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Annotation of Net2/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 and use in source and binary forms, with or without
        !             6:  * modification, are permitted provided that the following conditions
        !             7:  * are met:
        !             8:  * 1. Redistributions of source code must retain the above copyright
        !             9:  *    notice, this list of conditions and the following disclaimer.
        !            10:  * 2. Redistributions in binary form must reproduce the above copyright
        !            11:  *    notice, this list of conditions and the following disclaimer in the
        !            12:  *    documentation and/or other materials provided with the distribution.
        !            13:  * 3. All advertising materials mentioning features or use of this software
        !            14:  *    must display the following acknowledgement:
        !            15:  *     This product includes software developed by the University of
        !            16:  *     California, Berkeley and its contributors.
        !            17:  * 4. Neither the name of the University nor the names of its contributors
        !            18:  *    may be used to endorse or promote products derived from this software
        !            19:  *    without specific prior written permission.
        !            20:  *
        !            21:  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
        !            22:  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
        !            23:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
        !            24:  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
        !            25:  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
        !            26:  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
        !            27:  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
        !            28:  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
        !            29:  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
        !            30:  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
        !            31:  * SUCH DAMAGE.
        !            32:  *
        !            33:  *     @(#)if_imphost.h        7.7 (Berkeley) 6/28/90
        !            34:  */
        !            35: 
        !            36: /*
        !            37:  * Host structure used with IMP's.
        !            38:  * Used to hold outgoing packets which
        !            39:  * would exceed allowed RFNM count.
        !            40:  *
        !            41:  * These structures are packed into
        !            42:  * mbuf's and kept as small as possible.
        !            43:  */
        !            44: struct host {
        !            45:        struct  mbuf *h_q;              /* holding queue */
        !            46:        u_short h_timer;                /* used to stay off deletion */
        !            47:        u_short h_imp;                  /* host's imp number */
        !            48:        u_char  h_host;                 /* host's number on imp */
        !            49:        u_char  h_qcnt;                 /* size of holding q */
        !            50:        u_char  h_rfnm;                 /* # outstanding rfnm's */
        !            51:        u_char  h_flags;                /* see below */
        !            52: };
        !            53: 
        !            54: /*
        !            55:  * A host structure is kept around (even when there are no
        !            56:  * references to it) for a spell to avoid constant reallocation
        !            57:  * and also to reflect IMP status back to sites which aren't
        !            58:  * directly connected to the IMP.  When structures are marked
        !            59:  * idle, a timer is started; when the timer expires the structure
        !            60:  * is deallocated.  A structure may be reused before the timer expires.
        !            61:  * A structure holds a reference on the containing mbuf when it is marked
        !            62:  * HF_INUSE.
        !            63:  */
        !            64: #define        HF_INUSE        0x1
        !            65: #define        HF_DEAD         (1<<IMPTYPE_HOSTDEAD)
        !            66: #define        HF_UNREACH      (1<<IMPTYPE_HOSTUNREACH)
        !            67: 
        !            68: #define        HOSTTIMER       128             /* keep structure around awhile */
        !            69: 
        !            70: /*
        !            71:  * Mark a host structure free; used if host entry returned by hostlookup 
        !            72:  * isn't needed.  h_rfnm must be zero.
        !            73:  */
        !            74: #define        hostfree(hp) { \
        !            75:        if ((hp)->h_timer == 0 && (hp)->h_qcnt == 0 && \
        !            76:            (hp)->h_flags & HF_INUSE) \
        !            77:                hostrelease(hp); \
        !            78: }
        !            79: 
        !            80: /*
        !            81:  * Release a host entry when last rfnm is received.
        !            82:  */
        !            83: #define        hostidle(hp)    { (hp)->h_timer = HOSTTIMER; }
        !            84: 
        !            85: /*
        !            86:  * Host structures, as seen inside an mbuf.
        !            87:  * Hashing on the host and imp is used to
        !            88:  * select an index into the first mbuf.  Collisions
        !            89:  * are then resolved by searching successive
        !            90:  * mbuf's at the same index.  Reclamation is done
        !            91:  * automatically at the time a structure is freed.
        !            92:  */
        !            93: #define        HPMBUF  ((MLEN - sizeof(int)) / sizeof(struct host))
        !            94: /* don't need to swab as long as HPMBUF is odd */
        !            95: #if defined(notdef) && BYTE_ORDER == BIG_ENDIAN
        !            96: #define        HOSTHASH(imp, host)     ((unsigned)(ntohs(imp)+(host)) % HPMBUF)
        !            97: #else
        !            98: #define        HOSTHASH(imp, host)     ((unsigned)((imp)+(host)) % HPMBUF)
        !            99: #endif
        !           100: 
        !           101: /*
        !           102:  * In-line expansions for queuing operations on
        !           103:  * host message holding queue.  Queue is maintained
        !           104:  * as circular list with the head pointing to the
        !           105:  * last message in the queue.
        !           106:  */
        !           107: #define        HOST_ENQUE(hp, m) { \
        !           108:        register struct mbuf *n; \
        !           109:        (hp)->h_qcnt++; \
        !           110:        if ((n = (hp)->h_q) == 0) \
        !           111:                (hp)->h_q = (m)->m_act = (m); \
        !           112:        else { \
        !           113:                (m)->m_act = n->m_act; \
        !           114:                (hp)->h_q = n->m_act = (m); \
        !           115:        } \
        !           116: }
        !           117: #define        HOST_DEQUE(hp, m) { \
        !           118:        if ((m) = (hp)->h_q) { \
        !           119:                if ((m)->m_act == (m)) \
        !           120:                        (hp)->h_q = 0; \
        !           121:                else { \
        !           122:                        (m) = (m)->m_act; \
        !           123:                        (hp)->h_q->m_act = (m)->m_act; \
        !           124:                } \
        !           125:                (hp)->h_qcnt--; \
        !           126:                (m)->m_act = 0; \
        !           127:        } \
        !           128: }
        !           129: 
        !           130: struct hmbuf {
        !           131:        int     hm_count;               /* # of struct's in use */
        !           132:        struct  host hm_hosts[HPMBUF];  /* data structures proper */
        !           133: };
        !           134: 
        !           135: #ifdef KERNEL
        !           136: struct host *hostlookup();
        !           137: struct host *hostenter();
        !           138: #endif

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