jellyfin/Emby.Server.Implementations/TextEncoding/UniversalDetector/Core/CodingStateMachine.cs

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 * Contributor(s):
 *          Shy Shalom <shooshX@gmail.com>
 *          Kohei TAKETA <k-tak@void.in> (Java port)
 *          Rudi Pettazzi <rudi.pettazzi@gmail.com> (C# port)
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namespace UniversalDetector.Core
{
    /// <summary>
    /// Parallel state machine for the Coding Scheme Method
    /// </summary>
    public class CodingStateMachine
    {
        private int currentState;
        private SMModel model;
        private int currentCharLen;
        private int currentBytePos;

        public CodingStateMachine(SMModel model)
        {
            this.currentState = SMModel.START;
            this.model = model;
        }

        public int NextState(byte b)
        {
            // for each byte we get its class, if it is first byte,
            // we also get byte length
            int byteCls = model.GetClass(b);
            if (currentState == SMModel.START) {
                currentBytePos = 0;
                currentCharLen = model.charLenTable[byteCls];
            }

            // from byte's class and stateTable, we get its next state
            currentState = model.stateTable.Unpack(
                currentState * model.ClassFactor + byteCls);
            currentBytePos++;
            return currentState;
        }

        public void Reset()
        {
            currentState = SMModel.START;
        }

        public int CurrentCharLen => currentCharLen;

        public string ModelName => model.Name;
    }
}