seq_ports.c | Explore in Territory

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *   ALSA sequencer Ports
 *   Copyright (c) 1998 by Frank van de Pol <[email protected]>
 *                         Jaroslav Kysela <[email protected]>
 */

#include <sound/core.h>
#include <linux/slab.h>
#include <linux/module.h>
#include "seq_system.h"
#include "seq_ports.h"
#include "seq_clientmgr.h"

/*

   registration of client ports

 */


/* 

NOTE: the current implementation of the port structure as a linked list is
not optimal for clients that have many ports. For sending messages to all
subscribers of a port we first need to find the address of the port
structure, which means we have to traverse the list. A direct access table
(array) would be better, but big preallocated arrays waste memory.

Possible actions:

1) leave it this way, a client does normaly does not have more than a few
ports

2) replace the linked list of ports by a array of pointers which is
dynamicly kmalloced. When a port is added or deleted we can simply allocate
a new array, copy the corresponding pointers, and delete the old one. We
then only need a pointer to this array, and an integer that tells us how
much elements are in array.

*/

/* return pointer to port structure - port is locked if found */
struct snd_seq_client_port *snd_seq_port_use_ptr(struct snd_seq_client *client,
						 int num)
{ … }


/* search for the next port - port is locked if found */
struct snd_seq_client_port *snd_seq_port_query_nearest(struct snd_seq_client *client,
						       struct snd_seq_port_info *pinfo)
{ … }


/* initialize snd_seq_port_subs_info */
static void port_subs_info_init(struct snd_seq_port_subs_info *grp)
{ … }


/* create a port, port number or a negative error code is returned
 * the caller needs to unref the port via snd_seq_port_unlock() appropriately
 */
int snd_seq_create_port(struct snd_seq_client *client, int port,
			struct snd_seq_client_port **port_ret)
{ … }

/* */
static int subscribe_port(struct snd_seq_client *client,
			  struct snd_seq_client_port *port,
			  struct snd_seq_port_subs_info *grp,
			  struct snd_seq_port_subscribe *info, int send_ack);
static int unsubscribe_port(struct snd_seq_client *client,
			    struct snd_seq_client_port *port,
			    struct snd_seq_port_subs_info *grp,
			    struct snd_seq_port_subscribe *info, int send_ack);


static struct snd_seq_client_port *get_client_port(struct snd_seq_addr *addr,
						   struct snd_seq_client **cp)
{ … }

static void delete_and_unsubscribe_port(struct snd_seq_client *client,
					struct snd_seq_client_port *port,
					struct snd_seq_subscribers *subs,
					bool is_src, bool ack);

static inline struct snd_seq_subscribers *
get_subscriber(struct list_head *p, bool is_src)
{ … }

/*
 * remove all subscribers on the list
 * this is called from port_delete, for each src and dest list.
 */
static void clear_subscriber_list(struct snd_seq_client *client,
				  struct snd_seq_client_port *port,
				  struct snd_seq_port_subs_info *grp,
				  int is_src)
{ … }

/* delete port data */
static int port_delete(struct snd_seq_client *client,
		       struct snd_seq_client_port *port)
{ … }


/* delete a port with the given port id */
int snd_seq_delete_port(struct snd_seq_client *client, int port)
{ … }

/* delete the all ports belonging to the given client */
int snd_seq_delete_all_ports(struct snd_seq_client *client)
{ … }

/* set port info fields */
int snd_seq_set_port_info(struct snd_seq_client_port * port,
			  struct snd_seq_port_info * info)
{ … }

/* get port info fields */
int snd_seq_get_port_info(struct snd_seq_client_port * port,
			  struct snd_seq_port_info * info)
{ … }



/*
 * call callback functions (if any):
 * the callbacks are invoked only when the first (for connection) or
 * the last subscription (for disconnection) is done.  Second or later
 * subscription results in increment of counter, but no callback is
 * invoked.
 * This feature is useful if these callbacks are associated with
 * initialization or termination of devices (see seq_midi.c).
 */

static int subscribe_port(struct snd_seq_client *client,
			  struct snd_seq_client_port *port,
			  struct snd_seq_port_subs_info *grp,
			  struct snd_seq_port_subscribe *info,
			  int send_ack)
{ … }

static int unsubscribe_port(struct snd_seq_client *client,
			    struct snd_seq_client_port *port,
			    struct snd_seq_port_subs_info *grp,
			    struct snd_seq_port_subscribe *info,
			    int send_ack)
{ … }



/* check if both addresses are identical */
static inline int addr_match(struct snd_seq_addr *r, struct snd_seq_addr *s)
{ … }

/* check the two subscribe info match */
/* if flags is zero, checks only sender and destination addresses */
static int match_subs_info(struct snd_seq_port_subscribe *r,
			   struct snd_seq_port_subscribe *s)
{ … }

static int check_and_subscribe_port(struct snd_seq_client *client,
				    struct snd_seq_client_port *port,
				    struct snd_seq_subscribers *subs,
				    bool is_src, bool exclusive, bool ack)
{ … }

/* called with grp->list_mutex held */
static void __delete_and_unsubscribe_port(struct snd_seq_client *client,
					  struct snd_seq_client_port *port,
					  struct snd_seq_subscribers *subs,
					  bool is_src, bool ack)
{ … }

static void delete_and_unsubscribe_port(struct snd_seq_client *client,
					struct snd_seq_client_port *port,
					struct snd_seq_subscribers *subs,
					bool is_src, bool ack)
{ … }

/* connect two ports */
int snd_seq_port_connect(struct snd_seq_client *connector,
			 struct snd_seq_client *src_client,
			 struct snd_seq_client_port *src_port,
			 struct snd_seq_client *dest_client,
			 struct snd_seq_client_port *dest_port,
			 struct snd_seq_port_subscribe *info)
{ … }

/* remove the connection */
int snd_seq_port_disconnect(struct snd_seq_client *connector,
			    struct snd_seq_client *src_client,
			    struct snd_seq_client_port *src_port,
			    struct snd_seq_client *dest_client,
			    struct snd_seq_client_port *dest_port,
			    struct snd_seq_port_subscribe *info)
{ … }


/* get matched subscriber */
int snd_seq_port_get_subscription(struct snd_seq_port_subs_info *src_grp,
				  struct snd_seq_addr *dest_addr,
				  struct snd_seq_port_subscribe *subs)
{ … }

/*
 * Attach a device driver that wants to receive events from the
 * sequencer.  Returns the new port number on success.
 * A driver that wants to receive the events converted to midi, will
 * use snd_seq_midisynth_register_port().
 */
/* exported */
int snd_seq_event_port_attach(int client,
			      struct snd_seq_port_callback *pcbp,
			      int cap, int type, int midi_channels,
			      int midi_voices, char *portname)
{ … }
EXPORT_SYMBOL(…);

/*
 * Detach the driver from a port.
 */
/* exported */
int snd_seq_event_port_detach(int client, int port)
{ … }
EXPORT_SYMBOL(…);
linux/sound/core/seq/seq_ports.c
