===========================
Including uAPI header files
===========================
Sometimes, it is useful to include header files and C example codes in
order to describe the userspace API and to generate cross-references
between the code and the documentation. Adding cross-references for
userspace API files has an additional vantage: Sphinx will generate warnings
if a symbol is not found at the documentation. That helps to keep the
uAPI documentation in sync with the Kernel changes.
The :ref:`parse_headers.pl <parse_headers>` provide a way to generate such
cross-references. It has to be called via Makefile, while building the
documentation. Please see ``Documentation/userspace-api/media/Makefile`` for an example
about how to use it inside the Kernel tree.
.. _parse_headers:
parse_headers.pl
^^^^^^^^^^^^^^^^
NAME
****
parse_headers.pl - parse a C file, in order to identify functions, structs,
enums and defines and create cross-references to a Sphinx book.
SYNOPSIS
********
\ **parse_headers.pl**\ [<options>] <C_FILE> <OUT_FILE> [<EXCEPTIONS_FILE>]
Where <options> can be: --debug, --help or --usage.
OPTIONS
*******
\ **--debug**\
Put the script in verbose mode, useful for debugging.
\ **--usage**\
Prints a brief help message and exits.
\ **--help**\
Prints a more detailed help message and exits.
DESCRIPTION
***********
Convert a C header or source file (C_FILE), into a reStructuredText
included via ..parsed-literal block with cross-references for the
documentation files that describe the API. It accepts an optional
EXCEPTIONS_FILE with describes what elements will be either ignored or
be pointed to a non-default reference.
The output is written at the (OUT_FILE).
It is capable of identifying defines, functions, structs, typedefs,
enums and enum symbols and create cross-references for all of them.
It is also capable of distinguish #define used for specifying a Linux
ioctl.
The EXCEPTIONS_FILE contain two types of statements: \ **ignore**\ or \ **replace**\ .
The syntax for the ignore tag is:
ignore \ **type**\ \ **name**\
The \ **ignore**\ means that it won't generate cross references for a
\ **name**\ symbol of type \ **type**\ .
The syntax for the replace tag is:
replace \ **type**\ \ **name**\ \ **new_value**\
The \ **replace**\ means that it will generate cross references for a
\ **name**\ symbol of type \ **type**\ , but, instead of using the default
replacement rule, it will use \ **new_value**\ .
For both statements, \ **type**\ can be either one of the following:
\ **ioctl**\
The ignore or replace statement will apply to ioctl definitions like:
#define VIDIOC_DBG_S_REGISTER _IOW('V', 79, struct v4l2_dbg_register)
\ **define**\
The ignore or replace statement will apply to any other #define found
at C_FILE.
\ **typedef**\
The ignore or replace statement will apply to typedef statements at C_FILE.
\ **struct**\
The ignore or replace statement will apply to the name of struct statements
at C_FILE.
\ **enum**\
The ignore or replace statement will apply to the name of enum statements
at C_FILE.
\ **symbol**\
The ignore or replace statement will apply to the name of enum value
at C_FILE.
For replace statements, \ **new_value**\ will automatically use :c:type:
references for \ **typedef**\ , \ **enum**\ and \ **struct**\ types. It will use :ref:
for \ **ioctl**\ , \ **define**\ and \ **symbol**\ types. The type of reference can
also be explicitly defined at the replace statement.
EXAMPLES
********
ignore define _VIDEODEV2_H
Ignore a #define _VIDEODEV2_H at the C_FILE.
ignore symbol PRIVATE
On a struct like:
enum foo { BAR1, BAR2, PRIVATE };
It won't generate cross-references for \ **PRIVATE**\ .
replace symbol BAR1 :c:type:\`foo\`
replace symbol BAR2 :c:type:\`foo\`
On a struct like:
enum foo { BAR1, BAR2, PRIVATE };
It will make the BAR1 and BAR2 enum symbols to cross reference the foo
symbol at the C domain.
BUGS
****
Report bugs to Mauro Carvalho Chehab <[email protected]>
COPYRIGHT
*********
Copyright (c) 2016 by Mauro Carvalho Chehab <[email protected]>.
License GPLv2: GNU GPL version 2 <https://gnu.org/licenses/gpl.html>.
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
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