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Annotation of 43BSDReno/sys/netimp/if_imphost.h, revision 1.1

1.1     ! root        1: /*
        !             2:  * Copyright (c) 1982, 1986, 1988 Regents of the University of California.
        !             3:  * All rights reserved.
        !             4:  *
        !             5:  * Redistribution is only permitted until one year after the first shipment
        !             6:  * of 4.4BSD by the Regents.  Otherwise, redistribution and use in source and
        !             7:  * binary forms are permitted provided that: (1) source distributions retain
        !             8:  * this entire copyright notice and comment, and (2) distributions including
        !             9:  * binaries display the following acknowledgement:  This product includes
        !            10:  * software developed by the University of California, Berkeley and its
        !            11:  * contributors'' in the documentation or other materials provided with the
        !            12:  * distribution and in all advertising materials mentioning features or use
        !            13:  * of this software.  Neither the name of the University nor the names of
        !            14:  * its contributors may be used to endorse or promote products derived from
        !            15:  * this software without specific prior written permission.
        !            16:  * THIS SOFTWARE IS PROVIDED AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
        !            17:  * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
        !            18:  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
        !            19:  *
        !            20:  *     @(#)if_imphost.h        7.7 (Berkeley) 6/28/90
        !            21:  */
        !            22: 
        !            23: /*
        !            24:  * Host structure used with IMP's.
        !            25:  * Used to hold outgoing packets which
        !            26:  * would exceed allowed RFNM count.
        !            27:  *
        !            28:  * These structures are packed into
        !            29:  * mbuf's and kept as small as possible.
        !            30:  */
        !            31: struct host {
        !            32:        struct  mbuf *h_q;              /* holding queue */
        !            33:        u_short h_timer;                /* used to stay off deletion */
        !            34:        u_short h_imp;                  /* host's imp number */
        !            35:        u_char  h_host;                 /* host's number on imp */
        !            36:        u_char  h_qcnt;                 /* size of holding q */
        !            37:        u_char  h_rfnm;                 /* # outstanding rfnm's */
        !            38:        u_char  h_flags;                /* see below */
        !            39: };
        !            40: 
        !            41: /*
        !            42:  * A host structure is kept around (even when there are no
        !            43:  * references to it) for a spell to avoid constant reallocation
        !            44:  * and also to reflect IMP status back to sites which aren't
        !            45:  * directly connected to the IMP.  When structures are marked
        !            46:  * idle, a timer is started; when the timer expires the structure
        !            47:  * is deallocated.  A structure may be reused before the timer expires.
        !            48:  * A structure holds a reference on the containing mbuf when it is marked
        !            49:  * HF_INUSE.
        !            50:  */
        !            51: #define        HF_INUSE        0x1
        !            52: #define        HF_DEAD         (1<<IMPTYPE_HOSTDEAD)
        !            53: #define        HF_UNREACH      (1<<IMPTYPE_HOSTUNREACH)
        !            54: 
        !            55: #define        HOSTTIMER       128             /* keep structure around awhile */
        !            56: 
        !            57: /*
        !            58:  * Mark a host structure free; used if host entry returned by hostlookup 
        !            59:  * isn't needed.  h_rfnm must be zero.
        !            60:  */
        !            61: #define        hostfree(hp) { \
        !            62:        if ((hp)->h_timer == 0 && (hp)->h_qcnt == 0 && \
        !            63:            (hp)->h_flags & HF_INUSE) \
        !            64:                hostrelease(hp); \
        !            65: }
        !            66: 
        !            67: /*
        !            68:  * Release a host entry when last rfnm is received.
        !            69:  */
        !            70: #define        hostidle(hp)    { (hp)->h_timer = HOSTTIMER; }
        !            71: 
        !            72: /*
        !            73:  * Host structures, as seen inside an mbuf.
        !            74:  * Hashing on the host and imp is used to
        !            75:  * select an index into the first mbuf.  Collisions
        !            76:  * are then resolved by searching successive
        !            77:  * mbuf's at the same index.  Reclamation is done
        !            78:  * automatically at the time a structure is freed.
        !            79:  */
        !            80: #define        HPMBUF  ((MLEN - sizeof(int)) / sizeof(struct host))
        !            81: /* don't need to swab as long as HPMBUF is odd */
        !            82: #if defined(notdef) && BYTE_ORDER == BIG_ENDIAN
        !            83: #define        HOSTHASH(imp, host)     ((unsigned)(ntohs(imp)+(host)) % HPMBUF)
        !            84: #else
        !            85: #define        HOSTHASH(imp, host)     ((unsigned)((imp)+(host)) % HPMBUF)
        !            86: #endif
        !            87: 
        !            88: /*
        !            89:  * In-line expansions for queuing operations on
        !            90:  * host message holding queue.  Queue is maintained
        !            91:  * as circular list with the head pointing to the
        !            92:  * last message in the queue.
        !            93:  */
        !            94: #define        HOST_ENQUE(hp, m) { \
        !            95:        register struct mbuf *n; \
        !            96:        (hp)->h_qcnt++; \
        !            97:        if ((n = (hp)->h_q) == 0) \
        !            98:                (hp)->h_q = (m)->m_act = (m); \
        !            99:        else { \
        !           100:                (m)->m_act = n->m_act; \
        !           101:                (hp)->h_q = n->m_act = (m); \
        !           102:        } \
        !           103: }
        !           104: #define        HOST_DEQUE(hp, m) { \
        !           105:        if ((m) = (hp)->h_q) { \
        !           106:                if ((m)->m_act == (m)) \
        !           107:                        (hp)->h_q = 0; \
        !           108:                else { \
        !           109:                        (m) = (m)->m_act; \
        !           110:                        (hp)->h_q->m_act = (m)->m_act; \
        !           111:                } \
        !           112:                (hp)->h_qcnt--; \
        !           113:                (m)->m_act = 0; \
        !           114:        } \
        !           115: }
        !           116: 
        !           117: struct hmbuf {
        !           118:        int     hm_count;               /* # of struct's in use */
        !           119:        struct  host hm_hosts[HPMBUF];  /* data structures proper */
        !           120: };
        !           121: 
        !           122: #ifdef KERNEL
        !           123: struct host *hostlookup();
        !           124: struct host *hostenter();
        !           125: #endif

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