1 files changed, 17 insertions, 2 deletions
diff --git a/cores/arduino/wiring_shift.c b/cores/arduino/wiring_shift.c
index 956f864..cfe7867 100755
--- a/cores/arduino/wiring_shift.c
+++ b/cores/arduino/wiring_shift.c
@@ -24,9 +24,24 @@
 
 #include "wiring_private.h"
 
-void shiftOut(uint8_t dataPin, uint8_t clockPin, uint8_t bitOrder, byte val)
+uint8_t shiftIn(uint8_t dataPin, uint8_t clockPin, uint8_t 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(uint8_t dataPin, uint8_t clockPin, uint8_t bitOrder, uint8_t val)
 {
-	int i;
+	uint8_t i;
 
 	for (i = 0; i < 8; i++)  {
 		if (bitOrder == LSBFIRST)