text: /**
   * @file
   * TCP API (to be used from TCPIP thread)\n
   * See also @ref tcp_raw
   */
  
  /*
   * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without modification,
   * are permitted provided that the following conditions are met:
   *
   * 1. Redistributions of source code must retain the above copyright notice,
   *    this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright notice,
   *    this list of conditions and the following disclaimer in the documentation
   *    and/or other materials provided with the distribution.
   * 3. The name of the author may not be used to endorse or promote products
   *    derived from this software without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
   * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
   * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
   * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
   * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
   * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
   * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
   * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
   * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
   * OF SUCH DAMAGE.
   *
   * This file is part of the lwIP TCP/IP stack.
   *
   * Author: Adam Dunkels <adam@sics.se>
   *
   */
  #ifdef LIBOHIBOARD_ETHERNET_LWIP_2_0_3
  
  #ifndef LWIP_HDR_TCP_H
  #define LWIP_HDR_TCP_H
  
  #include "lwip/opt.h"
  
  #if LWIP_TCP /* don't build if not configured for use in lwipopts.h */
  
  #include "lwip/mem.h"
  #include "lwip/pbuf.h"
  #include "lwip/ip.h"
  #include "lwip/icmp.h"
  #include "lwip/err.h"
  #include "lwip/ip6.h"
  #include "lwip/ip6_addr.h"
  
  #ifdef __cplusplus
  extern "C" {
  #endif
  
  struct tcp_pcb;
  
  /** Function prototype for tcp accept callback functions. Called when a new
   * connection can be accepted on a listening pcb.
   *
   * @param arg Additional argument to pass to the callback function (@see tcp_arg())
   * @param newpcb The new connection pcb
   * @param err An error code if there has been an error accepting.
   *            Only return ERR_ABRT if you have called tcp_abort from within the
   *            callback function!
   */
  typedef err_t (*tcp_accept_fn)(void *arg, struct tcp_pcb *newpcb, err_t err);
  
  /** Function prototype for tcp receive callback functions. Called when data has
   * been received.
   *
   * @param arg Additional argument to pass to the callback function (@see tcp_arg())
   * @param tpcb The connection pcb which received data
   * @param p The received data (or NULL when the connection has been closed!)
   * @param err An error code if there has been an error receiving
   *            Only return ERR_ABRT if you have called tcp_abort from within the
   *            callback function!
   */
  typedef err_t (*tcp_recv_fn)(void *arg, struct tcp_pcb *tpcb,
                               struct pbuf *p, err_t err);
  
  /** Function prototype for tcp sent callback functions. Called when sent data has
   * been acknowledged by the remote side. Use it to free corresponding resources.
   * This also means that the pcb has now space available to send new data.
   *
   * @param arg Additional argument to pass to the callback function (@see tcp_arg())
   * @param tpcb The connection pcb for which data has been acknowledged
   * @param len The amount of bytes acknowledged
   * @return ERR_OK: try to send some data by calling tcp_output
   *            Only return ERR_ABRT if you have called tcp_abort from within the
   *            callback function!
   */
  typedef err_t (*tcp_sent_fn)(void *arg, struct tcp_pcb *tpcb,
                                u16_t len);
  
  /** Function prototype for tcp poll callback functions. Called periodically as
   * specified by @see tcp_poll.
   *
   * @param arg Additional argument to pass to the callback function (@see tcp_arg())
   * @param tpcb tcp pcb
   * @return ERR_OK: try to send some data by calling tcp_output
   *            Only return ERR_ABRT if you have called tcp_abort from within the
   *            callback function!
   */
  typedef err_t (*tcp_poll_fn)(void *arg, struct tcp_pcb *tpcb);
  
  /** Function prototype for tcp error callback functions. Called when the pcb
   * receives a RST or is unexpectedly closed for any other reason.
   *
   * @note The corresponding pcb is already freed when this callback is called!
   *
   * @param arg Additional argument to pass to the callback function (@see tcp_arg())
   * @param err Error code to indicate why the pcb has been closed
   *            ERR_ABRT: aborted through tcp_abort or by a TCP timer
   *            ERR_RST: the connection was reset by the remote host
   */
  typedef void  (*tcp_err_fn)(void *arg, err_t err);
  
  /** Function prototype for tcp connected callback functions. Called when a pcb
   * is connected to the remote side after initiating a connection attempt by
   * calling tcp_connect().
   *
   * @param arg Additional argument to pass to the callback function (@see tcp_arg())
   * @param tpcb The connection pcb which is connected
   * @param err An unused error code, always ERR_OK currently ;-) @todo!
   *            Only return ERR_ABRT if you have called tcp_abort from within the
   *            callback function!
   *
   * @note When a connection attempt fails, the error callback is currently called!
   */
  typedef err_t (*tcp_connected_fn)(void *arg, struct tcp_pcb *tpcb, err_t err);
  
  #if LWIP_WND_SCALE
  #define RCV_WND_SCALE(pcb, wnd) (((wnd) >> (pcb)->rcv_scale))
  #define SND_WND_SCALE(pcb, wnd) (((wnd) << (pcb)->snd_scale))
  #define TCPWND16(x)             ((u16_t)LWIP_MIN((x), 0xFFFF))
  #define TCP_WND_MAX(pcb)        ((tcpwnd_size_t)(((pcb)->flags & TF_WND_SCALE) ? TCP_WND : TCPWND16(TCP_WND)))
  typedef u32_t tcpwnd_size_t;
  #else
  #define RCV_WND_SCALE(pcb, wnd) (wnd)
  #define SND_WND_SCALE(pcb, wnd) (wnd)
  #define TCPWND16(x)             (x)
  #define TCP_WND_MAX(pcb)        TCP_WND
  typedef u16_t tcpwnd_size_t;
  #endif
  
  #if LWIP_WND_SCALE || TCP_LISTEN_BACKLOG || LWIP_TCP_TIMESTAMPS
  typedef u16_t tcpflags_t;
  #else
  typedef u8_t tcpflags_t;
  #endif
  
  enum tcp_state {
    CLOSED      = 0,
    LISTEN      = 1,
    SYN_SENT    = 2,
    SYN_RCVD    = 3,
    ESTABLISHED = 4,
    FIN_WAIT_1  = 5,
    FIN_WAIT_2  = 6,
    CLOSE_WAIT  = 7,
    CLOSING     = 8,
    LAST_ACK    = 9,
    TIME_WAIT   = 10
  };
  
  /**
   * members common to struct tcp_pcb and struct tcp_listen_pcb
   */
  #define TCP_PCB_COMMON(type) \
    type *next; /* for the linked list */ \
    void *callback_arg; \
    enum tcp_state state; /* TCP state */ \
    u8_t prio; \
    /* ports are in host byte order */ \
    u16_t local_port
  
  
  /** the TCP protocol control block for listening pcbs */
  struct tcp_pcb_listen {
  /** Common members of all PCB types */
    IP_PCB;
  /** Protocol specific PCB members */
    TCP_PCB_COMMON(struct tcp_pcb_listen);
  
  #if LWIP_CALLBACK_API
    /* Function to call when a listener has been connected. */
    tcp_accept_fn accept;
  #endif /* LWIP_CALLBACK_API */
  
  #if TCP_LISTEN_BACKLOG
    u8_t backlog;
    u8_t accepts_pending;
  #endif /* TCP_LISTEN_BACKLOG */
  };
  
  
  /** the TCP protocol control block */
  struct tcp_pcb {
  /** common PCB members */
    IP_PCB;
  /** protocol specific PCB members */
    TCP_PCB_COMMON(struct tcp_pcb);
  
    /* ports are in host byte order */
    u16_t remote_port;
  
    tcpflags_t flags;
  #define TF_ACK_DELAY   0x01U   /* Delayed ACK. */
  #define TF_ACK_NOW     0x02U   /* Immediate ACK. */
  #define TF_INFR        0x04U   /* In fast recovery. */
  #define TF_CLOSEPEND   0x08U   /* If this is set, tcp_close failed to enqueue the FIN (retried in tcp_tmr) */
  #define TF_RXCLOSED    0x10U   /* rx closed by tcp_shutdown */
  #define TF_FIN         0x20U   /* Connection was closed locally (FIN segment enqueued). */
  #define TF_NODELAY     0x40U   /* Disable Nagle algorithm */
  #define TF_NAGLEMEMERR 0x80U   /* nagle enabled, memerr, try to output to prevent delayed ACK to happen */
  #if LWIP_WND_SCALE
  #define TF_WND_SCALE   0x0100U /* Window Scale option enabled */
  #endif
  #if TCP_LISTEN_BACKLOG
  #define TF_BACKLOGPEND 0x0200U /* If this is set, a connection pcb has increased the backlog on its listener */
  #endif
  #if LWIP_TCP_TIMESTAMPS
  #define TF_TIMESTAMP   0x0400U   /* Timestamp option enabled */
  #endif
  
    /* the rest of the fields are in host byte order
       as we have to do some math with them */
  
    /* Timers */
    u8_t polltmr, pollinterval;
    u8_t last_timer;
    u32_t tmr;
  
    /* receiver variables */
    u32_t rcv_nxt;   /* next seqno expected */
    tcpwnd_size_t rcv_wnd;   /* receiver window available */
    tcpwnd_size_t rcv_ann_wnd; /* receiver window to announce */
    u32_t rcv_ann_right_edge; /* announced right edge of window */
  
    /* Retransmission timer. */
    s16_t rtime;
  
    u16_t mss;   /* maximum segment size */
  
    /* RTT (round trip time) estimation variables */
    u32_t rttest; /* RTT estimate in 500ms ticks */
    u32_t rtseq;  /* sequence number being timed */
    s16_t sa, sv; /* @todo document this */
  
    s16_t rto;    /* retransmission time-out */
    u8_t nrtx;    /* number of retransmissions */
  
    /* fast retransmit/recovery */
    u8_t dupacks;
    u32_t lastack; /* Highest acknowledged seqno. */
  
    /* congestion avoidance/control variables */
    tcpwnd_size_t cwnd;
    tcpwnd_size_t ssthresh;
  
    /* sender variables */
    u32_t snd_nxt;   /* next new seqno to be sent */
    u32_t snd_wl1, snd_wl2; /* Sequence and acknowledgement numbers of last
                               window update. */
    u32_t snd_lbb;       /* Sequence number of next byte to be buffered. */
    tcpwnd_size_t snd_wnd;   /* sender window */
    tcpwnd_size_t snd_wnd_max; /* the maximum sender window announced by the remote host */
  
    tcpwnd_size_t snd_buf;   /* Available buffer space for sending (in bytes). */
  #define TCP_SNDQUEUELEN_OVERFLOW (0xffffU-3)
    u16_t snd_queuelen; /* Number of pbufs currently in the send buffer. */
  
  #if TCP_OVERSIZE
    /* Extra bytes available at the end of the last pbuf in unsent. */
    u16_t unsent_oversize;
  #endif /* TCP_OVERSIZE */
  
    /* These are ordered by sequence number: */
    struct tcp_seg *unsent;   /* Unsent (queued) segments. */
    struct tcp_seg *unacked;  /* Sent but unacknowledged segments. */
  #if TCP_QUEUE_OOSEQ
    struct tcp_seg *ooseq;    /* Received out of sequence segments. */
  #endif /* TCP_QUEUE_OOSEQ */
  
    struct pbuf *refused_data; /* Data previously received but not yet taken by upper layer */
  
  #if LWIP_CALLBACK_API || TCP_LISTEN_BACKLOG
    struct tcp_pcb_listen* listener;
  #endif /* LWIP_CALLBACK_API || TCP_LISTEN_BACKLOG */
  
  #if LWIP_CALLBACK_API
    /* Function to be called when more send buffer space is available. */
    tcp_sent_fn sent;
    /* Function to be called when (in-sequence) data has arrived. */
    tcp_recv_fn recv;
    /* Function to be called when a connection has been set up. */
    tcp_connected_fn connected;
    /* Function which is called periodically. */
    tcp_poll_fn poll;
    /* Function to be called whenever a fatal error occurs. */
    tcp_err_fn errf;
  #endif /* LWIP_CALLBACK_API */
  
  #if LWIP_TCP_TIMESTAMPS
    u32_t ts_lastacksent;
    u32_t ts_recent;
  #endif /* LWIP_TCP_TIMESTAMPS */
  
    /* idle time before KEEPALIVE is sent */
    u32_t keep_idle;
  #if LWIP_TCP_KEEPALIVE
    u32_t keep_intvl;
    u32_t keep_cnt;
  #endif /* LWIP_TCP_KEEPALIVE */
  
    /* Persist timer counter */
    u8_t persist_cnt;
    /* Persist timer back-off */
    u8_t persist_backoff;
  
    /* KEEPALIVE counter */
    u8_t keep_cnt_sent;
  
  #if LWIP_WND_SCALE
    u8_t snd_scale;
    u8_t rcv_scale;
  #endif
  };
  
  #if LWIP_EVENT_API
  
  enum lwip_event {
    LWIP_EVENT_ACCEPT,
    LWIP_EVENT_SENT,
    LWIP_EVENT_RECV,
    LWIP_EVENT_CONNECTED,
    LWIP_EVENT_POLL,
    LWIP_EVENT_ERR
  };
  
  err_t lwip_tcp_event(void *arg, struct tcp_pcb *pcb,
           enum lwip_event,
           struct pbuf *p,
           u16_t size,
           err_t err);
  
  #endif /* LWIP_EVENT_API */
  
  /* Application program's interface: */
  struct tcp_pcb * tcp_new     (void);
  struct tcp_pcb * tcp_new_ip_type (u8_t type);
  
  void             tcp_arg     (struct tcp_pcb *pcb, void *arg);
  #if LWIP_CALLBACK_API
  void             tcp_recv    (struct tcp_pcb *pcb, tcp_recv_fn recv);
  void             tcp_sent    (struct tcp_pcb *pcb, tcp_sent_fn sent);
  void             tcp_err     (struct tcp_pcb *pcb, tcp_err_fn err);
  void             tcp_accept  (struct tcp_pcb *pcb, tcp_accept_fn accept);
  #endif /* LWIP_CALLBACK_API */
  void             tcp_poll    (struct tcp_pcb *pcb, tcp_poll_fn poll, u8_t interval);
  
  #if LWIP_TCP_TIMESTAMPS
  #define          tcp_mss(pcb)             (((pcb)->flags & TF_TIMESTAMP) ? ((pcb)->mss - 12)  : (pcb)->mss)
  #else /* LWIP_TCP_TIMESTAMPS */
  #define          tcp_mss(pcb)             ((pcb)->mss)
  #endif /* LWIP_TCP_TIMESTAMPS */
  #define          tcp_sndbuf(pcb)          (TCPWND16((pcb)->snd_buf))
  #define          tcp_sndqueuelen(pcb)     ((pcb)->snd_queuelen)
  /** @ingroup tcp_raw */
  #define          tcp_nagle_disable(pcb)   ((pcb)->flags |= TF_NODELAY)
  /** @ingroup tcp_raw */
  #define          tcp_nagle_enable(pcb)    ((pcb)->flags = (tcpflags_t)((pcb)->flags & ~TF_NODELAY))
  /** @ingroup tcp_raw */
  #define          tcp_nagle_disabled(pcb)  (((pcb)->flags & TF_NODELAY) != 0)
  
  #if TCP_LISTEN_BACKLOG
  #define          tcp_backlog_set(pcb, new_backlog) do { \
    LWIP_ASSERT("pcb->state == LISTEN (called for wrong pcb?)", (pcb)->state == LISTEN); \
    ((struct tcp_pcb_listen *)(pcb))->backlog = ((new_backlog) ? (new_backlog) : 1); } while(0)
  void             tcp_backlog_delayed(struct tcp_pcb* pcb);
  void             tcp_backlog_accepted(struct tcp_pcb* pcb);
  #else  /* TCP_LISTEN_BACKLOG */
  #define          tcp_backlog_set(pcb, new_backlog)
  #define          tcp_backlog_delayed(pcb)
  #define          tcp_backlog_accepted(pcb)
  #endif /* TCP_LISTEN_BACKLOG */
  #define          tcp_accepted(pcb) /* compatibility define, not needed any more */
  
  void             tcp_recved  (struct tcp_pcb *pcb, u16_t len);
  err_t            tcp_bind    (struct tcp_pcb *pcb, const ip_addr_t *ipaddr,
                                u16_t port);
  err_t            tcp_connect (struct tcp_pcb *pcb, const ip_addr_t *ipaddr,
                                u16_t port, tcp_connected_fn connected);
  
  struct tcp_pcb * tcp_listen_with_backlog_and_err(struct tcp_pcb *pcb, u8_t backlog, err_t *err);
  struct tcp_pcb * tcp_listen_with_backlog(struct tcp_pcb *pcb, u8_t backlog);
  /** @ingroup tcp_raw */
  #define          tcp_listen(pcb) tcp_listen_with_backlog(pcb, TCP_DEFAULT_LISTEN_BACKLOG)
  
  void             tcp_abort (struct tcp_pcb *pcb);
  err_t            tcp_close   (struct tcp_pcb *pcb);
  err_t            tcp_shutdown(struct tcp_pcb *pcb, int shut_rx, int shut_tx);
  
  /* Flags for "apiflags" parameter in tcp_write */
  #define TCP_WRITE_FLAG_COPY 0x01
  #define TCP_WRITE_FLAG_MORE 0x02
  
  err_t            tcp_write   (struct tcp_pcb *pcb, const void *dataptr, u16_t len,
                                u8_t apiflags);
  
  void             tcp_setprio (struct tcp_pcb *pcb, u8_t prio);
  
  #define TCP_PRIO_MIN    1
  #define TCP_PRIO_NORMAL 64
  #define TCP_PRIO_MAX    127
  
  err_t            tcp_output  (struct tcp_pcb *pcb);
  
  
  const char* tcp_debug_state_str(enum tcp_state s);
  
  /* for compatibility with older implementation */
  #define tcp_new_ip6() tcp_new_ip_type(IPADDR_TYPE_V6)
  
  #ifdef __cplusplus
  }
  #endif
  
  #endif /* LWIP_TCP */
  
  #endif /* LWIP_HDR_TCP_H */
  
  #endif /* LIBOHIBOARD_ETHERNET_LWIP_2_0_3 */
  