m2_encoder.h

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/*
 * Copyright (C) 2016 Robin Gareus <robin@gareus.org>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */
 
#ifndef _ardour_surfaces_m2encoder_h_
#define _ardour_surfaces_m2encoder_h_
 
#include <stdint.h>
#include "pbd/signals.h"
 
namespace ArdourSurface {
 
class M2EncoderInterface
{
        public:
                M2EncoderInterface () {}
                virtual ~M2EncoderInterface () {}
 
                /* user API */
                PBD::Signal1<void, int> changed;
                virtual float value () const { return 0.f; }
                virtual float range () const { return 0.f; }
 
                /* internal API - called from device thread */
                virtual bool set_value (unsigned int v) { return false; }
};
 
class M2Encoder : public M2EncoderInterface
{
        public:
                M2Encoder (unsigned int upper = 1000)
                        : M2EncoderInterface ()
                        , _upper (upper /* limit, exclusive. eg [0..15]: 16 */)
                        , _value (0)
                        , _initialized (false)
                {
                        assert (_upper > 7);
                        _wrapcnt = std::max (3U, upper / 6);
                }
 
                float value () const { return _value / (_upper - 1.f); }
                float range () const { return (_upper - 1.f); }
 
                bool set_value (unsigned int v) {
                        if (!_initialized) {
                                _initialized = true;
                                _value = v;
                                return false;
                        }
 
                        if (v == _value) {
                                return false;
                        }
 
                        int delta;
                        if (v < _wrapcnt && _value > _upper - _wrapcnt) {
                                // wrap around max -> min
                                delta = v + _upper - _value;
                        }
                        else if (_value < _wrapcnt && v > _upper - _wrapcnt) {
                                // wrap around min -> max
                                delta = v - _upper - _value;
                        }
                        else {
                                delta = v - _value;
                        }
 
                        _value = v;
                        changed (delta);
                        return true;
                }
 
        protected:
                unsigned int _upper;
                unsigned int _value;
                unsigned int _wrapcnt;
                bool _initialized;
};
 
} /* namespace */
#endif /* _ardour_surfaces_m2encoder_h_ */