[U-Boot] [PATCH v3] Add 16bpp BMP support

[Wolfgang Denk]

Dear Mark Jackson,

In message <49817E75.7060907 at mimc.co.uk> you wrote:
> >> +			bmap += (padded_line - width) * 2;
> >> +			fb   -= (width * 2 + lcd_line_length);
> > 
> > Is it intentional that you reverse padded_line and width here, i.e.
> > you are sure it's not
> > 
> > 			bmap += (width - padded_line) * 2;
> > ?
> 
> The "bmap += ..." line is to step forward to the start of the next line of bmp 
> data, taking into account any padding bytes.
> 
> If I read the code correct, padded_line is defined as ...
> 
> 	padded_line = (width&0x3) ? ((width&~0x3)+4) : (width);
> 
> ... so it will always be >= width.  Correct ?
> 
> If so, then ...
> 
> 	bmap += (width - padded_line) * 2;
> 
> ... will be <= 0, and so will actually step bmap back into the data you've 
> just used, whereas ...
> 
> 	bmap += (padded_line - width) * 2;
> 
> ... will be >= 0, and will step forward to the start of the next line as required.
> 
> Or have I misunderstood the bmp format and the existing code ?

I don't know - I'm just asking because the 16 bpp case is different
from the 1 and 8 bpp cases where the operands are swapped.

Best regards,

Wolfgang Denk

-- 
DENX Software Engineering GmbH,     MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de
Genius doesn't work on an assembly line basis.  You can't simply say,
"Today I will be brilliant."
	-- Kirk, "The Ultimate Computer", stardate 4731.3