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