struct writer: kill unused write_pointer and update documentation
[paraslash.git] / write.h
1 /*
2 * Copyright (C) 2006 Andre Noll <maan@systemlinux.org>
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation; either version 2 of the License, or
7 * (at your option) any later version.
8 *
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write to the Free Software
16 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111, USA.
17 */
18
19 /** \file write.h writer-related structures */
20
21 /** the list of supported writers */
22 enum writer_enum {WRITER_ENUM};
23
24 /**
25 * decbribes one running instance of a writer
26 */
27 struct writer_node {
28 /** points to the writer structure associated with this node */
29 struct writer *writer; /* FIXME: Should better be only the number */
30 /** writer-specific data */
31 void *private_data;
32 /** send that many bytes in one go */
33 int chunk_bytes;
34 /** pointer to the group this node belongs to */
35 struct writer_node_group *wng;
36 /** the writer-specific configuration of this node */
37 void *conf;
38 /** how much of the wng's buffer is already written */
39 size_t written;
40 };
41
42 /** describes one supported writer */
43 struct writer {
44 /**
45 * the init function of the writer
46 *
47 * It must fill in all other function pointers of the given
48 * writer structure.
49 *
50 */
51 void (*init)(struct writer *w);
52 /**
53 *
54 *
55 * the command line parser of the writer
56 *
57 * It should check whether the command line options given by \a options are
58 * valid. On success, it should return a pointer to the writer-specific
59 * configuration data determined by \a options. Note that this might be called
60 * more than once with different values of \a options.
61 *
62 */
63 void * (*parse_config)(char *options);
64 /**
65 *
66 * open one instance of this writer
67 *
68 * This function should perform any work necessary to write the incoming
69 * stream. If To this aim, it may allocate its private data structure and store
70 * a pointer to that structure via the given writer_node paramenter.
71 */
72 int (*open)(struct writer_node *);
73 /**
74 *
75 * write a chunk of audio data
76 *
77 * This is called from the writer node group task's pre_select(). It
78 * may use the sched pointer to add any file descriptors or to decrease
79 * the select timeout. It must return positive on success and negative
80 * on errors.
81 */
82 int (*pre_select)(struct sched *s, struct writer_node *wn);
83 /*
84 * Called from the post_select function of the wng task. It must keep
85 * track of the the number of bytes consumed from the wng's buffer via
86 * the wn->written variable (which may be modified by the wng handling
87 * functions). This function must return positive on success and
88 * negative on errors.
89 */
90 int (*post_select)(struct sched *s, struct writer_node *wn);
91 /**
92 * close one instance of the writer
93 *
94 * This function is assumed to succeed.
95 */
96 void (*close)(struct writer_node *);
97 /**
98 * shutdown the writer
99 *
100 * This is a optional function pointer used for cleaning
101 * up.
102 */
103 void (*shutdown)(struct writer_node *);
104 };
105
106 /**
107 * describes a set of writer nodes that all write the same stream.
108 */
109 struct writer_node_group {
110 /** number of nodes belonging to this group */
111 unsigned num_writers;
112 /** array of pointers to the corresponding writer nodes */
113 struct writer_node *writer_nodes;
114 /** the maximum of the chunk_bytes values of the writer nodes in this group */
115 size_t max_chunk_bytes;
116 /** non-zero if end of file was encountered by the feeding task */
117 int *input_eof;
118 /** non-zero if end of file was encountered */
119 int eof;
120 /** current output buffer */
121 char *buf;
122 /** number of bytes loaded in the output buffer */
123 size_t *loaded;
124 /** number of audio channels of the current stream */
125 unsigned int *channels;
126 /** sample rate of the current stream */
127 unsigned int *samplerate;
128 /** the task associated to this group */
129 struct task task;
130 };
131
132 /** loop over each writer node in a writer group */
133 #define FOR_EACH_WRITER_NODE(i, wng) for (i = 0; i < (wng)->num_writers; i++)
134 /** loop over each supported writer */
135 #define FOR_EACH_WRITER(i) for (i = 0; i < NUM_SUPPORTED_WRITERS; i++)
136
137 /** declare the init functions of all supported writers */
138 DECLARE_WRITER_INITS;
139
140 /** array containing the name of each writer */
141 extern const char *writer_names[];
142
143 /** the writer structure for each supported writer */
144 extern struct writer writers[NUM_SUPPORTED_WRITERS];