[Mesa-dev] [PATCH] gallium/util: add comment on util_is_format_compatible()

[Nicolai Hähnle]

Reviewed-by: Nicolai Hähnle <nicolai.haehnle at amd.com>

On 21.09.2016 17:25, Brian Paul wrote:
> From reading the code, it's not obvious what is src/dest compatible.
> The list of a->b copy-compatible formats comes from Jose's original
> check-in message, with some format name updates.
> ---
>  src/gallium/auxiliary/util/u_format.c | 24 ++++++++++++++++++++++++
>  1 file changed, 24 insertions(+)
>
> diff --git a/src/gallium/auxiliary/util/u_format.c b/src/gallium/auxiliary/util/u_format.c
> index cbdb5ce..8881618 100644
> --- a/src/gallium/auxiliary/util/u_format.c
> +++ b/src/gallium/auxiliary/util/u_format.c
> @@ -457,6 +457,30 @@ util_format_write_4i(enum pipe_format format,
>     format_desc->pack_rgba_sint(dst_row, dst_stride, src_row, src_stride, w, h);
>  }
>
> +/**
> + * Check if we can safely memcopy from the source format to the dest format.
> + * This basically covers the cases of a "used" channel copied to a typeless
> + * channel, plus some 1-channel cases.
> + * Examples of compatiblie copy formats include:
> + *    b8g8r8a8_unorm -> b8g8r8x8_unorm
> + *    a8r8g8b8_unorm -> x8r8g8b8_unorm
> + *    b5g5r5a1_unorm -> b5g5r5x1_unorm
> + *    b4g4r4a4_unorm -> b4g4r4x4_unorm
> + *    l8_unorm -> r8_unorm
> + *    i8_unorm -> l8_unorm
> + *    i8_unorm -> a8_unorm
> + *    i8_unorm -> r8_unorm
> + *    l16_unorm -> r16_unorm
> + *    z24_unorm_s8_uint -> z24x8_unorm
> + *    s8_uint_z24_unorm -> x8z24_unorm
> + *    r8g8b8a8_unorm -> r8g8b8x8_unorm
> + *    a8b8g8r8_srgb -> x8b8g8r8_srgb
> + *    b8g8r8a8_srgb -> b8g8r8x8_srgb
> + *    a8r8g8b8_srgb -> x8r8g8b8_srgb
> + *    a8b8g8r8_unorm -> x8b8g8r8_unorm
> + *    r10g10b10a2_uscaled -> r10g10b10x2_uscaled
> + *    r10sg10sb10sa2u_norm -> r10g10b10x2_snorm
> + */
>  boolean
>  util_is_format_compatible(const struct util_format_description *src_desc,
>                            const struct util_format_description *dst_desc)
>