Instead of storing all UTF-8 characters in the extended cell which means

that 14 bytes are wasted for each character in the BMP, only store
characters of three bytes or less in the cell itself and store others
(outside the BMP or with combining characters) in a separate global
tree. Can reduce grid memory use for heavy Unicode users by around 30%.

1 files changed, 23 insertions, 8 deletions

diff --git a/tmux.h b/tmux.h
index a94e7611..118faf9c 100644
--- a/tmux.h
+++ b/tmux.h
@@ -597,11 +597,11 @@ struct msg_write_close {
 #define MOTION_MOUSE_MODES (MODE_MOUSE_BUTTON|MODE_MOUSE_ALL)
 
 /*
- * A single UTF-8 character. UTF8_SIZE must be big enough to hold
- * combining characters as well, currently at most five (of three
- * bytes) are supported.
-*/
-#define UTF8_SIZE 18
+ * A single UTF-8 character. UTF8_SIZE must be big enough to hold combining
+ * characters as well. It can't be more than 32 bytes without changes to how
+ * big characters are stored.
+ */
+#define UTF8_SIZE 21
 struct utf8_data {
 	u_char	data[UTF8_SIZE];
 
@@ -609,7 +609,7 @@ struct utf8_data {
 	u_char	size;
 
 	u_char	width;	/* 0xff if invalid */
-} __packed;
+};
 enum utf8_state {
 	UTF8_MORE,
 	UTF8_DONE,
@@ -663,13 +663,25 @@ enum utf8_state {
 
 /* Grid cell data. */
 struct grid_cell {
-	struct utf8_data	data; /* 21 bytes */
+	struct utf8_data	data;
+	u_short			attr;
+	u_char			flags;
+	int			fg;
+	int			bg;
+	int			us;
+};
+
+/* Grid extended cell entry. */
+struct grid_extd_entry {
+	uint32_t		data;
 	u_short			attr;
 	u_char			flags;
 	int			fg;
 	int			bg;
 	int			us;
 } __packed;
+
+/* Grid cell entry. */
 struct grid_cell_entry {
 	u_char			flags;
 	union {
@@ -690,7 +702,7 @@ struct grid_line {
 	struct grid_cell_entry	*celldata;
 
 	u_int			 extdsize;
-	struct grid_cell	*extddata;
+	struct grid_extd_entry	*extddata;
 
 	int			 flags;
 } __packed;
@@ -2877,6 +2889,9 @@ u_int		 session_group_attached_count(struct session_group *);
 void		 session_renumber_windows(struct session *);
 
 /* utf8.c */
+uint32_t	 utf8_set_big(char, u_int);
+uint32_t	 utf8_map_big(const struct utf8_data *);
+void		 utf8_get_big(uint32_t, struct utf8_data *);
 void		 utf8_set(struct utf8_data *, u_char);
 void		 utf8_copy(struct utf8_data *, const struct utf8_data *);
 enum utf8_state	 utf8_open(struct utf8_data *, u_char);