#   else /* UIP_BYTE_ORDER == UIP_BIG_ENDIAN */
#      define HTONS(n) (u16_t)((((u16_t) (n)) << 8) | (((u16_t) (n)) >> 8))
#   endif /* UIP_BYTE_ORDER == UIP_BIG_ENDIAN */
#else
#error "HTONS already defined!"
#endif /* HTONS */

/**
 * Convert 16-bit quantity from host byte order to network byte order.
 *
 * This function is primarily used for converting variables from host
 * byte order to network byte order. For converting constants to
 * network byte order, use the HTONS() macro instead.
 */
#ifndef htons
u16_t htons(u16_t val);
#endif /* htons */
#ifndef ntohs
#define ntohs htons
#endif

/** @} */

/**
 * Pointer to the application data in the packet buffer.
 *
 * This pointer points to the application data when the application is
 * called. If the application wishes to send data, the application may
 * use this space to write the data into before calling uip_send().
 */
extern void *uip_appdata;

#if UIP_URGDATA > 0
/* u8_t *uip_urgdata:
 *
 * This pointer points to any urgent data that has been received. Only
 * present if compiled with support for urgent data (UIP_URGDATA).
 */
extern void *uip_urgdata;
#endif /* UIP_URGDATA > 0 */


/**
 * \defgroup uipdrivervars Variables used in uIP device drivers
 * @{
 *
 * uIP has a few global variables that are used in device drivers for
 * uIP.
 */

/**
 * The length of the packet in the uip_buf buffer.
 *
 * The global variable uip_len holds the length of the packet in the
 * uip_buf buffer.
 *
 * When the network device driver calls the uIP input function,
 * uip_len should be set to the length of the packet in the uip_buf
 * buffer.
 *
 * When sending packets, the device driver should use the contents of
 * the uip_len variable to determine the length of the outgoing
 * packet.
 *
 */
extern u16_t uip_len;

/** @} */

#if UIP_URGDATA > 0
extern u16_t uip_urglen, uip_surglen;
#endif /* UIP_URGDATA > 0 */


/**
 * Representation of a uIP TCP connection.
 *
 * The uip_conn structure is used for identifying a connection. All
 * but one field in the structure are to be considered read-only by an
 * application. The only exception is the appstate field whos purpose
 * is to let the application store application-specific state (e.g.,
 * file pointers) for the connection. The type of this field is
 * configured in the "uipopt.h" header file.
 */
struct uip_conn {
  uip_ipaddr_t ripaddr;   /**< The IP address of the remote host. */
  
  u16_t lport;        /**< The local TCP port, in network byte order. */
  u16_t rport;        /**< The local remote TCP port, in network byte
			 order. */
  
  u8_t rcv_nxt[4];    /**< The sequence number that we expect to
			 receive next. */
  u8_t snd_nxt[4];    /**< The sequence number that was last sent by
                         us. */
  u16_t len;          /**< Length of the data that was previously sent. */
  u16_t mss;          /**< Current maximum segment size for the
			 connection. */
  u16_t initialmss;   /**< Initial maximum segment size for the
			 connection. */
  u8_t sa;            /**< Retransmission time-out calculation state
			 variable. */
  u8_t sv;            /**< Retransmission time-out calculation state
			 variable. */
  u8_t rto;           /**< Retransmission time-out. */
  u8_t tcpstateflags; /**< TCP state and flags. */
  u8_t timer;         /**< The retransmission timer. */
  u8_t nrtx;          /**< The number of retransmissions for the last
			 segment sent. */

  /** The application state. */
  uip_tcp_appstate_t appstate;
};


/**
 * Pointer to the current TCP connection.
 *
 * The uip_conn pointer can be used to access the current TCP
 * connection.
 */
extern struct uip_conn *uip_conn;
/* The array containing all uIP connections. */
extern struct uip_conn uip_conns[UIP_CONNS];
/**
 * \addtogroup uiparch
 * @{
 */

/**
 * 4-byte array used for the 32-bit sequence number calculations.
 */
extern u8_t uip_acc32[4];

/** @} */


#if UIP_UDP
/**
 * Representation of a uIP UDP connection.
 */
struct uip_udp_conn {
  uip_ipaddr_t ripaddr;   /**< The IP address of the remote peer. */
  u16_t lport;        /**< The local port number in network byte order. */
  u16_t rport;        /**< The remote port number in network byte order. */
  u8_t  ttl;          /**< Default time-to-live. */

  /** The application state. */
  uip_udp_appstate_t appstate;
};

/**
 * The current UDP connection.
 */
extern struct uip_udp_conn *uip_udp_conn;
extern struct uip_udp_conn uip_udp_conns[UIP_UDP_CONNS];
#endif /* UIP_UDP */

/**
 * The structure holding the TCP/IP statistics that are gathered if
 * UIP_STATISTICS is set to 1.
 *
 */
struct uip_stats {
  struct {
    uip_stats_t drop;     /**< Number of dropped packets at the IP
			     layer. */
    uip_stats_t recv;     /**< Number of received packets at the IP
			     layer. */
    uip_stats_t sent;     /**< Number of sent packets at the IP
			     layer. */
    uip_stats_t vhlerr;   /**< Number of packets dropped due to wrong
			     IP version or header length. */
    uip_stats_t hblenerr; /**< Number of packets dropped due to wrong
			     IP length, high byte. */
    uip_stats_t lblenerr; /**< Number of packets dropped due to wrong
			     IP length, low byte. */
    uip_stats_t fragerr;  /**< Number of packets dropped since they
			     were IP fragments. */
    uip_stats_t chkerr;   /**< Number of packets dropped due to IP
			     checksum errors. */
    uip_stats_t protoerr; /**< Number of packets dropped since they
			     were neither ICMP, UDP nor TCP. */
  } ip;                   /**< IP statistics. */
  struct {
    uip_stats_t drop;     /**< Number of dropped ICMP packets. */
    uip_stats_t recv;     /**< Number of received ICMP packets. */
    uip_stats_t sent;     /**< Number of sent ICMP packets. */
    uip_stats_t typeerr;  /**< Number of ICMP packets with a wrong
			     type. */
  } icmp;                 /**< ICMP statistics. */
  struct {
    uip_stats_t drop;     /**< Number of dropped TCP segments. */
    uip_stats_t recv;     /**< Number of recived TCP segments. */
    uip_stats_t sent;     /**< Number of sent TCP segments. */
    uip_stats_t chkerr;   /**< Number of TCP segments with a bad
			     checksum. */
    uip_stats_t ackerr;   /**< Number of TCP segments with a bad ACK
			     number. */
    uip_stats_t rst;      /**< Number of recevied TCP RST (reset) segments. */
    uip_stats_t rexmit;   /**< Number of retransmitted TCP segments. */
    uip_stats_t syndrop;  /**< Number of dropped SYNs due to too few
			     connections was avaliable. */
    uip_stats_t synrst;   /**< Number of SYNs for closed ports,
			     triggering a RST. */
  } tcp;                  /**< TCP statistics. */
#if UIP_UDP
  struct {
    uip_stats_t drop;     /**< Number of dropped UDP segments. */
    uip_stats_t recv;     /**< Number of recived UDP segments. */
    uip_stats_t sent;     /**< Number of sent UDP segments. */
    uip_stats_t chkerr;   /**< Number of UDP segments with a bad
			     checksum. */
  } udp;                  /**< UDP statistics. */
#endif /* UIP_UDP */
};

/**
 * The uIP TCP/IP statistics.
 *
 * This is the variable in which the uIP TCP/IP statistics are gathered.
 */
extern struct uip_stats uip_stat;


/*---------------------------------------------------------------------------*/
/* All the stuff below this point is internal to uIP and should not be
 * used directly by an application or by a device driver.
 */
/*---------------------------------------------------------------------------*/
/* u8_t uip_flags:
 *
 * When the application is called, uip_flags will contain the flags
 * that are defined in this file. Please read below for more
 * infomation.
 */
extern u8_t uip_flags;

/* The following flags may be set in the global variable uip_flags
   before calling the application callback. The UIP_ACKDATA,
   UIP_NEWDATA, and UIP_CLOSE flags may both be set at the same time,
   whereas the others are mutualy exclusive. Note that these flags
   should *NOT* be accessed directly, but only through the uIP
   functions/macros. */

#define UIP_ACKDATA   1     /* Signifies that the outstanding data was
			       acked and the application should send
			       out new data instead of retransmitting
			       the last data. */
#define UIP_NEWDATA   2     /* Flags the fact that the peer has sent
			       us new data. */
#define UIP_REXMIT    4     /* Tells the application to retransmit the
			       data that was last sent. */
#define UIP_POLL      8     /* Used for polling the application, to
			       check if the application has data that
			       it wants to send. */
#define UIP_CLOSE     16    /* The remote host has closed the
			       connection, thus the connection has
			       gone away. Or the application signals
			       that it wants to close the
			       connection. */
#define UIP_ABORT     32    /* The remote host has aborted the
			       connection, thus the connection has
			       gone away. Or the application signals
			       that it wants to abort the
			       connection. */
#define UIP_CONNECTED 64    /* We have got a connection from a remote
                               host and have set up a new connection
                               for it, or an active connection has
                               been successfully established. */

#define UIP_TIMEDOUT  128   /* The connection has been aborted due to
			       too many retransmissions. */

/* uip_process(flag):
 *
 * The actual uIP function which does all the work.
 */
void uip_process(u8_t flag);

/* The following flags are passed as an argument to the uip_process()
   function. They are used to distinguish between the two cases where
   uip_process() is called. It can be called either because we have
   incoming data that should be processed, or because the periodic
   timer has fired. These values are never used directly, but only in
   the macrose defined in this file. */
 
#define UIP_DATA          1     /* Tells uIP that there is incoming
				   data in the uip_buf buffer. The
				   length of the data is stored in the
				   global variable uip_len. */
#define UIP_TIMER         2     /* Tells uIP that the periodic timer
				   has fired. */
#define UIP_POLL_REQUEST  3     /* Tells uIP that a connection should
				   be polled. */
#define UIP_UDP_SEND_CONN 4     /* Tells uIP that a UDP datagram
				   should be constructed in the
				   uip_buf buffer. */
#if UIP_UDP
#define UIP_UDP_TIMER     5
#endif /* UIP_UDP */

/* The TCP states used in the uip_conn->tcpstateflags. */
#define UIP_CLOSED      0
#define UIP_SYN_RCVD    1
#define UIP_SYN_SENT    2
#define UIP_ESTABLISHED 3
#define UIP_FIN_WAIT_1  4
#define UIP_FIN_WAIT_2  5
#define UIP_CLOSING     6
#define UIP_TIME_WAIT   7
#define UIP_LAST_ACK    8
#define UIP_TS_MASK     15
  
#define UIP_STOPPED      16

/* The TCP and IP headers. */
struct uip_tcpip_hdr {
#if UIP_CONF_IPV6
  /* IPv6 header. */
  u8_t vtc,
    tcflow;
  u16_t flow;
  u8_t len[2];
  u8_t proto, ttl;
  uip_ip6addr_t srcipaddr, destipaddr;
#else /* UIP_CONF_IPV6 */
  /* IPv4 header. */
  u8_t vhl,
    tos,
    len[2],
    ipid[2],
    ipoffset[2],
    ttl,
    proto;
  u16_t ipchksum;
  u16_t srcipaddr[2],
    destipaddr[2];
#endif /* UIP_CONF_IPV6 */
  
  /* TCP header. */
  u16_t srcport,
    destport;
  u8_t seqno[4],
    ackno[4],
    tcpoffset,
    flags,
    wnd[2];
  u16_t tcpchksum;
  u8_t urgp[2];
  u8_t optdata[4];
};

/* The ICMP and IP headers. */
struct uip_icmpip_hdr {
#if UIP_CONF_IPV6
  /* IPv6 header. */
  u8_t vtc,
    tcf;
  u16_t flow;
  u8_t len[2];
  u8_t proto, ttl;
  uip_ip6addr_t srcipaddr, destipaddr;
#else /* UIP_CONF_IPV6 */
  /* IPv4 header. */
  u8_t vhl,
    tos,
    len[2],
    ipid[2],
    ipoffset[2],
    ttl,
    proto;
  u16_t ipchksum;
  u16_t srcipaddr[2],
    destipaddr[2];
#endif /* UIP_CONF_IPV6 */
  
  /* ICMP (echo) header. */
  u8_t type, icode;
  u16_t icmpchksum;
#if !UIP_CONF_IPV6
  u16_t id, seqno;
#else /* !UIP_CONF_IPV6 */
  u8_t flags, reserved1, reserved2, reserved3;
  u8_t icmp6data[16];
  u8_t options[1];
#endif /* !UIP_CONF_IPV6 */
};


/* The UDP and IP headers. */
struct uip_udpip_hdr {
#if UIP_CONF_IPV6
  /* IPv6 header. */
  u8_t vtc,
    tcf;
  u16_t flow;
  u8_t len[2];
  u8_t proto, ttl;
  uip_ip6addr_t srcipaddr, destipaddr;
#else /* UIP_CONF_IPV6 */
  /* IP header. */
  u8_t vhl,
    tos,
    len[2],
    ipid[2],
    ipoffset[2],
    ttl,
    proto;
  u16_t ipchksum;
  u16_t srcipaddr[2],
    destipaddr[2];
#endif /* UIP_CONF_IPV6 */
  
  /* UDP header. */
  u16_t srcport,
    destport;
  u16_t udplen;
  u16_t udpchksum;
};



/**
 * The buffer size available for user data in the \ref uip_buf buffer.
 *
 * This macro holds the available size for user data in the \ref
 * uip_buf buffer. The macro is intended to be used for checking
 * bounds of available user data.
 *
 * Example:
 \code
 snprintf(uip_appdata, UIP_APPDATA_SIZE, "%u\n", i);
 \endcode
 *
 * \hideinitializer
 */
#define UIP_APPDATA_SIZE (UIP_BUFSIZE - UIP_LLH_LEN - UIP_TCPIP_HLEN)


#define UIP_PROTO_ICMP  1
#define UIP_PROTO_TCP   6
#define UIP_PROTO_UDP   17
#define UIP_PROTO_ICMP6 58

/* Header sizes. */
#if UIP_CONF_IPV6
#define UIP_IPH_LEN    40
#else /* UIP_CONF_IPV6 */
#define UIP_IPH_LEN    20    /* Size of IP header */
#endif /* UIP_CONF_IPV6 */
#define UIP_UDPH_LEN    8    /* Size of UDP header */
#define UIP_TCPH_LEN   20    /* Size of TCP header */
#define UIP_IPUDPH_LEN (UIP_UDPH_LEN + UIP_IPH_LEN)    /* Size of IP +
							  UDP
							  header */
#define UIP_IPTCPH_LEN (UIP_TCPH_LEN + UIP_IPH_LEN)    /* Size of IP +
							  TCP
							  header */
#define UIP_TCPIP_HLEN UIP_IPTCPH_LEN


#if UIP_FIXEDADDR
extern const uip_ipaddr_t uip_hostaddr, uip_netmask, uip_draddr;
#else /* UIP_FIXEDADDR */
extern uip_ipaddr_t uip_hostaddr, uip_netmask, uip_draddr;
#endif /* UIP_FIXEDADDR */



/**
 * Representation of a 48-bit Ethernet address.
 */
struct uip_eth_addr {
  u8_t addr[6];
};

/**
 * Calculate the Internet checksum over a buffer.
 *
 * The Internet checksum is the one's complement of the one's
 * complement sum of all 16-bit words in the buffer.
 *
 * See RFC1071.
 *
 * \param buf A pointer to the buffer over which the checksum is to be
 * computed.
 *
 * \param len The length of the buffer over which the checksum is to
 * be computed.
 *
 * \return The Internet checksum of the buffer.
 */
u16_t uip_chksum(u16_t *buf, u16_t len);

/**
 * Calculate the IP header checksum of the packet header in uip_buf.
 *
 * The IP header checksum is the Internet checksum of the 20 bytes of
 * the IP header.
 *
 * \return The IP header checksum of the IP header in the uip_buf
 * buffer.
 */
u16_t uip_ipchksum(void);

/**
 * Calculate the TCP checksum of the packet in uip_buf and uip_appdata.
 *
 * The TCP checksum is the Internet checksum of data contents of the
 * TCP segment, and a pseudo-header as defined in RFC793.
 *
 * \return The TCP checksum of the TCP segment in uip_buf and pointed
 * to by uip_appdata.
 */
u16_t uip_tcpchksum(void);

/**
 * Calculate the UDP checksum of the packet in uip_buf and uip_appdata.
 *
 * The UDP checksum is the Internet checksum of data contents of the
 * UDP segment, and a pseudo-header as defined in RFC768.
 *
 * \return The UDP checksum of the UDP segment in uip_buf and pointed
 * to by uip_appdata.
 */
u16_t uip_udpchksum(void);


#endif /* __UIP_H__ */


/** @} */