ref: 0ce98c7ac7ba66acaf504be9bb042796e12f2733
src/libs/mynewt-nimble/CODING_STANDARDS.md
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# Coding Style for Apache NimBLE Apache NimBLE project is part of Apache Mynewt projct and follows its coding style. # Coding Style for Apache Mynewt Core This document is meant to define the coding style for Apache Mynewt, and all subprojects of Apache Mynewt. This covers C and Assembly coding conventions, *only*. Other languages (such as Go), have their own coding conventions. ## Headers * All files that are newly written, should have the Apache License clause at the top of them. * For files that are copied from another source, but contain an Apache compatible license, the original license header shall be maintained. * For more information on applying the Apache license, the definitive source is here: http://www.apache.org/dev/apply-license.html * The Apache License clause for the top of files is as follows: ```no-highlight /* * Licensed to the Apache Software Foundation (ASF) under one * or more contributor license agreements. See the NOTICE file * distributed with this work for additional information * regarding copyright ownership. The ASF licenses this file * to you under the Apache License, Version 2.0 (the * "License"); you may not use this file except in compliance * with the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, * software distributed under the License is distributed on an * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY * KIND, either express or implied. See the License for the * specific language governing permissions and limitations * under the License. */ ``` ## Whitespace and Braces * Code must be indented to 4 spaces, tabs should not be used. * Do not add whitespace at the end of a line. * Put space after keywords (for, if, return, switch, while). * for, else, if, while statements must have braces around their code blocks, i.e., do: ``` if (x) { assert(0); } else { assert(0); } ``` Not: ``` if (x) assert(0); else assert(0); ``` * Braces for statements must be on the same line as the statement. Good: ``` for (i = 0; i < 10; i++) { if (i == 5) { break; } else { continue; } } ``` Not: ``` for (i = 0; i < 10; i++) { <-- brace must be on same line as for if (i == 5) { break; } <-- no new line between else else { continue; } } ``` * After a function declaration, the braces should be on a newline, i.e. do: ``` static void * function(int var1, int var2) { ``` not: ``` static void * function(int var1, int var2) { ``` ## Line Length and Wrap * Line length should never exceed 79 columns. * When you have to wrap a long statement, put the operator at the end of the line. i.e.: ``` if (x && y == 10 && b) ``` Not: ``` if (x && y == 10 && b) ``` ## Comments * No C++ style comments allowed. * When using a single line comment, put it above the line of code that you intend to comment, i.e., do: ``` /* check variable */ if (a) { ``` Not: ``` if (a) { /* check variable */ ``` * All public APIs should be commented with Doxygen style comments describing purpose, parameters and return values. Private APIs need not be documented. ## Header files * Header files must contain the following structure: * Apache License (see above) * ```#ifdef``` aliasing, to prevent multiple includes * ```#include``` directives for other required header files * ```#ifdef __cplusplus``` wrappers to maintain C++ friendly APIs * Contents of the header file * ```#ifdef``` aliasing, shall be in the following format, where the package name is "os" and the file name is "callout.h": ```no-highlight #ifndef _OS_CALLOUT_H #define _OS_CALLOUT_H ``` * ```#include``` directives must happen prior to the cplusplus wrapper. * The cplusplus wrapper must have the following format, and precedes any contents of the header file: ```no-highlight #ifdef __cplusplus #extern "C" { ##endif ``` ## Naming * Names of functions, structures and variables must be in all lowercase. * Names should be as short as possible, but no shorter. * Globally visible names must be prefixed with the name of the module, followed by the '_' character, i.e.: ``` os_callout_init(&c) ``` Not: ``` callout_init(c) ``` ## Functions * No spaces after function names when calling a function, i.e, do: ``` rc = function(a) ``` Not: ``` rc = function (a) ``` * Arguments to function calls should have spaces between the comma, i.e. do: ``` rc = function(a, b) ``` Not: ``` rc = function(a,b) ``` * The function type must be on a line by itself preceding the function, i.e. do: ``` static void * function(int var1, int var2) { ``` Not: ``` static void *function(int var1, int var2) { ``` * In general, for functions that return values that denote success or error, 0 shall be success, and non-zero shall be the failure code. ## Variables and Macros * Do not use typedefs for structures. This makes it impossible for applications to use pointers to those structures opaquely. * typedef may be used for non-structure types, where it is beneficial to hide or alias the underlying type used (e.g. ```os_time_t```.) Indicate typedefs by applying the ```_t``` marker to them. * Place all function-local variable definitions at the top of the function body, before any statements. ## Compiler Directives * Code must compile cleanly with -Wall enabled. |