[SLOF PATCH 0/2] fbuffer: Improve the speed of the cursor drawing
thuth at redhat.com
Tue Jul 28 20:19:53 AEST 2015
Greg Kurz recently already did a great work by introducing the
invert-region helpers to speed up the drawing of the cursor.
This made the grub2 command prompt and editor mode usable.
However, the editor mode of grub2 is still sluggish - because
grub2 always redraws the whole line (with cursor enabled!) when
you enter a character, and since cursor and character drawing
is still not super-fast in SLOF, this sums up to a noticable delay.
So I tried to speed up the drawing a little bit and came up
with the following patches. I've used a little "benchmark"
in Forth to see how the patches improve the drawing:
1 buffer: etest-buf
41 etest-buf c!
1b emit 5b emit [char] H emit
20 0 do 3a 0 do etest-buf 1 terminal-write drop loop cr loop
." Duration: " .d ." ms" cr
Without my patches, the etest function takes 1.8 s to draw.
With the first patch applied, the function take ca. 1.2 s.
With both patches applied, the function only takes ca. 0.8 s !
The first patch changes invert-region to use a bigger
access width if possible. And the second patch simply
decreases the size of the cursor from a full-character
size rectangle to an underscore-like cursor instead...
not sure whether this is acceptable, but at least I
think it looks as good as the original cursor.
Apart from my patches, I think grub2 should also disable
the cursor when redrawing a whole line in the editor.
However, I do not have much clue about the grub2 sources
yet ... is anybody familiar with this and could give some
Thomas Huth (2):
fbuffer: Improve invert-region helper
fbuffer: Use a smaller cursor
board-js2x/slof/helper.fs | 13 ++++++++-----
board-qemu/slof/helper.fs | 14 ++++++++++----
slof/fs/fbuffer.fs | 5 +++--
3 files changed, 21 insertions(+), 11 deletions(-)
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