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Annotation of coherent/d/kernel/USRSRC/coh/poll.c, revision 1.1

1.1     ! root        1: /* $Header: /newbits/kernel/USRSRC/coh/RCS/poll.c,v 1.4 91/07/24 07:51:32 bin Exp Locker: bin $ */
        !             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        !            11:  *     An unpublished work by INETCO Systems, Ltd.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 1.4  91/07/24  07:51:32  bin
        !            26:  * update prov by hal
        !            27:  * 
        !            28:  * 
        !            29:  * Revision 1.1        88/03/24  16:14:10      src
        !            30:  * Initial revision
        !            31:  * 
        !            32:  * 86/11/19    Allan Cornish           /usr/src/sys/coh/poll.c
        !            33:  * Ported to Coherent from RTX.
        !            34:  */
        !            35: 
        !            36: #include <sys/coherent.h>
        !            37: #include <sys/proc.h>
        !            38: #include <sys/uproc.h>
        !            39: 
        !            40: /*
        !            41:  * Patchable data.
        !            42:  */
        !            43: int    NPOLL  = 0;
        !            44: 
        !            45: /*
        !            46:  * Private data.
        !            47:  */
        !            48: static event_t * efreep;
        !            49: 
        !            50: /**
        !            51:  *
        !            52:  * event_t *
        !            53:  * pollinit()          -- allocate event buffers.
        !            54:  */
        !            55: event_t *
        !            56: pollinit()
        !            57: {
        !            58:        register event_t * ep;
        !            59:        register event_t * ap;
        !            60:        static int first = 1;
        !            61: 
        !            62:        /*
        !            63:         * If dynamically growing event pool is specified [NPOLL == 0],
        !            64:         * try to allocate an additional cluster of 32 on each call.
        !            65:         */
        !            66:        if ( NPOLL == 0 ) {
        !            67:                if ( ep = kalloc( 32 * sizeof(event_t) ) )
        !            68:                        ap = ep + 32;
        !            69:        }
        !            70: 
        !            71:        /*
        !            72:         * If statically sized event pool is specified [NPOLL != 0],
        !            73:         * try to allocate the pool on the first call.
        !            74:         */
        !            75:        else if ( first ) {
        !            76:                first = 0;
        !            77:                if ( ep = kalloc( NPOLL * sizeof(event_t) ) )
        !            78:                        ap = ep + NPOLL;
        !            79:        }
        !            80: 
        !            81:        /*
        !            82:         * If event cluster was allocated, insert into free event queue.
        !            83:         */
        !            84:        if ( ep ) {
        !            85:                do {
        !            86:                        ep->e_pnext = efreep;
        !            87:                        efreep = ep;
        !            88:                } while ( ++ep < ap );
        !            89:        }
        !            90: 
        !            91:        return efreep;
        !            92: }
        !            93: 
        !            94: /**
        !            95:  *
        !            96:  * int
        !            97:  * pollopen(qp) -- enable polling by current process on given event queue
        !            98:  * event_t * qp;
        !            99:  */
        !           100: pollopen( qp )
        !           101: register event_t * qp;
        !           102: {
        !           103:        register event_t * ep;
        !           104: 
        !           105:        /*
        !           106:         * Initialize device queue if required.
        !           107:         */
        !           108:        if ( qp->e_dnext == 0 )
        !           109:                qp->e_dnext = qp->e_dlast = qp;
        !           110: 
        !           111:        /*
        !           112:         * Obtain a free event buffer, or return.
        !           113:         */
        !           114:        if ( ((ep = efreep) == 0) && ((ep = pollinit()) == 0) ) {
        !           115:                printf("out of poll buffers\n");
        !           116:                return;
        !           117:        }
        !           118: 
        !           119:        /*
        !           120:         * Remove event buffer from free queue.
        !           121:         */
        !           122:        efreep = ep->e_pnext;
        !           123: 
        !           124:        /*
        !           125:         * Record process pointer in event buffer.
        !           126:         */
        !           127:        ep->e_procp = cprocp;
        !           128: 
        !           129:        /*
        !           130:         * Insert event at head of process event singularly-linked queue.
        !           131:         */
        !           132:        ep->e_pnext = cprocp->p_polls;
        !           133:        cprocp->p_polls = ep;
        !           134: 
        !           135:        /*
        !           136:         * Insert event at tail of circularly-linked device queue.
        !           137:         * This ensures that processes are first-in first-out.
        !           138:         */
        !           139:        ep->e_dnext  = qp;
        !           140:        (ep->e_dlast = qp->e_dlast)->e_dnext = ep;
        !           141:        qp->e_dlast  = ep;
        !           142: 
        !           143:        /*
        !           144:         * Record last process to enable polling on device.
        !           145:         */
        !           146:        qp->e_procp = cprocp;
        !           147: }
        !           148: 
        !           149: /**
        !           150:  *
        !           151:  * int
        !           152:  * pollwake( qp ) -- wake all processes waiting for poll on given queue
        !           153:  * event_t * qp;
        !           154:  */
        !           155: pollwake( qp )
        !           156: event_t * qp;
        !           157: {
        !           158:        register event_t * ep = qp;
        !           159:        register PROC    * pp;
        !           160: 
        !           161:        /*
        !           162:         * Clear device process pointer, indicating poll completed.
        !           163:         * NOTE: interrupt handlers may have already cleared it.
        !           164:         */
        !           165:        qp->e_procp = 0;
        !           166: 
        !           167:        if ( ep = qp->e_dnext ) {
        !           168: 
        !           169:                /*
        !           170:                 * Service circularly-linked polls on device queue.
        !           171:                 */
        !           172:                while ( ep != qp ) {
        !           173:                        /*
        !           174:                         * Wake process if it is sleeping.
        !           175:                         */
        !           176:                        if ( (pp = ep->e_procp) && (pp->p_state == PSSLEEP) )
        !           177:                                wakeup( &pp->p_polls );
        !           178: 
        !           179:                        ep = ep->e_dnext;
        !           180:                }
        !           181:        }
        !           182: }
        !           183: 
        !           184: /**
        !           185:  *
        !           186:  * int
        !           187:  * pollexit() -- terminate all polls opened by current process
        !           188:  */
        !           189: int
        !           190: pollexit()
        !           191: {
        !           192:        register PROC    * pp = cprocp;
        !           193:        register event_t * ep;
        !           194: 
        !           195:        /*
        !           196:         * Service all polling event buffers enabled by current process.
        !           197:         */
        !           198:        while ( ep = pp->p_polls ) {
        !           199: 
        !           200:                /*
        !           201:                 * Remove event buffer from circularly-linked device queue.
        !           202:                 */
        !           203:                (ep->e_dnext->e_dlast = ep->e_dlast)->e_dnext = ep->e_dnext;
        !           204: 
        !           205:                /*
        !           206:                 * Remove event buffer from singularly-linked process queue.
        !           207:                 */
        !           208:                pp->p_polls = ep->e_pnext;
        !           209: 
        !           210:                /*
        !           211:                 * Insert event buffer at head of free event buffer queue.
        !           212:                 */
        !           213:                ep->e_pnext = efreep;
        !           214:                efreep = ep;
        !           215:        }
        !           216: }

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