[FFmpeg-devel] [PATCH 06/10] avcodec/vc1: Arm 32-bit NEON deblocking filter fast paths

[Martin Storsjö]

On Fri, 25 Mar 2022, Lynne wrote:

> 25 Mar 2022, 19:52 by bavison at riscosopen.org:
>
>> +@ VC-1 in-loop deblocking filter for 4 pixel pairs at boundary of vertically-neighbouring blocks
>> +@ On entry:
>> +@   r0 -> top-left pel of lower block
>> +@   r1 = row stride, bytes
>> +@   r2 = PQUANT bitstream parameter
>> +function ff_vc1_v_loop_filter4_neon, export=1
>> +        sub             r3, r0, r1, lsl #2
>> +        vldr            d0, .Lcoeffs
>> +        vld1.32         {d1[0]}, [r0], r1       @ P5
>> +        vld1.32         {d2[0]}, [r3], r1       @ P1
>> +        vld1.32         {d3[0]}, [r3], r1       @ P2
>> +        vld1.32         {d4[0]}, [r0], r1       @ P6
>> +        vld1.32         {d5[0]}, [r3], r1       @ P3
>> +        vld1.32         {d6[0]}, [r0], r1       @ P7
>> +        vld1.32         {d7[0]}, [r3]           @ P4
>> +        vld1.32         {d16[0]}, [r0]          @ P8
>>
>
> Nice patches, but 2 notes so far:

Indeed, the first glance seems great so far, I haven't applied and poked 
them closer yet.

> What's with the weird comment syntax used only in this commit?

In 32 bit arm assembly, @ is a native assembler comment character, and 
lots of our existing 32 bit assembly uses that so far.

> Different indentation style used. We try to indent our Arm assembly to:
> <8 spaces><instruction><spaces until and column 24><instruction arguments>.

Hmm, I haven't applied this patch locally and checked yet, but at least 
from browsing just the patch, it seems to be quite correctly indented?

We already discussed this in the previous iteration of his patchset, and 
the cover letter mentioned that he had fixed it to match the convention 
now. (And even in the previous iteration, the 32 bit assembly matched the 
existing code.)

// Martin