[U-Boot] [PATCH 04/13] sparse: Simplify multiple logic

[Maxime Ripard <maxime.ripard@free-electrons.com>]

On Fri, Sep 04, 2015 at 01:20:38PM -0400, Tom Rini wrote:
> On Mon, Aug 31, 2015 at 04:46:04PM +0200, Maxime Ripard wrote:
> 
> > To check the alignment of the image blocks to the storage blocks, the
> > current code uses a convoluted syntax, while a simple mod also does the
> > work.
> > 
> > Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
> > ---
> >  common/aboot.c | 3 +--
> >  1 file changed, 1 insertion(+), 2 deletions(-)
> > 
> > diff --git a/common/aboot.c b/common/aboot.c
> > index 65e633acfcb9..c8556d9b23f4 100644
> > --- a/common/aboot.c
> > +++ b/common/aboot.c
> > @@ -269,8 +269,7 @@ void write_sparse_image(block_dev_desc_t *dev_desc,
> >  	}
> >  
> >  	/* verify sparse_header->blk_sz is an exact multiple of info->blksz */
> > -	if (sparse_header->blk_sz !=
> > -	    (sparse_header->blk_sz & ~(info->blksz - 1))) {
> > +	if (sparse_header->blk_sz % info->blksz) {
> 
> So, sometimes we have convoluted syntax like this to avoid what ends up
> as floating point math on 32bit platforms.

Now that you speak of this, we did have some compilers on some
platforms that ended up generating floating point related failures on
our branch, but I didn't have the time to look into it.

However, I don't really know how we can end up with floating point
math with a mod, is this some optimisations done by gcc?

> Maybe this needs to be one of the helpers in include/linux/math64.h?

Probably then, yes.

Thanks!
Maxime


-- 
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com
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