Merge pull request #395 from KurtE/shiftIn_shiftOut

core: arduino: add ShiftIn/ShiftOut implementation

Author: pennam

cores/arduino/wiring_shift.cpp

@@ -0,0 +1,49 @@
+/*
+ * Copyright (c) 2026 KurtE
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <Arduino.h>
+
+uint8_t shiftIn(pin_size_t dataPin, uint8_t clockPin, BitOrder bitOrder) {
+	uint8_t value = 0;
+	uint8_t mask;
+
+	if (bitOrder == LSBFIRST) {
+		for (mask = 0x01; mask; mask <<= 1) {
+			digitalWrite(clockPin, HIGH);
+			if (digitalRead(dataPin)) {
+				value |= mask;
+			}
+			digitalWrite(clockPin, LOW);
+		}
+	} else {
+		for (mask = 0x80; mask; mask >>= 1) {
+			digitalWrite(clockPin, HIGH);
+			if (digitalRead(dataPin)) {
+				value |= mask;
+			}
+			digitalWrite(clockPin, LOW);
+		}
+	}
+
+	return value;
+}
+
+void shiftOut(pin_size_t dataPin, uint8_t clockPin, BitOrder bitOrder, uint8_t val) {
+	uint8_t mask;
+
+	if (bitOrder == LSBFIRST) {
+		for (mask = 0x01; mask; mask <<= 1) {
+			digitalWrite(dataPin, !!(val & mask) ? HIGH : LOW);
+			digitalWrite(clockPin, HIGH);
+			digitalWrite(clockPin, LOW);
+		}
+	} else {
+		for (mask = 0x80; mask; mask >>= 1) {
+			digitalWrite(dataPin, !!(val & mask) ? HIGH : LOW);
+			digitalWrite(clockPin, HIGH);
+			digitalWrite(clockPin, LOW);
+		}
+	}
+}