cores/arduino/wiring_shift.c

/*
  Copyright (c) 2011 Arduino.  All right reserved.

  This library is free software; you can redistribute it and/or
  modify it under the terms of the GNU Lesser General Public
  License as published by the Free Software Foundation; either
  version 2.1 of the License, or (at your option) any later version.

  This library is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  See the GNU Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General Public
  License along with this library; if not, write to the Free Software
  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
*/

#include "Arduino.h"

#ifdef __cplusplus
extern "C"
{
#endif

    uint32_t shiftIn(uint32_t ulDataPin, uint32_t ulClockPin, uint32_t ulBitOrder)
    {
        uint8_t value = 0;
        uint8_t i;

        for (i = 0; i < 8; ++i)
        {
            digitalWrite(ulClockPin, HIGH);

            if (ulBitOrder == LSBFIRST)
            {
                value |= digitalRead(ulDataPin) << i;
            }
            else
            {
                value |= digitalRead(ulDataPin) << (7 - i);
            }

            digitalWrite(ulClockPin, LOW);
        }

        return value;
    }

    void shiftOut(uint32_t ulDataPin, uint32_t ulClockPin, uint32_t ulBitOrder, uint32_t ulVal)
    {
        uint8_t i;

        for (i = 0; i < 8; i++)
        {
            if (ulBitOrder == LSBFIRST)
            {
                digitalWrite(ulDataPin, !!(ulVal & (1 << i)));
            }
            else
            {
                digitalWrite(ulDataPin, !!(ulVal & (1 << (7 - i))));
            }

            digitalWrite(ulClockPin, HIGH);
            digitalWrite(ulClockPin, LOW);
        }
    }

#ifdef __cplusplus
} // extern "C"
#endif