You may be interested in the implementation in gallium/aux/util/u_math.h:
/**
* Returns the smallest power of two >= x
*/
static inline unsigned
util_next_power_of_two(unsigned x)
{
#if defined(HAVE___BUILTIN_CLZ)
if (x <= 1)
return 1;
return (1 << ((sizeof(unsigned) * 8) - __builtin_clz(x - 1)));
#else
I believe that ends up in fewer operations. Your call.
-ilia
On Wed, Aug 24, 2016 at 5:37 AM, Lionel Landwerlin
<llandwer...@gmail.com> wrote:
> A few inline asserts in anv assume alignments are power of 2, but with
> formats like R8G8B8 we have odd alignments.
>
> v2: round up to power of 2 (Ilia)
>
> Signed-off-by: Lionel Landwerlin <lionel.g.landwer...@intel.com>
> Cc: Ilia Mirkin <imir...@alum.mit.edu>
> Cc: Jason Ekstrand <ja...@jlekstrand.net>
> ---
> src/intel/isl/isl.c | 1 +
> src/intel/isl/isl_priv.h | 10 ++++++++++
> 2 files changed, 11 insertions(+)
>
> diff --git a/src/intel/isl/isl.c b/src/intel/isl/isl.c
> index 18e95e2..ae7b9af 100644
> --- a/src/intel/isl/isl.c
> +++ b/src/intel/isl/isl.c
> @@ -1182,6 +1182,7 @@ isl_surf_init_s(const struct isl_device *dev,
> base_alignment = MAX(base_alignment, fmtl->bpb / 8);
> }
> }
> + base_alignment = isl_round_up_to_power_of_two(base_alignment);
> } else {
> assert(phys_slice0_sa.w % fmtl->bw == 0);
> const uint32_t total_w_el = phys_slice0_sa.width / fmtl->bw;
> diff --git a/src/intel/isl/isl_priv.h b/src/intel/isl/isl_priv.h
> index 3a7af1a..19b5176 100644
> --- a/src/intel/isl/isl_priv.h
> +++ b/src/intel/isl/isl_priv.h
> @@ -99,6 +99,16 @@ isl_log2u(uint32_t n)
> }
>
> static inline uint32_t
> +isl_round_up_to_power_of_two(uint32_t value)
> +{
> + uint32_t r = 1 << isl_log2u(value);
> +
> + if ((~r & value) != 0)
> + return r << 1;
> + return r;
> +}
> +
> +static inline uint32_t
> isl_minify(uint32_t n, uint32_t levels)
> {
> if (unlikely(n == 0))
> --
> 2.9.3
>
_______________________________________________
mesa-dev mailing list
mesa-dev@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/mesa-dev
