Complete the coding style page

Co-authored-by: Rafal Kupiec <belliash@codingworkshop.eu.org>
Reviewed-on: #3
Reviewed-by: Rafal Kupiec <belliash@noreply.codingworkshop.git>
Co-authored-by: Aiken Harris <harraiken91@gmail.com>
Co-committed-by: Aiken Harris <harraiken91@gmail.com>

content/contributing/coding-style.md

@@ -2,5 +2,122 @@
 title = 'ExectOS Coding Style'
 date = 2024-06-18T00:20:07+02:00
 +++
-At the moment of writing this article, no coding style was established. You should check how existing code looks like and
+This document outlines our coding style guidelines. If you have suggestions for things that should be clarified better,
-follow its current formatting.
+[contact with us](/contact-us/). With a continuous stream of contributions and patches we would
+like the our code base to remain clean and easy to read and maintain.
+
+## General
+Each source file should contain a header:
+```
+/**
+ * PROJECT:         ExectOS
+ * COPYRIGHT:       See COPYING.md in the top level directory
+ * FILE:            path/to/source/file.c
+ * DESCRIPTION:     Description of the purpose of the code in this file
+ * DEVELOPERS:      Your Name <name@codingworkshop.eu.org>
+ */
+```
+You should only add yourself to the developer list if you are making a significant contribution, which means you
+understand the purpose of the code in this file and you can provide support to anyone.
+
+## Indentation and whitespace
+ * Set your editor to __4 spaces per tab; never use tabs__.
+ * Do not add a space or tab at the end of any line.
+ * Indent both a case label and the case statement of the switch statement.
+ * When wrapping a too long line, add indentation to match the function call parameter list or expression.
+ * Always separate operators with a space on both sides, except after C-style cast operator.
+ * Always use a space after comma.
+ * A line must not have more than __120 characters__.
+```
+switch(Condition)
+{
+    case 1:
+        CallFunction();
+        break;
+    default:
+        CallAnotherFunction();
+        break;
+}
+
+CallOtherFunction(Argument1, Argument2, Argument3,
+                  Argument4, Argument5);
+
+Pointer = (PVOID)Address;
+```
+
+## Miscellaneous formatting
+ * Include exactly one empty line between header and `#include` directives.
+ * Put exactly two empty lines after `#include` directives.
+ * Include single newline at every file end.
+
+## Identifiers
+ * Always use self-describing well chosen identifiers.
+ * Use full names such as `Message` over abbreviations such as `Mesg`.
+ * Function names and variables start with uppercase letters and use CamelCaseFormatting.
+ * Classes, structures, unions and type definitions are UPPERCASE and use underscore.
+```
+typedef char BOOL;
+
+typedef struct _NEW_STRUCTURE
+{
+    BOOL Enabled;
+    PVOID Pointer;
+} NEW_STRUCTURE, *PNEW_STRUCTURE;
+
+XTAPI
+VOID
+KeStartKernel();
+```
+
+## Variable declarations
+ * Always declare all variables at the beginning of the function.
+ * Use descriptive names, avoid reusing a single variable for different purposes.
+ * Always use XT API types over defined in C standard.
+
+## Comments
+ * Always comment your code properly.
+ * Use only C-style comments.
+ * Comment over and under the commented line to avoid producing long lines.
+ * Do not annotate your comments with your name or initials.
+ * Avoid expressing sentiments, instead explain why you consider the respective code a hack.
+```
+/* This is a C-style comment */
+
+/* This is a valid
+ * multi-line comment */
+```
+
+## Documentation
+ * We use JavaDoc style comments for API documentation.
+ * The comment separators `/**` and `*/` must be present.
+ * Every line must be indented.
+```
+/**
+ * Multi-line routine description.
+ *
+ * @param Parameter1
+ *        Description of the first parameter goes here.
+ *
+ * @param Parameter2
+ *        Description of the seconds parameter goes here.
+ *
+ * @return Short description about return values.
+ *
+ * @since Information from which version a given function is available.
+ *
+ * @see Optional link to documentation or reference implementation.
+ *
+ * @todo Optional description, telling what is missing in the function implementation.
+ */
+```
+
+## Miscellaneous
+ * Use NULLPTR instead of 0 for pointers.
+ * Avoid using assignments in while loops.
+ * Never use goto statements.
+ * Never use spaces around unary operators.
+ * Always put braces (`{` and `}`) on their own lines.
+ * One-line control clauses should use braces as well.
+ * Do not use reverse logic in control clauses.
+ * Do not use spaces around unary operators, before comma and semicolon, or between control statements and their
+   parentheses.