Add support for the hardware CDC in ESP32-C3 (#5614)

* Add support for the hardware CDC in ESP32-C3

cores/esp32/HWCDC.h

@@ -0,0 +1,82 @@
+// Copyright 2015-2020 Espressif Systems (Shanghai) PTE LTD
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+#pragma once
+
+#include "sdkconfig.h"
+#if CONFIG_IDF_TARGET_ESP32C3
+
+#include <inttypes.h>
+#include "Stream.h"
+
+class HWCDC: public Stream
+{
+public:
+    HWCDC();
+    ~HWCDC();
+
+    size_t setRxBufferSize(size_t);
+    size_t setTxBufferSize(size_t);
+    void begin(unsigned long baud=0);
+    void end();
+    
+    int available(void);
+    int availableForWrite(void);
+    int peek(void);
+    int read(void);
+    size_t read(uint8_t *buffer, size_t size);
+    size_t write(uint8_t);
+    size_t write(const uint8_t *buffer, size_t size);
+    void flush(void);
+    
+    inline size_t read(char * buffer, size_t size)
+    {
+        return read((uint8_t*) buffer, size);
+    }
+    inline size_t write(const char * buffer, size_t size)
+    {
+        return write((uint8_t*) buffer, size);
+    }
+    inline size_t write(const char * s)
+    {
+        return write((uint8_t*) s, strlen(s));
+    }
+    inline size_t write(unsigned long n)
+    {
+        return write((uint8_t) n);
+    }
+    inline size_t write(long n)
+    {
+        return write((uint8_t) n);
+    }
+    inline size_t write(unsigned int n)
+    {
+        return write((uint8_t) n);
+    }
+    inline size_t write(int n)
+    {
+        return write((uint8_t) n);
+    }
+    operator bool() const;
+    void setDebugOutput(bool);
+    uint32_t baudRate(){return 115200;}
+
+};
+
+#if ARDUINO_HW_CDC_ON_BOOT //Serial used for USB CDC
+extern HWCDC Serial;
+#else
+extern HWCDC USBSerial;
+#endif
+
+#endif /* CONFIG_IDF_TARGET_ESP32C3 */