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Annotation of researchv9/X11/src/X.V11R1/lib/X/XNextEvent.c, revision 1.1.1.1

1.1       root        1: #include "copyright.h"
                      2: 
                      3: /* $Header: XNextEvent.c,v 11.13 87/09/11 08:05:18 toddb Exp $ */
                      4: /* Copyright    Massachusetts Institute of Technology    1986  */
                      5: 
                      6: #define NEED_EVENTS
                      7: #include "Xlibint.h"
                      8: 
                      9: extern _XQEvent *_qfree;
                     10: 
                     11: /* 
                     12:  *Flush output and (wait for and) return the next event in the queue.
                     13:  */
                     14: 
                     15: XNextEvent (dpy, event)
                     16:        register Display *dpy;
                     17:        register XEvent *event;
                     18: {
                     19:        register _XQEvent *qelt;
                     20:        
                     21:        LockDisplay(dpy);
                     22:        _XFlush (dpy);
                     23:        
                     24:        /* if the queue is empty, read as many events as possible
                     25:           and enqueue them */
                     26:        while (dpy->head == NULL) {
                     27:            char buf[BUFSIZE];
                     28:            long pend_not_register; /* because can't "&" a register variable */
                     29:            register long pend;
                     30:            register xEvent *ev;
                     31: 
                     32:            /* find out how much data can be read */
                     33:            if (BytesReadable(dpy->fd, (char *) &pend_not_register) < 0)
                     34:                (*_XIOErrorFunction)(dpy);
                     35:            pend = pend_not_register;
                     36: 
                     37:            /* must read at least one xEvent; if none is pending, then
                     38:               we'll just block waiting for it */
                     39:            if (pend < sizeof(xEvent))
                     40:                pend = sizeof (xEvent);
                     41:                
                     42:            /* but we won't read more than the max buffer size */
                     43:            if (pend > BUFSIZE)
                     44:                pend = BUFSIZE;
                     45: 
                     46:            /* round down to an integral number of XReps */
                     47:            pend = (pend / sizeof (xEvent)) * sizeof (xEvent);
                     48: 
                     49:            _XRead (dpy, buf, pend);
                     50:            for (ev = (xEvent *) buf; pend > 0; ev++, pend -= sizeof(xEvent))
                     51:                if (ev->u.u.type == X_Error)
                     52:                    _XError (dpy, (xError *) ev);
                     53:                else  /* it's an event packet; enqueue it */
                     54:                    _XEnq (dpy, ev);
                     55:            }
                     56: 
                     57:        *event = (qelt = dpy->head)->event;
                     58: 
                     59:        /* move the head of the queue to the free list */
                     60:        if ((dpy->head = qelt->next) == NULL)
                     61:            dpy->tail = NULL;
                     62:        qelt->next = _qfree;
                     63:        _qfree = qelt;
                     64:        dpy->qlen--;
                     65:        UnlockDisplay(dpy);
                     66:        return;
                     67: }
                     68: 

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