text: /*
   * Udp.cpp: Library to send/receive UDP packets with the Arduino ethernet shield.
   * This version only offers minimal wrapping of socket.c/socket.h
   *
   * NOTE: UDP is fast, but has some important limitations (thanks to Warren Gray for mentioning these)
   * 1) UDP does not guarantee the order in which assembled UDP packets are received. This
   * might not happen often in practice, but in larger network topologies, a UDP
   * packet can be received out of sequence.
   * 2) UDP does not guard against lost packets - so packets *can* disappear without the sender being
   * aware of it. Again, this may not be a concern in practice on small local networks.
   * For more information, see http://www.cafeaulait.org/course/week12/35.html
   *
   * MIT License:
   * Copyright (c) 2008 Bjoern Hartmann
   * Permission is hereby granted, free of charge, to any person obtaining a copy
   * of this software and associated documentation files (the "Software"), to deal
   * in the Software without restriction, including without limitation the rights
   * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
   * copies of the Software, and to permit persons to whom the Software is
   * furnished to do so, subject to the following conditions:
   *
   * The above copyright notice and this permission notice shall be included in
   * all copies or substantial portions of the Software.
   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
   * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
   * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
   * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
   * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
   * THE SOFTWARE.
   *
   * bjoern@cs.stanford.edu 12/30/2008
   */
  #ifndef udp_h
  #define udp_h
  
  #define UDP_TX_PACKET_MAX_SIZE 24
  
  struct _udp_t {
      unsigned port;      // local port to listen on
      unsigned sock;      // socket ID for Wiz5100
  };
  typedef struct _udp_t udp_t;
  
  /*
   * Initialize, start listening on specified port.
   * Returns 1 if successful, 0 if there are no sockets available to use.
   */
  int udp_init (udp_t *u, unsigned port);
  
  /*
   * Has data been received?
   */
  unsigned udp_available (udp_t *u);
  
  /*
   * Finish with the UDP socket.
   */
  void udp_stop (udp_t *u);
  
  /*
   * Send a packet to specified peer.
   */
  uint16_t udp_send_packet (udp_t *u, const uint8_t *data, unsigned len,
                            uint8_t *ip, unsigned port);
  
  /*
   * Send a zero-terminated string to specified peer.
   */
  uint16_t udp_send_string (udp_t *u, const char *data,
                            uint8_t *ip, unsigned port);
  
  /*
   * Read a received packet, also return sender's ip and port.
   */
  int udp_read_packet (udp_t *u, uint8_t *buf, unsigned len, uint8_t *ip, unsigned *port);
  
  #endif
  