Operating systems

// // synch.h // // Include file for synchronization stuff. The synchronization // primitives include: // Semaphore // Lock // Condition // // Semaphores are the only "native" synchronization primitive. // Condition variables and locks are implemented using semaphores. // #ifndef _synch_h_ #define _synch_h_ #include "queue.h" #define MAX_SEMS 32 //Maximum 32 semaphores allowed in the system #define MAX_LOCKS 64 //Maximum 64 locks allowed in the system //This is because condition vars also use //locks from the same pool #define MAX_CONDS 32 //Maximum 32 conds allowed in the system typedef int sem_t; typedef int lock_t; typedef int cond_t; #define INVALID_SEM -1 #define INVALID_LOCK -1 #define INVALID_PROC -1 #define INVALID_COND -1 typedef struct Sem { Queue waiting; int count; uint32 inuse; //indicates whether the semaphore is being //used by any process } Sem; extern void SemInit (Sem *, int); extern void SemWait (Sem *); extern void SemSignal (Sem *); typedef struct Lock { sem_t mutex; uint32 inuse; int mypid; } Lock; typedef struct Cond { lock_t lock; sem_t sem; uint32 inuse; } Cond; #endif //_synch_h_