Re: [PATCH 3/5] wined3d: Optimize scanning changed shader constants in wined3d_device_apply_stateblock().

[Henri Verbeet]

On Mon, 10 Feb 2020 at 23:06, Matteo Bruni  wrote:
> +typedef HRESULT (CDECL *wined3d_device_shader_constant_setter)(struct wined3d_device *device,
> -
>    unsigned int start_idx, unsigned int count, const void *constants);
> -
>
> +static void device_apply_shader_constants(struct wined3d_device *device,
> -
>    const struct wined3d_stateblock_state *state,
> -
>    DWORD *bitmap, unsigned int bit_count, const void *data, unsigned int stride,
> -
>    wined3d_device_shader_constant_setter shader_constant_setter)
>
> +{
> - const unsigned int word_bit_count = sizeof(DWORD) * CHAR_BIT;
> - unsigned int i, j, idx, start, last;
> - const BYTE *byte_data = data;
> - DWORD map;
> -
> - start = last = ~0u;
> - for (i = 0; i < (bit_count + word_bit_count - 1) / word_bit_count; ++i)
> - {
> -
>    map = bitmap[i];
> -
> -
>    if (map == ~0u)
> -
>    {
> -
>        if (last != ~0u && last != i * word_bit_count - 1)
> -
>        {
> -
>            shader_constant_setter(device, start, last - start + 1, &byte_data[start * stride]);
> -
>            start = i * word_bit_count;
> -
>        }
> -
>        if (start == ~0u)
> -
>            start = i * word_bit_count;
> -
>        last = i * word_bit_count + word_bit_count - 1;
> -
>        continue;
> -
>    }
> -
>    while (map)
> -
>    {
> -
>        j = wined3d_bit_scan(&map);
> -
>        idx = i * word_bit_count + j;
> -
> -
>        if (start == ~0u)
> -
>        {
> -
>            start = last = idx;
> -
>        }
> -
>        else if (last != idx - 1)
> -
>        {
> -
>            shader_constant_setter(device, start, last - start + 1, &byte_data[start * stride]);
> -
>            start = last = idx;
> -
>        }
> -
>        else
> -
>        {
> -
>            last = idx;
> -
>        }
> -
>    }
> - }
> - if (start != ~0u)
> -
>    shader_constant_setter(device, start, last - start + 1, &byte_data[start * stride]);
>
> +}
> -

This looks like it's a fair bit more complicated than it needs to be.
I think the primitives you want are something like the following:

unsigned int wined3d_bitmap_ffs(uint32_t *bitmap, unsigned int
start, unsigned int count);
    unsigned int wined3d_bitmap_ffz(uint32_t *bitmap, unsigned int
start, unsigned int count);

and then you can extract the ranges relatively trivially.