CodingLoopBase.cs         |  4 +-
 .../OutputInputByteTableCodingLoop.cs         | 82 +++++++++++++++++++
 3 files changed, 85 insertions(+), 2 deletions(-)
 create mode 100644 Claunia.ReedSolomon/OutputInputByteTableCodingLoop.cs

diff --git a/Claunia.ReedSolomon/Claunia.ReedSolomon.csproj b/Claunia.ReedSolomon/Claunia.ReedSolomon.csproj
index 7950f4a..cc69839 100644
--- a/Claunia.ReedSolomon/Claunia.ReedSolomon.csproj
+++ b/Claunia.ReedSolomon/Claunia.ReedSolomon.csproj
@@ -53,6 +53,7 @@
         <Compile Include="OutputByteInputExpCodingLoop.cs" />
         <Compile Include="OutputByteInputTableCodingLoop.cs" />
         <Compile Include="OutputInputByteExpCodingLoop.cs" />
+        <Compile Include="OutputInputByteTableCodingLoop.cs" />
         <Compile Include="Properties\AssemblyInfo.cs" />
     </ItemGroup>
     <ItemGroup>
diff --git a/Claunia.ReedSolomon/CodingLoopBase.cs b/Claunia.ReedSolomon/CodingLoopBase.cs
index ce3a177..f008c3c 100644
--- a/Claunia.ReedSolomon/CodingLoopBase.cs
+++ b/Claunia.ReedSolomon/CodingLoopBase.cs
@@ -25,12 +25,12 @@ namespace Claunia.ReedSolomon
         [SuppressMessage("ReSharper", "InconsistentNaming")]
         public static readonly ICodingLoop[] ALL_CODING_LOOPS =
         {
-            /*new ByteInputOutputExpCodingLoop(), new ByteInputOutputTableCodingLoop(),
+            new ByteInputOutputExpCodingLoop(), new ByteInputOutputTableCodingLoop(),
             new ByteOutputInputExpCodingLoop(), new ByteOutputInputTableCodingLoop(),
             new InputByteOutputExpCodingLoop(), new InputByteOutputTableCodingLoop(),
             new InputOutputByteExpCodingLoop(), new InputOutputByteTableCodingLoop(),
             new OutputByteInputExpCodingLoop(), new OutputByteInputTableCodingLoop(),
-            new OutputInputByteExpCodingLoop(), new OutputInputByteTableCodingLoop()*/
+            new OutputInputByteExpCodingLoop(), new OutputInputByteTableCodingLoop()
         };
 
         public abstract void CodeSomeShards(byte[][] matrixRows, byte[][] inputs, int inputCount, byte[][] outputs,
diff --git a/Claunia.ReedSolomon/OutputInputByteTableCodingLoop.cs b/Claunia.ReedSolomon/OutputInputByteTableCodingLoop.cs
new file mode 100644
index 0000000..f296b4f
--- /dev/null
+++ b/Claunia.ReedSolomon/OutputInputByteTableCodingLoop.cs
@@ -0,0 +1,82 @@
+/**
+ * One specific ordering/nesting of the coding loops.
+ *
+ * Copyright 2015, Backblaze, Inc.  All rights reserved.
+ * Copyright © 2019 Natalia Portillo
+ */
+
+namespace Claunia.ReedSolomon
+{
+    public class OutputInputByteTableCodingLoop : CodingLoopBase
+    {
+        public override void CodeSomeShards(byte[][] matrixRows, byte[][] inputs, int inputCount, byte[][] outputs,
+                                            int outputCount, int offset, int byteCount)
+        {
+            byte[][] table = Galois.MULTIPLICATION_TABLE;
+
+            for(int iOutput = 0; iOutput < outputCount; iOutput++)
+            {
+                byte[] outputShard = outputs[iOutput];
+                byte[] matrixRow   = matrixRows[iOutput];
+
+                {
+                    int    iInput       = 0;
+                    byte[] inputShard   = inputs[iInput];
+                    byte[] multTableRow = table[matrixRow[iInput] & 0xFF];
+
+                    for(int iByte = offset; iByte < offset + byteCount; iByte++)
+                        outputShard[iByte] = multTableRow[inputShard[iByte] & 0xFF];
+                }
+
+                for(int iInput = 1; iInput < inputCount; iInput++)
+                {
+                    byte[] inputShard   = inputs[iInput];
+                    byte[] multTableRow = table[matrixRow[iInput] & 0xFF];
+
+                    for(int iByte = offset; iByte < offset + byteCount; iByte++)
+                        outputShard[iByte] ^= multTableRow[inputShard[iByte] & 0xFF];
+                }
+            }
+        }
+
+        public override bool CheckSomeShards(byte[][] matrixRows, byte[][] inputs, int inputCount, byte[][] toCheck,
+                                             int checkCount, int offset, int byteCount, byte[] tempBuffer)
+        {
+            if(tempBuffer == null)
+                return base.CheckSomeShards(matrixRows, inputs, inputCount, toCheck, checkCount, offset, byteCount,
+                                            null);
+
+            byte[][] table = Galois.MULTIPLICATION_TABLE;
+
+            for(int iOutput = 0; iOutput < checkCount; iOutput++)
+            {
+                byte[] outputShard = toCheck[iOutput];
+                byte[] matrixRow   = matrixRows[iOutput];
+
+                {
+                    int    iInput       = 0;
+                    byte[] inputShard   = inputs[iInput];
+                    byte[] multTableRow = table[matrixRow[iInput] & 0xFF];
+
+                    for(int iByte = offset; iByte < offset + byteCount; iByte++)
+                        tempBuffer[iByte] = multTableRow[inputShard[iByte] & 0xFF];
+                }
+
+                for(int iInput = 1; iInput < inputCount; iInput++)
+                {
+                    byte[] inputShard   = inputs[iInput];
+                    byte[] multTableRow = table[matrixRow[iInput] & 0xFF];
+
+                    for(int iByte = offset; iByte < offset + byteCount; iByte++)
+                        tempBuffer[iByte] ^= multTableRow[inputShard[iByte] & 0xFF];
+                }
+
+                for(int iByte = offset; iByte < offset + byteCount; iByte++)
+                    if(tempBuffer[iByte] != outputShard[iByte])
+                        return false;
+            }
+
+            return true;
+        }
+    }
+}
\ No newline at end of file