RingOscillatorNoiseSource.h

/*
 * Copyright (C) 2015 Southern Storm Software, Pty Ltd.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included
 * in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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 * DEALINGS IN THE SOFTWARE.
 */
 
#ifndef CRYPTO_RINGOSCILLATORNOISESOURCE_H
#define CRYPTO_RINGOSCILLATORNOISESOURCE_H
 
#include <inttypes.h>
#include "NoiseSource.h"
 
class RingOscillatorNoiseSource : public NoiseSource
{
public:
    RingOscillatorNoiseSource();
    virtual ~RingOscillatorNoiseSource();
 
    bool calibrating() const;
 
    void stir();
 
private:
    uint8_t prevBit;
    uint8_t posn;
    uint8_t bitNum;
    uint8_t calState;
    uint8_t buffer[32];
    unsigned long lastSignal;
 
    void restart();
};
 
#endif