[PATCH 1/5] wined3d: Use a bitmask for the {v, p}s_const_f fields in struct wined3d_saved_states.

[Matteo Bruni]

On Tue, Feb 11, 2020 at 5:33 PM Henri Verbeet <hverbeet at gmail.com> wrote:
>
> On Mon, 10 Feb 2020 at 23:06, Matteo Bruni <mbruni at codeweavers.com> wrote:
> > +static void wined3d_bitmask_set_bits(DWORD *bitmask, unsigned int offset, unsigned int count)
> > +{
> > +    const unsigned int word_bit_count = sizeof(*bitmask) * CHAR_BIT;
> > +    const unsigned int shift = offset % word_bit_count;
> > +
> > +    bitmask += offset / word_bit_count;
> > +    *bitmask |= ~0u >> (word_bit_count - min(count, word_bit_count)) << shift;
> > +    ++bitmask;
> > +    count -= min(count, word_bit_count - shift);
> > +    if (!count)
> > +        return;
> > +    if (count >= word_bit_count)
> > +    {
> > +        memset(bitmask, 0xffu, count / CHAR_BIT);
> > +        bitmask += count / word_bit_count;
> > +        count = count % word_bit_count;
> > +        if (!count)
> > +            return;
> > +    }
> > +    *bitmask |= (1u << count) - 1;
> > +}
> Does this intentionally not handle 0 count? I also suspect this has
> some room for simplification.

I wrote this patch a long time ago and looked through it so many times
that it's hard for me to see problems. That's where review helps I
guess :)
I think I intentionally don't handle 0 count, I guess I could add an
assert() at least. WRT simplification, this was originally written
when I was looking into a game that sets most (or all) the float
constants in one go so it somewhat reflects that (e.g. I think I
started from the memset() part and then tacked the rest around it
afterwards). I'll try to simplify it but I might ask for more specific
suggestions if I can't find anything substantial...