jack1/jack/jack.h

/*
    Copyright (C) 2001 Paul Davis
    Copyright (C) 2004 Jack O'Quin
    
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU Lesser General Public License as published by
    the Free Software Foundation; either version 2.1 of the License, or
    (at your option) any later version.
    
    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU Lesser General Public License for more details.
    
    You should have received a copy of the GNU Lesser General Public License
    along with this program; if not, write to the Free Software 
    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.

*/

#ifndef __jack_h__
#define __jack_h__

#ifdef __cplusplus
extern "C" {
#endif

#include <pthread.h>

#include <jack/types.h>
#include <jack/transport.h>

/**
 * Note: More documentation can be found in jack/types.h.
 */

/**
 * Open an external client session with a JACK server.  This interface
 * is more complex but more powerful than jack_client_new().  With it,
 * clients may choose which of several servers to connect, and control
 * whether and how to start the server automatically, if it was not
 * already running.  There is also an option for JACK to generate a
 * unique client name, when necessary.
 *
 * @param client_name of at most jack_client_name_size() characters.
 * The name scope is local to each server.  Unless forbidden by the
 * @ref JackUseExactName option, the server will modify this name to
 * create a unique variant, if needed.
 *
 * @param options formed by OR-ing together @ref JackOptions bits.
 * Only the @ref JackOpenOptions bits are allowed.
 *
 * @param status (if non-NULL) an address for JACK to return
 * information from the open operation.  This status word is formed by
 * OR-ing together the relevant @ref JackStatus bits.
 *
 *
 * <b>Optional parameters:</b> depending on corresponding [@a options
 * bits] additional parameters may follow @a status (in this order).
 *
 * @arg [@ref JackServerName] <em>(char *) server_name</em> selects
 * from among several possible concurrent server instances.  Server
 * names are unique to each user.  If unspecified, use "default"
 * unless \$JACK_DEFAULT_SERVER is defined in the process environment.
 *
 * @return Opaque client handle if successful.  If this is NULL, the
 * open operation failed, @a *status includes @ref JackFailure and the
 * caller is not a JACK client.
 */
jack_client_t *jack_client_open (const char *client_name,
				 jack_options_t options,
				 jack_status_t *status, ...);

/**
 * \bold THIS FUNCTION IS DEPRECATED AND SHOULD NOT BE USED IN
 *  NEW JACK CLIENTS
 *
 */
jack_client_t *jack_client_new (const char *client_name);

/**
 * Disconnects an external client from a JACK server.
 *
 * @return 0 on success, otherwise a non-zero error code
 */
int jack_client_close (jack_client_t *client);

/**
 * @return the maximum number of characters in a JACK client name
 * including the final NULL character.  This value is a constant.
 */
int jack_client_name_size (void);

/**
 * @return pointer to actual client name.  This is useful when @ref
 * JackUseExactName is not specified on open and @ref
 * JackNameNotUnique status was returned.  In that case, the actual
 * name will differ from the @a client_name requested.
 */
char *jack_get_client_name (jack_client_t *client);

/**
 * Load an internal client into the Jack server.
 *
 * Internal clients run inside the JACK server process.  They can use
 * most of the same functions as external clients.  Each internal
 * client must declare jack_initialize() and jack_finish() entry
 * points, called at load and unload times.  See inprocess.c for an
 * example of how to write an internal client.
 *
 * @deprecated Please use jack_internal_client_load().
 *
 * @param client_name of at most jack_client_name_size() characters.
 *
 * @param load_name of a shared object file containing the code for
 * the new client.
 *
 * @param load_init an arbitary string passed to the jack_initialize()
 * routine of the new client (may be NULL).
 *
 * @return 0 if successful.
 */
int jack_internal_client_new (const char *client_name,
			      const char *load_name,
			      const char *load_init);

/**
 * Remove an internal client from a JACK server.
 *
 * @deprecated Please use jack_internal_client_load().
 */
void jack_internal_client_close (const char *client_name);

/**
 * @param client pointer to JACK client structure.
 *
 * Check if the JACK subsystem is running with -R (--realtime).
 *
 * @return 1 if JACK is running realtime, 0 otherwise
 */
int jack_is_realtime (jack_client_t *client);

/** 
 * @param client pointer to JACK client structure.
 * @param function The jack_shutdown function pointer.
 * @param arg The arguments for the jack_shutdown function.
 *
 * Register a function (and argument) to be called if and when the
 * JACK server shuts down the client thread.  The function must
 * be written as if it were an asynchonrous POSIX signal
 * handler --- use only async-safe functions, and remember that it
 * is executed from another thread.  A typical function might
 * set a flag or write to a pipe so that the rest of the
 * application knows that the JACK client thread has shut
 * down.
 *
 * NOTE: clients do not need to call this.  It exists only
 * to help more complex clients understand what is going
 * on.  It should be called before jack_client_activate().
 */
void jack_on_shutdown (jack_client_t *client,
		       void (*function)(void *arg), void *arg);

/**
 * Tell the Jack server to call @a process_callback whenever there is
 * work be done, passing @a arg as the second argument.
 *
 * The code in the supplied function must be suitable for real-time
 * execution.  That means that it cannot call functions that might
 * block for a long time.  This includes malloc, free, printf,
 * pthread_mutex_lock, sleep, wait, poll, select, pthread_join,
 * pthread_cond_wait, etc, etc.  See
 * http://jackit.sourceforge.net/docs/design/design.html#SECTION00411000000000000000
 * for more information.
 *
 * @return 0 on success, otherwise a non-zero error code, causing JACK
 * to remove that client from the process() graph.
 */
int jack_set_process_callback (jack_client_t *client,
			       JackProcessCallback process_callback,
			       void *arg);
/**
 * Block until this JACK client should process data.
 * 
 * The @a status argument typically indicates the result
 * of some recent data processing.
 * 
 * @param client - pointer to a JACK client structure
 * @param status - if non-zero, calling thread should exit
 *
 * @return the number of frames of data to process
 */
jack_nframes_t jack_thread_wait (jack_client_t*, int status);

/**
 * Tell JACK to call @a thread_init_callback once just after
 * the creation of the thread in which all other callbacks 
 * will be handled.
 *
 * The code in the supplied function does not need to be
 * suitable for real-time execution.
 *
 * @return 0 on success, otherwise a non-zero error code, causing JACK
 * to remove that client from the process() graph.
 */
int jack_set_thread_init_callback (jack_client_t *client,
				   JackThreadInitCallback thread_init_callback,
				   void *arg);

/**
 * Tell the Jack server to call @a freewheel_callback
 * whenever we enter or leave "freewheel" mode, passing @a
 * arg as the second argument. The first argument to the
 * callback will be non-zero if JACK is entering freewheel
 * mode, and zero otherwise.
 *
 * @return 0 on success, otherwise a non-zero error code.
 */
int jack_set_freewheel_callback (jack_client_t *client,
				 JackFreewheelCallback freewheel_callback,
				 void *arg);

/**
 * Start/Stop JACK's "freewheel" mode.
 *
 * When in "freewheel" mode, JACK no longer waits for
 * any external event to begin the start of the next process
 * cycle. 
 *
 * As a result, freewheel mode causes "faster than realtime"
 * execution of a JACK graph. If possessed, real-time
 * scheduling is dropped when entering freewheel mode, and
 * if appropriate it is reacquired when stopping.
 * 
 * IMPORTANT: on systems using capabilities to provide real-time
 * scheduling (i.e. Linux kernel 2.4), if onoff is zero, this function
 * must be called from the thread that originally called jack_activate(). 
 * This restriction does not apply to other systems (e.g. Linux kernel 2.6 
 * or OS X).
 * 
 * @param client pointer to JACK client structure
 * @param onoff  if non-zero, freewheel mode starts. Otherwise
 *                  freewheel mode ends.
 *
 * @return 0 on success, otherwise a non-zero error code.
 */
int jack_set_freewheel(jack_client_t* client, int onoff);

/**
 * Change the buffer size passed to the @a process_callback.
 *
 * This operation stops the JACK engine process cycle, then calls all
 * registered @a bufsize_callback functions before restarting the
 * process cycle.  This will cause a gap in the audio flow, so it
 * should only be done at appropriate stopping points.
 *
 * @see jack_set_buffer_size_callback()
 *
 * @param client pointer to JACK client structure.
 * @param nframes new buffer size.  Must be a power of two.
 *
 * @return 0 on success, otherwise a non-zero error code
 */
int jack_set_buffer_size (jack_client_t *client, jack_nframes_t nframes);

/**
 * Tell JACK to call @a bufsize_callback whenever the size of the the
 * buffer that will be passed to the @a process_callback is about to
 * change.  Clients that depend on knowing the buffer size must supply
 * a @a bufsize_callback before activating themselves.
 *
 * @param client pointer to JACK client structure.
 * @param bufsize_callback function to call when the buffer size changes.
 * @param arg argument for @a bufsize_callback.
 *
 * @return 0 on success, otherwise a non-zero error code
 */
int jack_set_buffer_size_callback (jack_client_t *client,
				   JackBufferSizeCallback bufsize_callback,
				   void *arg);

/**
 * Tell the Jack server to call @a srate_callback whenever the system
 * sample rate changes.
 *
 * @return 0 on success, otherwise a non-zero error code
 */
int jack_set_sample_rate_callback (jack_client_t *client,
				   JackSampleRateCallback srate_callback,
				   void *arg);

/**
 * Tell the JACK server to call @a registration_callback whenever a
 * port is registered or unregistered, passing @a arg as a parameter.
 *
 * @return 0 on success, otherwise a non-zero error code
 */
int jack_set_client_registration_callback (jack_client_t *,
					   JackClientRegistrationCallback
					   registration_callback, void *arg);
	
/**
 * Tell the JACK server to call @a registration_callback whenever a
 * port is registered or unregistered, passing @a arg as a parameter.
 *
 * @return 0 on success, otherwise a non-zero error code
 */
int jack_set_port_registration_callback (jack_client_t *,
					 JackPortRegistrationCallback
					 registration_callback, void *arg);

/**
 * Tell the JACK server to call @a connect_callback whenever a
 * port is connected or disconnected, passing @a arg as a parameter.
 *
 * @return 0 on success, otherwise a non-zero error code
 */
int jack_set_port_connect_callback (jack_client_t *,
				    JackPortConnectCallback
				    connect_callback, void *arg);
/**
 * Tell the JACK server to call @a graph_callback whenever the
 * processing graph is reordered, passing @a arg as a parameter.
 *
 * @return 0 on success, otherwise a non-zero error code
 */
int jack_set_graph_order_callback (jack_client_t *,
				   JackGraphOrderCallback graph_callback,
				   void *);

/**
 * Tell the JACK server to call @a xrun_callback whenever there is a
 * xrun, passing @a arg as a parameter.
 *
 * @return 0 on success, otherwise a non-zero error code
 */
int jack_set_xrun_callback (jack_client_t *,
			    JackXRunCallback xrun_callback, void *arg);

/**
 * Tell the Jack server that the program is ready to start processing
 * audio.
 *
 * @return 0 on success, otherwise a non-zero error code
 */
int jack_activate (jack_client_t *client);

/**
 * Tell the Jack server to remove this @a client from the process
 * graph.  Also, disconnect all ports belonging to it, since inactive
 * clients have no port connections.
 *
 * @return 0 on success, otherwise a non-zero error code
 */
int jack_deactivate (jack_client_t *client);

/**
 * Create a new port for the client. This is an object used for moving
 * data of any type in or out of the client.  Ports may be connected
 * in various ways.
 *
 * Each port has a short name.  The port's full name contains the name
 * of the client concatenated with a colon (:) followed by its short
 * name.  The jack_port_name_size() is the maximum length of this full
 * name.  Exceeding that will cause the port registration to fail and
 * return NULL.
 *
 * All ports have a type, which may be any non-NULL and non-zero
 * length string, passed as an argument.  Some port types are built
 * into the JACK API, currently only JACK_DEFAULT_AUDIO_TYPE.
 *
 * @param client pointer to JACK client structure.
 * @param port_name non-empty short name for the new port (not
 * including the leading @a "client_name:").
 * @param port_type port type name.  If longer than
 * jack_port_type_size(), only that many characters are significant.
 * @param flags @ref JackPortFlags bit mask.
 * @param buffer_size must be non-zero if this is not a built-in @a
 * port_type.  Otherwise, it is ignored.
 *
 * @return jack_port_t pointer on success, otherwise NULL.
 */
jack_port_t *jack_port_register (jack_client_t *client,
                                 const char *port_name,
                                 const char *port_type,
                                 unsigned long flags,
                                 unsigned long buffer_size);

/** 
 * Remove the port from the client, disconnecting any existing
 * connections.
 *
 * @return 0 on success, otherwise a non-zero error code
 */
int jack_port_unregister (jack_client_t *, jack_port_t *);

/**
 * This returns a pointer to the memory area associated with the
 * specified port. For an output port, it will be a memory area
 * that can be written to; for an input port, it will be an area
 * containing the data from the port's connection(s), or
 * zero-filled. if there are multiple inbound connections, the data
 * will be mixed appropriately.  
 *
 * FOR OUTPUT PORTS ONLY
 * ---------------------
 * You may cache the value returned, but only between calls to
 * your "blocksize" callback. For this reason alone, you should
 * either never cache the return value or ensure you have
 * a "blocksize" callback and be sure to invalidate the cached
 * address from there.
 */
void *jack_port_get_buffer (jack_port_t *, jack_nframes_t);

/**
 * @return the full name of the jack_port_t (including the @a
 * "client_name:" prefix).
 *
 * @see jack_port_name_size().
 */
const char *jack_port_name (const jack_port_t *port);

/**
 * @return the short name of the jack_port_t (not including the @a
 * "client_name:" prefix).
 *
 * @see jack_port_name_size().
 */
const char *jack_port_short_name (const jack_port_t *port);

/**
 * @return the @ref JackPortFlags of the jack_port_t.
 */
int jack_port_flags (const jack_port_t *port);

/**
 * @return the @a port type, at most jack_port_type_size() characters
 * including a final NULL.
 */
const char *jack_port_type (const jack_port_t *port);

/** 
 * @return TRUE if the jack_port_t belongs to the jack_client_t.
 */
int jack_port_is_mine (const jack_client_t *, const jack_port_t *port);

/** 
 * @return number of connections to or from @a port.
 *
 * @pre The calling client must own @a port.
 */
int jack_port_connected (const jack_port_t *port);

/**
 * @return TRUE if the locally-owned @a port is @b directly connected
 * to the @a port_name.
 *
 * @see jack_port_name_size()
 */
int jack_port_connected_to (const jack_port_t *port,
			    const char *port_name);

/**
 * @return a null-terminated array of full port names to which the @a
 * port is connected.  If none, returns NULL.
 *
 * The caller is responsible for calling free(3) on any non-NULL
 * returned value.
 *
 * @param port locally owned jack_port_t pointer.
 *
 * @see jack_port_name_size(), jack_port_get_all_connections()
 */   
const char **jack_port_get_connections (const jack_port_t *port);

/**
 * @return a null-terminated array of full port names to which the @a
 * port is connected.  If none, returns NULL.
 *
 * The caller is responsible for calling free(3) on any non-NULL
 * returned value.
 *
 * This differs from jack_port_get_connections() in two important
 * respects:
 *
 *     1) You may not call this function from code that is
 *          executed in response to a JACK event. For example,
 *          you cannot use it in a GraphReordered handler.
 *
 *     2) You need not be the owner of the port to get information
 *          about its connections. 
 *
 * @see jack_port_name_size()
 */   
const char **jack_port_get_all_connections (const jack_client_t *client,
					    const jack_port_t *port);

/**
 * A client may call this on a pair of its own ports to 
 * semi-permanently wire them together. This means that
 * a client that wants to direct-wire an input port to
 * an output port can call this and then no longer
 * have to worry about moving data between them. Any data
 * arriving at the input port will appear automatically
 * at the output port.
 *
 * The 'destination' port must be an output port. The 'source'
 * port must be an input port. Both ports must belong to
 * the same client. You cannot use this to tie ports between
 * clients. That is what a connection is for.
 *
 * @return 0 on success, otherwise a non-zero error code
 */
int  jack_port_tie (jack_port_t *src, jack_port_t *dst);

/**
 * This undoes the effect of jack_port_tie(). The port
 * should be same as the 'destination' port passed to
 * jack_port_tie().
 *
 * @return 0 on success, otherwise a non-zero error code
 */
int  jack_port_untie (jack_port_t *port);

/** 
 * @return the time (in frames) between data being available or
 * delivered at/to a port, and the time at which it arrived at or is
 * delivered to the "other side" of the port.  E.g. for a physical
 * audio output port, this is the time between writing to the port and
 * when the signal will leave the connector.  For a physical audio
 * input port, this is the time between the sound arriving at the
 * connector and the corresponding frames being readable from the
 * port.
 */
jack_nframes_t jack_port_get_latency (jack_port_t *port);

/**
 * The maximum of the sum of the latencies in every
 * connection path that can be drawn between the port and other
 * ports with the @ref JackPortIsTerminal flag set.
 */
jack_nframes_t jack_port_get_total_latency (jack_client_t *,
					    jack_port_t *port);

/**
 * The port latency is zero by default. Clients that control
 * physical hardware with non-zero latency should call this
 * to set the latency to its correct value. Note that the value
 * should include any systemic latency present "outside" the
 * physical hardware controlled by the client. For example,
 * for a client controlling a digital audio interface connected
 * to an external digital converter, the latency setting should
 * include both buffering by the audio interface *and* the converter. 
 */
void jack_port_set_latency (jack_port_t *, jack_nframes_t);
	
/**
 * Request a complete recomputation of a port's total latency. This
 * can be called by a client that has just changed the internal
 * latency of its port using @function jack_port_set_latency
 * and wants to ensure that all signal pathways in the graph
 * are updated with respect to the values that will be returned
 * by @function jack_port_get_total_latency. 
 * 
 * @return zero for successful execution of the request. non-zero
 *         otherwise.
 */
int jack_recompute_total_latency (jack_client_t*, jack_port_t* port);

/**
 * Request a complete recomputation of all port latencies. This
 * can be called by a client that has just changed the internal
 * latency of its port using @function jack_port_set_latency
 * and wants to ensure that all signal pathways in the graph
 * are updated with respect to the values that will be returned
 * by @function jack_port_get_total_latency. It allows a client 
 * to change multiple port latencies without triggering a 
 * recompute for each change.
 * 
 * @return zero for successful execution of the request. non-zero
 *         otherwise.
 */
int jack_recompute_total_latencies (jack_client_t*);

/**
 * Modify a port's short name.  May be called at any time.  If the
 * resulting full name (including the @a "client_name:" prefix) is
 * longer than jack_port_name_size(), it will be truncated.
 *
 * @return 0 on success, otherwise a non-zero error code.
 */
int jack_port_set_name (jack_port_t *port, const char *port_name);

/**
 * Set @a alias as an alias for @a port.  May be called at any time.
 * If the alias is longer than jack_port_name_size(), it will be truncated.
 * 
 * After a successful call, and until JACK exits or
 * @function jack_port_unset_alias() is called, @alias may be
 * used as a alternate name for the port.
 *
 * Ports can have up to two aliases - if both are already 
 * set, this function will return an error.
 *
 * @return 0 on success, otherwise a non-zero error code.
 */
int jack_port_set_alias (jack_port_t *port, const char *alias);

/**
 * Remove @a alias as an alias for @a port.  May be called at any time.
 * 
 * After a successful call, @a alias can no longer be 
 * used as a alternate name for the port.
 *
 * @return 0 on success, otherwise a non-zero error code.
 */
int jack_port_unset_alias (jack_port_t *port, const char *alias);

/*
 * Get any aliases known for @port.
 *
 * @return the number of aliases discovered for the port
 */
int jack_port_get_aliases (const jack_port_t *port, char* const aliases[2]);

/**
 * If @ref JackPortCanMonitor is set for this @a port, turn input
 * monitoring on or off.  Otherwise, do nothing.
 */
int jack_port_request_monitor (jack_port_t *port, int onoff);

/**
 * If @ref JackPortCanMonitor is set for this @a port_name, turn input
 * monitoring on or off.  Otherwise, do nothing.
 *
 * @return 0 on success, otherwise a non-zero error code.
 *
 * @see jack_port_name_size()
 */
int jack_port_request_monitor_by_name (jack_client_t *client,
				       const char *port_name, int onoff);

/**
 * If @ref JackPortCanMonitor is set for a port, this function turns
 * on input monitoring if it was off, and turns it off if only one
 * request has been made to turn it on.  Otherwise it does nothing.
 *
 * @return 0 on success, otherwise a non-zero error code
 */
int jack_port_ensure_monitor (jack_port_t *port, int onoff);

/**
 * @return TRUE if input monitoring has been requested for @a port.
 */
int jack_port_monitoring_input (jack_port_t *port);

/**
 * Establish a connection between two ports.
 *
 * When a connection exists, data written to the source port will
 * be available to be read at the destination port.
 *
 * @pre The port types must be identical.
 *
 * @pre The @ref JackPortFlags of the @a source_port must include @ref
 * JackPortIsOutput.
 *
 * @pre The @ref JackPortFlags of the @a destination_port must include
 * @ref JackPortIsInput.
 *
 * @return 0 on success, EEXIST if the connection is already made,
 * otherwise a non-zero error code
 */
int jack_connect (jack_client_t *,
		  const char *source_port,
		  const char *destination_port);

/**
 * Remove a connection between two ports.
 *
 * @pre The port types must be identical.
 *
 * @pre The @ref JackPortFlags of the @a source_port must include @ref
 * JackPortIsOutput.
 *
 * @pre The @ref JackPortFlags of the @a destination_port must include
 * @ref JackPortIsInput.
 *
 * @return 0 on success, otherwise a non-zero error code
 */
int jack_disconnect (jack_client_t *,
		     const char *source_port,
		     const char *destination_port);

/**
 * Perform the same function as jack_disconnect() using port handles
 * rather than names.  This avoids the name lookup inherent in the
 * name-based version.
 *
 * Clients connecting their own ports are likely to use this function,
 * while generic connection clients (e.g. patchbays) would use
 * jack_disconnect().
 */
int jack_port_disconnect (jack_client_t *, jack_port_t *);

/**
 * @return the maximum number of characters in a full JACK port name
 * including the final NULL character.  This value is a constant.
 *
 * A port's full name contains the owning client name concatenated
 * with a colon (:) followed by its short name and a NULL
 * character.
 */
int jack_port_name_size(void);

/**
 * @return the maximum number of characters in a JACK port type name
 * including the final NULL character.  This value is a constant.
 */
int jack_port_type_size(void);

/**
 * @return the sample rate of the jack system, as set by the user when
 * jackd was started.
 */
jack_nframes_t jack_get_sample_rate (jack_client_t *);

/**
 * @return the current maximum size that will ever be passed to the @a
 * process_callback.  It should only be used *before* the client has
 * been activated.  This size may change, clients that depend on it
 * must register a @a bufsize_callback so they will be notified if it
 * does.
 *
 * @see jack_set_buffer_size_callback()
 */
jack_nframes_t jack_get_buffer_size (jack_client_t *);

/**
 * @param port_name_pattern A regular expression used to select 
 * ports by name.  If NULL or of zero length, no selection based 
 * on name will be carried out.
 * @param type_name_pattern A regular expression used to select 
 * ports by type.  If NULL or of zero length, no selection based 
 * on type will be carried out.
 * @param flags A value used to select ports by their flags.  
 * If zero, no selection based on flags will be carried out.
 *
 * @return a NULL-terminated array of ports that match the specified
 * arguments.  The caller is responsible for calling free(3) any
 * non-NULL returned value.
 *
 * @see jack_port_name_size(), jack_port_type_size()
 */
const char **jack_get_ports (jack_client_t *, 
			     const char *port_name_pattern, 
			     const char *type_name_pattern, 
			     unsigned long flags);

/**
 * @return address of the jack_port_t named @a port_name.
 *
 * @see jack_port_name_size()
 */
jack_port_t *jack_port_by_name (jack_client_t *, const char *port_name);

/**
 * @return address of the jack_port_t of a @a port_id.
 */
jack_port_t *jack_port_by_id (jack_client_t *client,
			      jack_port_id_t port_id);

/**
 * Old-style interface to become the timebase for the entire JACK
 * subsystem.
 *
 * @deprecated This function still exists for compatibility with the
 * earlier transport interface, but it does nothing.  Instead, see
 * transport.h and use jack_set_timebase_callback().
 *
 * @return ENOSYS, function not implemented.
 */
int  jack_engine_takeover_timebase (jack_client_t *);

/**
 * @return the time in frames that has passed since the JACK server
 * began the current process cycle.
 */
jack_nframes_t jack_frames_since_cycle_start (const jack_client_t *);

/**
 * @return an estimate of the current time in frames.  This is a
 * running counter, no significance should be attached to its value,
 * but it can be compared to a previously returned value.
 */
jack_nframes_t jack_frame_time (const jack_client_t *);

/**
 * @return the frame_time after the last processing of the graph
 * this is only to be used from the process callback. 
 *
 * This function can be used to put timestamps generated by 
 * jack_frame_time() in correlation to the current process cycle.
 */
jack_nframes_t jack_last_frame_time (const jack_client_t *client);

/**
 * @return estimated time in microseconds of the specified frame time
 */
jack_time_t jack_frames_to_time(const jack_client_t *client, jack_nframes_t);

/**
 * @return estimated time in frames for the specified system time.
 */
jack_nframes_t jack_time_to_frames(const jack_client_t *client, jack_time_t);

/**
 * @return return JACK's current system time in microseconds,
 *         using JACK clock source. 
 * 
 * The value returned is guaranteed to be monotonic, but not linear.
 *
 * This function is a client version of @function jack_get_microseconds().
 */
jack_time_t jack_get_time();

/**
 * @return the current CPU load estimated by JACK.  This is a running
 * average of the time it takes to execute a full process cycle for
 * all clients as a percentage of the real time available per cycle
 * determined by the buffer size and sample rate.
 */
float jack_cpu_load (jack_client_t *client);
	
/**
 * @return the pthread ID of the thread running the JACK client side
 * code.
 */
pthread_t jack_client_thread_id (jack_client_t *);

/**
 * Display JACK error message.
 *
 * Set via jack_set_error_function(), otherwise a JACK-provided
 * default will print @a msg (plus a newline) to stderr.
 *
 * @param msg error message text (no newline at end).
 */
extern void (*jack_error_callback)(const char *msg);

/**
 * Set the @ref jack_error_callback for error message display.
 *
 * The JACK library provides two built-in callbacks for this purpose:
 * default_jack_error_callback() and silent_jack_error_callback().
 */
void jack_set_error_function (void (*func)(const char *));

/**
 * Display JACK info message.
 *
 * Set via jack_set_info_function(), otherwise a JACK-provided
 * default will print @a msg (plus a newline) to stdout.
 *
 * @param msg info message text (no newline at end).
 */
extern void (*jack_info_callback)(const char *msg);

/**
 * Set the @ref jack_info_callback for info message display.
 */
void jack_set_info_function (void (*func)(const char *));

#ifdef __cplusplus
}
#endif

#endif /* __jack_h__ */