From d132ba5a487fbe16324883f46fef3fea2763251a Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Wed, 30 Nov 2016 08:34:02 +0530
Subject: [PATCH] Implement DECALN

---
 kitty/data-types.h |  3 ++-
 kitty/line-buf.c   | 12 ++++++------
 kitty/parser.c     |  7 +++++++
 kitty/screen.c     |  9 ++++++++-
 4 files changed, 23 insertions(+), 8 deletions(-)

diff --git a/kitty/data-types.h b/kitty/data-types.h
index 26ac576bb..befa12953 100644
--- a/kitty/data-types.h
+++ b/kitty/data-types.h
@@ -318,7 +318,7 @@ void line_right_shift(Line *, unsigned int , unsigned int );
 void line_add_combining_char(Line *, uint32_t , unsigned int );
 
 void linebuf_init_line(LineBuf *, index_type);
-void linebuf_clear(LineBuf *);
+void linebuf_clear(LineBuf *, char_type ch);
 void linebuf_init_line(LineBuf *, index_type);
 void linebuf_index(LineBuf* self, index_type top, index_type bottom);
 void linebuf_reverse_index(LineBuf *self, index_type top, index_type bottom);
@@ -333,6 +333,7 @@ void historybuf_add_line(HistoryBuf *self, const Line *line);
 void historybuf_rewrap(HistoryBuf *self, HistoryBuf *other);
 void historybuf_init_line(HistoryBuf *self, index_type num, Line *l);
 
+void screen_align(Screen*);
 void screen_restore_cursor(Screen *);
 void screen_save_cursor(Screen *);
 void screen_cursor_position(Screen*, unsigned int, unsigned int);
diff --git a/kitty/line-buf.c b/kitty/line-buf.c
index 84e6e751c..635a60293 100644
--- a/kitty/line-buf.c
+++ b/kitty/line-buf.c
@@ -9,16 +9,16 @@
 #include <structmember.h>
 
 static inline void
-clear_chars_to_space(LineBuf* linebuf, index_type y) {
+clear_chars_to(LineBuf* linebuf, index_type y, char_type ch) {
     char_type *chars = linebuf->chars + linebuf->xnum * y;
-    for (index_type i = 0; i < linebuf->xnum; i++) chars[i] = (1 << ATTRS_SHIFT) | 32;
+    for (index_type i = 0; i < linebuf->xnum; i++) chars[i] = (1 << ATTRS_SHIFT) | ch;
 }
 
-void linebuf_clear(LineBuf *self) {
+void linebuf_clear(LineBuf *self, char_type ch) {
     memset(self->buf, 0, self->block_size * CELL_SIZE);
     memset(self->continued_map, 0, self->ynum * sizeof(bool));
     for (index_type i = 0; i < self->ynum; i++) {
-        clear_chars_to_space(self, i);
+        clear_chars_to(self, i, ch);
         self->line_map[i] = i;
     }
 }
@@ -26,7 +26,7 @@ void linebuf_clear(LineBuf *self) {
 static PyObject*
 clear(LineBuf *self) {
 #define clear_doc "Clear all lines in this LineBuf"
-    linebuf_clear(self);
+    linebuf_clear(self, ' ');
     Py_RETURN_NONE;
 }
 
@@ -69,7 +69,7 @@ new(PyTypeObject *type, PyObject *args, PyObject UNUSED *kwds) {
             self->line->xnum = xnum;
             for(index_type i = 0; i < ynum; i++) {
                 self->line_map[i] = i;
-                clear_chars_to_space(self, i);
+                clear_chars_to(self, i, ' ');
             }
         }
     }
diff --git a/kitty/parser.c b/kitty/parser.c
index 5b0cd5144..1bb465e5a 100644
--- a/kitty/parser.c
+++ b/kitty/parser.c
@@ -191,6 +191,7 @@ handle_esc_mode_char(Screen *screen, uint32_t ch, PyObject DUMP_UNUSED *dump_cal
                 case '.':
                 case '/':
                 case ' ':
+                case '#':
                     screen->parser_buf[screen->parser_buf_pos++] = ch;
                     break;
                 default:
@@ -201,6 +202,12 @@ handle_esc_mode_char(Screen *screen, uint32_t ch, PyObject DUMP_UNUSED *dump_cal
         default:
             if ((screen->parser_buf[0] == '%' && ch == 'G') || (screen->parser_buf[0] == '(' && ch == 'B')) { 
                 // switch to utf-8 or ascii, since we are always in utf-8, ignore.
+            } else if (screen->parser_buf[0] == '#') {
+                if (ch == '8') {
+                    screen_align(screen);
+                } else {
+                    REPORT_ERROR("Unhandled Esc # code: 0x%x", ch);
+                }
             } else {
                 REPORT_ERROR("Unhandled charset related escape code: 0x%x 0x%x", screen->parser_buf[0], ch);
             }
diff --git a/kitty/screen.c b/kitty/screen.c
index 49a0da4b7..5ebb06b92 100644
--- a/kitty/screen.c
+++ b/kitty/screen.c
@@ -56,7 +56,7 @@ new(PyTypeObject *type, PyObject *args, PyObject UNUSED *kwds) {
 
 void screen_reset(Screen *self) {
     if (self->linebuf == self->alt_linebuf) screen_toggle_screen_buffer(self);
-    linebuf_clear(self->linebuf);
+    linebuf_clear(self->linebuf, ' ');
     self->modes = empty_modes;
     self->utf8_state = 0;
     self->margin_top = 0; self->margin_bottom = self->lines - 1;
@@ -189,6 +189,13 @@ screen_draw(Screen *self, uint32_t ch) {
     if (x != self->cursor->x || y != self->cursor->y) tracker_cursor_changed(self->change_tracker);
 }
 
+void
+screen_align(Screen *self) {
+    self->margin_top = 0; self->margin_bottom = self->lines - 1;
+    screen_cursor_position(self, 1, 1);
+    linebuf_clear(self->linebuf, 'E');
+}
+
 // }}}
 
 // Graphics {{{