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#ifndef _SEMAPHORE_H_
#define _SEMAPHORE_H_
#include <mini-os/wait.h>
#include <mini-os/spinlock.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;
};
/*
* the semaphore definition
*/
struct rw_semaphore {
signed long count;
spinlock_t wait_lock;
int debug;
};
#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 inline void init_SEMAPHORE(struct semaphore *sem, int count)
{
sem->count = count;
init_waitqueue_head(&sem->wait);
}
#define init_MUTEX(sem) init_SEMAPHORE(sem, 1)
static inline int trydown(struct semaphore *sem)
{
unsigned long flags;
int ret = 0;
local_irq_save(flags);
if (sem->count > 0) {
ret = 1;
sem->count--;
}
local_irq_restore(flags);
return ret;
}
static void inline down(struct semaphore *sem)
{
unsigned long flags;
while (1) {
wait_event(sem->wait, sem->count > 0);
local_irq_save(flags);
if (sem->count > 0)
break;
local_irq_restore(flags);
}
sem->count--;
local_irq_restore(flags);
}
static void inline up(struct semaphore *sem)
{
unsigned long flags;
local_irq_save(flags);
sem->count++;
wake_up(&sem->wait);
local_irq_restore(flags);
}
/* FIXME! Thre read/write semaphores are unimplemented! */
static inline void init_rwsem(struct rw_semaphore *sem)
{
sem->count = 1;
}
static inline void down_read(struct rw_semaphore *sem)
{
}
static inline void up_read(struct rw_semaphore *sem)
{
}
static inline void up_write(struct rw_semaphore *sem)
{
}
static inline void down_write(struct rw_semaphore *sem)
{
}
#endif /* _SEMAPHORE_H */
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