Start with STM32 architecture.

Use STM32 architecture allows to get the last features.
Based on STM32duino V1.2.0 from https://github.com/stm32duino/Arduino_Core_STM32.

Author: ridhaosWi6labs

cores/arduino/Arduino.h

@@ -0,0 +1,50 @@
+/*
+  Arduino.h - Main include file for the Arduino SDK
+  Copyright (c) 2005-2013 Arduino Team.  All right reserved.
+
+  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., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+*/
+
+#ifndef Arduino_h
+#define Arduino_h
+
+#ifndef GCC_VERSION
+#define GCC_VERSION (__GNUC__ * 10000 \
+                     + __GNUC_MINOR__ * 100 \
+                     + __GNUC_PATCHLEVEL__)
+#endif
+#if GCC_VERSION < 60300
+#error "GCC version 6.3 or higher is required"
+#endif
+
+#include "wiring.h"
+
+/* sketch */
+
+#ifdef __cplusplus
+extern "C"{
+#endif // __cplusplus
+extern void setup( void ) ;
+extern void loop( void ) ;
+
+void yield(void);
+#ifdef __cplusplus
+} // extern "C"
+#endif // __cplusplus
+
+// Include pins variant
+#include "pins_arduino.h"
+
+#endif // Arduino_h

cores/arduino/Client.h

@@ -0,0 +1,45 @@
+/*
+  Client.h - Base class that provides Client
+  Copyright (c) 2011 Adrian McEwen.  All right reserved.
+
+  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., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+*/
+
+#ifndef client_h
+#define client_h
+#include "Print.h"
+#include "Stream.h"
+#include "IPAddress.h"
+
+class Client : public Stream {
+
+public:
+  virtual int connect(IPAddress ip, uint16_t port) =0;
+  virtual int connect(const char *host, uint16_t port) =0;
+  virtual size_t write(uint8_t) =0;
+  virtual size_t write(const uint8_t *buf, size_t size) =0;
+  virtual int available() = 0;
+  virtual int read() = 0;
+  virtual int read(uint8_t *buf, size_t size) = 0;
+  virtual int peek() = 0;
+  virtual void flush() = 0;
+  virtual void stop() = 0;
+  virtual uint8_t connected() = 0;
+  virtual operator bool() = 0;
+protected:
+  uint8_t* rawIPAddress(IPAddress& addr) { return addr.raw_address(); };
+};
+
+#endif