On 2014-02-06 16:21:49 +0100, Diego Biurrun wrote:
> On Thu, Feb 06, 2014 at 12:40:51AM +0000, Christophe Gisquet wrote:
> > --- /dev/null
> > +++ b/libavcodec/x86/dca.h
> > @@ -0,0 +1,56 @@
> > +/*
> > + * Copyright (c) 2012 Christophe Gisquet <christophe.gisq...@gmail.com>
>
> Happy new year?
>
> > +#if HAVE_SSE2_INLINE
> > +# include "libavutil/x86/asm.h"
> > +# include "libavutil/mem.h"
> > +
> > +#undef int8x8_fmul_int32
> > +static inline void int8x8_fmul_int32(float *dst, const int8_t *src, int
> > scale)
> > +{
> > + DECLARE_ALIGNED(16, static const uint32_t, inverse16) = 0x3D800000;
> > + __asm__ volatile (
> > + "cvtsi2ss %2, %%xmm0 \n\t"
> > + "mulss %3, %%xmm0 \n\t"
> > +# if HAVE_SSE4_INLINE
> > + "pmovsxbd 0(%1), %%xmm1 \n\t"
> > + "pmovsxbd 4(%1), %%xmm2 \n\t"
> > +# else
> > + "movq (%1), %%xmm1 \n\t"
> > + "punpcklbw %%xmm1, %%xmm1 \n\t"
> > + "movaps %%xmm1, %%xmm2 \n\t"
> > + "punpcklwd %%xmm1, %%xmm1 \n\t"
> > + "punpckhwd %%xmm2, %%xmm2 \n\t"
> > + "psrad $24, %%xmm1 \n\t"
> > + "psrad $24, %%xmm2 \n\t"
> > +# endif
> > + "shufps $0, %%xmm0, %%xmm0 \n\t"
> > + "cvtdq2ps %%xmm1, %%xmm1 \n\t"
> > + "cvtdq2ps %%xmm2, %%xmm2 \n\t"
> > + "mulps %%xmm0, %%xmm1 \n\t"
> > + "mulps %%xmm0, %%xmm2 \n\t"
> > + "movaps %%xmm1, 0(%0) \n\t"
> > + "movaps %%xmm2, 16(%0) \n\t"
> > + :: "r"(dst), "r"(src), "m"(scale), "m"(inverse16)
> > + XMM_CLOBBERS_ONLY("xmm0", "xmm1", "xmm2")
> > + );
> > +}
> > +#define int8x8_fmul_int32(dsp) int8x8_fmul_int32
> > +#endif /* HAVE_SSE2_INLINE */
>
> Does this have to be inline assembly?
The function is very short so the function call overhead becomes
significant. 34 vs. 39 cycles on a cortex-a9, i.e. the inline version
is over 10% faster.
Janne
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