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

[Stefan Hajnoczi <stefanha@gmail.com>]

On Wed, Mar 27, 2013 at 05:52:56PM -0700, Richard Henderson wrote:
> On 2013-03-27 16:42, Andreas Färber wrote:
> >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?
> 
> It doesn't matter for this usage.
> 
> Nor, according to other threads that appeared on the list today, is this
> the right fix, since the bswap itself turns out to be bogus.

Dmitry said he's sending a fix, will wait for that.

Stefan