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Annotation of 42BSD/sys/netimp/if_imphost.h, revision 1.1

1.1     ! root        1: /*     if_imphost.h    6.1     83/07/29        */
        !             2: 
        !             3: /*
        !             4:  * Host structure used with IMP's.
        !             5:  * Used to hold outgoing packets which
        !             6:  * would exceed allowed RFNM count.
        !             7:  *
        !             8:  * These structures are packed into
        !             9:  * mbuf's and kept as small as possible.
        !            10:  */
        !            11: struct host {
        !            12:        struct  mbuf *h_q;              /* holding queue */
        !            13:        struct  in_addr h_addr;         /* host's address */
        !            14:        u_char  h_qcnt;                 /* size of holding q */
        !            15:        u_char  h_timer;                /* used to stay off deletion */
        !            16:        u_char  h_rfnm;                 /* # outstanding rfnm's */
        !            17:        u_char  h_flags;                /* see below */
        !            18: };
        !            19: 
        !            20: /*
        !            21:  * A host structure is kept around (even when there are no
        !            22:  * references to it) for a spell to avoid constant reallocation
        !            23:  * and also to reflect IMP status back to sites which aren't
        !            24:  * directly connected to the IMP.  When structures are marked
        !            25:  * free, a timer is started; when the timer expires the structure
        !            26:  * is scavenged.
        !            27:  */
        !            28: #define        HF_INUSE        0x1
        !            29: #define        HF_DEAD         (1<<IMPTYPE_HOSTDEAD)
        !            30: #define        HF_UNREACH      (1<<IMPTYPE_HOSTUNREACH)
        !            31: 
        !            32: #define        HOSTTIMER       128             /* keep structure around awhile */
        !            33: 
        !            34: /*
        !            35:  * Host structures, as seen inside an mbuf.
        !            36:  * Hashing on the host address is used to
        !            37:  * select an index into the first mbuf.  Collisions
        !            38:  * are then resolved by searching successive
        !            39:  * mbuf's at the same index.  Reclamation is done
        !            40:  * automatically at the time a structure is free'd.
        !            41:  */
        !            42: #define        HPMBUF  ((MLEN - sizeof(int)) / sizeof(struct host))
        !            43: #if vax
        !            44: #define        HOSTHASH(a)     ((((a).s_addr>>8)+(a).s_net) % HPMBUF)
        !            45: #endif
        !            46: 
        !            47: /*
        !            48:  * In-line expansions for queuing operations on
        !            49:  * host message holding queue.  Queue is maintained
        !            50:  * as circular list with the head pointing to the
        !            51:  * last message in the queue.
        !            52:  */
        !            53: #define        HOST_ENQUE(hp, m) { \
        !            54:        register struct mbuf *n; \
        !            55:        (hp)->h_qcnt++; \
        !            56:        if ((n = (hp)->h_q) == 0) \
        !            57:                (hp)->h_q = (m)->m_act = (m); \
        !            58:        else { \
        !            59:                (m)->m_act = n->m_act; \
        !            60:                (hp)->h_q = n->m_act = (m); \
        !            61:        } \
        !            62: }
        !            63: #define        HOST_DEQUE(hp, m) { \
        !            64:        if ((m) = (hp)->h_q) { \
        !            65:                if ((m)->m_act == (m)) \
        !            66:                        (hp)->h_q = 0; \
        !            67:                else { \
        !            68:                        (m) = (m)->m_act; \
        !            69:                        (hp)->h_q->m_act = (m)->m_act; \
        !            70:                } \
        !            71:                (hp)->h_qcnt--; \
        !            72:                (m)->m_act = 0; \
        !            73:        } \
        !            74: }
        !            75: 
        !            76: struct hmbuf {
        !            77:        int     hm_count;               /* # of struct's in use */
        !            78:        struct  host hm_hosts[HPMBUF];  /* data structures proper */
        !            79: };
        !            80: 
        !            81: #ifdef KERNEL
        !            82: struct host *hostlookup();
        !            83: struct host *hostenter();
        !            84: struct mbuf *hostdeque();
        !            85: #endif

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