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Date: Tue, 26 Mar 2013 11:14:05 +0100
From: Paolo Bonzini <pbonzini@redhat.com>
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Subject: Re: [Qemu-devel] [PATCHv5 02/10] add a zero splat vector to
	qemu-common.h
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To: Peter Lieven <pl@kamp.de>
Cc: Orit Wasserman <owasserm@redhat.com>, Stefan Hajnoczi <stefanha@gmail.com>, qemu-devel@nongnu.org, quintela@redhat.com

Il 26/03/2013 10:58, Peter Lieven ha scritto:
> Signed-off-by: Peter Lieven <pl@kamp.de>
> ---
>  include/qemu-common.h |    3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/include/qemu-common.h b/include/qemu-common.h
> index d7ad3a7..9022646 100644
> --- a/include/qemu-common.h
> +++ b/include/qemu-common.h
> @@ -453,6 +453,7 @@ void hexdump(const char *buf, FILE *fp, const char *prefix, size_t size);
>  #include <altivec.h>
>  #define VECTYPE        vector unsigned char
>  #define SPLAT(p)       vec_splat(vec_ld(0, p), 0)
> +#define ZERO_SPLAT     vec_splat(vec_ld(0, 0), 0)
>  #define ALL_EQ(v1, v2) vec_all_eq(v1, v2)
>  /* altivec.h may redefine the bool macro as vector type.
>   * Reset it to POSIX semantics. */
> @@ -462,10 +463,12 @@ void hexdump(const char *buf, FILE *fp, const char *prefix, size_t size);
>  #include <emmintrin.h>
>  #define VECTYPE        __m128i
>  #define SPLAT(p)       _mm_set1_epi8(*(p))
> +#define ZERO_SPLAT     _mm_setzero_si128()
>  #define ALL_EQ(v1, v2) (_mm_movemask_epi8(_mm_cmpeq_epi8(v1, v2)) == 0xFFFF)
>  #else
>  #define VECTYPE        unsigned long
>  #define SPLAT(p)       (*(p) * (~0UL / 255))
> +#define ZERO_SPLAT     0x0UL
>  #define ALL_EQ(v1, v2) ((v1) == (v2))
>  #endif

C trivia of the day: this can be written simply as

   (VECTYPE) {0}

Yes, it works even with unsigned long. :)  It is a C99 compound literal.

Paolo