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Annotation of coherent/b/STREAMS/coh.386/poll.c, revision 1.1

1.1     ! root        1: /* $Header: /ker/coh.386/RCS/poll.c,v 2.2 93/07/26 14:29:00 nigel Exp $ */
        !             2: /*
        !             3:  *     The  information  contained herein  is a trade secret  of INETCO
        !             4:  *     Systems, and is confidential information.   It is provided under
        !             5:  *     a license agreement,  and may be copied or disclosed  only under
        !             6:  *     the terms of that agreement.   Any reproduction or disclosure of
        !             7:  *     this  material  without  the express  written  authorization  of
        !             8:  *     INETCO Systems or persuant to the license agreement is unlawful.
        !             9:  *
        !            10:  *     Copyright (c) 1986
        !            11:  *     An unpublished work by INETCO Systems, Ltd.
        !            12:  *     All rights reserved.
        !            13:  */
        !            14: 
        !            15: /*
        !            16:  * [Stream] Polling.
        !            17:  *
        !            18:  *     void pollinit() -- allocate polling buffers
        !            19:  *     int pollopen(qp) -- enable polling  by current process  on given queue
        !            20:  *     int pollwake(qp) -- wake all processes waiting for poll on given queue
        !            21:  *     int pollexit() -- terminate all polls enabled by current process
        !            22:  *     event_t * ep;
        !            23:  *
        !            24:  * $Log:       poll.c,v $
        !            25:  * Revision 2.2  93/07/26  14:29:00  nigel
        !            26:  * Nigel's R80
        !            27:  * 
        !            28:  * Revision 1.3  93/04/14  10:06:42  root
        !            29:  * r75
        !            30:  * 
        !            31:  * Revision 1.2  92/01/06  11:59:56  hal
        !            32:  * Compile with cc.mwc.
        !            33:  * 
        !            34:  * Revision 1.1        88/03/24  16:14:10      src
        !            35:  * Initial revision
        !            36:  * 
        !            37:  * 86/11/19    Allan Cornish           /usr/src/sys/coh/poll.c
        !            38:  * Ported to Coherent from RTX.
        !            39:  */
        !            40: 
        !            41: #include <sys/coherent.h>
        !            42: #include <sys/proc.h>
        !            43: 
        !            44: /*
        !            45:  * Patchable data.
        !            46:  */
        !            47: int    NPOLL  = 0;
        !            48: 
        !            49: /*
        !            50:  * Private data.
        !            51:  */
        !            52: static event_t * efreep;
        !            53: 
        !            54: /**
        !            55:  *
        !            56:  * event_t *
        !            57:  * pollinit()          -- allocate event buffers.
        !            58:  */
        !            59: event_t *
        !            60: pollinit()
        !            61: {
        !            62:        register event_t * ep;
        !            63:        register event_t * ap;
        !            64:        static int first = 1;
        !            65: 
        !            66:        /*
        !            67:         * If dynamically growing event pool is specified [NPOLL == 0],
        !            68:         * try to allocate an additional cluster of 32 on each call.
        !            69:         */
        !            70:        if (NPOLL == 0) {
        !            71:                if (ep = kalloc(32 * sizeof(event_t)))
        !            72:                        ap = ep + 32;
        !            73:        }
        !            74: 
        !            75:        /*
        !            76:         * If statically sized event pool is specified [NPOLL != 0],
        !            77:         * try to allocate the pool on the first call.
        !            78:         */
        !            79:        else if (first) {
        !            80:                first = 0;
        !            81:                if (ep = kalloc(NPOLL * sizeof(event_t)))
        !            82:                        ap = ep + NPOLL;
        !            83:        }
        !            84: 
        !            85:        /*
        !            86:         * If event cluster was allocated, insert into free event queue.
        !            87:         */
        !            88:        if (ep) {
        !            89:                do {
        !            90:                        ep->e_pnext = efreep;
        !            91:                        efreep = ep;
        !            92:                } while (++ep < ap);
        !            93:        }
        !            94: 
        !            95:        return efreep;
        !            96: }
        !            97: 
        !            98: /**
        !            99:  *
        !           100:  * int
        !           101:  * pollopen(qp) -- enable polling by current process on given event queue
        !           102:  * event_t * qp;
        !           103:  */
        !           104: void
        !           105: pollopen(qp)
        !           106: register event_t * qp;
        !           107: {
        !           108:        register event_t * ep;
        !           109: 
        !           110:        /*
        !           111:         * Initialize device queue if required.
        !           112:         */
        !           113:        if (qp->e_dnext == 0)
        !           114:                qp->e_dnext = qp->e_dlast = qp;
        !           115: 
        !           116:        /*
        !           117:         * Obtain a free event buffer, or return.
        !           118:         */
        !           119:        if (((ep = efreep) == 0) && ((ep = pollinit()) == 0)) {
        !           120:                printf("out of poll buffers\n");
        !           121:                return;
        !           122:        }
        !           123: 
        !           124:        /*
        !           125:         * Remove event buffer from free queue.
        !           126:         */
        !           127:        efreep = ep->e_pnext;
        !           128: 
        !           129:        /*
        !           130:         * Record process pointer in event buffer.
        !           131:         */
        !           132:        ep->e_procp = cprocp;
        !           133: 
        !           134:        /*
        !           135:         * Insert event at head of process event singularly-linked queue.
        !           136:         */
        !           137:        ep->e_pnext = cprocp->p_polls;
        !           138:        cprocp->p_polls = ep;
        !           139: 
        !           140:        /*
        !           141:         * Insert event at tail of circularly-linked device queue.
        !           142:         * This ensures that processes are first-in first-out.
        !           143:         */
        !           144:        ep->e_dnext  = qp;
        !           145:        (ep->e_dlast = qp->e_dlast)->e_dnext = ep;
        !           146:        qp->e_dlast  = ep;
        !           147: 
        !           148:        /*
        !           149:         * Record last process to enable polling on device.
        !           150:         */
        !           151:        qp->e_procp = cprocp;
        !           152: }
        !           153: 
        !           154: /**
        !           155:  *
        !           156:  * int
        !           157:  * pollwake(qp) -- wake all processes waiting for poll on given queue
        !           158:  * event_t * qp;
        !           159:  *
        !           160:  * Go through extra step of deferring the pollwake to avoid race condition
        !           161:  * (in case interrupt handler does a pollwake() during upoll()).
        !           162:  */
        !           163: void
        !           164: pollwake(qp)
        !           165: event_t * qp;
        !           166: {
        !           167:        void dpollwake();
        !           168: 
        !           169:        defer(dpollwake, qp);
        !           170: }
        !           171: 
        !           172: void
        !           173: dpollwake(qp)
        !           174: event_t * qp;
        !           175: {
        !           176:        register event_t * ep = qp;
        !           177:        register PROC    * pp;
        !           178: 
        !           179:        /*
        !           180:         * Clear device process pointer, indicating poll completed.
        !           181:         * NOTE: interrupt handlers may have already cleared it.
        !           182:         */
        !           183:        qp->e_procp = 0;
        !           184: 
        !           185:        if (ep = qp->e_dnext) {
        !           186: 
        !           187:                /*
        !           188:                 * Service circularly-linked polls on device queue.
        !           189:                 */
        !           190:                while (ep != qp) {
        !           191:                        /*
        !           192:                         * Wake process if it is sleeping.
        !           193:                         */
        !           194:                        if ((pp = ep->e_procp) && ASLEEP(pp))
        !           195:                                wakeup(&pp->p_polls);
        !           196: 
        !           197:                        ep = ep->e_dnext;
        !           198:                }
        !           199:        }
        !           200: }
        !           201: 
        !           202: /**
        !           203:  *
        !           204:  * int
        !           205:  * pollexit() -- terminate all polls opened by current process
        !           206:  */
        !           207: int
        !           208: pollexit()
        !           209: {
        !           210:        register PROC    * pp = cprocp;
        !           211:        register event_t * ep;
        !           212: 
        !           213:        /*
        !           214:         * Service all polling event buffers enabled by current process.
        !           215:         */
        !           216:        while (ep = pp->p_polls) {
        !           217: 
        !           218:                /*
        !           219:                 * Remove event buffer from circularly-linked device queue.
        !           220:                 */
        !           221:                (ep->e_dnext->e_dlast = ep->e_dlast)->e_dnext = ep->e_dnext;
        !           222: 
        !           223:                /*
        !           224:                 * Remove event buffer from singularly-linked process queue.
        !           225:                 */
        !           226:                pp->p_polls = ep->e_pnext;
        !           227: 
        !           228:                /*
        !           229:                 * Insert event buffer at head of free event buffer queue.
        !           230:                 */
        !           231:                ep->e_pnext = efreep;
        !           232:                efreep = ep;
        !           233:        }
        !           234: }

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