Add DEC alignment test

This sequence was used by DEC personal in to for verifying the screen adjust
of terminals. It is the unique test sequence implemented by all the
emulators, and I think it is because they want be conforms with vttest which
uses this sequence in some tests.
---
 st.c |   31 +++++++++++++++++++++++--------
 1 file changed, 23 insertions(+), 8 deletions(-)

st.c

@@ -123,6 +123,7 @@ enum escape_state {
 	ESC_STR	= 4, /* DSC, OSC, PM, APC */
 	ESC_ALTCHARSET = 8,
 	ESC_STR_END    = 16, /* a final string was encountered */
+	ESC_TEST       = 32, /* Enter in test mode */
 };
 
 enum window_state {
@@ -289,7 +290,7 @@ static int tresize(int, int);
 static void tscrollup(int, int);
 static void tscrolldown(int, int);
 static void tsetattr(int*, int);
-static void tsetchar(char*);
+static void tsetchar(char *, Glyph *, int, int);
 static void tsetscroll(int, int);
 static void tswapscreen(void);
 static void tsetdirt(int, int);
@@ -1182,7 +1183,7 @@ tmoveto(int x, int y) {
 }
 
 void
-tsetchar(char *c) {
+tsetchar(char *c, Glyph *attr, int x, int y) {
 	static char *vt100_0[62] = { /* 0x41 - 0x7e */
 		"↑", "↓", "→", "←", "█", "▚", "☃", /* A - G */
 		0, 0, 0, 0, 0, 0, 0, 0, /* H - O */
@@ -1197,17 +1198,17 @@ tsetchar(char *c) {
 	/*
 	 * The table is proudly stolen from rxvt.
 	 */
-	if(term.c.attr.mode & ATTR_GFX) {
+	if(attr->mode & ATTR_GFX) {
 		if(c[0] >= 0x41 && c[0] <= 0x7e
 				&& vt100_0[c[0] - 0x41]) {
 			c = vt100_0[c[0] - 0x41];
 		}
 	}
 
-	term.dirty[term.c.y] = 1;
+	term.dirty[y] = 1;
-	term.line[term.c.y][term.c.x] = term.c.attr;
+	term.line[y][x] = *attr;
-	memcpy(term.line[term.c.y][term.c.x].c, c, UTF_SIZ);
+	memcpy(term.line[y][x].c, c, UTF_SIZ);
-	term.line[term.c.y][term.c.x].state |= GLYPH_SET;
+	term.line[y][x].state |= GLYPH_SET;
 }
 
 void
@@ -1893,11 +1894,25 @@ tputc(char *c, int len) {
 				fprintf(stderr, "esc unhandled charset: ESC ( %c\n", ascii);
 			}
 			term.esc = 0;
+		} else if(term.esc & ESC_TEST) {
+			if(ascii == '8') { /* DEC screen alignment test. */
+				char E[UTF_SIZ] = "E";
+				int x, y;
+
+				for(x = 0; x < term.col; ++x) {
+					for(y = 0; y < term.row; ++y)
+						tsetchar(E, &term.c.attr, x, y);
+				}
+			}
+			term.esc = 0;
 		} else {
 			switch(ascii) {
 			case '[':
 				term.esc |= ESC_CSI;
 				break;
+			case '#':
+				term.esc |= ESC_TEST;
+				break;
 			case 'P': /* DCS -- Device Control String */
 			case '_': /* APC -- Application Program Command */
 			case '^': /* PM -- Privacy Message */
@@ -1988,7 +2003,7 @@ tputc(char *c, int len) {
 		sel.bx = -1;
 	if(IS_SET(MODE_WRAP) && term.c.state & CURSOR_WRAPNEXT)
 		tnewline(1); /* always go to first col */
-	tsetchar(c);
+	tsetchar(c, &term.c.attr, term.c.x, term.c.y);
 	if(term.c.x+1 < term.col)
 		tmoveto(term.c.x+1, term.c.y);
 	else