Implement the DEC alignment test. With the last change this is enough for the

first cursor test in vttest (in ports) to pass; it still shops a few more
problems though.

input.c

@@ -630,6 +630,9 @@ input_handle_c1_control(u_char ch, struct input_ctx *ictx)
 	log_debug2("-- c1 %zu: %hhu (%c)", ictx->off, ch, ch);
 
 	switch (ch) {
+	case 'D':	/* IND */
+		screen_write_linefeed(&ictx->ctx);
+		break;
 	case 'E': 	/* NEL */
 		screen_write_carriagereturn(&ictx->ctx);
 		screen_write_linefeed(&ictx->ctx);
@@ -652,7 +655,7 @@ input_handle_private_two(u_char ch, struct input_ctx *ictx)
 	    "-- p2 %zu: %hhu (%c) %hhu", ictx->off, ch, ch, ictx->intermediate);
 
 	switch (ch) {
-	case '0':	/* Dscs (graphics) */
+	case '0':	/* SCS */
 		/*
 		 * Not really supported, but fake it up enough for those that
 		 * use it to switch character sets (by redefining G0 to
@@ -665,23 +668,37 @@ input_handle_private_two(u_char ch, struct input_ctx *ictx)
 		}
 		break;
 	case '=':	/* DECKPAM */
+		if (ictx->intermediate != '\0')
+			break;
 		screen_write_kkeypadmode(&ictx->ctx, 1);
 		log_debug("kkeypad on (application mode)");
 		break;
 	case '>':	/* DECKPNM */
+		if (ictx->intermediate != '\0')
+			break;
 		screen_write_kkeypadmode(&ictx->ctx, 0);
 		log_debug("kkeypad off (number mode)");
 		break;
 	case '7':	/* DECSC */
+		if (ictx->intermediate != '\0')
+			break;
 		memcpy(&ictx->saved_cell, &ictx->cell, sizeof ictx->saved_cell);
 		ictx->saved_cx = s->cx;
 		ictx->saved_cy = s->cy;
 		break;
-	case '8':	/* DECRC */
-		memcpy(&ictx->cell, &ictx->saved_cell, sizeof ictx->cell);
+	case '8':
+		switch (ictx->intermediate) {
+		case '\0':	/* DECRC */
+			memcpy(
+			    &ictx->cell, &ictx->saved_cell, sizeof ictx->cell);
 			screen_write_cursormove(
 			    &ictx->ctx, ictx->saved_cx, ictx->saved_cy);
 			break;
+		case '#':	/* DECALN */
+			screen_write_alignmenttest(&ictx->ctx);
+			break;
+		}
+		break;
 	default:
 		log_debug("unknown p2: %hhu", ch);
 		break;

screen-write.c

@@ -291,6 +291,31 @@ screen_write_cursorleft(struct screen_write_ctx *ctx, u_int nx)
 	s->cx -= nx;
 }
 
+/* VT100 alignment test. */
+void
+screen_write_alignmenttest(struct screen_write_ctx *ctx)
+{
+	struct screen		*s = ctx->s;
+	struct grid_cell       	 gc;
+	u_int			 xx, yy;
+
+	memcpy(&gc, &grid_default_cell, sizeof gc);
+	gc.data = 'E';
+	
+	for (yy = 0; yy < screen_size_y(s); yy++) {
+		for (xx = 0; xx < screen_size_x(s); xx++)
+			grid_view_set_cell(s->grid, xx, yy, &gc);
+	}
+	
+	s->cx = 0;
+	s->cy = 0;
+
+	s->rupper = 0;
+	s->rlower = screen_size_y(s) - 1;
+
+	tty_write_cmd(ctx->wp, TTY_ALIGNMENTTEST);
+}
+
 /* Insert nx characters. */
 void
 screen_write_insertcharacter(struct screen_write_ctx *ctx, u_int nx)

tmux.h

@@ -279,6 +279,7 @@ struct tty_term_code_entry {
 
 /* Output commands. */
 enum tty_cmd {
+	TTY_ALIGNMENTTEST,
 	TTY_CELL,
 	TTY_CLEARENDOFLINE,
 	TTY_CLEARENDOFSCREEN,
@@ -1363,6 +1364,7 @@ void	 screen_write_cursorup(struct screen_write_ctx *, u_int);
 void	 screen_write_cursordown(struct screen_write_ctx *, u_int);
 void	 screen_write_cursorright(struct screen_write_ctx *, u_int);
 void	 screen_write_cursorleft(struct screen_write_ctx *, u_int);
+void	 screen_write_alignmenttest(struct screen_write_ctx *);
 void	 screen_write_insertcharacter(struct screen_write_ctx *, u_int);
 void	 screen_write_deletecharacter(struct screen_write_ctx *, u_int);
 void	 screen_write_insertline(struct screen_write_ctx *, u_int);

tty.c

@@ -38,6 +38,7 @@ void	tty_attributes(struct tty *, const struct grid_cell *);
 void	tty_attributes_fg(struct tty *, const struct grid_cell *);
 void	tty_attributes_bg(struct tty *, const struct grid_cell *);
 
+void	tty_cmd_alignmenttest(struct tty *, struct window_pane *, va_list);
 void	tty_cmd_cell(struct tty *, struct window_pane *, va_list);
 void	tty_cmd_clearendofline(struct tty *, struct window_pane *, va_list);
 void	tty_cmd_clearendofscreen(struct tty *, struct window_pane *, va_list);
@@ -54,6 +55,7 @@ void	tty_cmd_raw(struct tty *, struct window_pane *, va_list);
 void	tty_cmd_reverseindex(struct tty *, struct window_pane *, va_list);
 
 void (*tty_cmds[])(struct tty *, struct window_pane *, va_list) = {
+	tty_cmd_alignmenttest,
 	tty_cmd_cell,
 	tty_cmd_clearendofline,
 	tty_cmd_clearendofscreen,
@@ -830,6 +832,24 @@ tty_cmd_clearscreen(
 	}
 }
 
+void
+tty_cmd_alignmenttest(
+    struct tty *tty, struct window_pane *wp, unused va_list ap)
+{
+	struct screen	*s = wp->screen;
+	u_int		 i, j;
+
+	tty_reset(tty);
+
+	tty_region(tty, 0, screen_size_y(s) - 1, wp->yoff);
+
+	for (j = 0; j < screen_size_y(s); j++) {
+		tty_cursor(tty, 0, j, wp->xoff, wp->yoff);
+		for (i = 0; i < screen_size_x(s); i++)
+			tty_putc(tty, 'E');
+	}
+}
+
 void
 tty_cmd_cell(struct tty *tty, struct window_pane *wp, va_list ap)
 {