SPI.h

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#ifndef SOFTWARE_SPI_H
#define SOFTWARE_SPI_H

#include "GPIO.h"
#include "SPI.h"

#ifndef CHARBITS
#define CHARBITS 8
#endif

namespace Software {
template<BOARD::pin_t MOSI_PIN,
         BOARD::pin_t MISO_PIN,
         BOARD::pin_t SCK_PIN>
class SPI : public ::SPI {
public:
  SPI() :
    ::SPI()
  {
    m_sck.output();
    m_mosi.output();
    m_miso.input();
  }

  virtual void acquire(uint8_t mode, uint8_t bitorder, uint8_t scale)
  {
    (void) scale;
    lock();
    m_sck = mode & 2;
    m_cpha = mode & 1;
    m_bitorder = bitorder;
  }

  virtual void release()
  {
    m_mosi = LOW;
    unlock();
  }

  virtual uint8_t transfer(uint8_t value)
  {
    const bool cpha = m_cpha;
    uint8_t bits = CHARBITS;
    if (m_bitorder == MSBFIRST) {
      do {
        if (cpha) m_sck.toggle();
        m_mosi = value & 0x80;
        m_sck.toggle();
        value <<= 1;
        value |= m_miso;
        if (!cpha) m_sck.toggle();
      } while (--bits);
    }
    else {
      do {
        if (cpha) m_sck.toggle();
        m_mosi = value & 0x01;
        m_sck.toggle();
        value >>= 1;
        value |= (m_miso ? 0x80 : 0x00);
        if (!cpha) m_sck.toggle();
      } while (--bits);
    }
    return (value);
  }

  using ::SPI::transfer;

protected:
  GPIO<SCK_PIN> m_sck;

  GPIO<MOSI_PIN> m_mosi;

  GPIO<MISO_PIN> m_miso;

  bool m_cpha;

  uint8_t m_bitorder;
};

};
#endif