usr/src/sys/netinet/tcp_seq.h

/*      tcp_seq.h       6.1     83/07/29        */

/*
 * TCP sequence numbers are 32 bit integers operated
 * on with modular arithmetic.  These macros can be
 * used to compare such integers.
 */
#define SEQ_LT(a,b)     ((int)((a)-(b)) < 0)
#define SEQ_LEQ(a,b)    ((int)((a)-(b)) <= 0)
#define SEQ_GT(a,b)     ((int)((a)-(b)) > 0)
#define SEQ_GEQ(a,b)    ((int)((a)-(b)) >= 0)

/*
 * Macros to initialize tcp sequence numbers for
 * send and receive from initial send and receive
 * sequence numbers.
 */
#define tcp_rcvseqinit(tp) \
        (tp)->rcv_nxt = (tp)->irs + 1

#define tcp_sendseqinit(tp) \
        (tp)->snd_una = (tp)->snd_nxt = (tp)->snd_max = (tp)->snd_up = \
            (tp)->iss

#define TCP_ISSINCR     128             /* increment for tcp_iss each second */

#ifdef KERNEL
tcp_seq tcp_iss;                /* tcp initial send seq # */
#endif