0002-Use-historical-conventions-for-delays-and-XCASE-spec.patch

From fd626eb5526886e34da7a0ecbc090ab1c044c1c1 Mon Sep 17 00:00:00 2001
From: Hugh Pyle <hughpyle@gmail.com>
Date: Fri, 6 Dec 2019 23:42:11 +0000
Subject: [PATCH 2/2] Use historical conventions for delays and XCASE special
 characters

Updates the implementation to match historical practice, where
XCASE has special handling for common punctuation that is not
available in ASCII-63 terminals:
  \^  ==>  ~
  \!  ==>  |
  \(  ==>  {
  \)  ==>  }
  \'  ==>  `
NL delays use two fill charcaters, and
CR delays use two (CR1, suitable for tty33 and tn300 terminals)
or four (CR2, suitable for tty37 and ti700) fill characters.

Also, if ONLRET, newline performs the carriage-return function
and should also use the carriage-return delays.
---
 drivers/tty/n_tty.c | 100 ++++++++++++++++++++++++++++++++++----------
 1 file changed, 78 insertions(+), 22 deletions(-)

diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c
index fca85cb134e2..859aaa46ef2d 100644
--- a/drivers/tty/n_tty.c
+++ b/drivers/tty/n_tty.c
@@ -27,7 +27,7 @@
  *		Also fixed a bug in BLOCKING mode where n_tty_write returns
  *		EAGAIN
  *
- * 2019/12/03   Experimental implementation of CRDLY, NLDLY and XCASE
+ * 2019/12/07   Experimental implementation of CRDLY, NLDLY and XCASE
  *		for mechanical terminals - Hugh Pyle <hughpyle@gmail.com>
  */
 
@@ -417,20 +417,21 @@ static inline int is_continuation(unsigned char c, struct tty_struct *tty)
  *	no space left.⏎
  */
 
-static inline int do_output_nl(struct tty_struct *tty, int space)
+static inline int do_output_withnldelay(unsigned char c, struct tty_struct *tty, int space)
 {
 	if (!space)
 		return -1;
+	tty_put_char(tty, c);
 	if (unlikely(O_NLDLY(tty) && O_OFILL(tty))) {
-		if (space < 2)
+		if (space < 3)
 			return -1;
 		if (O_OFDEL(tty))
-			tty->ops->write(tty, "\n\177", 2);
+			tty->ops->write(tty, "\177\177", 2);
 		else
-			tty->ops->write(tty, "\n\0", 2);
-		return 2;
+			tty->ops->write(tty, "\0\0", 2);
+		return 3;
 	}
-	return tty_put_char(tty, '\n');
+	return 1;
 }
 
 /**
@@ -440,30 +441,43 @@ static inline int do_output_nl(struct tty_struct *tty, int space)
  *	no space left.
  */
 
-static inline int do_output_cr(struct tty_struct *tty, int space)
+static inline int do_output_withcrdelay(unsigned char c, struct tty_struct *tty, int space)
 {
 	struct n_tty_data *ldata = tty->disc_data;
-	int	delays;
+	int	nchars;
 	if (!space)
 		return -1;
+	tty_put_char(tty, c);
 	if (unlikely(O_CRDLY(tty) && O_OFILL(tty))) {
-		// insert filler bytes after CR, based on the delay (CR1, CR2, CR3)
-		delays = 1;
-		if (O_CRDLY(tty) == CR2)
-			delays = 2;
-		if (O_CRDLY(tty) == CR3)
-			delays = 3;
-		if (space < delays+1)
+		nchars = 1;
+		if (O_CRDLY(tty) == CR1)  /* tty33, tn300 */
+			nchars = 2;
+		if (O_CRDLY(tty) == CR2)  /* tty37, ti700 */
+			nchars = 4;
+		if (space < nchars+1)
 			return -1;
 		ldata->canon_column = ldata->column = 0;
 		if (O_OFDEL(tty))
-			tty->ops->write(tty, "\r\177\177\177", delays+1);
+			tty->ops->write(tty, "\177\177\177\177", nchars);
 		else
-			tty->ops->write(tty, "\r\0\0\0", delays+1);
-		return delays;
+			tty->ops->write(tty, "\0\0\0\0", nchars);
+		return nchars + 1;
 	}
 	ldata->canon_column = ldata->column = 0;
-	return tty_put_char(tty, '\r');
+	return 1;
+}
+
+static inline int do_output_nl(struct tty_struct *tty, int space)
+{
+	if (unlikely(O_ONLRET(tty)))
+		return do_output_withcrdelay('\n', tty, space);
+	else
+		return do_output_withnldelay('\n', tty, space);
+}
+
+static inline int do_output_cr(struct tty_struct *tty, int space)
+{
+	return do_output_withcrdelay('\r', tty, space);
 }
 
 /**
@@ -543,13 +557,36 @@ static int do_output_char(unsigned char c, struct tty_struct *tty, int space)
 		if (!iscntrl(c)) {
 			if (L_XCASE(tty) && L_ICANON(tty))
 			{
+				unsigned char c1 = '\0';
 				if (isupper(c) && !is_continuation(c, tty))
+					c1 = c;
+				else
+				{
+					switch (c) {
+					case '~':
+						c1 = '^';
+						break;
+					case '|':
+						c1 = '!';
+						break;
+					case '{':
+						c1 = '(';
+						break;
+					case '}':
+						c1 = ')';
+						break;
+					case '`':
+						c1 = '\'';
+						break;
+					}
+				}
+				if (c1)
 				{
 					if (space < 2)
 						return -1;
 					tty_put_char(tty, '\\');
 					ldata->column++;
-					tty_put_char(tty, c);
+					tty_put_char(tty, c1);
 					ldata->column++;
 					return 2;
 				}
@@ -1603,7 +1640,26 @@ n_tty_receive_char_xcase(struct tty_struct *tty, unsigned char c, char flag)
 	if (likely(flag == TTY_NORMAL)) {
 		if (I_ISTRIP(tty))
 			c &= 0x7f;
-		c = toupper(c);
+		switch (c) {
+		case '^':
+			c = '~';
+			break;
+		case '!':
+			c = '|';
+			break;
+		case '(':
+			c = '{';
+			break;
+		case ')':
+			c = '}';
+			break;
+		case '\'':
+			c = '`';
+			break;
+		default:
+			c = toupper(c);
+			break;
+		}
 		n_tty_receive_char(tty, c);
 	} else
 		n_tty_receive_char_flagged(tty, c, flag);
-- 
2.20.1