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#ifndef FIO_SEQLOCK_H
#define FIO_SEQLOCK_H
#include "types.h"
#include "../arch/arch.h"
struct seqlock {
#ifdef __cplusplus
std::atomic<unsigned int> sequence;
#else
volatile unsigned int sequence;
#endif
};
static inline void seqlock_init(struct seqlock *s)
{
s->sequence = 0;
}
static inline unsigned int read_seqlock_begin(struct seqlock *s)
{
unsigned int seq;
do {
seq = atomic_load_acquire(&s->sequence);
if (!(seq & 1))
break;
nop;
} while (1);
return seq;
}
static inline bool read_seqlock_retry(struct seqlock *s, unsigned int seq)
{
read_barrier();
return s->sequence != seq;
}
static inline void write_seqlock_begin(struct seqlock *s)
{
s->sequence = atomic_load_acquire(&s->sequence) + 1;
}
static inline void write_seqlock_end(struct seqlock *s)
{
atomic_store_release(&s->sequence, s->sequence + 1);
}
#endif
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