[U-Boot] [PATCH] lcd: align bmp header when uncopmressing image

[Wolfgang Denk]

Dear Piotr Wilczek,

In message <000701ce6025$173886c0$45a99440$%wilczek at samsung.com> you wrote:
>
> > > +	/* align to 32-bit-aligned-address + 2 */
> > > +	if ((unsigned int)bmp % 0x04 != 0x02)
> > > +		bmp = (bmp_image_t *)(((unsigned int)dst + 0x02) & ~0x01);
> > 
> > This is wrong. Suppose that bmp % 4 == 3, then (dst + 2) % 4 == 1, and
> > thus ((dst + 2) & ~1) % 4 == 0, which is not an aligned+2 address.
> > 
> You are right but here I'm aligning a pointer returned by malloc which is
> guaranteed to be aligned to 8 bytes. In fact it is sufficient only to add
> two bytes.

Such assumptions are black magic at best.

Please always consider the mentalk welfare of your follow programmers
who for example might change this into a character array (say, a
buffer on the stack) and suddenly experience mysetrious crashes.

Please always write code such that it is NOT based on non-obvious
requirements.

> Anyway, to make the code universal I provide a better alignment method.

Thanks.

Best regards,

Wolfgang Denk

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