Самые-самые обёртки в lwip: #ifdef PACK_STRUCT_USE_INCLUDES
# include "arch/bpstruct.h"
#endif
PACK_STRUCT_BEGIN
struct udp_hdr {
PACK_STRUCT_FIELD(u16_t src);
PACK_STRUCT_FIELD(u16_t dest); /* src/dest UDP ports */
PACK_STRUCT_FIELD(u16_t len);
PACK_STRUCT_FIELD(u16_t chksum);
} PACK_STRUCT_STRUCT;
PACK_STRUCT_END
#ifdef PACK_STRUCT_USE_INCLUDES
# include "arch/epstruct.h"
#endif