[Mesa-dev] [PATCH 7.5/20] i965/fs: Import code to transform image coordinates into surface coordinates.

[Jason Ekstrand]

On Thu, Jul 23, 2015 at 10:33 AM, Francisco Jerez <currojerez at riseup.net> wrote:
> Accounting for the padding required for 1D arrays in certain cases.
> ---
>  .../drivers/dri/i965/brw_fs_surface_builder.cpp    | 52 ++++++++++++++++++++++
>  1 file changed, 52 insertions(+)
>
> diff --git a/src/mesa/drivers/dri/i965/brw_fs_surface_builder.cpp b/src/mesa/drivers/dri/i965/brw_fs_surface_builder.cpp
> index 0c879db..e6a3115 100644
> --- a/src/mesa/drivers/dri/i965/brw_fs_surface_builder.cpp
> +++ b/src/mesa/drivers/dri/i965/brw_fs_surface_builder.cpp
> @@ -218,6 +218,58 @@ namespace {
>
>     namespace image_coordinates {
>        /**
> +       * Return the total number of coordinates needed to address a texel of
> +       * the surface, which may be more than the sum of \p surf_dims and \p
> +       * arr_dims if padding is required.
> +       */
> +      unsigned
> +      num_image_coordinates(const fs_builder &bld,
> +                            unsigned surf_dims, unsigned arr_dims,
> +                            mesa_format format)
> +      {
> +         /* HSW in vec4 mode and our software coordinate handling for untyped
> +          * reads want the array index to be at the Z component.
> +          */
> +         const bool array_index_at_z =
> +            !image_format_info::has_matching_typed_format(
> +               bld.shader->devinfo, format);
> +         const unsigned zero_dims =
> +            (surf_dims == 1 && arr_dims == 1 && array_index_at_z ? 1 : 0);

Would you mind putting parens around the three equalities.  I don't
want to have to think about whether "&&" or "? :" comes first in
precedence order.  Other than that,

Reviewed-by: Jason Ekstrand <jason.ekstrand at intel.com>

> +
> +         return surf_dims + zero_dims + arr_dims;
> +      }
> +
> +      /**
> +       * Transform image coordinates into the form expected by the
> +       * implementation.
> +       */
> +      fs_reg
> +      emit_image_coordinates(const fs_builder &bld, const fs_reg &addr,
> +                             unsigned surf_dims, unsigned arr_dims,
> +                             mesa_format format)
> +      {
> +         const unsigned dims =
> +            num_image_coordinates(bld, surf_dims, arr_dims, format);
> +
> +         if (dims > surf_dims + arr_dims) {
> +            assert(surf_dims == 1 && arr_dims == 1 && dims == 3);
> +            /* The array index is required to be passed in as the Z component,
> +             * insert a zero at the Y component to shift it to the right
> +             * position.
> +             *
> +             * FINISHME: Factor out this frequently recurring pattern into a
> +             * helper function.
> +             */
> +            const fs_reg srcs[] = { addr, fs_reg(0), offset(addr, bld, 1) };
> +            const fs_reg dst = bld.vgrf(addr.type, dims);
> +            bld.LOAD_PAYLOAD(dst, srcs, dims, 0);
> +            return dst;
> +         } else {
> +            return addr;
> +         }
> +      }
> +
> +      /**
>         * Calculate the offset in memory of the texel given by \p coord.
>         *
>         * This is meant to be used with untyped surface messages to access a
> --
> 2.4.3
>