@ -52,6 +52,43 @@ extern "C" {
# define MIN(x,y) (((x) < (y)) ? (x) : (y))
# endif
/**
* Returns a pointer the the containing struct of a given member item .
*
* To demonstrate , the following example retrieves a pointer to
* ` example_container ` given only its ` destroy_listener ` member :
*
* @ code
* struct example_container {
* struct wl_listener destroy_listener ;
* // other members...
* } ;
*
* void example_container_destroy ( struct wl_listener * listener , void * data )
* {
* struct example_container * ctr ;
*
* ctr = wl_container_of ( listener , ctr , destroy_listener ) ;
* // destroy ctr...
* }
* @ endcode
*
* @ param ptr A valid pointer to the contained item .
*
* @ param type A pointer to the type of content that the list item
* stores . Type does not need be a valid pointer ; a null or
* an uninitialised pointer will suffice .
*
* @ param member The named location of ptr within the sample type .
*
* @ return The container for the specified pointer .
*/
# ifndef container_of
# define container_of(ptr, type, member) ({ \
const __typeof__ ( ( ( type * ) 0 ) - > member ) * __mptr = ( ptr ) ; \
( type * ) ( ( char * ) __mptr - offsetof ( type , member ) ) ; } )
# endif
# ifdef __cplusplus
}
# endif