debounce.h

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/******************************************************************************
The MIT License(MIT)
 
Embedded Template Library.
https://github.com/ETLCPP/etl
https://www.etlcpp.com
 
Copyright(c) 2016 John Wellbelove
 
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
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
******************************************************************************/
 
#ifndef ETL_DEBOUNCE_INCLUDED
#define ETL_DEBOUNCE_INCLUDED
 
#include "platform.h"
#include "static_assert.h"
 
#include <stdint.h>
 
namespace etl
{
  namespace private_debounce
  {
    class debounce_base
    {
    public:
 
      typedef uint_least8_t flags_t;
      typedef uint16_t      count_t;
 
      //*************************************************************************
      //*************************************************************************
      void add_sample(bool sample)
      {
        // Changed from last time?
        if (sample != ((flags & Sample) != 0))
        {
          count = 0;
          flags = static_cast<flags_t>((flags & static_cast<flags_t>(~Sample)) | (sample ? Sample : 0));
        }
 
        flags &= static_cast<flags_t>(~Change);
      }
 
      //*************************************************************************
      //*************************************************************************
      bool has_changed() const
      {
        return (flags & Change) != 0;
      }
 
      //*************************************************************************
      //*************************************************************************
      bool is_set() const
      {
        return ((flags & State) > Off);
      }
 
      //*************************************************************************
      //*************************************************************************
      bool is_held() const
      {
        return (flags & State) > On;
      }
 
      //*************************************************************************
      //*************************************************************************
      bool is_repeating() const
      {
        return ((flags & State) == Repeating);
      }
 
    protected:
 
      enum states
      {
        Off       = 0,
        On        = 1,
        Held      = 2,
        Repeating = 3,
        State     = 0x03U,
        Sample    = 4,
        Change    = 8
      };
 
      //*************************************************************************
      //*************************************************************************
      debounce_base(bool initial_state)
        : flags(initial_state ? On : Off)
        , count(0)
      {
      }
 
      //*************************************************************************
      //*************************************************************************
      ~debounce_base() {}
 
      //*************************************************************************
      //*************************************************************************
      void get_next(bool sample, bool condition_set, bool condition_clear, const uint_least8_t state_table[][2])
      {
        int index1 = ((flags & State) * 2) + (sample ? 1 : 0);
        int index2 = (sample ? (condition_set ? 0 : 1) : (condition_clear ? 0 : 1));
 
        flags_t next = flags;
 
        next &= static_cast<flags_t>(~State);
        next |= state_table[index1][index2];
 
        if (next != flags)
        {
          next |= Change;
        }
        else
        {
          next &= static_cast<flags_t>(~Change);
        }
 
        flags = next;
      }
 
      flags_t flags;
      count_t count;
    };
 
    //***************************************************************************
    //***************************************************************************
    class debounce2 : public debounce_base
    {
    protected:
 
      debounce2(bool initial_state)
        : debounce_base(initial_state)
      {
      }
 
      //*************************************************************************
      //*************************************************************************
      ~debounce2() {}
 
      //*************************************************************************
      //*************************************************************************
      void set_state(bool sample, bool condition_set, bool condition_clear)
      {
        static ETL_CONSTANT uint_least8_t state_table[4][2] = {
          /* Off 0 */ {debounce_base::Off, debounce_base::Off},
          /* Off 1 */ {debounce_base::On, debounce_base::Off},
          /* On  0 */ {debounce_base::Off, debounce_base::On},
          /* On  1 */ {debounce_base::On, debounce_base::On},
        };
 
        get_next(sample, condition_set, condition_clear, state_table);
      }
 
      //*************************************************************************
      //*************************************************************************
      bool process(bool sample, count_t valid_count)
      {
        add_sample(sample);
 
        if (count < UINT16_MAX)
        {
          ++count;
 
          bool valid = (count == valid_count);
 
          switch (flags & State)
          {
            case Off:
              {
                set_state(sample, valid, valid);
                break;
              }
 
            case On:
              {
                set_state(sample, valid, valid);
                break;
              }
 
            default:
              {
                break;
              }
          }
        }
 
        if (flags & Change)
        {
          count = 0;
        }
 
        return (flags & Change);
      }
    };
 
    //***************************************************************************
    //***************************************************************************
    class debounce3 : public debounce_base
    {
    protected:
 
      debounce3(bool initial_state)
        : debounce_base(initial_state)
      {
      }
 
      //*************************************************************************
      //*************************************************************************
      ~debounce3() {}
 
      //*************************************************************************
      //*************************************************************************
      void set_state(bool sample, bool condition_set, bool condition_clear)
      {
        static ETL_CONSTANT uint_least8_t state_table[6][2] = {/* Off  0 */ {debounce_base::Off, debounce_base::Off},
                                                       /* Off  1 */ {debounce_base::On, debounce_base::Off},
                                                       /* On   0 */ {debounce_base::Off, debounce_base::On},
                                                       /* On   1 */ {debounce_base::Held, debounce_base::On},
                                                       /* Held 0 */ {debounce_base::Off, debounce_base::Held},
                                                       /* Held 1 */ {debounce_base::Held, debounce_base::Held}};
 
        get_next(sample, condition_set, condition_clear, state_table);
      }
 
      //*************************************************************************
      //*************************************************************************
      bool process(bool sample, count_t valid_count, count_t hold_count)
      {
        add_sample(sample);
 
        if (count < UINT16_MAX)
        {
          ++count;
 
          bool valid = (count == valid_count);
          bool hold  = (count == hold_count);
 
          switch (flags & State)
          {
            case Off:
              {
                set_state(sample, valid, valid);
                break;
              }
 
            case On:
              {
                set_state(sample, hold, valid);
                break;
              }
 
            case Held:
              {
                set_state(sample, hold, valid);
                break;
              }
 
            default:
              {
                break;
              }
          }
        }
 
        if (flags & Change)
        {
          count = 0;
        }
 
        return (flags & Change);
      }
    };
 
    //***************************************************************************
    //***************************************************************************
    class debounce4 : public debounce_base
    {
    protected:
 
      debounce4(bool initial_state)
        : debounce_base(initial_state)
      {
      }
 
      //*************************************************************************
      //*************************************************************************
      ~debounce4() {}
 
      //*************************************************************************
      //*************************************************************************
      void set_state(bool sample, bool condition_set, bool condition_clear)
      {
        static ETL_CONSTANT uint_least8_t state_table[8][2] = {/* Off       0 */ {debounce_base::Off, debounce_base::Off},
                                                       /* Off       1 */ {debounce_base::On, debounce_base::Off},
                                                       /* On        0 */ {debounce_base::Off, debounce_base::On},
                                                       /* On        1 */ {debounce_base::Held, debounce_base::On},
                                                       /* Held      0 */ {debounce_base::Off, debounce_base::Held},
                                                       /* Held      1 */ {debounce_base::Repeating, debounce_base::Held},
                                                       /* Repeating 0 */ {debounce_base::Off, debounce_base::Repeating},
                                                       /* Repeating 1 */
                                                       {debounce_base::Repeating, debounce_base::Repeating}};
 
        get_next(sample, condition_set, condition_clear, state_table);
      }
 
      //*************************************************************************
      //*************************************************************************
      bool process(bool sample, count_t valid_count, count_t hold_count, count_t repeat_count)
      {
        add_sample(sample);
 
        if (count < UINT16_MAX)
        {
          ++count;
 
          bool valid  = (count == valid_count);
          bool hold   = (count == hold_count);
          bool repeat = (count == repeat_count);
 
          switch (flags & State)
          {
            case Off:
              {
                set_state(sample, valid, valid);
                break;
              }
 
            case On:
              {
                set_state(sample, hold, valid);
                break;
              }
 
            case Held:
              {
                set_state(sample, repeat, valid);
                break;
              }
 
            case Repeating:
              {
                set_state(sample, repeat, valid);
 
                if (sample && repeat)
                {
                  count = 0;
                  flags |= Change;
                }
                break;
              }
 
            default:
              {
                break;
              }
          }
        }
 
        if (flags & Change)
        {
          count = 0;
        }
 
        return (flags & Change);
      }
    };
  } // namespace private_debounce
 
  //***************************************************************************
  //***************************************************************************
  template <const uint16_t VALID_COUNT = 0, const uint16_t HOLD_COUNT = 0, const uint16_t REPEAT_COUNT = 0>
  class debounce : public private_debounce::debounce4
  {
  public:
 
    //*************************************************************************
    //*************************************************************************
    debounce(bool initial_state = false)
      : debounce4(initial_state)
    {
    }
 
    //*************************************************************************
    //*************************************************************************
    bool add(bool sample)
    {
      return process(sample, VALID_COUNT, HOLD_COUNT, REPEAT_COUNT);
    }
  };
 
  //***************************************************************************
  //***************************************************************************
  template <const uint16_t VALID_COUNT, const uint16_t HOLD_COUNT>
  class debounce<VALID_COUNT, HOLD_COUNT, 0> : public private_debounce::debounce3
  {
  public:
 
    //*************************************************************************
    //*************************************************************************
    debounce(bool initial_state = false)
      : debounce3(initial_state)
    {
    }
 
    //*************************************************************************
    //*************************************************************************
    bool add(bool sample)
    {
      return process(sample, VALID_COUNT, HOLD_COUNT);
    }
  };
 
  //***************************************************************************
  //***************************************************************************
  template <const uint16_t VALID_COUNT>
  class debounce<VALID_COUNT, 0, 0> : public private_debounce::debounce2
  {
  public:
 
    //*************************************************************************
    //*************************************************************************
    debounce(bool initial_state = false)
      : debounce2(initial_state)
    {
    }
 
    //*************************************************************************
    //*************************************************************************
    bool add(bool sample)
    {
      return process(sample, VALID_COUNT);
    }
  };
 
  //***************************************************************************
  //***************************************************************************
  template <>
  class debounce<0, 0, 0> : public private_debounce::debounce4
  {
  public:
 
    //*************************************************************************
    //*************************************************************************
    debounce(bool initial_state = false)
      : debounce4(initial_state)
      , valid_count(1)
      , hold_count(0)
      , repeat_count(0)
    {
    }
 
    //*************************************************************************
    //*************************************************************************
    debounce(count_t valid, count_t hold = 0, count_t repeat = 0)
      : debounce4(false)
    {
      set(valid, hold, repeat);
    }
 
    //*************************************************************************
    //*************************************************************************
    void set(count_t valid, count_t hold = 0, count_t repeat = 0)
    {
      valid_count  = valid;
      hold_count   = hold;
      repeat_count = repeat;
    }
 
    //*************************************************************************
    //*************************************************************************
    bool add(bool sample)
    {
      return process(sample, valid_count, hold_count, repeat_count);
    }
 
  private:
 
    count_t valid_count;
    count_t hold_count;
    count_t repeat_count;
  };
} // namespace etl
 
#endif