TWI.h

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#ifndef TWI_H
#define TWI_H

#include "iovec.h"
#include "bswap.h"

class TWI {
public:
  class Device {
  public:
    Device(TWI& twi, uint8_t addr) :
      m_twi(twi),
      m_addr(addr << 1)
    {
    }

    bool acquire()
    {
      return (m_twi.acquire());
    }

    bool release()
    {
      return (m_twi.release());
    }

    int read(void* buf, size_t count)
    {
      return (m_twi.read(m_addr, buf, count));
    }

    int write(const void* buf, size_t count)
    {
      return (m_twi.write(m_addr, buf, count));
    }

    int write(iovec_t* vp)
    {
      return (m_twi.write(m_addr, vp));
    }

  protected:
    TWI& m_twi;

    uint8_t m_addr;
  };

  static const uint32_t DEFAULT_FREQ = 100000L;

  TWI() :
    m_busy(false)
  {}

  virtual bool acquire() = 0;

  virtual bool release() = 0;

  virtual int read(uint8_t addr, void* buf, size_t count) = 0;

  virtual int write(uint8_t addr, const void* buf, size_t count)
  {
    iovec_t vec[2];
    iovec_t* vp = vec;
    iovec_arg(vp, buf, count);
    iovec_end(vp);
    return (write(addr, vec));
  }

  virtual int write(uint8_t addr, iovec_t* vp) = 0;

protected:
  volatile bool m_busy;

  void lock()
  {
    while (m_busy) yield();
    m_busy = true;
  }

  void unlock()
  {
    m_busy = false;
  }
};
#endif