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[paraslash.git] / write.h
1 /*
2 * Copyright (C) 2006-2011 Andre Noll <maan@systemlinux.org>
3 *
4 * Licensed under the GPL v2. For licencing details see COPYING.
5 */
6
7 /** \file write.h Writer-related structures. */
8
9 /** The list of supported writers. */
10 enum writer_enum {WRITER_ENUM};
11
12 /**
13 * Describes one running instance of a writer.
14 */
15 struct writer_node {
16 /** The number of this writer. */
17 int writer_num;
18 /** Writer-specific data. */
19 void *private_data;
20 /** The writer-specific configuration of this node. */
21 void *conf;
22 /** The buffer tree node associated with this writer node. */
23 struct btr_node *btrn;
24 /** The task of this writer node. */
25 struct task task;
26 /** The minimal input queue size (size of one audio sample). */
27 size_t min_iqs;
28 };
29
30 /** Describes one supported writer. */
31 struct writer {
32 /**
33 * The init function of the writer.
34 *
35 * It must fill in all other function pointers of the given
36 * writer structure.
37 */
38 void (*init)(struct writer *w);
39 /**
40 * The command line parser of the writer.
41 *
42 * It should check whether the command line options given by \a options
43 * are valid and return a pointer to the writer-specific configuration
44 * data determined by \a options. This function must either succeed or
45 * call exit(). Note that parse_config_or_die() might be called more
46 * than once with different values of \a options. \sa \ref
47 * free_config().
48 */
49 void *(*parse_config_or_die)(const char *options);
50 /**
51 * Dellocate all configuration resources.
52 *
53 * This should free whatever was allocated by \ref parse_config_or_die().
54 */
55 void (*free_config)(void *config);
56 /**
57 * Prepare the fd sets for select.
58 *
59 * This is called from scheduler. It may use the sched pointer to add
60 * any file descriptors or to decrease the select timeout.
61 */
62 void (*pre_select)(struct sched *s, struct task *t);
63 /**
64 * Write audio data.
65 *
66 * Called from the post_select function of the writer node's task.
67 */
68 void (*post_select)(struct sched *s, struct task *t);
69 /**
70 * Close one instance of the writer.
71 *
72 * This function is assumed to succeed.
73 */
74 void (*close)(struct writer_node *);
75 /**
76 * Shutdown the writer.
77 *
78 * This is a optional function pointer used for cleaning up.
79 */
80 void (*shutdown)(struct writer_node *);
81 /** The short and the log help text of this writer. */
82 struct ggo_help help;
83 /**
84 * The callback handler.
85 *
86 * Each writer may provide an ->execute callback which can be used for
87 * inter-node communication.
88 */
89 btr_command_handler execute;
90 };
91
92 /** Loop over each supported writer. */
93 #define FOR_EACH_WRITER(i) for (i = 0; i < NUM_SUPPORTED_WRITERS; i++)
94
95 /** Declare the init functions of all supported writers. */
96 DECLARE_WRITER_INITS;
97
98 /** Array containing the name of each writer. */
99 extern const char *writer_names[];
100
101 /** The writer structure for each supported writer. */
102 extern struct writer writers[NUM_SUPPORTED_WRITERS];