1 /* 2 * mbox.h 3 * 4 * Simple thread mailbox interface 5 */ 6 7 #ifndef _MBOX_H 8 #define _MBOX_H 9 10 #include "thread.h" 11 12 /* 13 * If a mailbox is allocated statically (as a struct mailbox), this 14 * is the number of slots it gets. 15 */ 16 #define MAILBOX_STATIC_SIZE 512 17 18 struct mailbox { 19 struct semaphore prod_sem; /* Producer semaphore (empty slots) */ 20 struct semaphore cons_sem; /* Consumer semaphore (data slots) */ 21 struct semaphore head_sem; /* Head pointer semaphore */ 22 struct semaphore tail_sem; /* Tail pointer semaphore */ 23 void **wrap; /* Where pointers wrap */ 24 void **head; /* Head pointer */ 25 void **tail; /* Tail pointer */ 26 27 void *data[MAILBOX_STATIC_SIZE]; /* Data array */ 28 }; 29 30 /* The number of bytes for an mailbox of size s */ 31 #define MBOX_BYTES(s) (sizeof(struct mailbox) + \ 32 ((s)-MAILBOX_STATIC_SIZE)*sizeof(void *)) 33 34 void mbox_init(struct mailbox *mbox, size_t size); 35 int mbox_post(struct mailbox *mbox, void *msg, mstime_t timeout); 36 mstime_t mbox_fetch(struct mailbox *mbox, void **msg, mstime_t timeout); 37 38 /* 39 * This marks a mailbox object as unusable; it will remain unusable 40 * until sem_init() is called on it again. This DOES NOT clear the 41 * list of blocked processes on this mailbox! 42 * 43 * It is also possible to mark the mailbox invalid by zeroing its 44 * memory structure. 45 */ 46 static inline void mbox_set_invalid(struct mailbox *mbox) 47 { 48 if (!!mbox) 49 sem_set_invalid(&mbox->prod_sem); 50 } 51 52 /* 53 * Ask if a mailbox object has been initialized. 54 */ 55 static inline bool mbox_is_valid(struct mailbox *mbox) 56 { 57 return ((!!mbox) && sem_is_valid(&mbox->prod_sem)); 58 } 59 60 #endif /* _MBOX_H */ 61
