Long overdue change to the way we store cells in the grid: now, instead

of storing a full grid_cell with UTF-8 data and everything, store a new
type grid_cell_entry. This can either be the cell itself (for ASCII
cells), or an offset into an extended array (per line) for UTF-8
data.

This avoid a large (8 byte) overhead on non-UTF-8 cells (by far the
majority for most users) without the complexity of the shadow array we
had before. Grid memory without any UTF-8 is about half.

The disadvantage that cells can no longer be modified in place and need
to be copied out of the grid and back but it turned out to be lot less
complicated than I expected.

1 files changed, 40 insertions, 32 deletions

diff --git a/tmux.h b/tmux.h
index cb7ed2c3..11f5fe58 100644
--- a/tmux.h
+++ b/tmux.h
@@ -621,11 +621,11 @@ struct mode_key_table {
 struct utf8_data {
 	u_char	data[UTF8_SIZE];
 
-	size_t	have;
-	size_t	size;
+	u_char	have;
+	u_char	size;
 
-	u_int	width;
-};
+	u_char	width;
+} __packed;
 
 /* Grid attributes. */
 #define GRID_ATTR_BRIGHT 0x1
@@ -641,41 +641,56 @@ struct utf8_data {
 #define GRID_FLAG_FG256 0x1
 #define GRID_FLAG_BG256 0x2
 #define GRID_FLAG_PADDING 0x4
+#define GRID_FLAG_EXTENDED 0x8
 
 /* Grid line flags. */
 #define GRID_LINE_WRAPPED 0x1
 
 /* Grid cell data. */
 struct grid_cell {
-	u_char	attr;
-	u_char	flags;
-	u_char	fg;
-	u_char	bg;
+	u_char			flags;
+	u_char			attr;
+	u_char			fg;
+	u_char			bg;
+	struct utf8_data	data;
 
-	u_char	xstate; /* top 4 bits width, bottom 4 bits size */
-	u_char	xdata[UTF8_SIZE];
+};
+struct grid_cell_entry {
+	u_char			flags;
+	union {
+		u_int		offset;
+		struct {
+			u_char	attr;
+			u_char	fg;
+			u_char	bg;
+			u_char	data;
+		} data;
+	};
 } __packed;
 
 /* Grid line. */
 struct grid_line {
-	u_int	cellsize;
-	struct grid_cell *celldata;
+	u_int			 cellsize;
+	struct grid_cell_entry	*celldata;
+
+	u_int			 extdsize;
+	struct grid_cell	*extddata;
 
-	int	flags;
+	int			 flags;
 } __packed;
 
 /* Entire grid of cells. */
 struct grid {
-	int	flags;
-#define GRID_HISTORY 0x1	/* scroll lines into history */
+	int			 flags;
+#define GRID_HISTORY 0x1 /* scroll lines into history */
 
-	u_int	sx;
-	u_int	sy;
+	u_int			 sx;
+	u_int			 sy;
 
-	u_int	hsize;
-	u_int	hlimit;
+	u_int			 hsize;
+	u_int			 hlimit;
 
-	struct grid_line *linedata;
+	struct grid_line	*linedata;
 };
 
 /* Option data structures. */
@@ -1854,9 +1869,8 @@ void	 grid_scroll_history(struct grid *);
 void	 grid_scroll_history_region(struct grid *, u_int, u_int);
 void	 grid_clear_history(struct grid *);
 void	 grid_expand_line(struct grid *, u_int, u_int);
-const struct grid_cell *grid_peek_cell(struct grid *, u_int, u_int);
 const struct grid_line *grid_peek_line(struct grid *, u_int);
-struct grid_cell *grid_get_cell(struct grid *, u_int, u_int);
+void	 grid_get_cell(struct grid *, u_int, u_int, struct grid_cell *);
 void	 grid_set_cell(struct grid *, u_int, u_int, const struct grid_cell *);
 void	 grid_clear(struct grid *, u_int, u_int, u_int, u_int);
 void	 grid_clear_lines(struct grid *, u_int, u_int);
@@ -1868,17 +1882,10 @@ void	 grid_duplicate_lines(
 	     struct grid *, u_int, struct grid *, u_int, u_int);
 u_int	 grid_reflow(struct grid *, struct grid *, u_int);
 
-/* grid-cell.c */
-u_int	 grid_cell_width(const struct grid_cell *);
-void	 grid_cell_get(const struct grid_cell *, struct utf8_data *);
-void	 grid_cell_set(struct grid_cell *, const struct utf8_data *);
-void	 grid_cell_one(struct grid_cell *, u_char);
-
 /* grid-view.c */
-const struct grid_cell *grid_view_peek_cell(struct grid *, u_int, u_int);
-struct grid_cell *grid_view_get_cell(struct grid *, u_int, u_int);
-void	 grid_view_set_cell(
-	     struct grid *, u_int, u_int, const struct grid_cell *);
+void	 grid_view_get_cell(struct grid *, u_int, u_int, struct grid_cell *);
+void	 grid_view_set_cell(struct grid *, u_int, u_int,
+	     const struct grid_cell *);
 void	 grid_view_clear_history(struct grid *);
 void	 grid_view_clear(struct grid *, u_int, u_int, u_int, u_int);
 void	 grid_view_scroll_region_up(struct grid *, u_int, u_int);
@@ -2183,6 +2190,7 @@ void		 session_renumber_windows(struct session *);
 /* utf8.c */
 u_int		 utf8_width(u_int);
 void		 utf8_set(struct utf8_data *, u_char);
+void		 utf8_copy(struct utf8_data *, const struct utf8_data *);
 int		 utf8_open(struct utf8_data *, u_char);
 int		 utf8_append(struct utf8_data *, u_char);
 u_int		 utf8_combine(const struct utf8_data *);