66f21cfe6e8256f088a1c9246a9b72b13a49b134
[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 };
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. 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 void (*pre_select_btr)(struct sched *s, struct task *t);
66 /**
67 * Write audio data.
68 *
69 * Called from the post_select function of the wng task. It must keep
70 * track of the number of bytes consumed from the wng's buffer via
71 * the \p wn->written variable (which may be modified by the wng handling
72 * functions). This function must return positive on success and
73 * negative on errors.
74 */
75 int (*post_select)(struct sched *s, struct writer_node *wn);
76 void (*post_select_btr)(struct sched *s, struct task *t);
77 /**
78 * Close one instance of the writer.
79 *
80 * This function is assumed to succeed.
81 */
82 void (*close)(struct writer_node *);
83 /**
84 * Shutdown the writer
85 *
86 * This is a optional function pointer used for cleaning up.
87 */
88 void (*shutdown)(struct writer_node *);
89 struct ggo_help help;
90 };
91
92 /**
93 * Describes a set of writer nodes that all write the same stream.
94 */
95 struct writer_node_group {
96 /** Number of nodes belonging to this group. */
97 unsigned num_writers;
98 /** Array of pointers to the corresponding writer nodes. */
99 struct writer_node *writer_nodes;
100 /** Non-zero if an error or end of file was encountered by the feeding task. */
101 int *input_error;
102 /** Current output buffer. */
103 char **bufp;
104 /** Number of bytes loaded in the output buffer. */
105 size_t *loaded;
106 /** Number of audio channels of the current stream. */
107 unsigned int *channels;
108 /** Sample rate of the current stream. */
109 unsigned int *samplerate;
110 /** The task associated to this group. */
111 struct task task;
112 /** Whether the group is open, i.e. wng_open() was called. */
113 int open;
114 /** Max number of bytes written in the previous post_select() call. */
115 int last_written;
116 };
117
118 /** Loop over each writer node in a writer group. */
119 #define FOR_EACH_WRITER_NODE(i, wng) for (i = 0; i < (wng)->num_writers; i++)
120 /** Loop over each supported writer. */
121 #define FOR_EACH_WRITER(i) for (i = 0; i < NUM_SUPPORTED_WRITERS; i++)
122
123 /** Declare the init functions of all supported writers. */
124 DECLARE_WRITER_INITS;
125
126 /** Array containing the name of each writer. */
127 extern const char *writer_names[];
128
129 /** The writer structure for each supported writer. */
130 extern struct writer writers[NUM_SUPPORTED_WRITERS];