From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: virtio-return-3537-cohuck=redhat.com@lists.oasis-open.org Sender: List-Post: List-Help: List-Unsubscribe: List-Subscribe: Date: Thu, 18 Mar 2021 14:23:33 -0400 From: "Michael S. Tsirkin" Message-ID: <20210318182314.163060-1-mst@redhat.com> MIME-Version: 1.0 Subject: [virtio] [PATCH v2] introduction: document #define syntax Content-Type: text/plain; charset=us-ascii Content-Disposition: inline To: virtio-comment@lists.oasis-open.org, virtio-dev@lists.oasis-open.org Cc: virtio@lists.oasis-open.org List-ID: 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}. +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 -- MST --------------------------------------------------------------------- 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