Make the 'struct video' contain an array of unicode characters rather than bytes

This is disgusting.  And quite frankly, it's debatable whether this will
ever work.  The "line" structure is still just an array of characters,
so that has to work with utf-8.

But the 'struct video' thing is what represents the actual screen
rectangle, and is fixed-size by the size of the screen.  So making it
contain actual 32-bit unicode characters *may* make sense.

Right now we translate things the same way we always used to, though, so
utf-8 in 'struct line' will not be translated to the proper unicode
array, but to the bytes of the utf-8 representation.  So this really
doesn't improve anything per se yet, just expands the memory use of the
video array.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

display.c

diff --git a/display.c b/display.c
index e6d9a41..0d0326e 100644
--- a/display.c
+++ b/display.c
@@ -20,6 +20,8 @@
 #include "version.h"
 #include "wrapper.h"
 
+typedef unsigned int unicode_t;
+
 struct video {
 	int v_flag;		/* Flags */
 #if	COLOR
@@ -28,7 +30,7 @@
 	int v_rfcolor;		/* requested forground color */
 	int v_rbcolor;		/* requested background color */
 #endif
-	char v_text[1];		/* Screen data. */
+	unicode_t v_text[1];	/* Screen data. */
 };
 
 #define VFCHG   0x0001		/* Changed flag                 */
@@ -58,7 +60,7 @@
 static int scrolls(int inserts);
 static void scrscroll(int from, int to, int count);
 static int texttest(int vrow, int prow);
-static int endofline(char *s, int n);
+static int endofline(unicode_t *s, int n);
 static void updext(void);
 static int updateline(int row, struct video *vp1, struct video *vp2);
 static void modeline(struct window *wp);
@@ -92,7 +94,7 @@
 	pscreen = xmalloc(term.t_mrow * sizeof(struct video *));
 #endif
 	for (i = 0; i < term.t_mrow; ++i) {
-		vp = xmalloc(sizeof(struct video) + term.t_mcol);
+		vp = xmalloc(sizeof(struct video) + term.t_mcol*4);
 		vp->v_flag = 0;
 #if	COLOR
 		vp->v_rfcolor = 7;
@@ -100,7 +102,7 @@
 #endif
 		vscreen[i] = vp;
 #if	MEMMAP == 0 || SCROLLCODE
-		vp = xmalloc(sizeof(struct video) + term.t_mcol);
+		vp = xmalloc(sizeof(struct video) + term.t_mcol*4);
 		vp->v_flag = 0;
 		pscreen[i] = vp;
 #endif
@@ -214,7 +216,7 @@
 static void vteeol(void)
 {
 /*  struct video *vp;	*/
-	char *vcp = vscreen[vtrow]->v_text;
+	unicode_t *vcp = vscreen[vtrow]->v_text;
 
 /*  vp = vscreen[vtrow];	*/
 	while (vtcol < term.t_ncol)
@@ -593,7 +595,7 @@
  */
 void updgar(void)
 {
-	char *txt;
+	unicode_t *txt;
 	int i, j;
 
 	for (i = 0; i < term.t_nrow; ++i) {
@@ -700,7 +702,7 @@
 		end = endofline(vpv->v_text, cols);
 		if (end == 0)
 			target = first;	/* newlines */
-		else if (strncmp(vpp->v_text, vpv->v_text, end) == 0)
+		else if (memcmp(vpp->v_text, vpv->v_text, 4*end) == 0)
 			target = first + 1;	/* broken line newlines */
 		else
 			target = first;
@@ -759,7 +761,7 @@
 		for (i = 0; i < count; i++) {
 			vpp = pscreen[to + i];
 			vpv = vscreen[to + i];
-			strncpy(vpp->v_text, vpv->v_text, cols);
+			memcpy(vpp->v_text, vpv->v_text, 4*cols);
 			vpp->v_flag = vpv->v_flag;	/* XXX */
 			if (vpp->v_flag & VFREV) {
 				vpp->v_flag &= ~VFREV;
@@ -778,7 +780,7 @@
 		}
 #if	MEMMAP == 0
 		for (i = from; i < to; i++) {
-			char *txt;
+			unicode_t *txt;
 			txt = pscreen[i]->v_text;
 			for (j = 0; j < term.t_ncol; ++j)
 				txt[j] = ' ';
@@ -807,13 +809,13 @@
 	struct video *vpv = vscreen[vrow];	/* virtual screen image */
 	struct video *vpp = pscreen[prow];	/* physical screen image */
 
-	return !memcmp(vpv->v_text, vpp->v_text, term.t_ncol);
+	return !memcmp(vpv->v_text, vpp->v_text, 4*term.t_ncol);
 }
 
 /*
  * return the index of the first blank of trailing whitespace
  */
-static int endofline(char *s, int n)
+static int endofline(unicode_t *s, int n)
 {
 	int i;
 	for (i = n - 1; i >= 0; i--)
@@ -866,8 +868,8 @@
 static int updateline(int row, struct video *vp1, struct video *vp2)
 {
 #if	SCROLLCODE
-	char *cp1;
-	char *cp2;
+	unicode_t *cp1;
+	unicode_t *cp2;
 	int nch;
 
 	cp1 = &vp1->v_text[0];
@@ -908,8 +910,8 @@
 #if RAINBOW
 /*	UPDATELINE specific code for the DEC rainbow 100 micro	*/
 
-	char *cp1;
-	char *cp2;
+	unicode_t *cp1;
+	unicode_t *cp2;
 	int nch;
 
 	/* since we don't know how to make the rainbow do this, turn it off */
@@ -930,11 +932,11 @@
 #else
 /*	UPDATELINE code for all other versions		*/
 
-	char *cp1;
-	char *cp2;
-	char *cp3;
-	char *cp4;
-	char *cp5;
+	unicode_t *cp1;
+	unicode_t *cp2;
+	unicode_t *cp3;
+	unicode_t *cp4;
+	unicode_t *cp5;
 	int nbflag;	/* non-blanks to the right flag? */
 	int rev;		/* reverse video flag */
 	int req;		/* reverse video request flag */

posix.c

diff --git a/posix.c b/posix.c
index 85eef87..25307f4 100644
--- a/posix.c
+++ b/posix.c
@@ -120,24 +120,25 @@
  */
 int ttputc(int c)
 {
-	/*
-	 * We always represent things in 1 byte, but if we output
-	 * in UTF-8, we may need to expand that into 2 bytes..
-	 *
-	 * Some day we might even be able to handle UTF-8 _content_.
-	 *
-	 * That day is not today.
-	 */
-	if (utf8_mode()) {
-		c &= 0xff;
-		if (c >= 0x80) {
-			unsigned char first = (c >> 6) | 0xc0;
-			fputc(first, stdout);
-			c = (c & 0x3f) | 0x80;
-		}
+	unsigned char utf8[6], *p = utf8+5;
+	int bytes = 1;
+
+	if (c < 0)
+		return 0;
+	*p = c;
+	if (c > 0x7f) {
+		int prefix = 0x40;
+		do {
+			*p = 0x80 + (c & 0x3f);
+			--p;
+			bytes++;
+			prefix >>= 1;
+			c >>= 6;
+		} while (c > prefix);
+		*p = c - 2*prefix;
 	}
-	fputc(c, stdout);
-	return TRUE;
+	fwrite(p, 1, bytes, stdout);
+	return 0;
 }
 
 /*