CodingStateMachine.cs

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 *          Rudi Pettazzi <rudi.pettazzi@gmail.com> (C# port)
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using Frost.SharpCharsetDetector.Models;

namespace Frost.SharpCharsetDetector {

    /// <summary>Parallel state machine for the Coding Scheme Method</summary>
    public class CodingStateMachine {
        private int _currentBytePos;
        private int _currentCharLen;
        private int _currentState;
        private readonly SMModel _model;

        public CodingStateMachine(SMModel model) {
            _currentState = SMModel.START;
            _model = model;
        }

        public int CurrentCharLen { get { return _currentCharLen; } }

        public string ModelName { get { return _model.Name; } }

        public int CodePage {get { return _model.WindowsCodePage; }}

        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;
        }
    }

}