From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: virtio-return-3538-cohuck=redhat.com@lists.oasis-open.org Sender: List-Post: List-Help: List-Unsubscribe: List-Subscribe: Date: Fri, 19 Mar 2021 13:30:08 +0100 From: Cornelia Huck Message-ID: <20210319133008.78402ffb.cohuck@redhat.com> In-Reply-To: <20210318182314.163060-1-mst@redhat.com> References: <20210318182314.163060-1-mst@redhat.com> MIME-Version: 1.0 Subject: Re: [virtio] [PATCH v2] introduction: document #define syntax Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit To: "Michael S. Tsirkin" Cc: virtio-comment@lists.oasis-open.org, virtio-dev@lists.oasis-open.org, virtio@lists.oasis-open.org List-ID: On Thu, 18 Mar 2021 14:23:33 -0400 "Michael S. Tsirkin" wrote: > We use the C #define syntax to refer to numeric values. > Let's document that. > > Signed-off-by: Michael S. Tsirkin > --- > > changes from v1: > address Cornelia's comments > > > introduction.tex | 23 +++++++++++++++++++++++ > 1 file changed, 23 insertions(+) > > diff --git a/introduction.tex b/introduction.tex > index cc38e29..47bebf5 100644 > --- a/introduction.tex > +++ b/introduction.tex > @@ -210,6 +210,29 @@ \section{Structure Specifications} > \begin{lstlisting} > CPU_TO_BE16(B << 15 | A) > \end{lstlisting} > +\section{Constant Specifications} > + > +In many cases, numeric values used in the interface between the device > +and the driver are documented using the C #define and /* */ > +comment syntax. Multiple related values are grouped together with > +a common name as a prefix, using _ as a separator. > +Using _XXX as a suffix refers to all values in a group. > +For example: > + > +\begin{lstlisting} > +/* Field Fld value A description */ > +#define VIRTIO_FLD_A (1 << 0) > +/* Field Fld value B description */ > +#define VIRTIO_FLD_B (1 << 1) > +\end{lstlisting} > +documents two numeric values for a field \field{Fld}, with > +\field{Fld} having value 1 referring to \field{A} and \field{Fld} > +having value 2 referring to \field{B}. The reader may infer a general Fld <-> FLD matching requirement here; but OTOH, this is only an example. I don't have an idea how to make that more explicit without being overly verbose, anyway. > +Note that $<<$ refers to the shift-left operation. > + > +Further, in this case VIRTIO_FLD_A and VIRTIO_FLD_B > +refer to values 1 and 2 of Fld respectively. Further, VIRTIO_FLD_XXX refers to > +either VIRTIO_FLD_A or VIRTIO_FLD_B. > > \newpage > Reviewed-by: Cornelia Huck --------------------------------------------------------------------- To unsubscribe from this mail list, you must leave the OASIS TC that generates this mail. Follow this link to all your TCs in OASIS at: https://www.oasis-open.org/apps/org/workgroup/portal/my_workgroups.php