text: /*
    HardwareSerial.h - Hardware serial library for Wiring
    Copyright (c) 2006 Nicholas Zambetti.  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
  
    Modified 28 September 2010 by Mark Sproul
  */
  
  #ifndef MarlinSerial_h
  #define MarlinSerial_h
  #include "Marlin.h"
  
  #ifndef SERIAL_PORT
    #define SERIAL_PORT 0
  #endif
  
  // The presence of the UBRRH register is used to detect a UART.
  #define UART_PRESENT(port) ((port == 0 && (defined(UBRRH) || defined(UBRR0H))) || \
  						(port == 1 && defined(UBRR1H)) || (port == 2 && defined(UBRR2H)) || \
  						(port == 3 && defined(UBRR3H)))				
  						
  // These are macros to build serial port register names for the selected SERIAL_PORT (C preprocessor
  // requires two levels of indirection to expand macro values properly)
  #define SERIAL_REGNAME(registerbase,number,suffix) SERIAL_REGNAME_INTERNAL(registerbase,number,suffix)
  #if SERIAL_PORT == 0 && (!defined(UBRR0H) || !defined(UDR0)) // use un-numbered registers if necessary
    #define SERIAL_REGNAME_INTERNAL(registerbase,number,suffix) registerbase##suffix
  #else
    #define SERIAL_REGNAME_INTERNAL(registerbase,number,suffix) registerbase##number##suffix
  #endif
  
  // Registers used by MarlinSerial class (these are expanded 
  // depending on selected serial port
  #define M_UCSRxA SERIAL_REGNAME(UCSR,SERIAL_PORT,A) // defines M_UCSRxA to be UCSRnA where n is the serial port number
  #define M_UCSRxB SERIAL_REGNAME(UCSR,SERIAL_PORT,B) 
  #define M_RXENx SERIAL_REGNAME(RXEN,SERIAL_PORT,)    
  #define M_TXENx SERIAL_REGNAME(TXEN,SERIAL_PORT,)    
  #define M_RXCIEx SERIAL_REGNAME(RXCIE,SERIAL_PORT,)    
  #define M_UDREx SERIAL_REGNAME(UDRE,SERIAL_PORT,)    
  #define M_UDRx SERIAL_REGNAME(UDR,SERIAL_PORT,)  
  #define M_UBRRxH SERIAL_REGNAME(UBRR,SERIAL_PORT,H)
  #define M_UBRRxL SERIAL_REGNAME(UBRR,SERIAL_PORT,L)
  #define M_RXCx SERIAL_REGNAME(RXC,SERIAL_PORT,)
  #define M_USARTx_RX_vect SERIAL_REGNAME(USART,SERIAL_PORT,_RX_vect)
  #define M_U2Xx SERIAL_REGNAME(U2X,SERIAL_PORT,)
  
  
  #define DEC 10
  #define HEX 16
  #define OCT 8
  #define BIN 2
  #define BYTE 0
  
  
  #ifndef USBCON
  // Define constants and variables for buffering incoming serial data.  We're
  // using a ring buffer (I think), in which rx_buffer_head is the index of the
  // location to which to write the next incoming character and rx_buffer_tail
  // is the index of the location from which to read.
  #define RX_BUFFER_SIZE 128
  
  
  struct ring_buffer {
    unsigned char buffer[RX_BUFFER_SIZE];
    int head;
    int tail;
  };
  
  #if UART_PRESENT(SERIAL_PORT)
    extern ring_buffer rx_buffer;
  #endif
  
  class MarlinSerial { //: public Stream
  
    public:
      MarlinSerial();
      void begin(long);
      void end();
      int peek(void);
      int read(void);
      void flush(void);
  
      FORCE_INLINE int available(void) {
        return (unsigned int)(RX_BUFFER_SIZE + rx_buffer.head - rx_buffer.tail) % RX_BUFFER_SIZE;
      }
  
      FORCE_INLINE void write(uint8_t c) {
        while (!TEST(M_UCSRxA, M_UDREx))
          ;
  
        M_UDRx = c;
      }
  
      FORCE_INLINE void checkRx(void) {
        if (TEST(M_UCSRxA, M_RXCx)) {
          unsigned char c  =  M_UDRx;
          int i = (unsigned int)(rx_buffer.head + 1) % RX_BUFFER_SIZE;
  
          // if we should be storing the received character into the location
          // just before the tail (meaning that the head would advance to the
          // current location of the tail), we're about to overflow the buffer
          // and so we don't write the character or advance the head.
          if (i != rx_buffer.tail) {
            rx_buffer.buffer[rx_buffer.head] = c;
            rx_buffer.head = i;
          }
        }
      }
  
    private:
      void printNumber(unsigned long, uint8_t);
      void printFloat(double, uint8_t);
  
    public:
      FORCE_INLINE void write(const char *str) { while (*str) write(*str++); }
      FORCE_INLINE void write(const uint8_t *buffer, size_t size) { while (size--) write(*buffer++); }
      FORCE_INLINE void print(const String &s) { for (int i = 0; i < (int)s.length(); i++) write(s[i]); }
      FORCE_INLINE void print(const char *str) { write(str); }
  
      void print(char, int = BYTE);
      void print(unsigned char, int = BYTE);
      void print(int, int = DEC);
      void print(unsigned int, int = DEC);
      void print(long, int = DEC);
      void print(unsigned long, int = DEC);
      void print(double, int = 2);
  
      void println(const String &s);
      void println(const char[]);
      void println(char, int = BYTE);
      void println(unsigned char, int = BYTE);
      void println(int, int = DEC);
      void println(unsigned int, int = DEC);
      void println(long, int = DEC);
      void println(unsigned long, int = DEC);
      void println(double, int = 2);
      void println(void);
  };
  
  extern MarlinSerial customizedSerial;
  #endif // !USBCON
  
  // Use the UART for Bluetooth in AT90USB configurations
  #if defined(USBCON) && ENABLED(BLUETOOTH)
    extern HardwareSerial bluetoothSerial;
  #endif
  
  #endif
  