--- Net2/sys/tty.h	2018/04/24 18:03:57	1.1
+++ Net2/sys/tty.h	2018/04/24 18:10:12	1.1.1.2
@@ -31,20 +31,55 @@
  * SUCH DAMAGE.
  *
  *	@(#)tty.h	7.10 (Berkeley) 6/26/91
+ * $Header: /var/lib/cvsd/net2/Net2/sys/tty.h,v 1.1.1.2 2018/04/24 18:10:12 root Exp $
+ *
+ * PATCHES MAGIC                LEVEL   PATCH THAT GOT US HERE
+ * --------------------         -----   ----------------------
+ * CURRENT PATCH LEVEL:         2       00061
+ * --------------------         -----   ----------------------
+ *
+ * 18 Aug 92	Stephen McKay		Fixed RB_LEN macro
+ * 11 Dec 92	Williams Jolitz		Fixed tty handling
+ * --------------------         -----   ----------------------
+ *
  */
 
 #include <sys/termios.h>
 
 /*
- * Clists are character lists, which is a variable length linked list
- * of cblocks, wiht a count of the number of characters in the list.
+ * Ring buffers provide a contiguous, dense storage for
+ * character data used by the tty driver.
  */
-struct clist {
-	int	c_cc;		/* count of characters in queue */
-	char	*c_cf;		/* first character/cblock */
-	char	*c_cl;		/* last chararacter/cblock */
+#define	RBSZ 1024
+
+struct ringb {
+	char	*rb_hd;	  /* head of buffer segment to be read */
+	char	*rb_tl;	  /* tail of buffer segment to be written */
+	char	rb_buf[RBSZ];	/* segment contents */
 };
 
+#define	RB_SUCC(rbp, p) \
+		((p) >= (rbp)->rb_buf + RBSZ - 1 ? (rbp)->rb_buf : (p) + 1)
+
+#define	RB_ROLLOVER(rbp, p) \
+		((p) > (rbp)->rb_buf + RBSZ - 1 ? (rbp)->rb_buf : (p))
+
+#define	RB_PRED(rbp, p) \
+		((p) <= (rbp)->rb_buf ? (rbp)->rb_buf + RBSZ - 1 : (p) - 1)
+
+#define	RB_LEN(rp) \
+		((rp)->rb_hd <= (rp)->rb_tl ? (rp)->rb_tl - (rp)->rb_hd : \
+		RBSZ - ((rp)->rb_hd - (rp)->rb_tl))
+
+#define	RB_CONTIGPUT(rp) \
+		(RB_PRED(rp, (rp)->rb_hd) < (rp)->rb_tl ?  \
+			(rp)->rb_buf + RBSZ - (rp)->rb_tl : \
+			RB_PRED(rp, (rp)->rb_hd) - (rp)->rb_tl)
+
+#define	RB_CONTIGGET(rp) \
+		((rp)->rb_hd <= (rp)->rb_tl ? (rp)->rb_tl - (rp)->rb_hd : \
+		(rp)->rb_buf + RBSZ - (rp)->rb_hd)
+
 /*
  * Per-tty structure.
  *
@@ -53,13 +88,10 @@ struct clist {
  * (low, high, timeout).
  */
 struct tty {
-	struct	clist t_rawq;		/* queues */
-	struct	clist t_canq;
-	struct	clist t_outq;
 	int	(*t_oproc)();		/* device */
 	int	(*t_param)();		/* device */
-	struct	proc *t_rsel;		/* tty */
-	struct	proc *t_wsel;
+	pid_t	t_rsel;			/* tty */
+	pid_t	t_wsel;
 	caddr_t	T_LINEP; 		/* XXX */
 	caddr_t	t_addr;			/* ??? */
 	dev_t	t_dev;			/* device */
@@ -87,6 +119,10 @@ struct tty {
 	long	t_rawcc;
 	long	t_outcc;
 	short	t_gen;			/* generation number */
+	short	t_mask;			/* interrupt mask */
+	struct	ringb t_raw;		/* ring buffers */
+	struct	ringb t_can;
+	struct	ringb t_out;
 };
 
 #define	TTIPRI	25			/* sleep priority for tty reads */
@@ -97,8 +133,8 @@ struct tty {
 #define	TTYHOG	1024
 
 #ifdef KERNEL
-#define TTMAXHIWAT	roundup(2048, CBSIZE)
-#define TTMINHIWAT	roundup(100, CBSIZE)
+#define TTMAXHIWAT	(RBSZ/2)	/* XXX */
+#define TTMINHIWAT	128
 #define TTMAXLOWAT	256
 #define TTMINLOWAT	32
 extern	struct ttychars ttydefaults;