make WiFi/Ethernet interface compatible with Arduino Ethernet API (#8645)

* make WiFi/Ethernet interface compatible with Arduino Ethernet API
provide some minimaly adapted examples from legacy

* move ethernet compat globals to EthernetCompat.h

* LegacyEthernet: add UDP example

* adjust comments

Co-authored-by: Max Prokhorov <prokhorov.max@outlook.com>

libraries/lwIP_Ethernet/src/EthernetCompat.h

@@ -0,0 +1,101 @@
+
+#pragma once
+
+#include <LwipEthernet.h>
+#include <WiFiUdp.h>
+#include <WiFiClient.h>
+#include <ArduinoWiFiServer.h>
+
+using EthernetUDP    = WiFiUDP;
+using EthernetClient = WiFiClient;
+using EthernetServer = ArduinoWiFiServer;
+
+enum EthernetLinkStatus
+{
+    Unknown,
+    LinkON,
+    LinkOFF
+};
+
+enum
+{
+    DHCP_CHECK_NONE        = 0,
+    DHCP_CHECK_RENEW_FAIL  = 1,
+    DHCP_CHECK_RENEW_OK    = 2,
+    DHCP_CHECK_REBIND_FAIL = 3,
+    DHCP_CHECK_REBIND_OK   = 4,
+};
+
+enum HardwareStatus
+{
+    EthernetNoHardware,
+    EthernetHardwareFound,
+};
+
+template<class RawDev>
+class ArduinoEthernet: public LwipIntfDev<RawDev>
+{
+public:
+    ArduinoEthernet(int8_t cs = SS, SPIClass& spi = SPI, int8_t intr = -1) :
+        LwipIntfDev<RawDev>(cs, spi, intr)
+    {
+        _hardwareStatus = EthernetNoHardware;
+        _linkStatus     = Unknown;
+    }
+
+    // Arduino-Ethernet API compatibility, order can be either:
+    // mac, ip, gateway, netmask, dns (esp8266 or natural order)
+    // mac, ip, dns, gateway, netmask (Arduino legacy)
+    boolean begin(const uint8_t* macAddress, const IPAddress& local_ip = IPADDR_NONE,
+                  const IPAddress& arg1 = IPADDR_NONE, const IPAddress& arg2 = IPADDR_NONE,
+                  const IPAddress& arg3 = IPADDR_NONE)
+    {
+        SPI4EthInit();  // Arduino Ethernet self-initializes SPI
+        bool ret = true;
+        if (local_ip.isSet())
+            ret = LwipIntfDev<RawDev>::config(local_ip, arg1, arg2, arg3);
+        if (ret)
+        {
+            ret = LwipIntfDev<RawDev>::begin(macAddress);
+            if (!local_ip.isSet())
+            {
+                // Arduino API waits for DHCP answer
+                while (!LwipIntfDev<RawDev>::connected())
+                {
+                    delay(100);
+                }
+            }
+        }
+
+        if (ret)
+        {
+            _hardwareStatus = EthernetHardwareFound;
+            _linkStatus     = LinkON;
+        }
+
+        return ret;
+    }
+
+    HardwareStatus hardwareStatus() const
+    {
+        return _hardwareStatus;
+    }
+
+    EthernetLinkStatus linkStatus() const
+    {
+        return _linkStatus;
+    }
+
+    int maintain() const
+    {
+        return DHCP_CHECK_NONE;
+    }
+
+protected:
+    HardwareStatus     _hardwareStatus;
+    EthernetLinkStatus _linkStatus;
+};
+
+using ArduinoWiznet5500lwIP = ArduinoEthernet<Wiznet5500>;
+using ArduinoWiznet5100lwIP = ArduinoEthernet<Wiznet5100>;
+using ArduinoENC28J60lwIP   = ArduinoEthernet<ENC28J60>;