add ARDUINO_ARCH_RTTHREAD to support RT-Thread

Adafruit_SSD1306.cpp

@@ -36,7 +36,7 @@
  *
  */
 
-#ifdef __AVR__
+#if defined(__AVR__) || defined(ARDUINO_ARCH_RTTHREAD)
 #include <avr/pgmspace.h>
 #elif defined(ESP8266) || defined(ESP32) || defined(ARDUINO_ARCH_RP2040)
 #include <pgmspace.h>

Adafruit_SSD1306.h

@@ -51,6 +51,8 @@ typedef uint8_t PortMask;
 typedef volatile RwReg PortReg;
 typedef uint32_t PortMask;
 #define HAVE_PORTREG
+#elif defined(ARDUINO_ARCH_RTTHREAD)
+#undef HAVE_PORTREG
 #elif (defined(__arm__) || defined(ARDUINO_FEATHER52)) &&                      \
     !defined(ARDUINO_ARCH_MBED) && !defined(ARDUINO_ARCH_RP2040)
 typedef volatile uint32_t PortReg;

README.md

@@ -51,6 +51,7 @@ Intel Curie |      X     |            |          |
 WICED       |      X     |            |          | No hardware SPI - bitbang only
 ATtiny85    |            |      X     |          |
 Particle    |      X     |            |          |
+RTduino     |      X     |            |          |
 
   * ATmega328 : Arduino UNO, Adafruit Pro Trinket, Adafruit Metro 328, Adafruit Metro Mini
   * ATmega32u4 : Arduino Leonardo, Arduino Micro, Arduino Yun, Teensy 2.0, Adafruit Flora, Bluefruit Micro
@@ -60,5 +61,6 @@ Particle    |      X     |            |          |
   * ATSAMD21 : Arduino Zero, M0 Pro, Adafruit Metro Express, Feather M0
   * ATtiny85 : Adafruit Gemma, Arduino Gemma, Adafruit Trinket
   * Particle: Particle Argon
+  * RTduino : [RTduino](https://github.com/RTduino/RTduino) is the Arduino ecosystem compatibility layer for [RT-Thread RTOS](https://github.com/RT-Thread/rt-thread) BSPs
 
 <!-- END COMPATIBILITY TABLE -->