93 lines
3.3 KiB
C#
93 lines
3.3 KiB
C#
/**
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* One specific ordering/nesting of the coding loops.
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*
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* Copyright 2015, Backblaze, Inc. All rights reserved.
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*/
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namespace fec
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{
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public class OutputInputByteTableCodingLoop : CodingLoopBase
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{
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public override void codeSomeShards(
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byte[][] matrixRows,
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byte[][] inputs, int inputCount,
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byte[][] outputs, int outputCount,
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int offset, int byteCount)
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{
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byte[][] table = Galois.MULTIPLICATION_TABLE;
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for (int iOutput = 0; iOutput < outputCount; iOutput++)
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{
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byte[] outputShard = outputs[iOutput];
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byte[] matrixRow = matrixRows[iOutput];
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{
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int iInput = 0;
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byte[] inputShard = inputs[iInput];
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byte[] multTableRow = table[matrixRow[iInput] ];
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for (int iByte = offset; iByte < offset + byteCount; iByte++)
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{
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outputShard[iByte] = multTableRow[inputShard[iByte]];
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}
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}
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for (int iInput = 1; iInput < inputCount; iInput++)
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{
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byte[] inputShard = inputs[iInput];
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byte[] multTableRow = table[matrixRow[iInput] & 0xFF];
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for (int iByte = offset; iByte < offset + byteCount; iByte++)
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{
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outputShard[iByte] ^= multTableRow[inputShard[iByte]];
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}
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}
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}
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}
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public override bool checkSomeShards(
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byte[][] matrixRows,
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byte[][] inputs, int inputCount,
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byte[][] toCheck, int checkCount,
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int offset, int byteCount,
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byte[] tempBuffer)
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{
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if (tempBuffer == null)
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{
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return base.checkSomeShards(matrixRows, inputs, inputCount, toCheck, checkCount, offset, byteCount,
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null);
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}
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byte[][] table = Galois.MULTIPLICATION_TABLE;
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for (int iOutput = 0; iOutput < checkCount; iOutput++)
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{
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byte[] outputShard = toCheck[iOutput];
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byte[] matrixRow = matrixRows[iOutput];
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{
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int iInput = 0;
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byte[] inputShard = inputs[iInput];
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byte[] multTableRow = table[matrixRow[iInput]];
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for (int iByte = offset; iByte < offset + byteCount; iByte++)
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{
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tempBuffer[iByte] = multTableRow[inputShard[iByte]];
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}
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}
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for (int iInput = 1; iInput < inputCount; iInput++)
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{
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byte[] inputShard = inputs[iInput];
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byte[] multTableRow = table[matrixRow[iInput]];
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for (int iByte = offset; iByte < offset + byteCount; iByte++)
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{
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tempBuffer[iByte] ^= multTableRow[inputShard[iByte]];
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}
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}
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for (int iByte = offset; iByte < offset + byteCount; iByte++)
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{
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if (tempBuffer[iByte] != outputShard[iByte])
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{
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return false;
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}
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}
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}
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return true;
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}
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}
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} |