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 parse_headers.pl provide a way to generate such cross-references. It has to be called via Makefile, while building the documentation. Please see Documentation/media/Makefile for an example about how to use it inside the Kernel tree.
parse_headers.pl - parse a C file, in order to identify functions, structs, enums and defines and create cross-references to a Sphinx book.
parse_headers.pl [<options>] <C_FILE> <OUT_FILE> [<EXCEPTIONS_FILE>]
Where <options> can be: –debug, –help or –man.
–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.
Convert a C header or source file (C_FILE), into a ReStructured Text 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 statements 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.
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.
Report bugs to Mauro Carvalho Chehab <mchehab@s-opensource.com>
Copyright (c) 2016 by Mauro Carvalho Chehab <mchehab@s-opensource.com>.
License GPLv2: GNU GPL version 2 <http://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.