[x264-devel] commit: Spare a vec_perm and a vec_mergeh though using a LUT of permutation vectors . (Guillaume Poirier )

[Guillaume POIRIER]

Hello,

On Tue, Feb 10, 2009 at 4:37 PM,  <maaanuuu at gmx.net> wrote:
> Hello,
>
> the output of this version differs slightly from earlier ones.

How can this be? What did I miss?


>> +        CV(0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,  /*
>> pix=mod16, i_stride=mod8  */
>> +           0x18, 0x19, 0x1A, 0x1B, 0x1C, 0x1D, 0x1E, 0x1F),
>> +    };
>
> isn't i_stride always mod16 now? Then the permutation vector should be

What I understood is that pix was always mod16 now.


> CV(0x08, 0x09, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F,
>        0x18, 0x19, 0x1A, 0x1B, 0x1C, 0x1D, 0x1E, 0x1F)
>
>
>> +    vec_u8_t perm = perm_tab[ ((i_stride & 8) >> 3) ];
>
> I think ((i_stride & 8) >> 3) has no effect, the index depends on pix
> being mod16 or mod8, or am I wrong?

Please run some experiments and submit a patch with a test case that
shows the problem (if you don't mind of course).

Guillaume
-- 
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