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[unix-history] / sys / dmr / vt.c

#
/*
* VT01 driver via DR11C to 11/20
*/

#include "/sys/nsys/param.h"
#include "/sys/nsys/user.h"

int     vtflag;

struct vtreg {
       int     csr;
       int     buf;
};

#define VTADDR  0167770
#define RQINT   01
#define BIENABL 040
#define SEOF    0100000
#define VTPRI   8

vtopen(dev, flag)
{
       if (!flag)
               u.u_error = ENXIO;
       else
               VTADDR->csr = BIENABL;
}

vtclose()
{
       VTADDR->buf = SEOF;
       VTADDR->csr =| RQINT;
}

vtwrite()
{
       int c;
       int register count;

       while (cpass(&c) >= 0) {
           retry:
               for (count=0; count<10; count++)
                       if ((VTADDR->csr&RQINT)==0) {
                               VTADDR->buf = c&0377;
                               VTADDR->csr =| RQINT;
                               goto contin;
                       }
               spl5();
               if (VTADDR->csr&RQINT) {
                       vtflag++;
                       sleep(VTADDR, VTPRI);
               }
               spl0();
               goto retry;
   contin:;
       }
}

vtintr()
{
       VTADDR->csr =& ~RQINT;
       if (vtflag) {
               vtflag = 0;
               wakeup(VTADDR);
       }
}