/** @page styleguide Style Guides The goals for each of these guides are: - to produce correct code that appears clean, consistent, and readable, - to allow developers to create patches that conform to a standard, and - to eliminate these issues as points of future contention. Some of these rules may be ignored in the spirit of these stated goals; however, such exceptions should be fairly rare. The following style guides describe a formatting, naming, and other conventions that should be followed when writing or changing the OpenOCD code: - @subpage styletcl - @subpage stylec - @subpage styleperl - @subpage styleautotools In addition, the following style guides provide information for providing documentation, either as part of the C code or stand-alone. - @subpage styledoxygen - @subpage styletexinfo - @subpage stylelatex Feedback would be welcome to improve the OpenOCD guidelines. */ /** @page styletcl TCL Style Guide OpenOCD needs to expand its Jim/TCL Style Guide. Many of the guidelines listed on the @ref stylec page should apply to OpenOCD's Jim/TCL code as well. */ /** @page stylec C Style Guide This page contains guidelines for writing new C source code for the OpenOCD project. @section styleformat Formatting Guide - remove any trailing white space at the end of lines. - use TAB characters for indentation; do NOT use spaces. - displayed TAB width is 4 characters. - use Unix line endings ('\\n'); do NOT use DOS endings ('\\r\\n') - limit adjacent empty lines to at most two (2). - remove any trailing empty lines at the end of source files - do not "comment out" code from the tree; instead, one should either: -# remove it entirely (git can retrieve the old version), or -# use an @c \#if/\#endif block. Finally, try to avoid lines of code that are longer than than 72-80 columns: - long lines frequently indicate other style problems: - insufficient use of static functions, macros, or temporary variables - poor flow-control structure; "inverted" logical tests - a few lines may be wider than this limit (typically format strings), but: - all C compilers will concatenate series of string constants. - all long string constants should be split across multiple lines. @section stylenames Naming Rules - most identifiers must use lower-case letters (and digits) only. - macros must use upper-case letters (and digits) only. - OpenOCD identifiers should NEVER use @c MixedCaps. - @c typedef names must end with the '_t' suffix. - This should be reserved for types that should be passed by value. - Do @b not mix the typedef keyword with @c struct. - use underline characters between consecutive words in identifiers (e.g. @c more_than_one_word). @section stylec99 C99 Rules - inline functions - @c // comments -- in new code, prefer these for single-line comments - trailing comma allowed in enum declarations - designated initializers (@{ .field = value @}) - variables declarations should occur at the point of first use - new block scopes for selection and iteration statements - use malloc() to create dynamic arrays. Do @b not use @c alloca or variable length arrays on the stack. non-MMU hosts(uClinux) and pthreads require modest and predictable stack usage. @section styletypes Type Guidelines - use native types (@c int or @c unsigned) if the type is not important - if size matters, use the types from \ or \: - @c int8_t, @c int16_t, @c int32_t, or @c int64_t: signed types of specified size - @c uint8_t, @c uint16_t, @c uint32_t, or @c uint64_t: unsigned types of specified size - do @b NOT redefine @c uN types from "types.h" @section stylefunc Functions - static inline functions should be prefered over macros: @code /** do NOT define macro-like functions like this... */ #define CUBE(x) ((x) * (x) * (x)) /** instead, define the same expression using a C99 inline function */ static inline int cube(int x) { return x * x * x; } @endcode - Functions should be declared static unless required by other modules - define static functions before first usage to avoid forward declarations. - Functions should have no space between its name and its parameter list: @code int f(int x1, int x2) { ... int y = f(x1, x2 - x1); ... } @endcode - Separate assignment and logical test statements. In other words, you should write statements like the following: @code // separate statements should be preferred result = foo(); if (ERROR_OK != result) ... @endcode More directly, do @b not combine these kinds of statements: @code // Combined statements should be avoided if (ERROR_OK != (result = foo())) return result; @endcode */ /** @page styledoxygen Doxygen Style Guide The following sections provide guidelines for OpenOCD developers who wish to write Doxygen comments in the code or this manual. For an introduction to Doxygen documentation, see the @ref primerdoxygen. @section styledoxyblocks Doxygen Block Selection Several different types of Doxygen comments can be used; often, one style will be the most appropriate for a specific context. The following guidelines provide developers with heuristics for selecting an appropriate form and writing consistent documentation comments. -# use @c /// to for one-line documentation of instances. -# for documentation requiring multiple lines, use a "block" style: @verbatim /** * @brief First sentence is short description. Remaining text becomes * the full description block, where "empty" lines start new paragraphs. * * One can make text appear in @a italics, @b bold, @c monospace, or * in blocks such as the one in which this example appears in the Style * Guide. See the Doxygen Manual for the full list of commands. * * @param foo For a function, describe the parameters (e.g. @a foo). * @returns The value(s) returned, or possible error conditions. */ @endverbatim -# The block should start on the line following the opening @c /**. -# The end of the block, \f$*/\f$, should also be on its own line. -# Every line in the block should have a @c '*' in-line with its start: - A leading space is required to align the @c '*' with the @c /** line. - A single "empty" line should separate the function documentation from the block of parameter and return value descriptions. - Except to separate paragraphs of documentation, other extra "empty" lines should be removed from the block. -# Only single spaces should be used; do @b not add mid-line indentation. -# If the total line length will be less than 72-80 columns, then - The @c /**< form can be used on the same line. - This style should be used sparingly; the best use is for fields: @code int field; /**< field description */ @endcode @section styledoxyall Doxygen Style Guide The following guidelines apply to all Doxygen comment blocks: -# Use the @c '\@cmd' form for all doxygen commands (do @b not use @c '\\cmd'). -# Use symbol names such that Doxygen automatically creates links: -# @c function_name() can be used to reference functions (e.g. flash_set_dirty()). -# @c struct_name::member_name should be used to reference structure fields in the documentation (e.g. @c flash_driver::name). -# URLS get converted to markup automatically, without any extra effort. -# new pages can be linked into the heirarchy by using the @c \@subpage command somewhere the page(s) under which they should be linked: -# use @c \@ref in other contexts to create links to pages and sections. -# Use good Doxygen mark-up: -# '\@a' (italics) should be used to reference parameters (e.g. foo). -# '\@b' (bold) should be used to emphasizing single words. -# '\@c' (monospace) should be used with file names and code symbols, so they appear visually distinct from surrounding text. -# To mark-up multiple words, the HTML alternatives must be used. -# Two spaces should be used when nesting lists; do @b not use '\\t' in lists. -# Code examples provided in documentation must conform to the Style Guide. @section styledoxytext Doxygen Text Inputs In addition to the guidelines in the preceding sections, the following additional style guidelines should be considered when writing documentation as part of standalone text files: -# Text files must contain Doxygen at least one comment block: -# Documentation should begin in the first column (except for nested lists). -# Do NOT use the @c '*' convention that must be used in the source code. -# Each file should contain at least one @c \@page block. -# Each new page should be listed as a \@subpage in the \@page block of the page that should serve as its parent. -# Large pages should be structure in parts using meaningful \@section and \@subsection commands. -# Include a @c \@file block at the end of each Doxygen @c .txt file to document its contents: - Doxygen creates such pages for files automatically, but no content will appear on them for those that only contain manual pages. - The \@file block should provide useful meta-documentation to assist techincal writers; typically, a list of the pages that it contains. - For example, the @ref styleguide exists in @c doc/manual/style.txt, which contains a reference back to itself. -# The \@file and \@page commands should begin on the same line as the start of the Doxygen comment: @verbatim /** @page pagename Page Title Documentation for the page. */ /** @file This file contains the @ref pagename page. */ @endverbatim For an example, the Doxygen source for this Style Guide can be found in @c doc/manual/style.txt, alongside other parts of The Manual. */ /** @page styletexinfo Texinfo Style Guide The User's Guide is there to provide two basic kinds of information. It is a guide for how and why to use each feature or mechanism of OpenOCD. It is also the reference manual for all commands and options involved in using them, including interface, flash, target, and other drivers. At this time, it is the only user-targetted documentation; everything else is addressing OpenOCD developers. There are two key audiences for the User's Guide, both developer based. The primary audience is developers using OpenOCD as a tool in their work, or who may be starting to use it that way. A secondary audience includes developers who are supporting those users by packaging or customizing it for their hardware, installing it as part of some software distribution, or by evolving OpenOCD itself. There is some crossover between those audiences. We encourage contributions from users as the fundamental way to evolve and improve OpenOCD. In particular, creating a board or target specific configuration file is something that many users will end up doing at some point, and we like to see such files become part of the mainline release. General documentation rules to remember include: - Be concise and clear. It's work to remove those extra words and sentences, but such "noise" doesn't help readers. - Make it easy to skim and browse. "Tell what you're going to say, then say it". Help readers decide whether to dig in now, or leave it for later. - Make sure the chapters flow well. Presentations should not jump around, and should move easily from overview down to details. - Avoid using the passive voice. - Address the reader to clarify roles ("your config file", "the board you are debugging", etc.); "the user" (etc) is artificial. - Use good English grammar and spelling. Remember also that English will not be the first language for many readers. Avoid complex or idiomatic usage that could create needless barriers. - Use examples to highlight fundamental ideas and common idioms. - Don't overuse list constructs. This is not a slide presentation; prefer paragraphs. When presenting features and mechanisms of OpenOCD: - Explain key concepts before presenting commands using them. - Tie examples to common developer tasks. - When giving instructions, you can \@enumerate each step both to clearly delineate the steps, and to highlight that this is not explanatory text. - When you provide "how to use it" advice or tutorials, keep it in separate sections from the reference material. - Good indexing is something of a black art. Use \@cindex for important concepts, but don't overuse it. In particular, rely on the \@deffn indexing, and use \@cindex primarily with significant blocks of text such as \@subsection. The \@dfn of a key term may merit indexing. - Use \@xref (and \@anchor) with care. Hardcopy versions, from the PDF, must make sense without clickable links (which don't work all that well with Texinfo in any case). If you find you're using many links, read that as a symptom that the presentation may be disjointed and confusing. - Avoid font tricks like \@b, but use \@option, \@file, \@dfn, \@emph and related mechanisms where appropriate. For technical reference material: - It's OK to start sections with explanations and end them with detailed lists of the relevant commands. - Use the \@deffn style declarations to define all commands and drivers. These will automatically appear in the relevant index, and those declarations help promote consistent presentation and style. - It's a "Command" if it can be used interactively. - Else it's a "Config Command" if it must be used before the configuration stage completes. - For a "Driver", list its name. - Use EBNF style regular expressions to define parameters: brackets around zero-or-one choices, parentheses around exactly-one choices. - Use \@option, \@file, \@var and other mechanisms where appropriate. - Say what output it displays, and what value it returns to callers. - Explain clearly what the command does. Sometimes you will find that it can't be explained clearly. That usually means the command is poorly designed; replace it with something better, if you can. - Be complete: document all commands, except as part of a strategy to phase something in or out. - Be correct: review the documentation against the code, and vice versa. - Alphabetize the \@defn declarations for all commands in each section. - Keep the per-command documentation focussed on exactly what that command does, not motivation, advice, suggestions, or big examples. When commands deserve such expanded text, it belongs elsewhere. Solutions might be using a \@section explaining a cluster of related commands, or acting as a mini-tutorial. - Details for any given driver should be grouped together. The User's Guide is the first place most users will start reading, after they begin using OpenOCD. Make that investment of their time be as productive as possible. Needing to look at OpenOCD source code, to figure out how to use it is a bad sign, though it's OK to need to look at the User's guide to figure out what a config script is doing. */ /** @page stylelatex LaTeX Style Guide This page needs to provide style guidelines for using LaTeX, the typesetting language used by The References for OpenOCD Hardware. Likewise, the @ref primerlatex for using this guide needs to be completed. */ /** @page styleperl Perl Style Guide This page provides some style guidelines for using Perl, a scripting language used by several small tools in the tree: -# Ensure all Perl scripts use the proper suffix (@c .pl for scripts, and @c .pm for modules) -# Pass files as script parameters or piped as input: - Do NOT code paths to files in the tree, as this breaks out-of-tree builds. - If you must, then you must also use an automake rule to create the script. -# use @c '#!/usr/bin/perl' as the first line of Perl scripts. -# always use strict and use warnings -# invoke scripts indirectly in Makefiles or other scripts: @code perl script.pl @endcode Maintainers must also be sure to follow additional guidelines: -# Ensure that Perl scripts are committed as executables: Use "chmod +x script.pl" @a before using "git add script.pl" */ /** @page styleautotools Autotools Style Guide This page contains style guidelines for the OpenOCD autotools scripts. The following guidelines apply to the @c configure.in file: - Better guidelines need to be developed, but until then... - Use good judgement. The following guidelines apply to @c Makefile.am files: -# When assigning variables with long lists of items: -# Separate the values on each line to make the files "patch friendly": @code VAR = \ value1 \ value2 \ ... value9 \ value10 @endcode */ /** @file This file contains the @ref styleguide pages. The @ref styleguide pages include the following Style Guides for their respective code and documentation languages: - @ref styletcl - @ref stylec - @ref styledoxygen - @ref styletexinfo - @ref stylelatex - @ref styleperl - @ref styleautotools */