[PATCH] fbuffer: improve toggle cursor performance

[Greg Kurz]

SLOF currently calls hv-logical-load and hv-logical-store for every pixel
when enabling or disabling the cursor. This is suboptimal when writing one
char at a time to the console since terminal-write always toggles the cursor.
And this is precisely what grub is doing when the user wants to edit a menu
entry... the result is an incredibly slow and barely usable interface.

The inner loop in fb8-toggle-cursor handles a contiguous region: it can be
converted to hv-logical-memop. The result is 32 times less hcalls per char
and a serious improvement in grub usability.

Signed-off-by: Greg Kurz <gkurz at linux.vnet.ibm.com>
---
 slof/fs/fbuffer.fs |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/slof/fs/fbuffer.fs b/slof/fs/fbuffer.fs
index 756f05a..46b59bf 100644
--- a/slof/fs/fbuffer.fs
+++ b/slof/fs/fbuffer.fs
@@ -99,8 +99,8 @@ CREATE bitmap-buffer 400 4 * allot
 : fb8-toggle-cursor ( -- )
 	line# fb8-line2addr column# fb8-columns2bytes +
 	char-height 0 ?DO
-		char-width screen-depth * 0 ?DO dup dup rb@ -1 xor swap rb! 1+ LOOP
-		screen-width screen-depth * + char-width screen-depth * -
+		dup dup 0 char-width screen-depth * 1 hv-logical-memop drop
+		screen-width screen-depth * +
 	LOOP drop
 ;