"Ronald S. Bultje" <[email protected]> writes:

> From: Anton Mitrofanov <[email protected]>
>
> ptrdiff_t can be 4 bytes, which leads to the next element being 4-byte
> aligned and thus at a different offset than intended. Forcing 8-byte
> alignment forces equal offset of dither16/32 on x86-32 and x86-64.
>
> Signed-off-by: Ronald S. Bultje <[email protected]>
> ---
>  libswscale/swscale_internal.h |    4 ++--
>  1 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/libswscale/swscale_internal.h b/libswscale/swscale_internal.h
> index b602541..a6d4a2f 100644
> --- a/libswscale/swscale_internal.h
> +++ b/libswscale/swscale_internal.h
> @@ -347,8 +347,8 @@ typedef struct SwsContext {
>      int32_t  alpMmxFilter[4*MAX_FILTER_SIZE];
>      DECLARE_ALIGNED(8, ptrdiff_t, uv_off_px);   ///< offset (in pixels) 
> between u and v planes
>      DECLARE_ALIGNED(8, ptrdiff_t, uv_off_byte); ///< offset (in bytes) 
> between u and v planes
> -    uint16_t dither16[8];
> -    uint32_t dither32[8];
> +    DECLARE_ALIGNED(8, uint16_t, dither16)[8];
> +    DECLARE_ALIGNED(8, uint32_t, dither32)[8];
>
>      const uint8_t *chrDither8, *lumDither8;
>
> -- 

Since the asm is inline, why not pass the offset using an operand with
"i" constraint instead of this?

If those fields really need 8-byte alignment for some other reason, the
commit message should state that instead or in addition.

-- 
Måns Rullgård
[email protected]
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