typedef unsigned uint32_t; typedef unsigned char uint8_t; typedef unsigned short uint16_t; typedef struct { uint32_t mbxOwner:1; uint32_t mbxHc:1; uint32_t mbxReserved:6; uint32_t mbxCommand : 8; uint32_t mbxStatus : 16; } MAILBOX_t; uint32_t f(void) { uint32_t mbox; mbox = 0; ((MAILBOX_t *)&mbox)->mbxCommand = 0x24; ((MAILBOX_t *)&mbox)->mbxOwner = 1; return mbox; }