Make SCS work in 8-bit mode.

This means we can finally do things like VT100 box drawing when using
Syscons (8-bit characters). As far as I know, the only remaining issue
is the absense of proper escape sequences for special keyboard
characters (cursor, F1 to F12, etc) and xterm emulation should be ready
for general use.

Enabling xterm would have the following advantages:

- Easier possible migration to Unicode. cons25 termcap entries are very
  8-bit centric. They use things like CP437 characters for box drawing,
  etc.

- Better support for SSH'ing to other operating systems/devices. Most
  switches use VT100-style admin interfaces.

- Reduced bandwidth, because applications can now use things like
  scrolling regions.

- You can finally use applications like dtach(1) on both the console and
  inside an xterm.

4 files changed, 24 insertions, 13 deletions

diff --git a/sys/teken/teken.c b/sys/teken/teken.c
index da5c056..c928510 100644
--- a/sys/teken/teken.c
+++ b/sys/teken/teken.c
@@ -48,10 +48,6 @@
 static FILE *df;
 #endif /* __FreeBSD__ && _KERNEL */
 
-#include "teken.h"
-#include "teken_wcwidth.h"
-#include "teken_scs.h"
-
 /* Private flags for t_stateflags. */
 #define	TS_FIRSTDIGIT	0x01	/* First numeric digit in escape sequence. */
 #define	TS_INSERT	0x02	/* Insert mode. */
@@ -64,6 +60,10 @@ static FILE *df;
 /* Character that blanks a cell. */
 #define	BLANK	' '
 
+#include "teken.h"
+#include "teken_wcwidth.h"
+#include "teken_scs.h"
+
 static teken_state_t	teken_state_init;
 
 /*
diff --git a/sys/teken/teken.h b/sys/teken/teken.h
index 65ee05e..4e73f7b 100644
--- a/sys/teken/teken.h
+++ b/sys/teken/teken.h
@@ -109,7 +109,7 @@ typedef struct {
 	tf_respond_t	*tf_respond;
 } teken_funcs_t;
 
-typedef teken_char_t teken_scs_t(teken_char_t);
+typedef teken_char_t teken_scs_t(teken_t *, teken_char_t);
 
 /*
  * Terminal state.
diff --git a/sys/teken/teken_scs.h b/sys/teken/teken_scs.h
index baeb296..f877130 100644
--- a/sys/teken/teken_scs.h
+++ b/sys/teken/teken_scs.h
@@ -58,39 +58,49 @@ static teken_char_t
 teken_scs_process(teken_t *t, teken_char_t c)
 {
 
-	return (t->t_scs[t->t_curscs](c));
+	return (t->t_scs[t->t_curscs](t, c));
 }
 
 /* Unicode points for VT100 box drawing. */
-static const uint16_t teken_boxdrawing[31] = {
+static const uint16_t teken_boxdrawing_unicode[31] = {
     0x25c6, 0x2592, 0x2409, 0x240c, 0x240d, 0x240a, 0x00b0, 0x00b1,
     0x2424, 0x240b, 0x2518, 0x2510, 0x250c, 0x2514, 0x253c, 0x23ba,
     0x23bb, 0x2500, 0x23bc, 0x23bd, 0x251c, 0x2524, 0x2534, 0x252c,
     0x2502, 0x2264, 0x2265, 0x03c0, 0x2260, 0x00a3, 0x00b7
 };
 
+/* CP437 points for VT100 box drawing. */
+static const uint8_t teken_boxdrawing_8bit[31] = {
+    0x04, 0xb1, 0x48, 0x46, 0x43, 0x4c, 0xf8, 0xf1,
+    0x4e, 0x56, 0xd9, 0xbf, 0xda, 0xc0, 0xc5, 0xc4,
+    0xc4, 0xc4, 0xc4, 0xc4, 0xc3, 0xb4, 0xc1, 0xc2,
+    0xb3, 0xf3, 0xf2, 0xe3, 0xd8, 0x9c, 0xfa,
+};
+
 static teken_char_t
-teken_scs_special_graphics(teken_char_t c)
+teken_scs_special_graphics(teken_t *t, teken_char_t c)
 {
 
 	/* Box drawing. */
 	if (c >= '`' && c <= '~')
-		return (teken_boxdrawing[c - '`']);
+		return (t->t_stateflags & TS_8BIT ?
+		    teken_boxdrawing_8bit[c - '`'] :
+		    teken_boxdrawing_unicode[c - '`']);
 	return (c);
 }
 
 static teken_char_t
-teken_scs_uk_national(teken_char_t c)
+teken_scs_uk_national(teken_t *t, teken_char_t c)
 {
 
 	/* Pound sign. */
 	if (c == '#')
-		return (0xa3);
+		return (t->t_stateflags & TS_8BIT ? 0x9c : 0xa3);
 	return (c);
 }
 
 static teken_char_t
-teken_scs_us_ascii(teken_char_t c)
+teken_scs_us_ascii(teken_t *t, teken_char_t c)
 {
 
 	/* No processing. */
diff --git a/sys/teken/teken_subr.h b/sys/teken/teken_subr.h
index ab3e759..9e84b9c 100644
--- a/sys/teken/teken_subr.h
+++ b/sys/teken/teken_subr.h
@@ -802,8 +802,9 @@ teken_subr_regular_character(teken_t *t, teken_char_t c)
 	int width;
 
 	if (t->t_stateflags & TS_8BIT) {
-		if (!(t->t_stateflags & TS_CONS25) && c <= 0x1B)
+		if (!(t->t_stateflags & TS_CONS25) && (c <= 0x1b || c == 0x7f))
 			return;
+		c = teken_scs_process(t, c);
 		width = 1;
 	} else {
 		c = teken_scs_process(t, c);