Code Style C

This is just a brief overview of the C Code Style used for our projects. The EDK II Project requires the use of uncrustify to automatically format C code to match the EDK II C Coding Standard. Details on how to install and run uncrustify for EDK II can be found at EDK II Code Formatting.

The official C Coding Standards specification can be found at:

• EDK II C Coding Standards 2.2 HTML | .PDF

Table of Contents Overview Example of Properly Formatted Code Examples CamelCase UPPERCASE Use UEFI types 2 spaces of indentation Always use { }

Overview

• CamelCase used for variables, functions and file names
• UPPERCASE used for types and macros
• Use UEFI types rather than C types
  • int=>INTN; unsigned int=>UINTN; void=>VOID; etc...
• Limit line length to 80 characters
• 2 spaces of indentation
• Never use tab characters.
  • Set editor to insert spaces rather than a tab character.
• if, for, while, etc. always use { }, even when there is only one statement
  • The opening brace ({) should always appear at the end of the line previous line.
• The opening brace ({) for a function should always appear separately on the a new line.

Example of Properly Formatted Code

C File Example:

 /**
   Brief and Detailed Descriptions.
 
   @param[in]      Arg1 Description of Arg1.
   @param[in]      Arg2 Description of Arg2, which is optional.
   @param[out]     Arg3 Description of Arg3.
   @param[in, out] Arg4 Description of Arg4.
 
   @retval EFI_SUCCESS   Description of what EFI_SUCCESS means.
   @retval !EFI_SUCCESS  Failure.
 
 **/
 EFI_STATUS
 EFIAPI
 FooName (
   IN     UINTN  Arg1,
   IN     UINTN  Arg2 OPTIONAL,
      OUT UINTN  *Arg3,
   IN OUT UINTN  *Arg4
   )
 {
   UINTN Local;
   UINTN AnotherLocal;
 
   ...
 
   for (Local = 0; Local < 5; Local++) {
     if (Local == 2) {
       Print (L"Local: %d (yes! 2)\n", Local);
     } else {
       Print (L"Local: %d\n", Local);
     }
   }
 
   ...
 }

H File Example:

 #define FOO_MACRO(a, b) ((a) * (b))
 
 #define FOO_CONSTANT  0xcafe
 
 /**
   Brief and Detailed Descriptions.
 
   @param[in]      Arg1 Description of Arg1.
   @param[in]      Arg2 Description of Arg2, which is optional.
   @param[out]     Arg3 Description of Arg3.
   @param[in, out] Arg4 Description of Arg4.
 
   @retval EFI_SUCCESS   Description of what EFI_SUCCESS means.
   @retval !EFI_SUCCESS  Failure.
 
 **/
 EFI_STATUS
 EFIAPI
 FooName (
   IN     UINTN  Arg1,
   IN     UINTN  Arg2 OPTIONAL,
      OUT UINTN  *Arg3,
   IN OUT UINTN  *Arg4
   );
 
 ...
 
 #endif

Examples

CamelCase

Used for variables, functions and file names

Correct:

 #include "FooFileName.h"
 ...
 VOID SuperFunction (
 ...
   UINTN ALocalVariable;
   UINTN UefiVersion;

Incorrect:

 #include "foo-file_name.h"
 ...
 VOID superFunction (
 ...
   UINTN a_local_variable;
   UINTN UEFIVersion;

UPPERCASE

Used for types and macros

Correct:

 #define FOO_MACRO(a, b) ((a) * (b))
 typedef struct _STRUCT_NAME STRUCT_NAME;
 struct _STRUCT_NAME {
   ...
 };

Incorrect:

 #define FooMacro(a, b) ((a) * (b))
 #define Foo_Macro(a, b) ((a) * (b))
 typedef struct _Struct_Name StructName;

Use UEFI types

Don't use C types directly

Correct:

   INTN   ALocalVariable;
   UINTN  UefiVersion;
   VOID   *Ptr;

Incorrect:

   int           ALocalVariable;
   unsigned int  UefiVersion;
   void          *Ptr;

2 spaces of indentation

Correct:

   if (TRUE) {
     Print (L"Hello, world!\n");
   }

Incorrect:

   if (TRUE) {
       Print (L"Hello, world!\n");
   }

Always use { }

If, for, while, etc. always use { }, even when there is only one statement

Correct:

   if (TRUE) {
     Print (L"Hello, world!\n");
   }

Incorrect:

   if (TRUE)
     Print (L"Hello, world!\n");