Re: [Qemu-devel] [PATCH] vmxnet: Don't use bswap_64 for constants

["Andreas Färber" <afaerber@suse.de>]

Am 27.03.2013 19:47, schrieb Richard Henderson:
> This macro is used in the context of defining enum values.
> We can't use a function call in that case.
> 
> Cc: qemu-trivial@nongnu.org
> Signed-off-by: Richard Henderson <rth@twiddle.net>
> ---
>  hw/vmxnet3.h | 10 +++++++++-
>  1 file changed, 9 insertions(+), 1 deletion(-)
> 
> diff --git a/hw/vmxnet3.h b/hw/vmxnet3.h
> index 7db0c8f..cd9ac85 100644
> --- a/hw/vmxnet3.h
> +++ b/hw/vmxnet3.h
> @@ -37,7 +37,15 @@
>  #define __packed QEMU_PACKED
>  
>  #if defined(HOST_WORDS_BIGENDIAN)
> -#define const_cpu_to_le64(x) bswap_64(x)
> +#define const_cpu_to_le64(x) \
> +        (((x & 0x00000000000000ffULL) << 56) | \
> +         ((x & 0x000000000000ff00ULL) << 40) | \
> +         ((x & 0x0000000000ff0000ULL) << 24) | \
> +         ((x & 0x00000000ff000000ULL) <<  8) | \
> +         ((x & 0x000000ff00000000ULL) >>  8) | \
> +         ((x & 0x0000ff0000000000ULL) >> 24) | \
> +         ((x & 0x00ff000000000000ULL) >> 40) | \
> +         ((x & 0xff00000000000000ULL) >> 56))

Being a macro, shouldn't this better use (x) for operator precedence?

Andreas

>  #define __BIG_ENDIAN_BITFIELD
>  #else
>  #define const_cpu_to_le64(x) (x)
> 


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