text: /*
    serial.c - Low level functions for sending and recieving bytes via the serial port
    Part of Grbl
  
    Copyright (c) 2011-2015 Sungeun K. Jeon
    Copyright (c) 2009-2011 Simen Svale Skogsrud
  
    Grbl is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.
  
    Grbl 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 General Public License for more details.
  
    You should have received a copy of the GNU General Public License
    along with Grbl.  If not, see <http://www.gnu.org/licenses/>.
  */
  
  #ifndef serial_h
  #define serial_h
  
  
  #ifndef RX_BUFFER_SIZE
    #define RX_BUFFER_SIZE 128
  #endif
  #ifndef TX_BUFFER_SIZE
    #define TX_BUFFER_SIZE 64
  #endif
  
  #define SERIAL_NO_DATA 0xff
  
  #ifdef ENABLE_XONXOFF
    #define RX_BUFFER_FULL 96 // XOFF high watermark
    #define RX_BUFFER_LOW 64 // XON low watermark
    #define SEND_XOFF 1
    #define SEND_XON 2
    #define XOFF_SENT 3
    #define XON_SENT 4
    #define XOFF_CHAR 0x13
    #define XON_CHAR 0x11
  #endif
  
  void serial_init(void);
  
  // Writes one byte to the TX serial buffer. Called by main program.
  void serial_write(uint8_t data);
  
  // Fetches the first byte in the serial read buffer. Called by main program.
  uint8_t serial_read(void);
  
  // Reset and empty data in read buffer. Used by e-stop and reset.
  void serial_reset_read_buffer(void);
  
  // Returns the number of bytes used in the RX serial buffer.
  uint8_t serial_get_rx_buffer_count(void);
  
  // Returns the number of bytes used in the TX serial buffer.
  // NOTE: Not used except for debugging and ensuring no TX bottlenecks.
  uint8_t serial_get_tx_buffer_count(void);
  
  #endif
  