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/*
* Operating system kernel abstraction -- reference counting.
*
* Copyright (C) 2010 Cambridge Silicon Radio Ltd.
*
* Refer to LICENSE.txt included with this source code for details on
* the license terms.
*/
#ifndef __OSKA_REFCOUNT_H
#define __OSKA_REFCOUNT_H
#include "spinlock.h"
/**
* @defgroup refcount Reference Counting
*
* A reference count is an atomic counter. A callback function is
* called whenever the count reaches zero.
*
* A generic implementation is provided that is suitable for all
* platforms that support the spinlock API in <oska/spinlock.h> (see
* \ref spinlock).
*/
typedef void (*os_refcount_callback_f)(void *arg);
struct __os_refcount_impl {
unsigned count;
os_spinlock_t lock;
os_refcount_callback_f func;
void *arg;
};
/**
* A reference count object.
*
* @ingroup refcount
*/
typedef struct __os_refcount_impl os_refcount_t;
/**
* Initialize a reference count to 1.
*
* Initialized reference counts must be destroyed by calling
* os_refcount_destroy().
*
* @param refcount the reference count.
* @param func the function which will be called when the
* reference count reaches 0.
* @param arg an argument to pass to func.
*
* @ingroup refcount
*/
void os_refcount_init(os_refcount_t *refcount, os_refcount_callback_f func, void *arg);
/**
* Destroy a reference count object.
*
* @param refcount the reference count.
*
* @ingroup refcount
*/
void os_refcount_destroy(os_refcount_t *refcount);
/**
* Atomically increase the reference count by 1.
*
* @param refcount the reference count.
*
* @ingroup refcount
*/
void os_refcount_get(os_refcount_t *refcount);
/**
* Atomically decrease the reference count by 1.
*
* The callback function passed to the call to os_refcount_init() is
* called if the count was decreased to zero.
*
* @param refcount the reference count.
*
* @ingroup refcount
*/
void os_refcount_put(os_refcount_t *refcount);
#endif /* #ifndef __OSKA_REFCOUNT_H */
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