LibrePilot/flight/pios/osx/inc/pios_struct_helper.h

/* Taken from include/linux/kernel.h from the Linux kernel tree */

/**
 * container_of - cast a member of a structure out to the containing structure
 * @ptr:	the pointer to the member.
 * @type:	the type of the container struct this is embedded in.
 * @member:	the name of the member within the struct.
 *
 */
#define container_of(ptr, type, member) \
    ({                      \
         const typeof(((type *)0)->member) * __mptr = (ptr);    \
         (type *)((char *)__mptr - offsetof(type, member)); } \
    )