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Annotation of 43BSD/contrib/X/Xlib/XNextEvent.c, revision 1.1.1.1

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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