refcnt.h

/*
 * Reference counting API.
 *
 * By definition a reference count is always a positive value. The object should
 * be freed when the count reaches 0 (by means of refcnt_put()), and any further
 * attempts to increase this count will panic.
 */
 
#ifndef KERNEL_REFCNT_H
#define KERNEL_REFCNT_H
 
#include <kernel/atomic.h>
#include <kernel/logger.h>
 
typedef atomic_t refcnt_t;
 
static inline void refcnt_init(refcnt_t *ref)
{
    atomic_write(ref, 1);
}
 
#define REFCNT_INIT_STATIC() ((refcnt_t){.val = 1})
 
static inline unsigned int refcnt_read(refcnt_t *ref)
{
    return atomic_read(ref);
}
 
static inline unsigned int refcnt_get(refcnt_t *ref)
{
    unsigned int refs;
 
    /*
     * All references to this object have been released already.
     * Do not 'resurrect' it as it may have been scheduled to be
     * garbage collected (e.g. process API).
     */
    refs = atomic_inc(ref);
    ASSERT(refs > 0);
 
    return refs;
}
 
static inline unsigned int refcnt_put(refcnt_t *ref)
{
    return atomic_dec(ref) - 1;
}
 
#endif /* KERNEL_REFCNT_H */