Introduce prepare_writer_node().
[paraslash.git] / write.h
1 /*
2 * Copyright (C) 2006-2009 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 /** Pointer to the group this node belongs to. */
21 struct writer_node_group *wng;
22 /** The writer-specific configuration of this node. */
23 void *conf;
24 /** How much of the wng's buffer is already written. */
25 size_t written;
26 struct btr_node *btrn;
27 struct task task;
28 size_t min_iqs;
29 };
30
31 /** Describes one supported writer. */
32 struct writer {
33 /**
34 * The init function of the writer.
35 *
36 * It must fill in all other function pointers of the given
37 * writer structure.
38 */
39 void (*init)(struct writer *w);
40 /**
41 * The command line parser of the writer.
42 *
43 * It should check whether the command line options given by \a options are
44 * valid. On success, it should return a pointer to the writer-specific
45 * configuration data determined by \a options. Note that this might be called
46 * more than once with different values of \a options.
47 */
48 void *(*parse_config)(const char *options);
49 /**
50 * Open one instance of this writer.
51 *
52 * This function should perform any work necessary to write the incoming
53 * stream. To this aim, it may allocate its private data structure and store
54 * a pointer to that structure via the given writer_node parameter.
55 */
56 int (*open)(struct writer_node *);
57 /**
58 * Prepare the fd sets for select.
59 *
60 * This is called from the writer node group task's pre_select(). It
61 * may use the sched pointer to add any file descriptors or to decrease
62 * the select timeout. It must return positive on success and negative
63 * on errors.
64 */
65 int (*pre_select)(struct sched *s, struct writer_node *wn);
66 void (*pre_select_btr)(struct sched *s, struct task *t);
67 /**
68 * Write audio data.
69 *
70 * Called from the post_select function of the wng task. It must keep
71 * track of the number of bytes consumed from the wng's buffer via
72 * the \p wn->written variable (which may be modified by the wng handling
73 * functions). This function must return positive on success and
74 * negative on errors.
75 */
76 int (*post_select)(struct sched *s, struct writer_node *wn);
77 void (*post_select_btr)(struct sched *s, struct task *t);
78 /**
79 * Close one instance of the writer.
80 *
81 * This function is assumed to succeed.
82 */
83 void (*close)(struct writer_node *);
84 /**
85 * Shutdown the writer
86 *
87 * This is a optional function pointer used for cleaning up.
88 */
89 void (*shutdown)(struct writer_node *);
90 struct ggo_help help;
91 btr_command_handler execute;
92 };
93
94 /**
95 * Describes a set of writer nodes that all write the same stream.
96 */
97 struct writer_node_group {
98 /** Number of nodes belonging to this group. */
99 unsigned num_writers;
100 /** Array of pointers to the corresponding writer nodes. */
101 struct writer_node *writer_nodes;
102 /** Non-zero if an error or end of file was encountered by the feeding task. */
103 int *input_error;
104 /** Current output buffer. */
105 char **bufp;
106 /** Number of bytes loaded in the output buffer. */
107 size_t *loaded;
108 /** Number of audio channels of the current stream. */
109 unsigned int *channels;
110 /** Sample rate of the current stream. */
111 unsigned int *samplerate;
112 /** The task associated to this group. */
113 struct task task;
114 /** Whether the group is open, i.e. wng_open() was called. */
115 int open;
116 /** Max number of bytes written in the previous post_select() call. */
117 int last_written;
118 };
119
120 /** Loop over each writer node in a writer group. */
121 #define FOR_EACH_WRITER_NODE(i, wng) for (i = 0; i < (wng)->num_writers; i++)
122 /** Loop over each supported writer. */
123 #define FOR_EACH_WRITER(i) for (i = 0; i < NUM_SUPPORTED_WRITERS; i++)
124
125 /** Declare the init functions of all supported writers. */
126 DECLARE_WRITER_INITS;
127
128 /** Array containing the name of each writer. */
129 extern const char *writer_names[];
130
131 /** The writer structure for each supported writer. */
132 extern struct writer writers[NUM_SUPPORTED_WRITERS];