1 /**
2 * \file pcm/pcm_empty.c
3 * \ingroup PCM_Plugins
4 * \brief PCM Empty Plugin Interface
5 * \author Jaroslav Kysela <perex@perex.cz>
6 * \date 2006
7 */
8 /*
9 * PCM - Empty plugin
10 * Copyright (c) 2006 by Jaroslav Kysela <perex@perex.cz>
11 *
12 *
13 * This library is free software; you can redistribute it and/or modify
14 * it under the terms of the GNU Lesser General Public License as
15 * published by the Free Software Foundation; either version 2.1 of
16 * the License, or (at your option) any later version.
17 *
18 * This program is distributed in the hope that it will be useful,
19 * but WITHOUT ANY WARRANTY; without even the implied warranty of
20 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
21 * GNU Lesser General Public License for more details.
22 *
23 * You should have received a copy of the GNU Lesser General Public
24 * License along with this library; if not, write to the Free Software
25 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
26 *
27 */
28
29 #include "pcm_local.h"
30 #include "pcm_plugin.h"
31
32 #ifndef PIC
33 /* entry for static linking */
34 const char *_snd_module_pcm_empty = "";
35 #endif
36
37 /*! \page pcm_plugins
38
39 \section pcm_plugins_empty Plugin: Empty
40
41 This plugin just redirects the PCM stream to another plugin.
42
43 \code
44 pcm.name {
45 type empty # Null PCM
46 slave STR # Slave name
47 # or
48 slave { # Slave definition
49 pcm STR # Slave PCM name
50 # or
51 pcm { } # Slave PCM definition
52 [format STR] # Slave format
53 [channels INT] # Slave channels
54 }
55 }
56 \endcode
57
58 \subsection pcm_plugins_empty_funcref Function reference
59
60 <UL>
61 <LI>_snd_pcm_empty_open()
62 </UL>
63
64 */
65
66 /**
67 * \brief Creates a new Empty PCM
68 * \param pcmp Returns created PCM handle
69 * \param name Name of PCM
70 * \param root Root configuration node
71 * \param conf Configuration node with empty PCM description
72 * \param stream Stream type
73 * \param mode Stream mode
74 * \retval zero on success otherwise a negative error code
75 * \warning Using of this function might be dangerous in the sense
76 * of compatibility reasons. The prototype might be freely
77 * changed in future.
78 */
_snd_pcm_empty_open(snd_pcm_t ** pcmp,const char * name ATTRIBUTE_UNUSED,snd_config_t * root,snd_config_t * conf,snd_pcm_stream_t stream,int mode)79 int _snd_pcm_empty_open(snd_pcm_t **pcmp, const char *name ATTRIBUTE_UNUSED,
80 snd_config_t *root, snd_config_t *conf,
81 snd_pcm_stream_t stream, int mode)
82 {
83 snd_config_t *slave = NULL, *sconf;
84 snd_config_iterator_t i, next;
85 int err;
86
87 snd_config_for_each(i, next, conf) {
88 snd_config_t *n = snd_config_iterator_entry(i);
89 const char *id;
90 if (snd_config_get_id(n, &id) < 0)
91 continue;
92 if (snd_pcm_conf_generic_id(id))
93 continue;
94 if (strcmp(id, "slave") == 0) {
95 slave = n;
96 continue;
97 }
98 SNDERR("Unknown field %s", id);
99 return -EINVAL;
100 }
101 if (!slave) {
102 SNDERR("slave is not defined");
103 return -EINVAL;
104 }
105 err = snd_pcm_slave_conf(root, slave, &sconf, 0);
106 if (err < 0)
107 return err;
108 err = snd_pcm_open_named_slave(pcmp, name, root, sconf, stream,
109 mode, conf);
110 snd_config_delete(sconf);
111 return err;
112 }
113 #ifndef DOC_HIDDEN
114 SND_DLSYM_BUILD_VERSION(_snd_pcm_empty_open, SND_PCM_DLSYM_VERSION);
115 #endif
116