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#ifndef _SEMAPHORE_H_
#define _SEMAPHORE_H_
#include <wait.h>
/*
* Implementation of semaphore in Mini-os is simple, because
* there are no preemptive threads, the atomicity is guaranteed.
*/
struct semaphore
{
int count;
struct wait_queue_head wait;
};
#define __SEMAPHORE_INITIALIZER(name, n) \
{ \
.count = n, \
.wait = __WAIT_QUEUE_HEAD_INITIALIZER((name).wait) \
}
#define __MUTEX_INITIALIZER(name) \
__SEMAPHORE_INITIALIZER(name,1)
#define __DECLARE_SEMAPHORE_GENERIC(name,count) \
struct semaphore name = __SEMAPHORE_INITIALIZER(name,count)
#define DECLARE_MUTEX(name) __DECLARE_SEMAPHORE_GENERIC(name,1)
#define DECLARE_MUTEX_LOCKED(name) __DECLARE_SEMAPHORE_GENERIC(name,0)
static void inline down(struct semaphore *sem)
{
wait_event(sem->wait, sem->count > 0);
sem->count--;
}
static void inline up(struct semaphore *sem)
{
sem->count++;
wake_up(&sem->wait);
}
#endif /* _SEMAPHORE_H */
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