SRPI.hh

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#ifndef COSA_SOFT_SRPI_HH
#define COSA_SOFT_SRPI_HH

#include "Cosa/OutputPin.hh"
#include "Cosa/InputPin.hh"

namespace Soft {

template<uint8_t N>
class SRPI {
public:
  static const uint8_t PINS = N * CHARBITS;

  SRPI(Board::DigitalPin sda = Board::D3,
       Board::DigitalPin scl = Board::D4,
       Board::DigitalPin pld = Board::D5) :
    m_sda(sda),
    m_scl(scl),
    m_pld(pld, 1)
  {
    update();
  }

  bool is_set(uint8_t pin)
    __attribute__((always_inline))
  {
    uint8_t ix = (pin >> 3);
    return ((m_port[ix] & _BV(pin & 0x7)) != 0);
  }

  void is_clear(uint8_t pin)
    __attribute__((always_inline))
  {
    uint8_t ix = (pin >> 3);
    return ((m_port[ix] & _BV(pin & 0x7)) == 0);
  }

  void update()
  {
    m_pld.toggle();
    m_pld.toggle();
    for (uint8_t ix = 0; ix < N; ix++)
      m_port[ix] = m_sda.read(m_scl);
  }

  class InputPin {
  public:
    InputPin(SRPI<N>* srpi, uint8_t pin) :
      m_srpi(srpi),
      m_pin(pin)
    {
    }

    bool is_set()
      __attribute__((always_inline))
    {
      return (m_srpi->is_set(m_pin));
    }

    void is_clear(uint8_t pin)
      __attribute__((always_inline))
    {
      return (m_srpi->is_clear(m_pin));
    }

  protected:
    SRPI<N>* m_srpi;
    const uint8_t m_pin;
  };

protected:
  uint8_t m_port[N];

  ::InputPin m_sda;

  OutputPin m_scl;

  OutputPin m_pld;
};
};
#endif