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Annotation of 43BSD/contrib/X/Xlib/XNextEvent.c, revision 1.1

1.1     ! root        1: #include <X/mit-copyright.h>
        !             2: 
        !             3: /* $Header: XNextEvent.c,v 10.4 86/02/01 15:37:26 tony Rel $ */
        !             4: /* Copyright    Massachusetts Institute of Technology    1985  */
        !             5: 
        !             6: #include "XlibInternal.h"
        !             7: 
        !             8: extern _QEvent *_qfree;
        !             9: 
        !            10: /* Flush output and (wait for and) return the next event in the queue.
        !            11: */
        !            12: 
        !            13: XNextEvent (event)
        !            14:        register XEvent *event;
        !            15: {
        !            16:        register _QEvent *qelt;
        !            17:        register Display *dpy = _XlibCurrentDisplay;
        !            18:        
        !            19:        _XFlush (dpy);
        !            20:        
        !            21:        /* if the queue is empty, read as many events as possible
        !            22:           and enqueue them */
        !            23:        while (dpy->head == NULL) {
        !            24:            char buf[BUFSIZE];
        !            25:            int pend_not_register; /* because can't "&" a register variable */
        !            26:            register int pend;
        !            27:            register XRep *rep;
        !            28: 
        !            29:            /* find out how much data can be read */
        !            30:            if (ioctl(dpy->fd, FIONREAD, &pend_not_register) < 0)
        !            31:                _XIOError(dpy);
        !            32:            pend = pend_not_register;
        !            33: 
        !            34:            /* must read at least one XRep; if none is pending, then
        !            35:               we'll just block waiting for it */
        !            36:            if (pend < sizeof(XRep))
        !            37:                pend = sizeof (XRep);
        !            38:                
        !            39:            /* but we won't read more than the max buffer size */
        !            40:            if (pend > BUFSIZE)
        !            41:                pend = BUFSIZE;
        !            42: 
        !            43:            /* round down to an integral number of XReps */
        !            44:            pend = (pend / sizeof (XRep)) * sizeof (XRep);
        !            45: 
        !            46:            _XRead (dpy, buf, pend);
        !            47:            for (rep = (XRep *) buf; pend > 0; rep++, pend -= sizeof(XRep))
        !            48:                if (rep->code == X_Error)
        !            49:                    _XError (dpy, (XErrorEvent *) rep);
        !            50:                else  /* it's an event packet; enqueue it */
        !            51:                    _XEnq (dpy, (XEvent *) rep);
        !            52:            }
        !            53: 
        !            54:        *event = (qelt = dpy->head)->event;
        !            55: 
        !            56:        /* move the head of the queue to the free list */
        !            57:        if ((dpy->head = qelt->next) == NULL)
        !            58:            dpy->tail = NULL;
        !            59:        qelt->next = _qfree;
        !            60:        _qfree = qelt;
        !            61:        dpy->qlen--;
        !            62: }
        !            63: 

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