[realtek-ambz] Implement SoftwareSerial class

arduino/libretuya/api/SoftwareSerial.cpp

@@ -0,0 +1,41 @@
+/* Copyright (c) Kuba Szczodrzyński 2022-07-03. */
+
+#include "SoftwareSerial.h"
+
+SoftwareSerial::SoftwareSerial(pin_size_t receivePin, pin_size_t transmitPin, bool inverted) {
+	data.rx.buf = NULL;
+	data.tx.buf = NULL;
+	data.rx.pin = receivePin;
+	data.tx.pin = transmitPin;
+	data.invert = inverted == true;
+}
+
+int SoftwareSerial::available() {
+	return data.rx.buf->available();
+}
+
+int SoftwareSerial::peek() {
+	return data.rx.buf->peek();
+}
+
+int SoftwareSerial::read() {
+	return data.rx.buf->read_char();
+}
+
+void SoftwareSerial::flush() {
+	while (data.rx.buf->available()) {
+		yield();
+	}
+}
+
+size_t SoftwareSerial::write(uint8_t c) {
+	while (data.tx.buf->isFull()) {
+		yield();
+	}
+	data.tx.buf->store_char(c);
+	if (data.tx.state == SS_IDLE) {
+		data.tx.state = SS_START;
+		this->startTx();
+	}
+	return 1;
+}