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| -rw-r--r-- | src/include/compiler.h | 36 |
1 files changed, 36 insertions, 0 deletions
diff --git a/src/include/compiler.h b/src/include/compiler.h index f481f38a..ea81fc89 100644 --- a/src/include/compiler.h +++ b/src/include/compiler.h @@ -179,6 +179,42 @@ REQUEST_EXPANDED ( CONFIG_SYMBOL ); /** Select file identifier for errno.h (if used) */ #define ERRFILE PREFIX_OBJECT ( ERRFILE_ ) +/** + * @defgroup weakmacros Macros to manage weak symbol definitions + * + * Weak symbols allow one to reference a function in another file + * without necessarily requiring that file to be linked in. In their + * native form, the function will be @c NULL if its file is not linked + * in; these macros provide an inline wrapper that returns an + * appropriate error indication or default value. + * + * @{ + */ +#ifndef ASSEMBLY + +/** Mangle @a name into its weakly-referenced implementation */ +#define __weak_impl( name ) _w_ ## name + +/** + * Declare a weak function with inline safety wrapper + * + * @v ret Return type of weak function + * @v name Name of function to expose + * @v proto Parenthesized list of arguments with types + * @v args Parenthesized list of argument names + * @v dfl Value to return if weak function is not available + */ +#define __weak_decl( ret, name, proto, args, dfl ) \ + ret __weak_impl( name ) proto __attribute__ (( weak )); \ + static inline ret name proto { \ + if ( __weak_impl( name ) ) \ + return __weak_impl( name ) args; \ + return dfl; \ + } + +#endif +/** @} */ + /** @defgroup dbg Debugging infrastructure * @{ */ |