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opus_pvq_search: only use rsqrtps approximation on CPUs with avx

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Makes the search produce idential results with the C version.

Signed-off-by: Rostislav Pehlivanov <atomnuker@gmail.com>
This commit is contained in:
Rostislav Pehlivanov 2017-08-18 17:28:40 +01:00
parent 8e53cd1fab
commit f386dd70ac
1 changed files with 6 additions and 12 deletions
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18
libavcodec/x86/opus_pvq_search.asm
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@ -28,12 +28,6 @@
ALIGNMODE p6
%endif
; Use float op that give half precision but execute for around 3 cycles.
; On Skylake & Ryzen the division is much faster (around 11c/3),
; that makes the full precision code about 2% slower.
; Opus also does use rsqrt approximation in their intrinsics code.
%define USE_APPROXIMATION 1
SECTION_RODATA 64
const_float_abs_mask: times 8 dd 0x7fffffff
@ -102,17 +96,17 @@ align 16
movaps m4, [tmpY + r4] ; y[i]
movaps m5, [tmpX + r4] ; X[i]
%if USE_APPROXIMATION == 1
%if !cpuflag(avx) ; for crappy ancient CPUs that have slow packed divs but fast 1/sqrt
xorps m0, m0
cmpps m0, m0, m5, 4 ; m0 = (X[i] != 0.0)
%endif
%endif
addps m4, m6 ; m4 = Syy_new = y[i] + Syy_norm
addps m5, m7 ; m5 = Sxy_new = X[i] + Sxy_norm
%if USE_APPROXIMATION == 1
%if !cpuflag(avx)
andps m5, m0 ; if(X[i] == 0) Sxy_new = 0; Prevent aproximation error from setting pulses in array padding.
%endif
%endif
%else
movaps m5, [tmpY + r4] ; m5 = y[i]
@ -125,7 +119,7 @@ align 16
andps m5, m0 ; (0<y)?m5:0
%endif
%if USE_APPROXIMATION == 1
%if !cpuflag(avx)
rsqrtps m4, m4
mulps m5, m4 ; m5 = p = Sxy_new*approx(1/sqrt(Syy) )
%else
@ -261,7 +255,7 @@ align 16
jz %%zero_input ; if (Sx==0) goto zero_input
cvtsi2ss xm0, dword Kd ; m0 = K
%if USE_APPROXIMATION == 1
%if !cpuflag(avx)
rcpss xm1, xm1 ; m1 = approx(1/Sx)
mulss xm0, xm1 ; m0 = K*(1/Sx)
%else