MIDI Sequencer

Modules
	Sequencer Client Interface
	Sequencer Port Interface
	Sequencer Port Subscription
	Sequencer Queue Interface
	Sequencer Event API
	Sequencer Miscellaneous
	Sequencer Event Type Checks
	Sequencer Event Definitions
	Sequencer Middle Level Interface
	Sequencer event <-> MIDI byte stream coder
Defines
#define	SND_SEQ_DLSYM_VERSION   _dlsym_seq_001
#define	SND_SEQ_OPEN_OUTPUT   1
#define	SND_SEQ_OPEN_INPUT   2
#define	SND_SEQ_OPEN_DUPLEX   (SND_SEQ_OPEN_OUTPUT|SND_SEQ_OPEN_INPUT)
#define	SND_SEQ_NONBLOCK   0x0001
#define	SND_SEQ_ADDRESS_UNKNOWN   253
#define	SND_SEQ_ADDRESS_SUBSCRIBERS   254
#define	SND_SEQ_ADDRESS_BROADCAST   255
#define	SND_SEQ_CLIENT_SYSTEM   0
#define	snd_seq_system_info_alloca(ptr)   SND_ALLOCA(snd_seq_system_info, ptr)
Typedefs
typedef _snd_seq	snd_seq_t
typedef enum _snd_seq_type	snd_seq_type_t
typedef _snd_seq_system_info	snd_seq_system_info_t
Enumerations
enum	_snd_seq_type { SND_SEQ_TYPE_HW, SND_SEQ_TYPE_SHM, SND_SEQ_TYPE_INET }
Functions
int	snd_seq_open (snd_seq_t **handle, const char *name, int streams, int mode)
	Open the ALSA sequencer.
int	snd_seq_open_lconf (snd_seq_t **handle, const char *name, int streams, int mode, snd_config_t *lconf)
	Open the ALSA sequencer using local configuration.
const char *	snd_seq_name (snd_seq_t *seq)
	get identifier of sequencer handle
snd_seq_type_t	snd_seq_type (snd_seq_t *seq)
	get type of sequencer handle
int	snd_seq_close (snd_seq_t *handle)
	Close the sequencer.
int	snd_seq_poll_descriptors_count (snd_seq_t *handle, short events)
	Returns the number of poll descriptors.
int	snd_seq_poll_descriptors (snd_seq_t *handle, struct pollfd *pfds, unsigned int space, short events)
	Get poll descriptors.
int	snd_seq_poll_descriptors_revents (snd_seq_t *seq, struct pollfd *pfds, unsigned int nfds, unsigned short *revents)
	get returned events from poll descriptors
int	snd_seq_nonblock (snd_seq_t *handle, int nonblock)
	Set nonblock mode.
int	snd_seq_client_id (snd_seq_t *handle)
	Get the client id.
size_t	snd_seq_get_output_buffer_size (snd_seq_t *handle)
	Return the size of output buffer.
size_t	snd_seq_get_input_buffer_size (snd_seq_t *handle)
	Return the size of input buffer.
int	snd_seq_set_output_buffer_size (snd_seq_t *handle, size_t size)
	Change the size of output buffer.
int	snd_seq_set_input_buffer_size (snd_seq_t *handle, size_t size)
	Resize the input buffer.
size_t	snd_seq_system_info_sizeof (void)
	Get size of snd_seq_system_info_t.
int	snd_seq_system_info_malloc (snd_seq_system_info_t **ptr)
	Allocate an empty snd_seq_system_info_t using standard malloc.
void	snd_seq_system_info_free (snd_seq_system_info_t *ptr)
	Frees a previously allocated snd_seq_system_info_t.
void	snd_seq_system_info_copy (snd_seq_system_info_t *dst, const snd_seq_system_info_t *src)
	Copy one snd_seq_system_info_t to another.
int	snd_seq_system_info_get_queues (const snd_seq_system_info_t *info)
	Get maximum number of queues.
int	snd_seq_system_info_get_clients (const snd_seq_system_info_t *info)
	Get maximum number of clients.
int	snd_seq_system_info_get_ports (const snd_seq_system_info_t *info)
	Get maximum number of ports.
int	snd_seq_system_info_get_channels (const snd_seq_system_info_t *info)
	Get maximum number of channels.
int	snd_seq_system_info_get_cur_clients (const snd_seq_system_info_t *info)
	Get the current number of clients.
int	snd_seq_system_info_get_cur_queues (const snd_seq_system_info_t *info)
	Get the current number of queues.
int	snd_seq_system_info (snd_seq_t *handle, snd_seq_system_info_t *info)
	obtain the sequencer system information

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Detailed Description

MIDI Sequencer Interface. See Sequencer interface page for more details.

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Define Documentation

#define SND_SEQ_ADDRESS_BROADCAST   255

send event to all queues/clients/ports/channels

#define SND_SEQ_ADDRESS_SUBSCRIBERS   254

send event to all subscribed ports

#define SND_SEQ_ADDRESS_UNKNOWN   253

unknown source

#define SND_SEQ_CLIENT_SYSTEM   0

system client

#define SND_SEQ_DLSYM_VERSION   _dlsym_seq_001

dlsym version for interface entry callback

#define SND_SEQ_NONBLOCK   0x0001

non-blocking mode (flag to open mode)

#define SND_SEQ_OPEN_DUPLEX   (SND_SEQ_OPEN_OUTPUT|SND_SEQ_OPEN_INPUT)

open for both input and output (read/write)

#define SND_SEQ_OPEN_INPUT   2

open for input (read)

#define SND_SEQ_OPEN_OUTPUT   1

open for output (write)

#define snd_seq_system_info_alloca (  ptr   )     SND_ALLOCA(snd_seq_system_info, ptr)

allocate a snd_seq_system_info_t container on stack

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Typedef Documentation

typedef struct _snd_seq_system_info snd_seq_system_info_t

system information container

typedef struct _snd_seq snd_seq_t

Sequencer handle

typedef enum _snd_seq_type snd_seq_type_t

sequencer handle type

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Enumeration Type Documentation

enum _snd_seq_type

sequencer handle type Enumeration values: SND_SEQ_TYPE_HW  hardware SND_SEQ_TYPE_SHM  shared memory (NYI) SND_SEQ_TYPE_INET  network (NYI)

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Function Documentation

int snd_seq_client_id (  snd_seq_t *  seq  )

Get the client id. Parameters: seq  sequencer handle Returns: the client id Returns the id of the specified client. If an error occurs, function returns the negative error code. A client id is necessary to inquiry or to set the client information. A user client is assigned from 128 to 191. See also: snd_seq_open()

int snd_seq_close (  snd_seq_t *  seq  )

Close the sequencer. Parameters: seq  Handle returned from snd_seq_open() Returns: 0 on success otherwise a negative error code Closes the sequencer client and releases its resources. After a client is closed, an event with SND_SEQ_EVENT_CLIENT_EXIT is broadcast to announce port. The connection between other clients are disconnected. Call this just before exiting your program. See also: snd_seq_close()

size_t snd_seq_get_input_buffer_size (  snd_seq_t *  seq  )

Return the size of input buffer. Parameters: seq  sequencer handle Returns: the size of input buffer in bytes Obtains the size of input buffer. This buffer is used to read byte-stream of input events from sequencer. See also: snd_seq_set_input_buffer_size()

size_t snd_seq_get_output_buffer_size (  snd_seq_t *  seq  )

Return the size of output buffer. Parameters: seq  sequencer handle Returns: the size of output buffer in bytes Obtains the size of output buffer. This buffer is used to store decoded byte-stream of output events before transferring to sequencer. See also: snd_seq_set_output_buffer_size()

const char* snd_seq_name (  snd_seq_t *  seq  )

get identifier of sequencer handle Parameters: seq  sequencer handle Returns: ascii identifier of sequencer handle Returns the ASCII identifier of the given sequencer handle. It's the same identifier specified in snd_seq_open(). See also: snd_seq_open()

int snd_seq_nonblock (  snd_seq_t *  seq, int  nonblock )

Set nonblock mode. Parameters: seq  sequencer handle nonblock  0 = block, 1 = nonblock mode Returns: 0 on success otherwise a negative error code Change the blocking mode of the given client. In block mode, the client falls into sleep when it fills the output memory pool with full events. The client will be woken up after a certain amount of free space becomes available. See also: snd_seq_open()

int snd_seq_open (  snd_seq_t **  seqp, const char *  name, int  streams, int  mode )

Open the ALSA sequencer. Parameters: seqp  Pointer to a snd_seq_t pointer. This pointer must be kept and passed to most of the other sequencer functions. name  The sequencer's "name". This is not a name you make up for your own purposes; it has special significance to the ALSA library. Usually you need to pass "default" here. streams  The read/write mode of the sequencer. Can be one of three values: SND_SEQ_OPEN_OUTPUT - open the sequencer for output only SND_SEQ_OPEN_INPUT - open the sequencer for input only SND_SEQ_OPEN_DUPLEX - open the sequencer for output and input Note: Internally, these are translated to O_WRONLY, O_RDONLY and O_RDWR respectively and used as the second argument to the C library open() call. Parameters: mode  Optional modifier. Can be either 0, or SND_SEQ_NONBLOCK, which will make read/write operations non-blocking. This can also be set later using snd_seq_nonblock(). Returns: 0 on success otherwise a negative error code Creates a new handle and opens a connection to the kernel sequencer interface. After a client is created successfully, an event with SND_SEQ_EVENT_CLIENT_START is broadcast to announce port. See also: snd_seq_open_lconf(), snd_seq_close(), snd_seq_type(), snd_seq_name(), snd_seq_nonblock(), snd_seq_client_id()

int snd_seq_open_lconf (  snd_seq_t **  seqp, const char *  name, int  streams, int  mode, snd_config_t *  lconf )

Open the ALSA sequencer using local configuration. Parameters: seqp  Pointer to a snd_seq_t pointer. name  The name to open streams  The read/write mode of the sequencer. mode  Optional modifier lconf  Local configuration Returns: 0 on success otherwise a negative error code See the snd_seq_open() function for further details. The extension is that the given configuration is used to resolve abstract name. See also: snd_seq_open()

int snd_seq_poll_descriptors (  snd_seq_t *  seq, struct pollfd *  pfds, unsigned int  space, short  events )

Get poll descriptors. Parameters: seq  sequencer handle pfds  array of poll descriptors space  space in the poll descriptor array events  polling events to be checked (POLLIN and POLLOUT) Returns: count of filled descriptors Get poll descriptors assigned to the sequencer handle. Since a sequencer handle can duplex streams, you need to set which direction(s) is/are polled in events argument. When POLLIN bit is specified, the incoming events to the ports are checked. To check the returned poll-events, call snd_seq_poll_descriptors_revents() instead of reading the pollfd structs directly. See also: snd_seq_poll_descriptors_count(), snd_seq_poll_descriptors_revents()

int snd_seq_poll_descriptors_count (  snd_seq_t *  seq, short  events )

Returns the number of poll descriptors. Parameters: seq  sequencer handle events  the poll events to be checked (POLLIN and POLLOUT) Returns: the number of poll descriptors. Get the number of poll descriptors. The polling events to be checked can be specified by the second argument. When both input and output are checked, pass POLLIN|POLLOUT See also: snd_seq_poll_descriptors()

int snd_seq_poll_descriptors_revents (  snd_seq_t *  seq, struct pollfd *  pfds, unsigned int  nfds, unsigned short *  revents )

get returned events from poll descriptors Parameters: seq  sequencer handle pfds  array of poll descriptors nfds  count of poll descriptors revents  returned events Returns: zero if success, otherwise a negative error code See also: snd_seq_poll_descriptors()

int snd_seq_set_input_buffer_size (  snd_seq_t *  seq, size_t  size )

Resize the input buffer. Parameters: seq  sequencer handle size  the size of input buffer to be changed in bytes Returns: 0 on success otherwise a negative error code Changes the size of input buffer. See also: snd_seq_get_input_buffer_size()

int snd_seq_set_output_buffer_size (  snd_seq_t *  seq, size_t  size )

Change the size of output buffer. Parameters: seq  sequencer handle size  the size of output buffer to be changed in bytes Returns: 0 on success otherwise a negative error code Changes the size of output buffer. See also: snd_seq_get_output_buffer_size()

int snd_seq_system_info (  snd_seq_t *  seq, snd_seq_system_info_t *  info )

obtain the sequencer system information Parameters: seq  sequencer handle info  the pointer to be stored Returns: 0 on success otherwise a negative error code Stores the global system information of ALSA sequencer system. The returned data contains the maximum available numbers of queues, clients, ports and channels.

void snd_seq_system_info_copy (  snd_seq_system_info_t *  dst, const snd_seq_system_info_t *  src )

Copy one snd_seq_system_info_t to another. Parameters: dst  pointer to destination src  pointer to source

void snd_seq_system_info_free (  snd_seq_system_info_t *  obj  )

Frees a previously allocated snd_seq_system_info_t. Parameters: obj  pointer to object to free

int snd_seq_system_info_get_channels (  const snd_seq_system_info_t *  info  )

Get maximum number of channels. Parameters: info  snd_seq_system_info_t container Returns: maximum number of channels See also: snd_seq_system_info()

int snd_seq_system_info_get_clients (  const snd_seq_system_info_t *  info  )

Get maximum number of clients. Parameters: info  snd_seq_system_info_t container Returns: maximum number of clients See also: snd_seq_system_info()

int snd_seq_system_info_get_cur_clients (  const snd_seq_system_info_t *  info  )

Get the current number of clients. Parameters: info  snd_seq_system_info_t container Returns: current number of clients See also: snd_seq_system_info()

int snd_seq_system_info_get_cur_queues (  const snd_seq_system_info_t *  info  )

Get the current number of queues. Parameters: info  snd_seq_system_info_t container Returns: current number of queues See also: snd_seq_system_info()

int snd_seq_system_info_get_ports (  const snd_seq_system_info_t *  info  )

Get maximum number of ports. Parameters: info  snd_seq_system_info_t container Returns: maximum number of ports See also: snd_seq_system_info()

int snd_seq_system_info_get_queues (  const snd_seq_system_info_t *  info  )

Get maximum number of queues. Parameters: info  snd_seq_system_info_t container Returns: maximum number of queues See also: snd_seq_system_info()

int snd_seq_system_info_malloc (  snd_seq_system_info_t **  ptr  )

Allocate an empty snd_seq_system_info_t using standard malloc. Parameters: ptr  returned pointer Returns: 0 on success otherwise negative error code

size_t snd_seq_system_info_sizeof (  void   )

Get size of snd_seq_system_info_t. Returns: size in bytes

snd_seq_type_t snd_seq_type (  snd_seq_t *  seq  )

get type of sequencer handle Parameters: seq  sequencer handle Returns: type of sequencer handle Returns the type snd_seq_type_t of the given sequencer handle. See also: snd_seq_open()

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