1 /** 2 * \file pcm/pcm_empty.c 3 * \ingroup PCM_Plugins 4 * \brief PCM Null Plugin Interface 5 * \author Jaroslav Kysela <perex (at) perex.cz> 6 * \date 2006 7 */ 8 /* 9 * PCM - Null plugin 10 * Copyright (c) 2006 by Jaroslav Kysela <perex (at) 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 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_null Plugin: Null 40 41 This plugin discards contents of a PCM stream or creates a stream with zero 42 samples. 43 44 Note: This implementation uses devices /dev/null (playback, must be writable) 45 and /dev/full (capture, must be readable). 46 47 \code 48 pcm.name { 49 type null # Null PCM 50 } 51 \endcode 52 53 \subsection pcm_plugins_null_funcref Function reference 54 55 <UL> 56 <LI>_snd_pcm_empty_open() 57 </UL> 58 59 */ 60 61 /** 62 * \brief Creates a new Empty PCM 63 * \param pcmp Returns created PCM handle 64 * \param name Name of PCM 65 * \param root Root configuration node 66 * \param conf Configuration node with empty PCM description 67 * \param stream Stream type 68 * \param mode Stream mode 69 * \retval zero on success otherwise a negative error code 70 * \warning Using of this function might be dangerous in the sense 71 * of compatibility reasons. The prototype might be freely 72 * changed in future. 73 */ 74 int _snd_pcm_empty_open(snd_pcm_t **pcmp, const char *name ATTRIBUTE_UNUSED, 75 snd_config_t *root, snd_config_t *conf, 76 snd_pcm_stream_t stream, int mode) 77 { 78 snd_config_t *slave = NULL, *sconf; 79 snd_config_iterator_t i, next; 80 int err; 81 82 snd_config_for_each(i, next, conf) { 83 snd_config_t *n = snd_config_iterator_entry(i); 84 const char *id; 85 if (snd_config_get_id(n, &id) < 0) 86 continue; 87 if (snd_pcm_conf_generic_id(id)) 88 continue; 89 if (strcmp(id, "slave") == 0) { 90 slave = n; 91 continue; 92 } 93 SNDERR("Unknown field %s", id); 94 return -EINVAL; 95 } 96 if (!slave) { 97 SNDERR("slave is not defined"); 98 return -EINVAL; 99 } 100 err = snd_pcm_slave_conf(root, slave, &sconf, 0); 101 if (err < 0) 102 return err; 103 err = snd_pcm_open_named_slave(pcmp, name, root, sconf, stream, 104 mode, conf); 105 snd_config_delete(sconf); 106 return err; 107 } 108 #ifndef DOC_HIDDEN 109 SND_DLSYM_BUILD_VERSION(_snd_pcm_empty_open, SND_PCM_DLSYM_VERSION); 110 #endif 111
