#ifndef LIB_URING_H
  #define LIB_URING_H

  #ifdef __cplusplus
  extern "C" {
  #endif

  #include <sys/uio.h>
  #include <signal.h>
  #include <string.h>
  #include "../../include/uapi/linux/io_uring.h"

  #include <inttypes.h>
  #include "barrier.h"

  
  /*
   * Library interface to io_uring
   */
  struct io_uring_sq {
  	unsigned *khead;
  	unsigned *ktail;
  	unsigned *kring_mask;
  	unsigned *kring_entries;
  	unsigned *kflags;
  	unsigned *kdropped;
  	unsigned *array;
  	struct io_uring_sqe *sqes;
  
  	unsigned sqe_head;
  	unsigned sqe_tail;
  
  	size_t ring_sz;
  };
  
  struct io_uring_cq {
  	unsigned *khead;
  	unsigned *ktail;
  	unsigned *kring_mask;
  	unsigned *kring_entries;
  	unsigned *koverflow;
  	struct io_uring_cqe *cqes;
  
  	size_t ring_sz;
  };
  
  struct io_uring {
  	struct io_uring_sq sq;
  	struct io_uring_cq cq;
  	int ring_fd;
  };
  
  /*
   * System calls
   */
  extern int io_uring_setup(unsigned entries, struct io_uring_params *p);

  extern int io_uring_enter(int fd, unsigned to_submit,

  	unsigned min_complete, unsigned flags, sigset_t *sig);
  extern int io_uring_register(int fd, unsigned int opcode, void *arg,
  	unsigned int nr_args);
  
  /*
   * Library interface
   */
  extern int io_uring_queue_init(unsigned entries, struct io_uring *ring,
  	unsigned flags);
  extern int io_uring_queue_mmap(int fd, struct io_uring_params *p,
  	struct io_uring *ring);
  extern void io_uring_queue_exit(struct io_uring *ring);

  extern int io_uring_peek_cqe(struct io_uring *ring,

  	struct io_uring_cqe **cqe_ptr);

  extern int io_uring_wait_cqe(struct io_uring *ring,

  	struct io_uring_cqe **cqe_ptr);
  extern int io_uring_submit(struct io_uring *ring);
  extern struct io_uring_sqe *io_uring_get_sqe(struct io_uring *ring);
  
  /*

   * Must be called after io_uring_{peek,wait}_cqe() after the cqe has
   * been processed by the application.
   */
  static inline void io_uring_cqe_seen(struct io_uring *ring,
  				     struct io_uring_cqe *cqe)
  {
  	if (cqe) {
  		struct io_uring_cq *cq = &ring->cq;
  
  		(*cq->khead)++;
  		/*
  		 * Ensure that the kernel sees our new head, the kernel has
  		 * the matching read barrier.
  		 */
  		write_barrier();
  	}
  }
  
  /*

   * Command prep helpers
   */
  static inline void io_uring_sqe_set_data(struct io_uring_sqe *sqe, void *data)
  {
  	sqe->user_data = (unsigned long) data;
  }

  static inline void *io_uring_cqe_get_data(struct io_uring_cqe *cqe)
  {
  	return (void *) (uintptr_t) cqe->user_data;
  }

  static inline void io_uring_prep_rw(int op, struct io_uring_sqe *sqe, int fd,

  				    const void *addr, unsigned len,
  				    off_t offset)

  {
  	memset(sqe, 0, sizeof(*sqe));
  	sqe->opcode = op;
  	sqe->fd = fd;
  	sqe->off = offset;
  	sqe->addr = (unsigned long) addr;
  	sqe->len = len;
  }
  
  static inline void io_uring_prep_readv(struct io_uring_sqe *sqe, int fd,

  				       const struct iovec *iovecs,
  				       unsigned nr_vecs, off_t offset)

  {
  	io_uring_prep_rw(IORING_OP_READV, sqe, fd, iovecs, nr_vecs, offset);
  }
  
  static inline void io_uring_prep_read_fixed(struct io_uring_sqe *sqe, int fd,
  					    void *buf, unsigned nbytes,
  					    off_t offset)
  {
  	io_uring_prep_rw(IORING_OP_READ_FIXED, sqe, fd, buf, nbytes, offset);
  }
  
  static inline void io_uring_prep_writev(struct io_uring_sqe *sqe, int fd,

  					const struct iovec *iovecs,
  					unsigned nr_vecs, off_t offset)

  {
  	io_uring_prep_rw(IORING_OP_WRITEV, sqe, fd, iovecs, nr_vecs, offset);
  }
  
  static inline void io_uring_prep_write_fixed(struct io_uring_sqe *sqe, int fd,

  					     const void *buf, unsigned nbytes,

  					     off_t offset)
  {
  	io_uring_prep_rw(IORING_OP_WRITE_FIXED, sqe, fd, buf, nbytes, offset);
  }
  
  static inline void io_uring_prep_poll_add(struct io_uring_sqe *sqe, int fd,
  					  short poll_mask)
  {
  	memset(sqe, 0, sizeof(*sqe));
  	sqe->opcode = IORING_OP_POLL_ADD;
  	sqe->fd = fd;
  	sqe->poll_events = poll_mask;
  }
  
  static inline void io_uring_prep_poll_remove(struct io_uring_sqe *sqe,
  					     void *user_data)
  {
  	memset(sqe, 0, sizeof(*sqe));
  	sqe->opcode = IORING_OP_POLL_REMOVE;
  	sqe->addr = (unsigned long) user_data;
  }
  
  static inline void io_uring_prep_fsync(struct io_uring_sqe *sqe, int fd,

  				       unsigned fsync_flags)

  {
  	memset(sqe, 0, sizeof(*sqe));
  	sqe->opcode = IORING_OP_FSYNC;
  	sqe->fd = fd;

  	sqe->fsync_flags = fsync_flags;
  }
  
  static inline void io_uring_prep_nop(struct io_uring_sqe *sqe)
  {
  	memset(sqe, 0, sizeof(*sqe));
  	sqe->opcode = IORING_OP_NOP;
  }
  
  #ifdef __cplusplus

  }

  #endif

  
  #endif