[FFmpeg-devel] [PATCH 1/2] lavu/intmath.h: Add msvc/icl ctzll optimisations.

[James Almer]

On 10/15/2015 11:07 AM, Matt Oliver wrote:
> This patch just adds the msvc and icl equivalent ctzll optimisations to
> correspond with the recently added gcc variant
> 
> 
> 0001-lavu-intmath.h-Add-msvc-icl-ctzll-optimisations.patch
> 
> 
> From 2b8e7757cdb8595181a01bb18756d60662c41fde Mon Sep 17 00:00:00 2001
> From: Matt Oliver <protogonoi at gmail.com>
> Date: Thu, 15 Oct 2015 19:42:31 +1100
> Subject: [PATCH 1/2] lavu/intmath.h: Add msvc/icl ctzll optimisations.
> 
> Signed-off-by: Matt Oliver <protogonoi at gmail.com>
> ---
>  libavutil/x86/intmath.h | 28 ++++++++++++++++++++++++++++
>  1 file changed, 28 insertions(+)
> 
> diff --git a/libavutil/x86/intmath.h b/libavutil/x86/intmath.h
> index fefad20..613903b 100644
> --- a/libavutil/x86/intmath.h
> +++ b/libavutil/x86/intmath.h
> @@ -60,6 +60,34 @@ static av_always_inline av_const unsigned av_mod_uintp2_bmi2(unsigned a, unsigne
>  
>  #endif /* __BMI2__ */
>  
> +#elif defined(_MSC_VER)

Don't use elif if this code is also supposed to work on icl. That compiler defines __GNUC__.

> +#define ff_ctzll ff_ctzll_c
> +static av_always_inline av_const int ff_ctzll_c(long long v)

nit: ff_ctzll_x86 for the inline version. And you need to check HAVE_INLINE_ASM for it as
well.

> +{
> +#if defined(__INTEL_COMPILER) 
> +#if ARCH_X86_64
> +    uint64_t c;
> +    __asm__("bsfq %1,%0" : "=r" (c) : "r" (v));
> +    return c;
> +#else
> +    return ((uint32_t)v == 0) ? _bit_scan_forward(((uint32_t *)&v)[1]) + 32 : _bit_scan_forward((uint32_t)v);

(uint32_t)(v >> 32)

> +#endif
> +#else
> +    unsigned long c;
> +#if ARCH_X86_64
> +    _BitScanForward64(&c, v);
> +#else
> +    if ((uint32_t)v == 0) {
> +        _BitScanForward(&c, ((uint32_t *)&v)[1]);

Same

> +        c += 32;
> +    } else {
> +        _BitScanForward(&c, (uint32_t)v);
> +    }
> +#endif
> +    return c;
> +#endif
> +}
> +
>  #endif /* __GNUC__ */
>  
>  #endif /* AVUTIL_X86_INTMATH_H */
> -- 1.9.5.github.0
> 
> 
> 
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