[SLOF] [PATCH v2 0/2] fbuffer: Improve the speed of the cursor drawing

[Alexey Kardashevskiy]

On 07/30/2015 10:56 PM, Thomas Huth wrote:
> 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
>   : etest
>     erase-screen
>     41 etest-buf c!
>     1b emit 5b emit [char] H emit
>     cursor-on
>     milliseconds
>      20 0 do 3a 0 do etest-buf 1 terminal-write drop loop cr loop
>     milliseconds
>     swap -
>     ." 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.
>
>
> Changes:
>
> v2:
> - Small optimization in the first patch with "3 and" according
>    to the suggestion of Segher
> - Decreased the size of the cursor to 2 lines instead of 3 in
>    the second patch - IMHO still looks fine and saves some more
>    few precious cycles.


Thanks, applied.

>
>
> 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(-)
>


-- 
Alexey