[Ffmpeg-devel] [PATCH] SSE counterpart of ff_imdct_calc_3dn2

[Loren Merritt]

On Thu, 24 Aug 2006, Luca Barbato wrote:

> Zuxy Meng wrote:
>
>> +    z += n8;
>
>[...]
>> +    for(k = 0; k < n8; k += 2) {
>[...]
>> +        asm (
>> +            "movaps          %4, %%xmm0 \n\t"   // xmm0 = 0 1 2 3
>> +            "movaps          %5, %%xmm1 \n\t"   // xmm1 = 4 5 6 7
>[...]
>> +            :"m"(z[k]), "m"(z[-2 - k])
>
> I'm missing something or it could be unaligned?
> z is 8 byte not 16.

The array index is even. In order for n8 to be odd you'd need an 8 element 
fft. Nothing in ffmpeg does one that small, and the simd code would 
break for more reasons than just alignment.

--Loren Merritt