On Fri, Jan 26, 2018 at 05:59:34PM -0800, Jason Ekstrand wrote:
> ---
> src/intel/isl/isl.c | 30 ++++++++++++++++++++++++++++++
> src/intel/isl/isl.h | 2 ++
> 2 files changed, 32 insertions(+)
>
> diff --git a/src/intel/isl/isl.c b/src/intel/isl/isl.c
> index a2d3ae6..420d387 100644
> --- a/src/intel/isl/isl.c
> +++ b/src/intel/isl/isl.c
> @@ -2379,3 +2379,33 @@ isl_swizzle_compose(struct isl_swizzle first, struct
> isl_swizzle second)
> .a = swizzle_select(first.a, second),
> };
> }
> +
> +/**
> + * Returns a swizzle that is the pseudo-inverse of this swizzle.
> + */
> +struct isl_swizzle
> +isl_swizzle_invert(struct isl_swizzle swizzle)
> +{
> + /* Default to zero for channels which do not show up in the swizzle */
> + enum isl_channel_select chans[4] = {
> + ISL_CHANNEL_SELECT_ZERO,
> + ISL_CHANNEL_SELECT_ZERO,
> + ISL_CHANNEL_SELECT_ZERO,
> + ISL_CHANNEL_SELECT_ZERO,
> + };
> +
> + /* We go in ABGR order so that, if there are any duplicates, the first one
> + * is taken if you look at it in RGBA order. This is what Haswell
> hardware
> + * does for render target swizzles.
> + */
> + if ((unsigned)(swizzle.a - ISL_CHANNEL_SELECT_RED) < 4)
> + chans[swizzle.a - ISL_CHANNEL_SELECT_RED] = ISL_CHANNEL_SELECT_ALPHA;
> + if ((unsigned)(swizzle.b - ISL_CHANNEL_SELECT_RED) < 4)
> + chans[swizzle.b - ISL_CHANNEL_SELECT_RED] = ISL_CHANNEL_SELECT_BLUE;
> + if ((unsigned)(swizzle.g - ISL_CHANNEL_SELECT_RED) < 4)
> + chans[swizzle.g - ISL_CHANNEL_SELECT_RED] = ISL_CHANNEL_SELECT_GREEN;
> + if ((unsigned)(swizzle.r - ISL_CHANNEL_SELECT_RED) < 4)
> + chans[swizzle.r - ISL_CHANNEL_SELECT_RED] = ISL_CHANNEL_SELECT_RED;
> +
> + return (struct isl_swizzle) { chans[0], chans[1], chans[2], chans[3] };
If given
swizzle == { ISL_CHANNEL_SELECT_RED,
ISL_CHANNEL_SELECT_GREEN,
ISL_CHANNEL_SELECT_BLUE,
ISL_CHANNEL_SELECT_ALPHA },
then
chans[ISL_CHANNEL_SELECT_ALPHA - ISL_CHANNEL_SELECT_RED] == chans[3] ==
ISL_CHANNEL_SELECT_ALPHA
and so on, and the function returns the same swizzle as given?
> +}
> diff --git a/src/intel/isl/isl.h b/src/intel/isl/isl.h
> index da29baa..16412fc 100644
> --- a/src/intel/isl/isl.h
> +++ b/src/intel/isl/isl.h
> @@ -1686,6 +1686,8 @@ isl_swizzle_supports_rendering(const struct
> gen_device_info *devinfo,
>
> struct isl_swizzle
> isl_swizzle_compose(struct isl_swizzle first, struct isl_swizzle second);
> +struct isl_swizzle
> +isl_swizzle_invert(struct isl_swizzle swizzle);
>
> #define isl_surf_init(dev, surf, ...) \
> isl_surf_init_s((dev), (surf), \
> --
> 2.5.0.400.gff86faf
>
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