[SeaBIOS] introduce a patch to enhance seabios splash picture showing ability

[Wayne Xia]

Hello, guys,
    Sorry to take u time again. I made a patch for sea-bios, want to let
the bios show a logo picture when KVM start. The reason and details for
this patch is described below, which was sent in a mail a few days before:


Patch description:
******************************************************
    There is suggestion to let KVM be able to show a logo when it start
up. Although the sea-bios already included a mechanism to show
"bootsplash.jpg" when it was configured with "menu=on" option, it would
not show it when the system was normally boot up, so I would like
do some modification in the sea-bios code to let the bios showing it
without "menu" option, also make this function configurable by the emulator.
    I tried the tiny jpeg decoder originally included, it seems there
will be some observable visual quality lose and if the VESA is in 24BPP
mode, the picture data would not be copied correctly for the reason that
the byte number per line of that mode is not equal to 3*width, So I
would like add some function to fix this, and also added some function
to show 24bpp BMP file instead of JPEG as an option to get better visual
effect.

    Following is what I did in details:
    1 in the "boot.c", function "interactive_bootmenu", add codes to
"romfile_loadfile" the "bootsplash.cfg" file. From it, the seabios get
two configuration data : first is whether it should show the picture
without menu enabled, second is how long it should show it. if this file
loading failed, the sea-bios would act as before.
    2 in the "bootsplash.c", function "enable_bootsplash(void)", add
codes to try "romfile_loadfile" the "bootsplash.bmp", besides
"bootsplash.jpg". Add a function to fix the problem when Bytes per line
of VESA mode is not equal to picture width * 3. Also add additional code
to show the BMP file instead of JPEG.
    3 ADD "bmp.c" and "bmp.h" to support above code.
*****************************************************

    I didn't found the maintainer of seabios, could anyone help review
about it, or help notice the maintainer? Many thanks.


-- 
Best Regards

Wayne Xia
mail:xiawenc at cn.ibm.com
tel:86-010-82450803