synch.h

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#ifndef THREADS_SYNCH_H
#define THREADS_SYNCH_H
 
#include <list.h>
#include <stdbool.h>
 
/** A counting semaphore. */
struct semaphore 
  {
    unsigned value;             /**< Current value. */
    struct list waiters;        /**< List of waiting threads. */
  };
 
void sema_init (struct semaphore *, unsigned value);
void sema_down (struct semaphore *);
bool sema_try_down (struct semaphore *);
void sema_up (struct semaphore *);
void sema_self_test (void);
 
/** Lock. */
struct lock 
  {
    struct thread *holder;      /**< Thread holding lock (for debugging). */
    struct semaphore semaphore; /**< Binary semaphore controlling access. */
  };
 
void lock_init (struct lock *);
void lock_acquire (struct lock *);
bool lock_try_acquire (struct lock *);
void lock_release (struct lock *);
bool lock_held_by_current_thread (const struct lock *);
 
/** Condition variable. */
struct condition 
  {
    struct list waiters;        /**< List of waiting threads. */
  };
 
void cond_init (struct condition *);
void cond_wait (struct condition *, struct lock *);
void cond_signal (struct condition *, struct lock *);
void cond_broadcast (struct condition *, struct lock *);
 
/** Optimization barrier.
 
   The compiler will not reorder operations across an
   optimization barrier.  See "Optimization Barriers" in the
   reference guide for more information.*/
#define barrier() asm volatile ("" : : : "memory")
 
#endif /**< threads/synch.h */