X-Git-Url: https://git.subgeniuskitty.com/unix-history/.git/blobdiff_plain/6d27b2c67ea2a12e49912503a4f041b1eb372315..5513375c86e602a9163497b7ad7e66f860de9efb:/usr/src/sys/kern/tty.c

diff --git a/usr/src/sys/kern/tty.c b/usr/src/sys/kern/tty.c
index 36e3217396..2d61be7ad0 100644
--- a/usr/src/sys/kern/tty.c
+++ b/usr/src/sys/kern/tty.c
@@ -1,7 +1,7 @@
-/*	tty.c	3.16	%G%	*/
+/*	tty.c	4.3	%G%	*/
 
 /*
- * general TTY subroutines
+ * TTY subroutines common to more than one line discipline
  */
 #include "../h/param.h"
 #include "../h/systm.h"
@@ -57,42 +57,13 @@ char	maptab[] ={
 	'X','Y','Z',000,000,000,000,000,
 };
 
-
-/*
- * shorthand
- */
-#define	q1	tp->t_rawq
-#define	q2	tp->t_canq
-#define	q3	tp->t_outq
-#define	q4	tp->t_un.t_ctlq
+short	tthiwat[16] =
+   { 100,100,100,100,100,100,100,200,200,400,400,400,650,650,650,650 };
+short	ttlowat[16] =
+   {  30, 30, 30, 30, 30, 30, 30, 50, 50,120,120,120,125,125,125,125 };
 
 #define	OBUFSIZ	100
 
-/*
- * routine called on first teletype open.
- * establishes a process group for distribution
- * of quits and interrupts from the tty.
- */
-ttyopen(dev, tp)
-dev_t dev;
-register struct tty *tp;
-{
-	register struct proc *pp;
-
-	pp = u.u_procp;
-	tp->t_dev = dev;
-	if(pp->p_pgrp == 0) {
-		u.u_ttyp = tp;
-		u.u_ttyd = dev;
-		if (tp->t_pgrp == 0)
-			tp->t_pgrp = pp->p_pid;
-		pp->p_pgrp = tp->t_pgrp;
-	}
-	tp->t_state &= ~WOPEN;
-	tp->t_state |= ISOPEN;
-	tp->t_line = 0;		/* conservative */
-}
-
 /*
  * set default control characters.
  */
@@ -115,115 +86,123 @@ register struct tty *tp;
 	tlun.t_flushc = CTRL(o);
 	tlun.t_werasc = CTRL(w);
 	tlun.t_lnextc = CTRL(v);
-	tlun.t_lintr = CTRL(c);
-	tlun.t_lerase = CTRL(h);
-	tlun.t_lkill = CTRL(u);
 	tp->t_local = 0;
 	tp->t_lstate = 0;
 /* end local */
 }
 
 /*
- * clean tp on last close
+ * Wait for output to drain, then flush input waiting.
  */
-ttyclose(tp)
+wflushtty(tp)
 register struct tty *tp;
 {
 
-	tp->t_pgrp = 0;
-	wflushtty(tp);
-	tp->t_state = 0;
-	tp->t_line = 0;
+	(void) spl5();
+	while (tp->t_outq.c_cc && tp->t_state&CARR_ON) {
+		(*tp->t_oproc)(tp);
+		tp->t_state |= ASLEEP;
+		sleep((caddr_t)&tp->t_outq, TTOPRI);
+	}
+	flushtty(tp, FREAD|FWRITE);
+	(void) spl0();
 }
 
 /*
- * stty/gtty writearound
+ * flush all TTY queues
  */
-stty()
+flushtty(tp, rw)
+register struct tty *tp;
 {
-	u.u_arg[2] = u.u_arg[1];
-	u.u_arg[1] = TIOCSETP;
-	ioctl();
+	register s;
+
+	if (tp->t_line == NETLDISC)
+		return;
+	s = spl6();
+	if (rw & FREAD) {
+		while (getc(&tp->t_canq) >= 0)
+			;
+		wakeup((caddr_t)&tp->t_rawq);
+	}
+	if (rw & FWRITE) {
+		wakeup((caddr_t)&tp->t_outq);
+		tp->t_state &= ~TTSTOP;
+		(*cdevsw[major(tp->t_dev)].d_stop)(tp);
+		while (getc(&tp->t_outq) >= 0)
+			;
+	}
+	if (rw & FREAD) {
+		while (getc(&tp->t_rawq) >= 0)
+			;
+		tp->t_delct = 0;
+		tp->t_rocount = 0;		/* local */
+		tp->t_rocol = 0;
+		tp->t_lstate = 0;
+	}
+	splx(s);
 }
 
-gtty()
+/*
+ * Send stop character on input overflow.
+ */
+ttyblock(tp)
+register struct tty *tp;
 {
-	u.u_arg[2] = u.u_arg[1];
-	u.u_arg[1] = TIOCGETP;
-	ioctl();
+	register x;
+	x = tp->t_rawq.c_cc + tp->t_canq.c_cc;
+	if (tp->t_rawq.c_cc > TTYHOG) {
+		flushtty(tp, FREAD|FWRITE);
+		tp->t_state &= ~TBLOCK;
+	}
+	if (x >= TTYHOG/2) {
+		if (putc(tun.t_stopc, &tp->t_outq)==0) {
+			tp->t_state |= TBLOCK;
+			tp->t_char++;
+			ttstart(tp);
+		}
+	}
 }
 
 /*
- * Do nothing specific version of line
- * discipline specific ioctl command.
+ * Restart typewriter output following a delay
+ * timeout.
+ * The name of the routine is passed to the timeout
+ * subroutine and it is called during a clock interrupt.
  */
-/*ARGSUSED*/
-nullioctl(tp, cmd, addr)
+ttrstrt(tp)
 register struct tty *tp;
-caddr_t addr;
 {
 
-	return (cmd);
+	tp->t_state &= ~TIMEOUT;
+	ttstart(tp);
 }
 
 /*
- * ioctl system call
- * Check legality, execute common code, and switch out to individual
- * device routine.
+ * Start output on the typewriter. It is used from the top half
+ * after some characters have been put on the output queue,
+ * from the interrupt routine to transmit the next
+ * character, and after a timeout has finished.
  */
-ioctl()
+ttstart(tp)
+register struct tty *tp;
 {
-	register struct file *fp;
-	register struct inode *ip;
-	register struct a {
-		int	fdes;
-		int	cmd;
-		caddr_t	cmarg;
-	} *uap;
-	register dev_t dev;
-	register fmt;
-
-	uap = (struct a *)u.u_ap;
-	if ((fp = getf(uap->fdes)) == NULL)
-		return;
-	if ((fp->f_flag & (FREAD|FWRITE)) == 0) {
-		u.u_error = EBADF;
-		return;
-	}
-	if (uap->cmd==FIOCLEX) {
-		u.u_pofile[uap->fdes] |= EXCLOSE;
-		return;
-	}
-	if (uap->cmd==FIONCLEX) {
-		u.u_pofile[uap->fdes] &= ~EXCLOSE;
-		return;
-	}
-	ip = fp->f_inode;
-	fmt = ip->i_mode & IFMT;
-	if (fmt != IFCHR && fmt != IFMPC) {
-/* begin local */
-		if (uap->cmd==FIONREAD && (fmt == IFREG || fmt == IFDIR)) {
-			off_t nread = ip->i_size - fp->f_un.f_offset;
+	register s;
 
-			if (copyout((caddr_t)&nread, uap->cmarg, sizeof(off_t)))
-				u.u_error = EFAULT;
-		} else
-/* end local */
-			u.u_error = ENOTTY;
-		return;
-	}
-	dev = ip->i_un.i_rdev;
-	u.u_r.r_val1 = 0;
-	(*cdevsw[major(dev)].d_ioctl)(dev, uap->cmd, uap->cmarg, fp->f_flag);
+	s = spl5();
+	if((tp->t_state&(TIMEOUT|TTSTOP|BUSY)) == 0)
+		(*tp->t_oproc)(tp);
+	splx(s);
 }
 
 /*
- * Common code for several tty ioctl commands
+ * Common code for tty ioctls.
  */
-ttioccomm(com, tp, addr, dev)
+/*ARGSUSED*/
+ttioctl(tp, com, addr, flag)
 register struct tty *tp;
 caddr_t addr;
 {
+	int dev;
 	unsigned t;
 	struct sgttyb iocb;
 	struct clist tq;
@@ -231,10 +210,59 @@ caddr_t addr;
 	register c;
 	int temp;
 
+	/*
+	 * This is especially so that isatty() will
+	 * fail when carrier is gone.
+	 */
+	if ((tp->t_state&CARR_ON) == 0) {
+		u.u_error = EBADF;
+		return (1);
+	}
+
+	dev = tp->t_dev;
+	/*
+	 * If the ioctl involves modification,
+	 * insist on being able to write the device,
+	 * and hang if in the background.
+	 */
+	switch(com) {
+
+	case TIOCSETD:
+	case TIOCSETP:
+	case TIOCSETN:
+	case TIOCFLUSH:
+	case TIOCSETC:
+	case TIOCSLTC:
+	case TIOCSPGRP:
+	case TIOCLBIS:
+	case TIOCLBIC:
+	case TIOCLSET:
+	case TIOCSTI:
+/* this is reasonable, but impractical... 
+		if ((flag & FWRITE) == 0) {
+			u.u_error = EBADF;
+			return (1);
+		}
+ */
+		while (tp->t_line == NTTYDISC &&
+		   u.u_procp->p_pgrp != tp->t_pgrp && tp == u.u_ttyp &&
+		   (u.u_procp->p_flag&SVFORK) == 0 &&
+		   u.u_signal[SIGTTOU] != SIG_IGN &&
+		   u.u_signal[SIGTTOU] != SIG_HOLD &&
+		   (u.u_procp->p_flag&SDETACH)==0) {
+			gsignal(u.u_procp->p_pgrp, SIGTTOU);
+			sleep((caddr_t)&lbolt, TTOPRI);
+		}
+		break;
+	}
+
+	/*
+	 * Process the ioctl.
+	 */
 	switch(com) {
 
 	/*
-	 * get discipline number
+	 * Get discipline number
 	 */
 	case TIOCGETD:
 		t = tp->t_line;
@@ -243,7 +271,7 @@ caddr_t addr;
 		break;
 
 	/*
-	 * set line discipline
+	 * Set line discipline
 	 */
 	case TIOCSETD:
 		if (copyin(addr, (caddr_t)&t, sizeof(t))) {
@@ -265,7 +293,7 @@ caddr_t addr;
 		break;
 
 	/*
-	 * prevent more opens on channel
+	 * Prevent more opens on channel
 	 */
 	case TIOCEXCL:
 		tp->t_state |= XCLUDE;
@@ -290,6 +318,9 @@ caddr_t addr;
 				wflushtty(tp);
 			while (canon(tp)>=0) 
 				;
+#ifdef notdef
+			wakeup((caddr_t)&tp->t_rawq);
+#endif
 		} else if (tp->t_line == NTTYDISC) {
 			if (tp->t_flags&RAW || iocb.sg_flags&RAW ||
 			    com == TIOCSETP)
@@ -304,9 +335,11 @@ caddr_t addr;
 					tp->t_local |= LPENDIN;
 					if (tp->t_canq.c_cc)
 						panic("ioccom canq");
+#ifdef notdef
 					if (tp->t_chan)
 						(void) sdata(tp->t_chan);
 					else
+#endif
 						wakeup((caddr_t)&tp->t_rawq);
 				}
 			}
@@ -322,7 +355,7 @@ caddr_t addr;
 		break;
 
 	/*
-	 * send current parameters to user
+	 * Send current parameters to user
 	 */
 	case TIOCGETP:
 		iocb.sg_ispeed = tp->t_ispeed;
@@ -337,7 +370,6 @@ caddr_t addr;
 	/*
 	 * Hang up line on last close
 	 */
-
 	case TIOCHPCL:
 		tp->t_state |= HUPCLS;
 		break;
@@ -347,16 +379,7 @@ caddr_t addr;
 		break;
 
 	/*
-	 * ioctl entries to line discipline
-	 */
-	case DIOCSETP:
-	case DIOCGETP:
-		if ((*linesw[tp->t_line].l_ioctl)(com, tp, addr))
-			u.u_error = ENOTTY;
-		break;
-
-	/*
-	 * set and fetch special characters
+	 * Set and fetch special characters
 	 */
 	case TIOCSETC:
 		if (copyin(addr, (caddr_t)&tun, sizeof(struct tchars)))
@@ -369,6 +392,9 @@ caddr_t addr;
 		break;
 
 /* local ioctls */
+	/*
+	 * Set/get local special characters.
+	 */
 	case TIOCSLTC:
 		if (copyin(addr, (caddr_t)&tlun, sizeof (struct ltchars)))
 			u.u_error = EFAULT;
@@ -379,6 +405,9 @@ caddr_t addr;
 			u.u_error = EFAULT;
 		break;
 
+	/*
+	 * Return number of characters immediately available.
+	 */
 	case FIONREAD: {
 		off_t nread;
 
@@ -449,11 +478,18 @@ caddr_t addr;
 			u.u_error = EFAULT;
 		break;
 
+	/*
+	 * Return number of characters in
+	 * the output.
+	 */
 	case TIOCOUTQ:
 		if (copyout((caddr_t)&tp->t_outq.c_cc, addr, sizeof(tp->t_outq.c_cc)))
 			u.u_error = EFAULT;
 		break;
 
+	/*
+	 * Simulate typing of a character at the terminal.
+	 */
 	case TIOCSTI:
 		c = fubyte(addr);
 		if (u.u_uid && u.u_ttyp != tp || c < 0)
@@ -468,526 +504,3 @@ caddr_t addr;
 	}
 	return(1);
 }
-
-/*
- * Wait for output to drain, then flush input waiting.
- */
-wflushtty(tp)
-register struct tty *tp;
-{
-
-	(void) spl5();
-	while (tp->t_outq.c_cc && tp->t_state&CARR_ON) {
-		(*tp->t_oproc)(tp);
-		tp->t_state |= ASLEEP;
-		sleep((caddr_t)&tp->t_outq, TTOPRI);
-	}
-	flushtty(tp, FREAD|FWRITE);
-	(void) spl0();
-}
-
-/*
- * flush all TTY queues
- */
-flushtty(tp, rw)
-register struct tty *tp;
-{
-	register s;
-
-	if (tp->t_line == NETLDISC)
-		return;
-	s = spl6();
-	if (rw & FREAD) {
-		while (getc(&tp->t_canq) >= 0)
-			;
-		wakeup((caddr_t)&tp->t_rawq);
-	}
-	if (rw & FWRITE) {
-		wakeup((caddr_t)&tp->t_outq);
-		tp->t_state &= ~TTSTOP;
-		(*cdevsw[major(tp->t_dev)].d_stop)(tp);
-		while (getc(&tp->t_outq) >= 0)
-			;
-	}
-	if (rw & FREAD) {
-		while (getc(&tp->t_rawq) >= 0)
-			;
-		tp->t_delct = 0;
-		tp->t_rocount = 0;		/* local */
-		tp->t_rocol = 0;
-		tp->t_lstate = 0;
-	}
-	splx(s);
-}
-
-
-
-/*
- * transfer raw input list to canonical list,
- * doing erase-kill processing and handling escapes.
- * It waits until a full line has been typed in cooked mode,
- * or until any character has been typed in raw mode.
- */
-canon(tp)
-register struct tty *tp;
-{
-	register char *bp;
-	char *bp1;
-	register int c;
-	int mc;
-	int s;
-
-	if ((tp->t_flags&(RAW|CBREAK))==0 && tp->t_delct==0
-	    || (tp->t_flags&(RAW|CBREAK))!=0 && tp->t_rawq.c_cc==0) {
-		return(-1);
-	}
-	s = spl0();
-loop:
-	bp = &canonb[2];
-	while ((c=getc(&tp->t_rawq)) >= 0) {
-		if ((tp->t_flags&(RAW|CBREAK))==0) {
-			if (c==0377) {
-				tp->t_delct--;
-				break;
-			}
-			if (bp[-1]!='\\') {
-				if (c==tp->t_erase) {
-					if (bp > &canonb[2])
-						bp--;
-					continue;
-				}
-				if (c==tp->t_kill)
-					goto loop;
-				if (c==tun.t_eofc)
-					continue;
-			} else {
-				mc = maptab[c];
-				if (c==tp->t_erase || c==tp->t_kill)
-					mc = c;
-				if (mc && (mc==c || (tp->t_flags&LCASE))) {
-					if (bp[-2] != '\\')
-						c = mc;
-					bp--;
-				}
-			}
-		}
-		*bp++ = c;
-		if (bp>=canonb+CANBSIZ)
-			break;
-	}
-	bp1 = &canonb[2];
-	(void) b_to_q(bp1, bp-bp1, &tp->t_canq);
-
-	if (tp->t_state&TBLOCK && tp->t_rawq.c_cc < TTYHOG/5) {
-		if (putc(tun.t_startc, &tp->t_outq)==0) {
-			tp->t_state &= ~TBLOCK;
-			ttstart(tp);
-		}
-		tp->t_char = 0;
-	}
-
-	splx(s);
-	return(0);
-}
-
-
-/*
- * block transfer input handler.
- */
-ttyrend(tp, pb, pe)
-register struct tty *tp;
-register char *pb, *pe;
-{
-	int	tandem;
-
-	tandem = tp->t_flags&TANDEM;
-	if (tp->t_flags&RAW) {
-		(void) b_to_q(pb, pe-pb, &tp->t_rawq);
-		if (tp->t_chan)
-			(void) sdata(tp->t_chan); else
-			wakeup((caddr_t)&tp->t_rawq);
-	} else {
-		tp->t_flags &= ~TANDEM;
-		while (pb < pe)
-			ttyinput(*pb++, tp);
-		tp->t_flags |= tandem;
-	}
-	if (tandem)
-		ttyblock(tp);
-}
-
-/*
- * Place a character on raw TTY input queue, putting in delimiters
- * and waking up top half as needed.
- * Also echo if required.
- * The arguments are the character and the appropriate
- * tty structure.
- */
-ttyinput(c, tp)
-register c;
-register struct tty *tp;
-{
-	register int t_flags;
-	register struct chan *cp;
-
-	tk_nin += 1;
-	c &= 0377;
-	t_flags = tp->t_flags;
-	if (t_flags&TANDEM)
-		ttyblock(tp);
-	if ((t_flags&RAW)==0) {
-		c &= 0177;
-		if (tp->t_state&TTSTOP) {
-			if (c==tun.t_startc) {
-				tp->t_state &= ~TTSTOP;
-				ttstart(tp);
-				return;
-			}
-			if (c==tun.t_stopc)
-				return;
-			tp->t_state &= ~TTSTOP;
-			ttstart(tp);
-		} else {
-			if (c==tun.t_stopc) {
-				tp->t_state |= TTSTOP;
-				(*cdevsw[major(tp->t_dev)].d_stop)(tp);
-				return;
-			}
-			if (c==tun.t_startc)
-				return;
-		}
-		if (c==tun.t_quitc || c==tun.t_intrc) {
-			flushtty(tp, FREAD|FWRITE);
-			c = (c==tun.t_intrc) ? SIGINT:SIGQUIT;
-			if (tp->t_chan)
-				scontrol(tp->t_chan, M_SIG, c);
-			else
-				gsignal(tp->t_pgrp, c);
-			return;
-		}
-		if (c=='\r' && t_flags&CRMOD)
-			c = '\n';
-	}
-	if (tp->t_rawq.c_cc>TTYHOG) {
-		flushtty(tp, FREAD|FWRITE);
-		return;
-	}
-	if (t_flags&LCASE && c>='A' && c<='Z')
-		c += 'a'-'A';
-	(void) putc(c, &tp->t_rawq);
-	if (t_flags&(RAW|CBREAK)||(c=='\n'||c==tun.t_eofc||c==tun.t_brkc)) {
-		if ((t_flags&(RAW|CBREAK))==0 && putc(0377, &tp->t_rawq)==0)
-			tp->t_delct++;
-		if ((cp=tp->t_chan)!=NULL)
-			(void) sdata(cp); else
-			wakeup((caddr_t)&tp->t_rawq);
-	}
-	if (t_flags&ECHO) {
-		ttyoutput(c, tp);
-		if (c==tp->t_kill && (t_flags&(RAW|CBREAK))==0)
-			ttyoutput('\n', tp);
-		ttstart(tp);
-	}
-}
-
-
-/*
- * Send stop character on input overflow.
- */
-ttyblock(tp)
-register struct tty *tp;
-{
-	register x;
-	x = q1.c_cc + q2.c_cc;
-	if (q1.c_cc > TTYHOG) {
-		flushtty(tp, FREAD|FWRITE);
-		tp->t_state &= ~TBLOCK;
-	}
-	if (x >= TTYHOG/2) {
-		if (putc(tun.t_stopc, &tp->t_outq)==0) {
-			tp->t_state |= TBLOCK;
-			tp->t_char++;
-			ttstart(tp);
-		}
-	}
-}
-
-/*
- * put character on TTY output queue, adding delays,
- * expanding tabs, and handling the CR/NL bit.
- * It is called both from the top half for output, and from
- * interrupt level for echoing.
- * The arguments are the character and the tty structure.
- */
-ttyoutput(c, tp)
-register c;
-register struct tty *tp;
-{
-	register char *colp;
-	register ctype;
-
-	/*
-	 * Ignore EOT in normal mode to avoid hanging up
-	 * certain terminals.
-	 * In raw mode dump the char unchanged.
-	 */
-	if ((tp->t_flags&RAW)==0) {
-		c &= 0177;
-		if ((tp->t_flags&CBREAK)==0 && c==CEOT)
-			return;
-	} else {
-		tk_nout++;
-		(void) putc(c, &tp->t_outq);
-		return;
-	}
-
-	/*
-	 * Turn tabs to spaces as required
-	 */
-	if (c=='\t' && (tp->t_flags&TBDELAY)==XTABS) {
-		c = 8 - (tp->t_col & 7);
-		(void) b_to_q("        ", c, &tp->t_outq);
-		tp->t_col += c;
-		tk_nout += c;
-		return;
-	}
-	tk_nout++;
-	/*
-	 * for upper-case-only terminals,
-	 * generate escapes.
-	 */
-	if (tp->t_flags&LCASE) {
-		colp = "({)}!|^~'`";
-		while(*colp++)
-			if(c == *colp++) {
-				ttyoutput('\\', tp);
-				c = colp[-2];
-				break;
-			}
-		if ('a'<=c && c<='z')
-			c += 'A' - 'a';
-	}
-	/*
-	 * turn <nl> to <cr><lf> if desired.
-	 */
-	if (c=='\n' && tp->t_flags&CRMOD)
-		ttyoutput('\r', tp);
-	(void) putc(c, &tp->t_outq);
-	/*
-	 * Calculate delays.
-	 * The numbers here represent clock ticks
-	 * and are not necessarily optimal for all terminals.
-	 * The delays are indicated by characters above 0200.
-	 * In raw mode there are no delays and the
-	 * transmission path is 8 bits wide.
-	 */
-	colp = &tp->t_col;
-	ctype = partab[c];
-	c = 0;
-	switch (ctype&077) {
-
-	/* ordinary */
-	case 0:
-		(*colp)++;
-
-	/* non-printing */
-	case 1:
-		break;
-
-	/* backspace */
-	case 2:
-		if (*colp)
-			(*colp)--;
-		break;
-
-	/* newline */
-	case 3:
-		ctype = (tp->t_flags >> 8) & 03;
-		if(ctype == 1) { /* tty 37 */
-			if (*colp)
-				c = max(((unsigned)*colp>>4) + 3, (unsigned)6);
-		} else
-		if(ctype == 2) { /* vt05 */
-			c = 6;
-		}
-		*colp = 0;
-		break;
-
-	/* tab */
-	case 4:
-		ctype = (tp->t_flags >> 10) & 03;
-		if(ctype == 1) { /* tty 37 */
-			c = 1 - (*colp | ~07);
-			if(c < 5)
-				c = 0;
-		}
-		*colp |= 07;
-		(*colp)++;
-		break;
-
-	/* vertical motion */
-	case 5:
-		if(tp->t_flags & VTDELAY) /* tty 37 */
-			c = 0177;
-		break;
-
-	/* carriage return */
-	case 6:
-		ctype = (tp->t_flags >> 12) & 03;
-		if(ctype == 1) { /* tn 300 */
-			c = 5;
-		} else if(ctype == 2) { /* ti 700 */
-			c = 10;
-		} else if(ctype == 3) { /* concept 100 */
-			int i;
-			if ((i = *colp) >= 0)
-				for (; i<9; i++)
-					(void) putc(0177, &tp->t_outq);
-		}
-		*colp = 0;
-	}
-	if(c)
-		(void) putc(c|0200, &tp->t_outq);
-}
-
-/*
- * Restart typewriter output following a delay
- * timeout.
- * The name of the routine is passed to the timeout
- * subroutine and it is called during a clock interrupt.
- */
-ttrstrt(tp)
-register struct tty *tp;
-{
-
-	tp->t_state &= ~TIMEOUT;
-	ttstart(tp);
-}
-
-/*
- * Start output on the typewriter. It is used from the top half
- * after some characters have been put on the output queue,
- * from the interrupt routine to transmit the next
- * character, and after a timeout has finished.
- */
-ttstart(tp)
-register struct tty *tp;
-{
-	register s;
-
-	s = spl5();
-	if((tp->t_state&(TIMEOUT|TTSTOP|BUSY)) == 0)
-		(*tp->t_oproc)(tp);
-	splx(s);
-}
-
-/*
- * Called from device's read routine after it has
- * calculated the tty-structure given as argument.
- */
-ttread(tp)
-register struct tty *tp;
-{
-register s;
-
-	if ((tp->t_state&CARR_ON)==0)
-		return(-1);
-	s = spl5();
-	if (tp->t_canq.c_cc==0)
-		while (canon(tp)<0)
-			if (tp->t_chan==NULL) {
-				sleep((caddr_t)&tp->t_rawq, TTIPRI); 
-			} else {
-				splx(s);
-				return(0);
-			}
-	splx(s);
-	while (tp->t_canq.c_cc && passc(getc(&tp->t_canq))>=0)
-			;
-	return(tp->t_rawq.c_cc+tp->t_canq.c_cc);
-}
-
-/*
- * Called from the device's write routine after it has
- * calculated the tty-structure given as argument.
- */
-caddr_t
-ttwrite(tp)
-register struct tty *tp;
-{
-	/*
-	 * THE POSITIONING OF CP, CC, AND CE ARE CRITICAL
-	 * AND MUST NOT BE CHANGED WITHOUT PATCHING
-	 * THE 'ASM' INLINES BELOW.  WATCH OUT.
-	 */
-	register char *cp;
-	register int cc, ce;
-	register i;
-	char obuf[OBUFSIZ];
-
-	if ((tp->t_state&CARR_ON)==0)
-		return(NULL);
-	while (u.u_count) {
-		cc = MIN(u.u_count, OBUFSIZ);
-		cp = obuf;
-		iomove(cp, (unsigned)cc, B_WRITE);
-		if (u.u_error)
-			break;
-		(void) spl5();
-		while (tp->t_outq.c_cc > TTHIWAT) {
-			ttstart(tp);
-			tp->t_state |= ASLEEP;
-			if (tp->t_chan) {
-				u.u_base -= cc;
-				u.u_offset -= cc;
-				u.u_count += cc;
-				(void) spl0();
-				return((caddr_t)&tp->t_outq);
-			}
-			sleep((caddr_t)&tp->t_outq, TTOPRI);
-		}
-		(void) spl0();
-		if (tp->t_flags&LCASE) {
-			while (cc--)
-				ttyoutput(*cp++,tp);
-			continue;
-		}
-		while (cc) {
-			if (tp->t_flags&RAW)
-				ce=cc;
-			else {
-#ifdef VAX
-				asm("	scanc	r9,(r10),_partab,$077");
-				asm("	subl3	r0,r9,r8");
-#else
-				ce=0;
-				while(((partab[*(cp+ce)]&077)==0)&&(ce<cc))
-					ce++;
-#endif
-				if (ce==0) {
-					ttyoutput(*cp++,tp);
-					cc--;
-					goto check;
-				}
-			}
-			i=b_to_q(cp,ce,&tp->t_outq);
-			ce-=i;
-			tk_nout+=ce;
-			tp->t_col+=ce;
-			cp+=ce;
-			cc-=ce;
-check:
-			if (tp->t_outq.c_cc > TTHIWAT) {
-				(void) spl5();
-				while (tp->t_outq.c_cc > TTHIWAT) {
-					ttstart(tp);
-					tp->t_state |= ASLEEP;
-					sleep((caddr_t)&tp->t_outq, TTOPRI);
-				}
-				(void) spl0();
-			}
-		}
-	}
-	ttstart(tp);
-	return(NULL);
-}