[ovs-dev] [PATCH 5/6] nx-match: New function nxm_read_field().
blp at nicira.com
Thu Aug 11 09:36:32 PDT 2011
On Wed, Aug 10, 2011 at 05:21:42PM -0700, Ethan Jackson wrote:
> nxm_read_field() simplifies reading of NXM fields with an ofs_nbits
> parameter. This patch updates nxm_execute_reg_move() to use the
> new function. A user outside of the nx-match module will be added
> in future patches.
The return value semantics of nxm_read_field() are surprising in that
it just masks off the bits not being read. If I had not read the code
for the function, I would have guessed that it also shifted the bits
so that the least-significant bit being read was the least-significant
bit in the return value. If the existing behavior is actually the
most convenient, it'd be good for the function's comment to mention
Instead of nxm_read_field__() and nxm_read_field(), I'd be inclined to
keep nxm_read_field()'s existing name and name the new function
nxm_read_subfield() or nxm_read_field_bits(). It sounds more
descriptive to me.
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