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/* SPDX-License-Identifier: GPL-2.0 */
/** \file recv.h Receiver API
*
* Receivers are part of para_audiod(1), para_recv(1) and para_play(1). Each
* receiver is implemented in a separate file which defines a non-static a \ref
* receiver structure. An instance of the receiver, a \ref receiver_node,
* is created by calling \ref receiver::open. The receiver node is set
* up by making it the root of a buffer tree and registering it to the
* scheduler. Once scheduling is started the receiver node performs I/O as
* long as there is input available and space left in the output buffer.
*
* The few functions declared here are defined in \ref recv_common.c.
*/
/**
* Describes one instance of a receiver.
*/
struct receiver_node {
/** Points to the corresponding receiver. */
const struct receiver *receiver;
/** Receiver-specific data. */
void *private_data;
/** The parsed command line options for this instance. */
struct lls_parse_result *lpr;
/** The task associated with this instance. */
struct task *task;
/** The receiver node is always the root of the buffer tree. */
struct btr_node *btrn;
/** Each receiver node maintains a buffer pool for the received data. */
struct btr_pool *btrp;
/**
* The file descriptor to receive the stream.
*
* The pre_monitor function of the receiver adds this file descriptor to
* the set of file descriptors which are watched for readability or
* writability, depending on the state of the connection (if any).
*
* If the file descriptor is readable, the post_monitor function of the
* receiver reads data from this descriptor into the buffer pool area.
*
* \sa \ref receiver.
*/
int fd;
};
/**
* Describes a possible data source for audio streams.
*
* A paraslash receiver is a modular piece of software which is capable of
* receiving an audio data stream from a data source. Received audio data is
* fed to consumers through the buffer tree mechanism.
*
* This structure contains the methods which have to be implemented by each
* receiver.
*
* \sa \ref http_recv.c, \ref udp_recv.c, \ref afh_recv.c, struct \ref
* receiver_node, struct \ref filter, struct \ref writer.
*/
struct receiver {
/**
* Open one instance of the receiver.
*
* This should allocate the output buffer of the given receiver node
* and prepare it for retrieving the audio stream according to the
* configuration stored in rn->lpr.
*/
int (*open)(struct receiver_node *rn);
/**
* Close this instance of the receiver.
*
* It should free all resources associated with given receiver node
* that were allocated during the corresponding open call.
*
* \sa \ref receiver_node.
*/
void (*close)(struct receiver_node *rn);
/** Ask the scheduler to monitor receive fds. */
void (*pre_monitor)(struct sched *s, void *context);
/** Receive data and make it available to consumers. */
int (*post_monitor)(struct sched *s, void *context);
/**
* Answer a buffer tree query.
*
* This optional function pointer allows for inter node communication
* of the buffer tree nodes. See \ref btr_command_handler for details.
*/
btr_command_handler execute;
};
/** \cond doxygen_ignore */
#define RECV_CMD(_num) (lls_cmd(_num, recv_cmd_suite))
#define RECV_CMD_OPT_RESULT(_recv, _opt, _lpr) \
(lls_opt_result(LSG_RECV_CMD_ ## _recv ## _OPT_ ## _opt, _lpr))
#define RECV_CMD_OPT_GIVEN(_recv, _opt, _lpr) \
(lls_opt_given(RECV_CMD_OPT_RESULT(_recv, _opt, _lpr)))
#define RECV_CMD_OPT_STRING_VAL(_recv, _opt, _lpr) \
(lls_string_val(0, RECV_CMD_OPT_RESULT(_recv, _opt, _lpr)))
#define RECV_CMD_OPT_UINT32_VAL(_recv, _opt, _lpr) \
(lls_uint32_val(0, RECV_CMD_OPT_RESULT(_recv, _opt, _lpr)))
#define RECV_CMD_OPT_INT32_VAL(_recv, _opt, _lpr) \
(lls_int32_val(0, RECV_CMD_OPT_RESULT(_recv, _opt, _lpr)))
/** \endcond */
int check_receiver_arg(const char *ra, struct lls_parse_result **lprp);
void print_receiver_helps(bool detailed);
int generic_recv_pre_monitor(struct sched *s, struct receiver_node *rn);
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