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Annotation of xinu/sys/psend.c, revision 1.1

1.1     ! root        1: /* psend.c - psend */
        !             2: 
        !             3: #include <conf.h>
        !             4: #include <kernel.h>
        !             5: #include <mark.h>
        !             6: #include <ports.h>
        !             7: 
        !             8: /*------------------------------------------------------------------------
        !             9:  *  psend  --  send a message to a port by enqueuing it
        !            10:  *------------------------------------------------------------------------
        !            11:  */
        !            12: SYSCALL        psend(portid, msg)
        !            13: int    portid;
        !            14: int    msg;
        !            15: {
        !            16:        PStype  ps;
        !            17:        struct  pt      *ptptr;
        !            18:        int     seq;
        !            19:        struct  ptnode  *freenode;
        !            20:        
        !            21: 
        !            22:        disable(ps);
        !            23:        if ( isbadport(portid) ||
        !            24: #ifdef MEMMARK
        !            25:             unmarked(ptmark) ||
        !            26: #endif
        !            27:             (ptptr= &ports[portid])->ptstate != PTALLOC ) {
        !            28:                restore(ps);
        !            29:                return(SYSERR);
        !            30:        }
        !            31: 
        !            32:        /* wait for space and verify port is still allocated */
        !            33: 
        !            34:        seq = ptptr->ptseq;
        !            35:        if (wait(ptptr->ptssem) == SYSERR
        !            36:            || ptptr->ptstate != PTALLOC
        !            37:            || ptptr->ptseq != seq) {
        !            38:                restore(ps);
        !            39:                return(SYSERR);
        !            40:        }
        !            41:        if (ptfree == (struct ptnode *)NULL)
        !            42:                panic("psend: out of nodes");
        !            43:        freenode = ptfree;
        !            44:        ptfree  = freenode->ptnext;
        !            45:        freenode->ptnext = (struct ptnode *)NULL;
        !            46:        freenode->ptmsg  = msg;
        !            47:        if (ptptr->pttail == (struct ptnode *)NULL)     /* empty queue */
        !            48:                ptptr->pttail = ptptr->pthead = freenode;
        !            49:        else {
        !            50:                (ptptr->pttail)->ptnext = freenode;
        !            51:                ptptr->pttail = freenode;
        !            52:        }
        !            53:        signal(ptptr->ptrsem);
        !            54:        restore(ps);
        !            55:        return(OK);
        !            56: }

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