/// <summary>
/// Hashes the byte buffer using the BuzHash algorithm
/// </summary>
/// <param name="buffer">byte byffer to hash</param>
/// <param name="offset"> beginning of the window in the buffer</param>
/// <param name="windowSize">window size in bytes</param>
/// <returns>hash</returns>
public uint Hash(byte[] buffer, int offset, int windowSize)
{
uint result = seed;
for (var i = offset; i < offset + windowSize; i++)
{
result = result.BSL(1) ^ hashFunctionTable[buffer[i]];
}
return(result);
}
/// <summary>
/// Hashes the byte buffer using the BuzHash algorithm
/// </summary>
/// <param name="stream">stream to hash</param>
/// <param name="windowSize">window size in bytes</param>
/// <returns>hash</returns>
public uint Hash(Stream stream, int windowSize)
{
uint result = seed;
for (int i = 0; i < windowSize && stream.Position < stream.Length; i++)
{
result = result.BSL(1) ^ hashFunctionTable[stream.ReadByte()];
}
return(result);
}
/// <summary>
/// This method is intended for use with sliding window hashing, and not for anything else. It allows to recalculate the hash
/// when the window is sliden to the next byte
/// </summary>
/// <param name="oldHash">The hashcode of the byte before the window was sliden</param>
/// <param name="newByte">New byte that was added to the window</param>
/// <param name="oldByte">Old byte that was removed from the window</param>
/// <param name="windowSize">Size of the window (in bytes)</param>
/// <returns></returns>
public uint UpdateHash(uint oldHash, byte newByte, byte oldByte, int windowSize)
{
return(oldHash.BSL(1) ^ hashFunctionTable[oldByte].BSL(windowSize) ^ hashFunctionTable[newByte]);
}
