Arduino_mbedSPI.h
/*
 * start rewrite from:
 * https://github.com/arduino/ArduinoCore-mbed/blob/master/libraries/SPI/SPI.cpp
 */
#ifdef ARDUINO_ARCH_NRF52840

#ifndef _ARDUINO_MBEDSPI_H_
#define _ARDUINO_MBEDSPI_H_

#include <SPI.h>
#if !defined(ARDUINO_AS_MBED_LIBRARY)
#include "drivers/SPIMaster.h"
#else
#include "drivers/SPI.h"
#endif

#include "Arduino_DataBus.h"

#ifndef MBEDSPI_MAX_PIXELS_AT_ONCE
#define MBEDSPI_MAX_PIXELS_AT_ONCE 32
#endif

class Arduino_mbedSPI : public Arduino_DataBus
{
public:
  Arduino_mbedSPI(int8_t dc, int8_t cs = GFX_NOT_DEFINED); // Constructor

  bool begin(int32_t speed = GFX_NOT_DEFINED, int8_t dataMode = GFX_NOT_DEFINED) override;
  void beginWrite() override;
  void endWrite() override;
  void writeCommand(uint8_t) override;
  void writeCommand16(uint16_t) override;
  void writeCommandBytes(uint8_t *data, uint32_t len) override;
  void write(uint8_t) override;
  void write16(uint16_t) override;
  void writeRepeat(uint16_t p, uint32_t len) override;
  void writePixels(uint16_t *data, uint32_t len) override;

  void writeC8D8(uint8_t c, uint8_t d) override;
  void writeC8D16(uint8_t c, uint16_t d) override;
  void writeC8D16D16(uint8_t c, uint16_t d1, uint16_t d2) override;
  void writeBytes(uint8_t *data, uint32_t len) override;

private:
  INLINE void WRITE(uint8_t d);
  INLINE void WRITE16(uint16_t d);
  INLINE void WRITEBUF(uint8_t *buf, size_t count);
  INLINE void DC_HIGH(void);
  INLINE void DC_LOW(void);
  INLINE void CS_HIGH(void);
  INLINE void CS_LOW(void);

  int8_t _dc, _cs;
  mbed::SPI *_dev;
  PORTreg_t _csPortSet;
  PORTreg_t _csPortClr;
  PORTreg_t _dcPortSet;
  PORTreg_t _dcPortClr;
  ARDUINOGFX_PORT_t _dcPinMask;
  ARDUINOGFX_PORT_t _csPinMask;

  union
  {
    uint8_t _buffer[MBEDSPI_MAX_PIXELS_AT_ONCE * 2] = {0};
    uint16_t _buffer16[MBEDSPI_MAX_PIXELS_AT_ONCE];
    uint32_t _buffer32[MBEDSPI_MAX_PIXELS_AT_ONCE / 2];
  };
};

#endif // _ARDUINO_MBEDSPI_H_

#endif // #ifdef ARDUINO_ARCH_NRF52840