mrbuffer.h

#ifndef _MRBUFFER_H
#define _MRBUFFER_H

#include <sys/types.h>

struct mrbuffer {
  size_t head;
  size_t tail;
  size_t size;
  void *vaddr;
  unsigned int order;
  unsigned int flags;
};

#define MRBUF_FLAG_SHMAT    (0x1U << 0)
#define MRBUF_FLAG_MMAP     (0x1U << 1)

#define MRBUF_IS_SHMAT(x)   (!(!(((x)->flags)&(MRBUF_FLAG_SHMAT))))
#define MRBUF_IS_MMAP(x)    (!(!(((x)->flags)&(MRBUF_FLAG_MMAP))))

#define MRBUF_IS_NOT_SHMAT(x) (!(((x)->flags)&(MRBUF_FLAG_SHMAT)))
#define MRBUF_IS_NOT_MMAP(x)  (!(((x)->flags)&(MRBUF_FLAG_MMAP)))

#define MRBUF_SET_SHMAT(x)    (((x)->flags)|=(MRBUF_FLAG_SHMAT))
#define MRBUF_SET_MMAP(x)   (((x)->flags)|=(MRBUF_FLAG_MMAP))

#define MRBUF_UNSET_SHMAT(x)  (((x)->flags)&=(~(MRBUF_FLAG_SHMAT)))
#define MRBUF_UNSET_MMAP(x)   (((x)->flags)&=(~(MRBUF_FLAG_MMAP)))

#define MRBUF_FREE_LEN(x)   ((x->size - x->head + x->tail - 1UL) % x->size)
#define MRBUF_DATA_LEN(x)   ((x->size - x->tail + x->head) % x->size)

#define MRBUF_READ_ADDR(x)    (x->vaddr + x->tail)
#define MRBUF_WRITE_ADDR(x)   (x->vaddr + x->head)

#define MRBUF_READ_OFFSET(x)    (x->tail)
#define MRBUF_WRITE_OFFSET(x)   (x->head)

#define MRBUF_FULL(x)     (!MRBUF_FREE_LEN(x))
#define MRBUF_EMPTY(x)      (!MRBUF_DATA_LEN(x))

struct mrbuffer *mrbuffer_alloc(unsigned int flags, unsigned int order);
void mrbuffer_free(struct mrbuffer *mrbuf);
size_t mrbuffer_bytes_to_write(struct mrbuffer *mrbuf);
size_t mrbuffer_bytes_to_read(struct mrbuffer *mrbuf);
size_t mrbuffer_write(struct mrbuffer *mrbuf, size_t len, void *data);
size_t mrbuffer_read(struct mrbuffer *mrbuf, size_t len, void *data);
size_t mrbuffer_give(struct mrbuffer *mrbuf, size_t len);
size_t mrbuffer_take(struct mrbuffer *mrbuf, size_t len);

#endif /* _MRBUFFER_H */