Core: copy MBed version of ShiftIn/ShiftOut

Copy from MBED
but run through clang_format

Author: KurtE

cores/arduino/wiring_shift.cpp

@@ -0,0 +1,54 @@
+/*
+  wiring_shift.cpp - shiftOut() function
+  Part of Arduino - http://www.arduino.cc/
+
+  Copyright (c) 2005-2006 David A. Mellis
+
+  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., 59 Temple Place, Suite 330,
+  Boston, MA  02111-1307  USA
+*/
+
+#include <Arduino.h>
+
+uint8_t shiftIn(pin_size_t dataPin, uint8_t clockPin, BitOrder bitOrder) {
+	uint8_t value = 0;
+	uint8_t i;
+
+	for (i = 0; i < 8; ++i) {
+		digitalWrite(clockPin, HIGH);
+		if (bitOrder == LSBFIRST) {
+			value |= digitalRead(dataPin) << i;
+		} else {
+			value |= digitalRead(dataPin) << (7 - i);
+		}
+		digitalWrite(clockPin, LOW);
+	}
+	return value;
+}
+
+void shiftOut(pin_size_t dataPin, uint8_t clockPin, BitOrder bitOrder, uint8_t val) {
+	uint8_t i;
+
+	for (i = 0; i < 8; i++) {
+		if (bitOrder == LSBFIRST) {
+			digitalWrite(dataPin, !!(val & (1 << i)) ? HIGH : LOW);
+		} else {
+			digitalWrite(dataPin, !!(val & (1 << (7 - i))) ? HIGH : LOW);
+		}
+
+		digitalWrite(clockPin, HIGH);
+		digitalWrite(clockPin, LOW);
+	}
+}