Re: [PATCH libdrm] tests: fix MAKE_RGBA macro for 10bpp modes

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Thu, Nov 23, 2017 at 01:59:28PM -0500, Ilia Mirkin wrote:
> We need to shift the values up, otherwise we'd end up with a negative
> shift. This works for up-to 16-bit components, which is fine for now.

Shouldn't we actually replicate the high bits in the low bits?

> 
> Signed-off-by: Ilia Mirkin <imirkin@alum.mit.edu>
> ---
>  tests/util/pattern.c | 14 ++++++++++----
>  1 file changed, 10 insertions(+), 4 deletions(-)
> 
> diff --git a/tests/util/pattern.c b/tests/util/pattern.c
> index 41fb541b..2f9bb384 100644
> --- a/tests/util/pattern.c
> +++ b/tests/util/pattern.c
> @@ -64,11 +64,17 @@ struct color_yuv {
>  	  .u = MAKE_YUV_601_U(r, g, b), \
>  	  .v = MAKE_YUV_601_V(r, g, b) }
>  
> +static inline uint32_t shiftcolor(const struct util_color_component *comp,
> +				  uint32_t value)
> +{
> +	return ((value << 8) >> (16 - comp->length)) << comp->offset;
> +}
> +
>  #define MAKE_RGBA(rgb, r, g, b, a) \
> -	((((r) >> (8 - (rgb)->red.length)) << (rgb)->red.offset) | \
> -	 (((g) >> (8 - (rgb)->green.length)) << (rgb)->green.offset) | \
> -	 (((b) >> (8 - (rgb)->blue.length)) << (rgb)->blue.offset) | \
> -	 (((a) >> (8 - (rgb)->alpha.length)) << (rgb)->alpha.offset))
> +	(shiftcolor(&(rgb)->red, (r)) | \
> +	 shiftcolor(&(rgb)->green, (g)) | \
> +	 shiftcolor(&(rgb)->blue, (b)) | \
> +	 shiftcolor(&(rgb)->alpha, (a)))
>  
>  #define MAKE_RGB24(rgb, r, g, b) \
>  	{ .value = MAKE_RGBA(rgb, r, g, b, 0) }
> -- 
> 2.13.6
> 
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-- 
Ville Syrjälä
Intel OTC
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