/*! \file select.h
 *  select loop abstraction.
 */

#pragma once

#include <osmocom/core/linuxlist.h>
#include <stdbool.h>
#include <time.h>

/*! \defgroup select Select loop abstraction
 *  @{
 * \file select.h */

/*! Indicate interest in reading from the file descriptor */
#define OSMO_FD_READ	0x0001
/*! Indicate interest in writing to the file descriptor */
#define OSMO_FD_WRITE	0x0002
/*! Indicate interest in exceptions from the file descriptor */
#define OSMO_FD_EXCEPT	0x0004

/* legacy naming dating back to early OpenBSC / bsc_hack of 2008 */
#define BSC_FD_READ	OSMO_FD_READ
#define BSC_FD_WRITE	OSMO_FD_WRITE
#define BSC_FD_EXCEPT	OSMO_FD_EXCEPT

/*! Structure representing a file dsecriptor */
struct osmo_fd {
	/*! linked list for internal management */
	struct llist_head list;	
	/*! actual operating-system level file decriptor */
	int fd;
	/*! bit-mask or of \ref OSMO_FD_READ, \ref OSMO_FD_WRITE and/or
	 * \ref OSMO_FD_EXCEPT */
	unsigned int when;
	/*! call-back function to be called once file descriptor becomes
	 * available */
	int (*cb)(struct osmo_fd *fd, unsigned int what);
	/*! data pointer passed through to call-back function */
	void *data;
	/*! private number, extending \a data */
	unsigned int priv_nr;
};

void osmo_fd_setup(struct osmo_fd *ofd, int fd, unsigned int when,
		   int (*cb)(struct osmo_fd *fd, unsigned int what),
		   void *data, unsigned int priv_nr);

bool osmo_fd_is_registered(struct osmo_fd *fd);
int osmo_fd_register(struct osmo_fd *fd);
void osmo_fd_unregister(struct osmo_fd *fd);
void osmo_fd_close(struct osmo_fd *fd);
int osmo_select_main(int polling);

struct osmo_fd *osmo_fd_get_by_fd(int fd);

/*
 * foreign event loop integration
 */
int osmo_fd_fill_fds(void *readset, void *writeset, void *exceptset);
int osmo_fd_disp_fds(void *readset, void *writeset, void *exceptset);

/* timerfd integration */
int osmo_timerfd_disable(struct osmo_fd *ofd);
int osmo_timerfd_schedule(struct osmo_fd *ofd, const struct timespec *first,
			  const struct timespec *interval);
int osmo_timerfd_setup(struct osmo_fd *ofd, int (*cb)(struct osmo_fd *, unsigned int), void *data);

/*! @} */