write.h: Cosmetics.
[paraslash.git] / write.h
1 /*
2 * Copyright (C) 2006-2008 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 /** Points to the writer structure associated with this node. */
17 struct writer *writer; /* FIXME: Should better be only the number. */
18 /** Writer-specific data. */
19 void *private_data;
20 /** Send that many bytes in one go. */
21 int chunk_bytes;
22 /** Pointer to the group this node belongs to. */
23 struct writer_node_group *wng;
24 /** The writer-specific configuration of this node. */
25 void *conf;
26 /** How much of the wng's buffer is already written. */
27 size_t written;
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 are
43 * valid. On success, it should return a pointer to the writer-specific
44 * configuration data determined by \a options. Note that this might be called
45 * more than once with different values of \a options.
46 */
47 void *(*parse_config)(const char *options);
48 /**
49 * Open one instance of this writer.
50 *
51 * This function should perform any work necessary to write the incoming
52 * stream. If To this aim, it may allocate its private data structure and store
53 * a pointer to that structure via the given writer_node parameter.
54 */
55 int (*open)(struct writer_node *);
56 /**
57 * Prepare the fd sets for select.
58 *
59 * This is called from the writer node group task's pre_select(). It
60 * may use the sched pointer to add any file descriptors or to decrease
61 * the select timeout. It must return positive on success and negative
62 * on errors.
63 */
64 int (*pre_select)(struct sched *s, struct writer_node *wn);
65 /**
66 * Write audio data.
67 *
68 * Called from the post_select function of the wng task. It must keep
69 * track of the number of bytes consumed from the wng's buffer via
70 * the \p wn->written variable (which may be modified by the wng handling
71 * functions). This function must return positive on success and
72 * negative on errors.
73 */
74 int (*post_select)(struct sched *s, struct writer_node *wn);
75 /**
76 * Close one instance of the writer.
77 *
78 * This function is assumed to succeed.
79 */
80 void (*close)(struct writer_node *);
81 /**
82 * Shutdown the writer
83 *
84 * This is a optional function pointer used for cleaning up.
85 */
86 void (*shutdown)(struct writer_node *);
87 };
88
89 /**
90 * Describes a set of writer nodes that all write the same stream.
91 */
92 struct writer_node_group {
93 /** Number of nodes belonging to this group. */
94 unsigned num_writers;
95 /** Array of pointers to the corresponding writer nodes. */
96 struct writer_node *writer_nodes;
97 /** The maximum of the chunk_bytes values of the writer nodes in this group. */
98 size_t max_chunk_bytes;
99 /** Non-zero if an error or end of file was encountered by the feeding task. */
100 int *input_error;
101 /** Current output buffer. */
102 char *buf;
103 /** Number of bytes loaded in the output buffer. */
104 size_t *loaded;
105 /** Number of audio channels of the current stream. */
106 unsigned int *channels;
107 /** Sample rate of the current stream. */
108 unsigned int *samplerate;
109 /** The task associated to this group. */
110 struct task task;
111 /** Whether the group is open, i.e. wng_open() was called. */
112 int open;
113 };
114
115 /** Loop over each writer node in a writer group. */
116 #define FOR_EACH_WRITER_NODE(i, wng) for (i = 0; i < (wng)->num_writers; i++)
117 /** Loop over each supported writer. */
118 #define FOR_EACH_WRITER(i) for (i = 0; i < NUM_SUPPORTED_WRITERS; i++)
119
120 /** Declare the init functions of all supported writers. */
121 DECLARE_WRITER_INITS;
122
123 /** Array containing the name of each writer. */
124 extern const char *writer_names[];
125
126 /** The writer structure for each supported writer. */
127 extern struct writer writers[NUM_SUPPORTED_WRITERS];