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using System;
namespace Org.BouncyCastle.Utilities.Encoders
{
/// <summary>
/// A hex translator.
/// </summary>
public class HexTranslator : ITranslator
{
private static readonly byte[] hexTable =
{
(byte)'0', (byte)'1', (byte)'2', (byte)'3', (byte)'4', (byte)'5', (byte)'6', (byte)'7',
(byte)'8', (byte)'9', (byte)'a', (byte)'b', (byte)'c', (byte)'d', (byte)'e', (byte)'f'
};
/// <summary>
/// Return encoded block size.
/// </summary>
/// <returns>2</returns>
public int GetEncodedBlockSize()
{
return 2;
}
/// <summary>
/// Encode some data.
/// </summary>
/// <param name="input">Input data array.</param>
/// <param name="inOff">Start position within input data array.</param>
/// <param name="length">The amount of data to process.</param>
/// <param name="outBytes">The output data array.</param>
/// <param name="outOff">The offset within the output data array to start writing from.</param>
/// <returns>Amount of data encoded.</returns>
public int Encode(
byte[] input,
int inOff,
int length,
byte[] outBytes,
int outOff)
{
for (int i = 0, j = 0; i < length; i++, j += 2)
{
outBytes[outOff + j] = hexTable[(input[inOff] >> 4) & 0x0f];
outBytes[outOff + j + 1] = hexTable[input[inOff] & 0x0f];
inOff++;
}
return length * 2;
}
/// <summary>
/// Returns the decoded block size.
/// </summary>
/// <returns>1</returns>
public int GetDecodedBlockSize()
{
return 1;
}
/// <summary>
/// Decode data from a byte array.
/// </summary>
/// <param name="input">The input data array.</param>
/// <param name="inOff">Start position within input data array.</param>
/// <param name="length">The amounty of data to process.</param>
/// <param name="outBytes">The output data array.</param>
/// <param name="outOff">The position within the output data array to start writing from.</param>
/// <returns>The amount of data written.</returns>
public int Decode(
byte[] input,
int inOff,
int length,
byte[] outBytes,
int outOff)
{
int halfLength = length / 2;
byte left, right;
for (int i = 0; i < halfLength; i++)
{
left = input[inOff + i * 2];
right = input[inOff + i * 2 + 1];
if (left < (byte)'a')
{
outBytes[outOff] = (byte)((left - '0') << 4);
}
else
{
outBytes[outOff] = (byte)((left - 'a' + 10) << 4);
}
if (right < (byte)'a')
{
outBytes[outOff] += (byte)(right - '0');
}
else
{
outBytes[outOff] += (byte)(right - 'a' + 10);
}
outOff++;
}
return halfLength;
}
}
}
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