2019-03-23 15:23 GMT+01:00, Lynne <d...@lynne.ee>:
> 16 Mar 2019, 16:34 by d...@lynne.ee:
>
>> 153372 UNITS in postfilter_c, 65536 runs, 0 skips
>> 73164 UNITS in postfilter_neon, 65536 runs, 0 skips -> 2.1x speedup
>>
>> 80591 UNITS in deemphasis_c, 131072 runs, 0 skips
>> 43969 UNITS in deemphasis_neon, 131072 runs, 0 skips -> 1.83x
>> speedup
>>
>> Total decoder speedup: ~15% on a Raspberry Pi 3 (from 28.1x to 33.5x
>> realtime)
>>
>> Deemphasis SIMD based on the following unrolling:
>> const float c1 = CELT_EMPH_COEFF, c2 = c1*c1, c3 = c2*c1, c4 = c3*c1;
>> float state = coeff;
>>
>> for (int i = 0; i < len; i += 4) {
>> y[0] = x[0] + c1*state;
>> y[1] = x[1] + c2*state + c1*x[0];
>> y[2] = x[2] + c3*state + c1*x[1] + c2*x[0];
>> y[3] = x[3] + c4*state + c1*x[2] + c2*x[1] + c3*x[0];
>>
>> state = y[3];
>> y += 4;
>> x += 4;
>> }
>>
>> Unlike the x86 version, duplication is used instead of pslldq so
>> the structure and tables are different.
>> Same approach tested on x86 (3x pslldq -> vbroadcastss + shufps + pslldq)
>> had the same performance, so 3x pslldq was kept as vbroadcastss has a
>> higher latency.
>
> Could someone review the patches?
Which toolchains did you test?
(For compilation, not performance.)
Carl Eugen
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