[SLOF] [PATCH 2/4] fbuffer: Precalculate line length in bytes

[Nikunj A Dadhania]

Thomas Huth <thuth at redhat.com> writes:

> The framebuffer code calculates the length of a line in bytes over
> and over again, even in the tight innermost loops of the drawing
> functions. We can easily avoid this multiplication and make the
> code more readable by storing this value in a variable instead.
>
> Signed-off-by: Thomas Huth <thuth at redhat.com>

Reviewed-by: Nikunj A Dadhania <nikunj at linux.vnet.ibm.com>

> ---
>  slof/fs/fbuffer.fs | 25 ++++++++++++++-----------
>  1 file changed, 14 insertions(+), 11 deletions(-)
>
> diff --git a/slof/fs/fbuffer.fs b/slof/fs/fbuffer.fs
> index bfe7ebf..4704608 100644
> --- a/slof/fs/fbuffer.fs
> +++ b/slof/fs/fbuffer.fs
> @@ -19,6 +19,7 @@
>  0 VALUE screen-height
>  0 VALUE screen-width
>  0 VALUE screen-depth
> +0 VALUE screen-line-bytes
>  0 VALUE window-top
>  0 VALUE window-left
>
> @@ -54,10 +55,10 @@
>  : fb8-background inverse? ;
>  : fb8-foreground inverse? invert ;
>
> -: fb8-lines2bytes ( #lines -- #bytes ) char-height * screen-width * screen-depth * ;
> +: fb8-lines2bytes ( #lines -- #bytes ) char-height * screen-line-bytes * ;
>  : fb8-columns2bytes ( #columns -- #bytes ) char-width * screen-depth * ;
>  : fb8-line2addr ( line# -- addr )
> -	char-height * window-top + screen-width * screen-depth *
> +	char-height * window-top + screen-line-bytes *
>  	frame-buffer-adr + window-left screen-depth * +
>  ;
>
> @@ -98,10 +99,10 @@ CREATE bitmap-buffer 400 4 * allot
>
>  : fb8-toggle-cursor ( -- )
>  	line# fb8-line2addr column# fb8-columns2bytes +
> -	char-height 2 - screen-width screen-depth * * +
> +	char-height 2 - screen-line-bytes * +
>  	2 0 ?DO
>  		dup char-width screen-depth * invert-region
> -		screen-width screen-depth * +
> +		screen-line-bytes +
>  	LOOP drop
>  ;
>
> @@ -111,7 +112,7 @@ CREATE bitmap-buffer 400 4 * allot
>  	line# fb8-line2addr column# fb8-columns2bytes + ( bitmap-buf fb-addr )
>  	char-height 0 ?DO
>  		2dup char-width screen-depth * mrmove
> -		screen-width screen-depth * + >r char-width screen-depth * + r>
> +		screen-line-bytes + >r char-width screen-depth * + r>
>  	LOOP 2drop
>      ELSE 2drop r> 3drop THEN
>  ;
> @@ -136,12 +137,12 @@ CREATE bitmap-buffer 400 4 * allot
>  		fb8-columns2bytes swap fb8-columns2bytes tuck -
>  		over r@ tuck + rot char-height 0 ?DO
>  			3dup rmove
> -			-rot screen-width screen-depth * tuck + -rot + swap rot
> +			-rot screen-line-bytes tuck + -rot + swap rot
>  		LOOP
>  		3drop r>
>  	THEN
>  	char-height 0 ?DO
> -		dup 2 pick fb8-erase-block screen-width screen-depth * +
> +		dup 2 pick fb8-erase-block screen-line-bytes +
>  	LOOP
>  	2drop
>  ;
> @@ -154,12 +155,12 @@ CREATE bitmap-buffer 400 4 * allot
>  		fb8-columns2bytes swap fb8-columns2bytes tuck -
>  		over r@ + 2dup + r> swap >r rot char-height 0 ?DO
>  			3dup rmove
> -			-rot screen-width screen-depth * tuck + -rot + swap rot
> +			-rot screen-line-bytes tuck + -rot + swap rot
>  		LOOP
>  		3drop r> over -
>  	THEN
>  	char-height 0 ?DO
> -		dup 2 pick fb8-erase-block screen-width screen-depth * +
> +		dup 2 pick fb8-erase-block screen-line-bytes +
>  	LOOP
>  	2drop
>  ;
> @@ -167,11 +168,11 @@ CREATE bitmap-buffer 400 4 * allot
>  : fb8-reset-screen ( -- ) ( Left as no-op by design ) ;
>
>  : fb8-erase-screen ( -- )
> -	frame-buffer-adr screen-height screen-width * screen-depth * fb8-erase-block
> +	frame-buffer-adr screen-height screen-line-bytes * fb8-erase-block
>  ;
>
>  : fb8-invert-screen ( -- )
> -	frame-buffer-adr screen-height screen-width * screen-depth * invert-region
> +	frame-buffer-adr screen-height screen-line-bytes * invert-region
>  ;
>
>  : fb8-blink-screen ( -- ) fb8-invert-screen fb8-invert-screen ;
> @@ -179,6 +180,7 @@ CREATE bitmap-buffer 400 4 * allot
>  : fb8-install ( width height #columns #lines -- )
>  	1 to screen-depth
>  	2swap  to screen-height  to screen-width
> +	screen-width to screen-line-bytes
>  	screen-#rows min to #lines
>  	screen-#columns min to #columns
>  	screen-height char-height #lines * - 2/ to window-top
> @@ -200,6 +202,7 @@ CREATE bitmap-buffer 400 4 * allot
>  	>r
>  	fb8-install
>  	r> to screen-depth
> +	screen-width screen-depth * to screen-line-bytes
>  ;
>
>
> -- 
> 1.8.3.1