PCF8574.hh

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#ifndef COSA_PCF8574_HH
#define COSA_PCF8574_HH

#include "Cosa/TWI.hh"

class PCF8574 : private TWI::Driver {
public:
  PCF8574(uint8_t subaddr = 7) :
    TWI::Driver(0x20 | (subaddr & 0x7)),
    m_ddr(0xff),
    m_port(0)
  {}

  bool data_direction(uint8_t ddr);

  bool input_pin(uint8_t pin)
    __attribute__((always_inline))
  {
    return (data_direction(m_ddr | _BV(pin & PIN_MASK)));
  }

  bool output_pin(uint8_t pin)
    __attribute__((always_inline))
  {
    return (data_direction(m_ddr & ~_BV(pin & PIN_MASK)));
  }

  bool read(uint8_t pin)
    __attribute__((always_inline))
  {
    return ((read() & _BV(pin & PIN_MASK)) != 0);
  }

  uint8_t read();

  bool write(uint8_t pin, uint8_t value);

  bool write(uint8_t value);

  bool write(void* buf, size_t size);

protected:
  static const uint8_t PIN_MASK = 0x07;

  uint8_t m_ddr;

  uint8_t m_port;

  PCF8574(uint8_t addr, uint8_t subaddr) :
    TWI::Driver(addr | (subaddr & 0x7)),
    m_ddr(0xff),
    m_port(0)
  {}
};

class PCF8574A : protected PCF8574 {
public:
  PCF8574A(uint8_t subaddr = 7) : PCF8574(0x38, subaddr) {}
};
#endif