On Wed, 22 Feb 2017, SIMRAN SINGHAL wrote:
>
>
> On Wednesday, February 22, 2017 at 2:57:17 PM UTC+5:30, Julia Lawall wrote:
> > @@ -117,7 +118,7 @@ static int alloc_dbr(u16 size)
> > return DBR_SIZE; /* out of memory */
> >
> > for (i = 0; i < DBR_MAP_SIZE; i++) {
> > - u32 const blocks = (size + DBR_BLOCK_SIZE -
> 1) / DBR_BLOCK_SIZE;
> > + u32 const blocks = DIV_ROUND_UP(size,
> DBR_BLOCK_SIZE);
> > u32 mask = ~((~(u32)0) << blocks);
>
> Totally unrelated to DIV_ROUND_UP, would this code be a
> candidate for
> GENMASK?
>
>
> Not sure, what you are trying to say.
There was a discussion on the list recently about GENMASK, which allows to
create a mask containing a sequence of 1s, like 000011110000. It looks
like that is what is being done here, because ~0 is 11111111 and then it
ie being shifted left and all the bits inverted. But Joe had another
suggestion. One could double check that his suggestion gives the right
result.
julia
>
>
>
> julia
>
> >
> > do {
> > @@ -137,7 +138,7 @@ static int alloc_dbr(u16 size)
> > static void free_dbr(int offs, int size)
> > {
> > int block_idx = offs / DBR_BLOCK_SIZE;
> > - u32 const blocks = (size + DBR_BLOCK_SIZE - 1) /
> DBR_BLOCK_SIZE;
> > + u32 const blocks = DIV_ROUND_UP(size,
> DBR_BLOCK_SIZE);
> > u32 mask = ~((~(u32)0) << blocks);
> >
> > mask <<= block_idx % 32;
> > --
> > 2.7.4
> >
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