/* Upper sub-layer (LAPB) definitions */

/* Control field templates */
#define I	0x00	/* Information frames */
#define S	0x01	/* Supervisory frames */
#define RR	0x01	/* Receiver ready */
#define RNR	0x05	/* Receiver not ready */
#define REJ	0x09	/* Reject */
#define SREJ	0x0d	/* Selective Reject */
#define U	0x03	/* Unnumbered frames */
#define UI	0x03	/* Unnumbered information */
#define SIM	0x07	/* Set Initialization Mode (req) */
#define RIM	0x07	/* Request Initialization Mode (rsp) */
#define DM	0x0f	/* Disconnected mode (rsp) */
#define SARM	0x0f	/* Set Asynchronous Response Mode (req) */
#define UP	0x23	/* Unnumbered Poll */
#define SABM	0x2f	/* Set Asynchronous Balanced Mode */
#define DISC	0x43	/* Disconnect (req) */
#define RD	0x43	/* Request Disconnect (rsp) */
#define SARME	0x4f	/* Set Normal Response Mode Extended */
#define UA	0x63	/* Unnumbered acknowledge */
#define SABME	0x6f	/* Set Asynchronous Balanced Mode Extended */
#define SNRM	0x83	/* Set Normal Response Mode */
#define XID	0xaf	/* eXchange ID */
#define FRMR	0x87	/* Frame reject */
#define RSET	0x8f	/* Reset */
#define SNRME	0xcf	/* Set Normal Response Mode Extended */
#define TEST	0xe3	/* Test */
#define PF	0x10	/* Poll/final bit */

#define MMASK	7	/* Mask for modulo-8 sequence numbers */

/* FRMR reason bits */
#define W	1	/* Invalid control field */
#define X	2	/* Unallowed I-field */
#define Y	4	/* Too-long I-field */
#define Z	8	/* Invalid sequence number */

/* Per-connection link control block
 * These are created and destroyed dynamically,
 * and are indexed through a hash table.
 * One exists for each logical AX.25 Level 2 connection
 */
struct ax25_cb {
	struct ax25_cb *next;		/* Doubly linked list pointers */
	struct ax25_cb *prev;

	struct mbuf *txq;		/* Transmit queue */
	struct mbuf *rxasm;		/* Receive reassembly buffer */
	struct mbuf *rxq;		/* Receive queue */
	struct mbuf *sammlq[8];		/* "Frame Sammler" */
	char sammlchk[8];		/* checksums for "Frame Sammler" */

	struct ax25 addr;		/* Address header */

	struct interface *interface;	/* Associated interface */

	char rejsent;			/* REJ frame has been sent */
	char remotebusy;		/* Remote sent RNR */
	char waitack;			/* Wait for F-bit Ack */
	char response;			/* Response owed to other end */
	char fin;			/* Disc after ACK of all frames */

	char vs;			/* Our send state variable */
	char vr;			/* Our receive state variable */
	char sent;			/* Number of frames sent (unacked) */
	char unack;			/* Number of unacked frames */
	int maxframe;			/* Transmit flow control level */
	int maxsamml;			/* Maximum lookahead by sammler */
	int16 paclen;			/* Maximum outbound packet size */
	int16 window;			/* Local flow control limit */
	char proto;			/* Protocol version */
#define V1	1			/* AX.25 Version 1 */
#define V2	2			/* AX.25 Version 2 */
	int16	pthresh;		/* Poll threshold */
	unsigned retries;		/* Retry counter */
	unsigned n2;			/* Retry limit */
	int state;			/* Link state */
#define DISCONNECTED	0
#define SETUP		1
#define DISCPENDING	2
#define CONNECTED	3
#define FRAMEREJECT	4
	char control;			/* Control field of last rcvd frame */
	char frmrinfo[3];		/* I-field for FRMR message */
	struct timer t1;		/* Retry timer */
	struct timer t2;		/* Acknowledgement delay timer */
	struct timer t3;		/* Keep-alive poll timer */
	struct timer t4;		/* Link-idle disconnect timer */

	void (*r_upcall)();		/* Receiver upcall */
	void (*t_upcall)();		/* Transmit upcall */
	void (*s_upcall)();		/* State change upcall */
	char *user;			/* User pointer */
};
#define NULLAX25	((struct ax25_cb *)0)
extern struct ax25_cb ax25default;
extern struct ax25_cb *ax25_cb[];
#define NHASH	17

#if (defined(ATARI_ST) && defined(__TURBOC__))
extern log_ax(struct ax25_cb *,char *,...);
#endif

/* State change messages sent to client */
#define LAPBNOMS	0		/* no message */
#define LAPBCONN	1		/* CONNECTED to */
#define LAPBDISC	2		/* DISCONNECTED from */
#define LAPBBUSY	3		/* BUSY from */
#define LAPBFAIL	4		/* LINK FAILURE with */
#define LAPBRESF	5		/* LINK RESET from */
#define LAPBREST	6		/* LINK RESET to */
#define LAPBFRMF	7		/* FRAME REJECT from */
#define LAPBFRMT	8		/* FRAME REJECT to */

#define YES	1
#define NO	0