jack2/common/jack/eventport.h

/*
    Copyright (C) 2004 Ian Esten

    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_MIDIPORT_H
#define __JACK_MIDIPORT_H

#ifdef __cplusplus
extern "C" {
#endif

#include <jack/weakmacros.h>
#include <jack/types.h>
#include <stdlib.h>


/** Type for raw event data contained in @ref jack_event_event_t. */
typedef unsigned char jack_event_data_t;


/** A Jack event. */
typedef struct _jack_event
{
	jack_nframes_t     time;   /**< Sample index at which event is valid */
	size_t             size;   /**< Number of bytes of data in \a buffer */
	jack_event_data_t *buffer; /**< Raw event data */
} jack_event_t;


/**
 * @defgroup EVENTAPI Reading and writing event data
 * @{
 */

/** Get number of events in a port buffer.
 *
 * @param port_buffer Port buffer from which to retrieve event.
 * @return number of events inside @a port_buffer
 */
uint32_t
jack_event_get_count(void* port_buffer) JACK_OPTIONAL_WEAK_EXPORT;


/** Get an event from an event port buffer. It is up to the caller to determine
 * which protocol to interpret the data with. The port's type and the metadata
 * API should suffice to do so.
 * 
 * If the event represents MIDI data:
 *
 * Jack MIDI is normalised, the MIDI event returned by this function is
 * guaranteed to be a complete MIDI event (the status byte will always be
 * present, and no realtime events will interspered with the event).
 *
 * This rule does not apply to System Exclusive MIDI messages
 * since they can be of arbitrary length.
 * To maintain smooth realtime operation such events CAN be deliverd
 * as multiple, non-normalised events.
 * The maximum size of one event "chunk" depends on the MIDI backend in use.
 * For example the midiseq driver will create chunks of 256 bytes.
 * The first SysEx "chunked" event starts with 0xF0 and the last
 * delivered chunk ends with 0xF7.
 * To receive the full SysEx message, a caller of jack_midi_event_get()
 * must concatenate chunks until a chunk ends with 0xF7.
 *
 * @param event Event structure to store retrieved event in.
 * @param port_buffer Port buffer from which to retrieve event.
 * @param event_index Index of event to retrieve.
 * @return 0 on success, ENODATA if buffer is empty.
 */
int
jack_event_get(jack_event_t *event,
                    void        *port_buffer,
                    uint32_t    event_index) JACK_OPTIONAL_WEAK_EXPORT;


/** Clear an event buffer.
 *
 * This should be called at the beginning of each process cycle before calling
 * @ref jack_event_reserve or @ref jack_event_write. This
 * function may not be called on an input port's buffer.
 *
 * @param port_buffer Port buffer to clear (must be an output port buffer).
 */
void
jack_event_clear_buffer(void *port_buffer) JACK_OPTIONAL_WEAK_EXPORT;

/** Reset an event buffer (from data allocated outside of JACK).
 *
 * This should be called at the beginning of each process cycle before calling
 * @ref jack_event_reserve or @ref jack_event_write. This
 * function may not be called on an input port's buffer.
 *
 * @deprecated Please use jack_event_clear_buffer().
 *
 * @param port_buffer Port buffer to reset.
 */
void
jack_event_reset_buffer(void *port_buffer) JACK_OPTIONAL_WEAK_DEPRECATED_EXPORT;


/** Get the size of the largest event that can be stored by the port.
 *
 * This function returns the current space available, taking into account
 * events already stored in the port.
 *
 * @param port_buffer Port buffer to check size of.
 */
size_t
jack_event_max_size(void* port_buffer) JACK_OPTIONAL_WEAK_EXPORT;


/** Allocate space for an event to be written to an event port buffer.
 *
 * Clients are to write the actual event data to be written starting at the
 * pointer returned by this function. Clients must not write more than
 * @a data_size bytes into this buffer. Clients may write arbitrary binary data,
 * but should only write events using the protocol associated with the port.
 * 
 * If this is a MIDI port, clients must write normalised
 * MIDI data to the port - no running status and no (1-byte) realtime
 * messages interspersed with other messages (realtime messages are fine
 * when they occur on their own, like other messages).
 *
 * Events must be written in order, sorted by their sample offsets.
 * JACK will not sort the events for you, and will refuse to store
 * out-of-order events.
 *
 * @param port_buffer Buffer to write event to.
 * @param time Sample offset of event.
 * @param data_size Length of event's raw data in bytes.
 * @return Pointer to the beginning of the reserved event's data buffer, or
 * NULL on error (ie not enough space).
 */
jack_event_data_t*
jack_event_reserve(void *port_buffer,
                        jack_nframes_t  time,
                        size_t data_size) JACK_OPTIONAL_WEAK_EXPORT;


/** Write an event into an event port buffer.
 *
 * This function is simply a wrapper for @ref jack_event_reserve
 * which writes the event data into the space reserved in the buffer.
 *
 * Clients must not write more than
 * @a data_size bytes into this buffer. Clients may write arbitrary binary data,
 * but should only write events using the protocol associated with the port. 
 * If this is a MIDI port, clients must write normalised
 * MIDI data to the port - no running status and no (1-byte) realtime
 * messages interspersed with other messages (realtime messages are fine
 * when they occur on their own, like other messages).
 *
 * Events must be written in order, sorted by their sample offsets.
 * JACK will not sort the events for you, and will refuse to store
 * out-of-order events.
 *
 * @param port_buffer Buffer to write event to.
 * @param time Sample offset of event.
 * @param data Message data to be written.
 * @param data_size Length of @a data in bytes.
 * @return 0 on success, ENOBUFS if there's not enough space in buffer for event.
 */
int
jack_event_write(void *port_buffer,
                      jack_nframes_t time,
                      const jack_event_data_t *data,
                      size_t data_size) JACK_OPTIONAL_WEAK_EXPORT;


/** Get the number of events that could not be written to @a port_buffer.
 *
 * This function returning a non-zero value implies @a port_buffer is full.
 * Currently the only way this can happen is if events are lost on port mixdown
 * (when multiple event output ports are connected to one input port).
 *
 * @param port_buffer Port to receive count for.
 * @returns Number of events that could not be written to @a port_buffer.
 */
uint32_t
jack_event_get_lost_count(void *port_buffer) JACK_OPTIONAL_WEAK_EXPORT;

/*@}*/

#ifdef __cplusplus
}
#endif


#endif /* __JACK_MIDIPORT_H */