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/**
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* \file pcm/pcm_null.c
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* \ingroup PCM_Plugins
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* \brief PCM Null Plugin Interface
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* \author Abramo Bagnara <abramo@alsa-project.org>
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* \date 2000-2001
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*/
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/*
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* PCM - Null plugin
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* Copyright (c) 2000 by Abramo Bagnara <abramo@alsa-project.org>
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*
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*
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* This library is free software; you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License as
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* published by the Free Software Foundation; either version 2.1 of
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* the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*
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*/
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#include "bswap.h"
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#include <limits.h>
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#include "pcm_local.h"
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#include "pcm_plugin.h"
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#ifndef PIC
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/* entry for static linking */
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const char *_snd_module_pcm_null = "";
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#endif
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#ifndef DOC_HIDDEN
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typedef struct {
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snd_htimestamp_t trigger_tstamp;
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snd_pcm_state_t state;
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snd_pcm_uframes_t appl_ptr;
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snd_pcm_uframes_t hw_ptr;
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int poll_fd;
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snd_pcm_chmap_query_t **chmap;
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} snd_pcm_null_t;
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#endif
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static int snd_pcm_null_close(snd_pcm_t *pcm)
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{
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snd_pcm_null_t *null = pcm->private_data;
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close(null->poll_fd);
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free(null);
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return 0;
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}
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static int snd_pcm_null_nonblock(snd_pcm_t *pcm ATTRIBUTE_UNUSED, int nonblock ATTRIBUTE_UNUSED)
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{
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return 0;
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}
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static int snd_pcm_null_async(snd_pcm_t *pcm ATTRIBUTE_UNUSED, int sig ATTRIBUTE_UNUSED, pid_t pid ATTRIBUTE_UNUSED)
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{
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return -ENOSYS;
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}
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static int snd_pcm_null_info(snd_pcm_t *pcm, snd_pcm_info_t * info)
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{
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memset(info, 0, sizeof(*info));
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info->stream = pcm->stream;
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info->card = -1;
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if (pcm->name) {
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snd_strlcpy((char *)info->id, pcm->name, sizeof(info->id));
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snd_strlcpy((char *)info->name, pcm->name, sizeof(info->name));
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snd_strlcpy((char *)info->subname, pcm->name, sizeof(info->subname));
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}
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info->subdevices_count = 1;
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return 0;
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}
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static snd_pcm_sframes_t snd_pcm_null_avail_update(snd_pcm_t *pcm)
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{
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snd_pcm_null_t *null = pcm->private_data;
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if (null->state == SND_PCM_STATE_PREPARED) {
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/* it is required to return the correct avail count for */
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/* the prepared stream, otherwise the start is not called */
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return snd_pcm_mmap_avail(pcm);
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}
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return pcm->buffer_size;
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}
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static int snd_pcm_null_status(snd_pcm_t *pcm, snd_pcm_status_t * status)
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{
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snd_pcm_null_t *null = pcm->private_data;
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memset(status, 0, sizeof(*status));
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status->state = null->state;
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status->trigger_tstamp = null->trigger_tstamp;
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gettimestamp(&status->tstamp, pcm->tstamp_type);
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status->avail = snd_pcm_null_avail_update(pcm);
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status->avail_max = pcm->buffer_size;
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return 0;
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}
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static snd_pcm_state_t snd_pcm_null_state(snd_pcm_t *pcm)
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{
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snd_pcm_null_t *null = pcm->private_data;
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return null->state;
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}
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static int snd_pcm_null_hwsync(snd_pcm_t *pcm ATTRIBUTE_UNUSED)
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{
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return 0;
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}
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static int snd_pcm_null_delay(snd_pcm_t *pcm ATTRIBUTE_UNUSED, snd_pcm_sframes_t *delayp)
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{
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*delayp = 0;
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return 0;
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}
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static int snd_pcm_null_reset(snd_pcm_t *pcm)
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{
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*pcm->appl.ptr = 0;
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*pcm->hw.ptr = 0;
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return 0;
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}
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static int snd_pcm_null_prepare(snd_pcm_t *pcm)
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{
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snd_pcm_null_t *null = pcm->private_data;
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null->state = SND_PCM_STATE_PREPARED;
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return snd_pcm_null_reset(pcm);
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}
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static int snd_pcm_null_start(snd_pcm_t *pcm)
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{
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snd_pcm_null_t *null = pcm->private_data;
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assert(null->state == SND_PCM_STATE_PREPARED);
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null->state = SND_PCM_STATE_RUNNING;
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if (pcm->stream == SND_PCM_STREAM_CAPTURE)
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*pcm->hw.ptr = *pcm->appl.ptr + pcm->buffer_size;
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else
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*pcm->hw.ptr = *pcm->appl.ptr;
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return 0;
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}
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static int snd_pcm_null_drop(snd_pcm_t *pcm)
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{
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snd_pcm_null_t *null = pcm->private_data;
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assert(null->state != SND_PCM_STATE_OPEN);
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null->state = SND_PCM_STATE_SETUP;
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return 0;
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}
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static int snd_pcm_null_drain(snd_pcm_t *pcm)
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{
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snd_pcm_null_t *null = pcm->private_data;
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assert(null->state != SND_PCM_STATE_OPEN);
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null->state = SND_PCM_STATE_SETUP;
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return 0;
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}
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static int snd_pcm_null_pause(snd_pcm_t *pcm, int enable)
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{
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snd_pcm_null_t *null = pcm->private_data;
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if (enable) {
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if (null->state != SND_PCM_STATE_RUNNING)
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return -EBADFD;
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null->state = SND_PCM_STATE_PAUSED;
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} else {
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if (null->state != SND_PCM_STATE_PAUSED)
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return -EBADFD;
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null->state = SND_PCM_STATE_RUNNING;
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}
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return 0;
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}
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static snd_pcm_sframes_t snd_pcm_null_rewindable(snd_pcm_t *pcm)
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{
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return pcm->buffer_size;
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}
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static snd_pcm_sframes_t snd_pcm_null_forwardable(snd_pcm_t *pcm ATTRIBUTE_UNUSED)
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{
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return 0;
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}
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static snd_pcm_sframes_t snd_pcm_null_rewind(snd_pcm_t *pcm, snd_pcm_uframes_t frames)
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{
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snd_pcm_null_t *null = pcm->private_data;
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switch (null->state) {
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case SND_PCM_STATE_RUNNING:
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snd_pcm_mmap_hw_backward(pcm, frames);
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/* Fall through */
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case SND_PCM_STATE_PREPARED:
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snd_pcm_mmap_appl_backward(pcm, frames);
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return frames;
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default:
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return -EBADFD;
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}
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}
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static snd_pcm_sframes_t snd_pcm_null_forward(snd_pcm_t *pcm, snd_pcm_uframes_t frames)
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{
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snd_pcm_null_t *null = pcm->private_data;
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switch (null->state) {
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case SND_PCM_STATE_RUNNING:
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snd_pcm_mmap_hw_forward(pcm, frames);
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/* Fall through */
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case SND_PCM_STATE_PREPARED:
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snd_pcm_mmap_appl_forward(pcm, frames);
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return frames;
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default:
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return -EBADFD;
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}
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}
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static int snd_pcm_null_resume(snd_pcm_t *pcm ATTRIBUTE_UNUSED)
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{
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return 0;
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}
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static snd_pcm_sframes_t snd_pcm_null_xfer_areas(snd_pcm_t *pcm,
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const snd_pcm_channel_area_t *areas ATTRIBUTE_UNUSED,
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snd_pcm_uframes_t offset ATTRIBUTE_UNUSED,
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snd_pcm_uframes_t size)
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{
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snd_pcm_mmap_appl_forward(pcm, size);
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snd_pcm_mmap_hw_forward(pcm, size);
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return size;
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}
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static snd_pcm_sframes_t snd_pcm_null_writei(snd_pcm_t *pcm, const void *buffer ATTRIBUTE_UNUSED, snd_pcm_uframes_t size)
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|
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{
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return snd_pcm_write_areas(pcm, NULL, 0, size, snd_pcm_null_xfer_areas);
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}
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static snd_pcm_sframes_t snd_pcm_null_writen(snd_pcm_t *pcm, void **bufs ATTRIBUTE_UNUSED, snd_pcm_uframes_t size)
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|
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{
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return snd_pcm_write_areas(pcm, NULL, 0, size, snd_pcm_null_xfer_areas);
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}
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static snd_pcm_sframes_t snd_pcm_null_readi(snd_pcm_t *pcm, void *buffer ATTRIBUTE_UNUSED, snd_pcm_uframes_t size)
|
|
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{
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return snd_pcm_read_areas(pcm, NULL, 0, size, snd_pcm_null_xfer_areas);
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}
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|
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static snd_pcm_sframes_t snd_pcm_null_readn(snd_pcm_t *pcm, void **bufs ATTRIBUTE_UNUSED, snd_pcm_uframes_t size)
|
|
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{
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|
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return snd_pcm_read_areas(pcm, NULL, 0, size, snd_pcm_null_xfer_areas);
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}
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static snd_pcm_sframes_t snd_pcm_null_mmap_commit(snd_pcm_t *pcm,
|
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snd_pcm_uframes_t offset ATTRIBUTE_UNUSED,
|
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snd_pcm_uframes_t size)
|
|
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{
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|
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return snd_pcm_null_forward(pcm, size);
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}
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|
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static int snd_pcm_null_hw_refine(snd_pcm_t *pcm ATTRIBUTE_UNUSED, snd_pcm_hw_params_t *params)
|
|
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{
|
|
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4a16fb |
int err;
|
|
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4a16fb |
|
|
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/* Do not return a period size of 0 because for example portaudio cannot
|
|
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* handle it.
|
|
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*/
|
|
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err = _snd_pcm_hw_param_set_min(params, SND_PCM_HW_PARAM_PERIOD_SIZE, 1,
|
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4a16fb |
0);
|
|
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if (err < 0)
|
|
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return err;
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|
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4a16fb |
|
|
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4a16fb |
err = snd_pcm_hw_refine_soft(pcm, params);
|
|
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4a16fb |
params->info = SND_PCM_INFO_MMAP | SND_PCM_INFO_MMAP_VALID |
|
|
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SND_PCM_INFO_RESUME | SND_PCM_INFO_PAUSE;
|
|
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params->fifo_size = 0;
|
|
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return err;
|
|
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}
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|
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static int snd_pcm_null_hw_params(snd_pcm_t *pcm ATTRIBUTE_UNUSED, snd_pcm_hw_params_t * params ATTRIBUTE_UNUSED)
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{
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return 0;
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}
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static int snd_pcm_null_hw_free(snd_pcm_t *pcm ATTRIBUTE_UNUSED)
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{
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return 0;
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}
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static int snd_pcm_null_sw_params(snd_pcm_t *pcm ATTRIBUTE_UNUSED, snd_pcm_sw_params_t * params ATTRIBUTE_UNUSED)
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{
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return 0;
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}
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static snd_pcm_chmap_query_t **snd_pcm_null_query_chmaps(snd_pcm_t *pcm)
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{
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snd_pcm_null_t *null = pcm->private_data;
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if (null->chmap)
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return _snd_pcm_copy_chmap_query(null->chmap);
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return NULL;
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}
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static snd_pcm_chmap_t *snd_pcm_null_get_chmap(snd_pcm_t *pcm)
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{
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snd_pcm_null_t *null = pcm->private_data;
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if (null->chmap)
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return _snd_pcm_choose_fixed_chmap(pcm, null->chmap);
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return NULL;
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}
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static void snd_pcm_null_dump(snd_pcm_t *pcm, snd_output_t *out)
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{
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snd_output_printf(out, "Null PCM\n");
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if (pcm->setup) {
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snd_output_printf(out, "Its setup is:\n");
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snd_pcm_dump_setup(pcm, out);
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}
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}
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static const snd_pcm_ops_t snd_pcm_null_ops = {
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.close = snd_pcm_null_close,
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.info = snd_pcm_null_info,
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.hw_refine = snd_pcm_null_hw_refine,
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.hw_params = snd_pcm_null_hw_params,
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.hw_free = snd_pcm_null_hw_free,
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.sw_params = snd_pcm_null_sw_params,
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.channel_info = snd_pcm_generic_channel_info,
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.dump = snd_pcm_null_dump,
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.nonblock = snd_pcm_null_nonblock,
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.async = snd_pcm_null_async,
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.mmap = snd_pcm_generic_mmap,
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.munmap = snd_pcm_generic_munmap,
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.query_chmaps = snd_pcm_null_query_chmaps,
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.get_chmap = snd_pcm_null_get_chmap,
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.set_chmap = NULL,
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};
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static const snd_pcm_fast_ops_t snd_pcm_null_fast_ops = {
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.status = snd_pcm_null_status,
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.state = snd_pcm_null_state,
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.hwsync = snd_pcm_null_hwsync,
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.delay = snd_pcm_null_delay,
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.prepare = snd_pcm_null_prepare,
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.reset = snd_pcm_null_reset,
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.start = snd_pcm_null_start,
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.drop = snd_pcm_null_drop,
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.drain = snd_pcm_null_drain,
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.pause = snd_pcm_null_pause,
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.rewindable = snd_pcm_null_rewindable,
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.rewind = snd_pcm_null_rewind,
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.forwardable = snd_pcm_null_forwardable,
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.forward = snd_pcm_null_forward,
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.resume = snd_pcm_null_resume,
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.writei = snd_pcm_null_writei,
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.writen = snd_pcm_null_writen,
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.readi = snd_pcm_null_readi,
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.readn = snd_pcm_null_readn,
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.avail_update = snd_pcm_null_avail_update,
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.mmap_commit = snd_pcm_null_mmap_commit,
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.htimestamp = snd_pcm_generic_real_htimestamp,
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};
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|
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4a16fb |
/**
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* \brief Creates a new null PCM
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* \param pcmp Returns created PCM handle
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* \param name Name of PCM
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* \param stream Stream type
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* \param mode Stream mode
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* \retval zero on success otherwise a negative error code
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* \warning Using of this function might be dangerous in the sense
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* of compatibility reasons. The prototype might be freely
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* changed in future.
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|
Packit |
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*/
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int snd_pcm_null_open(snd_pcm_t **pcmp, const char *name, snd_pcm_stream_t stream, int mode)
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{
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snd_pcm_t *pcm;
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snd_pcm_null_t *null;
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int fd;
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int err;
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assert(pcmp);
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if (stream == SND_PCM_STREAM_PLAYBACK) {
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fd = open("/dev/null", O_WRONLY);
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if (fd < 0) {
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SYSERR("Cannot open /dev/null");
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return -errno;
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}
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} else {
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4a16fb |
fd = open("/dev/full", O_RDONLY);
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if (fd < 0) {
|
|
Packit |
4a16fb |
SYSERR("Cannot open /dev/full");
|
|
Packit |
4a16fb |
return -errno;
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|
Packit |
4a16fb |
}
|
|
Packit |
4a16fb |
}
|
|
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4a16fb |
null = calloc(1, sizeof(snd_pcm_null_t));
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4a16fb |
if (!null) {
|
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Packit |
4a16fb |
close(fd);
|
|
Packit |
4a16fb |
return -ENOMEM;
|
|
Packit |
4a16fb |
}
|
|
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4a16fb |
null->poll_fd = fd;
|
|
Packit |
4a16fb |
null->state = SND_PCM_STATE_OPEN;
|
|
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4a16fb |
|
|
Packit |
4a16fb |
err = snd_pcm_new(&pcm, SND_PCM_TYPE_NULL, name, stream, mode);
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4a16fb |
if (err < 0) {
|
|
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4a16fb |
close(fd);
|
|
Packit |
4a16fb |
free(null);
|
|
Packit |
4a16fb |
return err;
|
|
Packit |
4a16fb |
}
|
|
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pcm->ops = &snd_pcm_null_ops;
|
|
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4a16fb |
pcm->fast_ops = &snd_pcm_null_fast_ops;
|
|
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4a16fb |
pcm->private_data = null;
|
|
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4a16fb |
pcm->poll_fd = fd;
|
|
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4a16fb |
pcm->poll_events = stream == SND_PCM_STREAM_PLAYBACK ? POLLOUT : POLLIN;
|
|
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4a16fb |
snd_pcm_set_hw_ptr(pcm, &null->hw_ptr, -1, 0);
|
|
Packit |
4a16fb |
snd_pcm_set_appl_ptr(pcm, &null->appl_ptr, -1, 0);
|
|
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4a16fb |
*pcmp = pcm;
|
|
Packit |
4a16fb |
|
|
Packit |
4a16fb |
return 0;
|
|
Packit |
4a16fb |
}
|
|
Packit |
4a16fb |
|
|
Packit |
4a16fb |
/*! \page pcm_plugins
|
|
Packit |
4a16fb |
|
|
Packit |
4a16fb |
\section pcm_plugins_null Plugin: Null
|
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Packit |
4a16fb |
|
|
Packit |
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This plugin discards contents of a PCM stream or creates a stream with zero
|
|
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samples.
|
|
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4a16fb |
|
|
Packit |
4a16fb |
Note: This implementation uses devices /dev/null (playback, must be writable)
|
|
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and /dev/full (capture, must be readable).
|
|
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4a16fb |
|
|
Packit |
4a16fb |
\code
|
|
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pcm.name {
|
|
Packit |
4a16fb |
type null # Null PCM
|
|
Packit |
4a16fb |
[chmap MAP] # Provide channel maps; MAP is a string array
|
|
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4a16fb |
}
|
|
Packit |
4a16fb |
\endcode
|
|
Packit |
4a16fb |
|
|
Packit |
4a16fb |
\subsection pcm_plugins_null_funcref Function reference
|
|
Packit |
4a16fb |
|
|
Packit |
4a16fb |
|
|
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snd_pcm_null_open()
|
|
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4a16fb |
_snd_pcm_null_open()
|
|
Packit |
4a16fb |
|
|
Packit |
4a16fb |
|
|
Packit |
4a16fb |
*/
|
|
Packit |
4a16fb |
|
|
Packit |
4a16fb |
/**
|
|
Packit |
4a16fb |
* \brief Creates a new Null PCM
|
|
Packit |
4a16fb |
* \param pcmp Returns created PCM handle
|
|
Packit |
4a16fb |
* \param name Name of PCM
|
|
Packit |
4a16fb |
* \param root Root configuration node
|
|
Packit |
4a16fb |
* \param conf Configuration node with Null PCM description
|
|
Packit |
4a16fb |
* \param stream Stream type
|
|
Packit |
4a16fb |
* \param mode Stream mode
|
|
Packit |
4a16fb |
* \retval zero on success otherwise a negative error code
|
|
Packit |
4a16fb |
* \warning Using of this function might be dangerous in the sense
|
|
Packit |
4a16fb |
* of compatibility reasons. The prototype might be freely
|
|
Packit |
4a16fb |
* changed in future.
|
|
Packit |
4a16fb |
*/
|
|
Packit |
4a16fb |
int _snd_pcm_null_open(snd_pcm_t **pcmp, const char *name,
|
|
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4a16fb |
snd_config_t *root ATTRIBUTE_UNUSED, snd_config_t *conf,
|
|
Packit |
4a16fb |
snd_pcm_stream_t stream, int mode)
|
|
Packit |
4a16fb |
{
|
|
Packit |
4a16fb |
snd_config_iterator_t i, next;
|
|
Packit |
4a16fb |
snd_pcm_null_t *null;
|
|
Packit |
4a16fb |
snd_pcm_chmap_query_t **chmap = NULL;
|
|
Packit |
4a16fb |
int err;
|
|
Packit |
4a16fb |
|
|
Packit |
4a16fb |
snd_config_for_each(i, next, conf) {
|
|
Packit |
4a16fb |
snd_config_t *n = snd_config_iterator_entry(i);
|
|
Packit |
4a16fb |
const char *id;
|
|
Packit |
4a16fb |
if (snd_config_get_id(n, &id) < 0)
|
|
Packit |
4a16fb |
continue;
|
|
Packit |
4a16fb |
if (snd_pcm_conf_generic_id(id))
|
|
Packit |
4a16fb |
continue;
|
|
Packit |
4a16fb |
if (strcmp(id, "chmap") == 0) {
|
|
Packit |
4a16fb |
snd_pcm_free_chmaps(chmap);
|
|
Packit |
4a16fb |
chmap = _snd_pcm_parse_config_chmaps(n);
|
|
Packit |
4a16fb |
if (!chmap) {
|
|
Packit |
4a16fb |
SNDERR("Invalid channel map for %s", id);
|
|
Packit |
4a16fb |
return -EINVAL;
|
|
Packit |
4a16fb |
}
|
|
Packit |
4a16fb |
continue;
|
|
Packit |
4a16fb |
}
|
|
Packit |
4a16fb |
SNDERR("Unknown field %s", id);
|
|
Packit |
4a16fb |
snd_pcm_free_chmaps(chmap);
|
|
Packit |
4a16fb |
return -EINVAL;
|
|
Packit |
4a16fb |
}
|
|
Packit |
4a16fb |
err = snd_pcm_null_open(pcmp, name, stream, mode);
|
|
Packit |
4a16fb |
if (err < 0) {
|
|
Packit |
4a16fb |
snd_pcm_free_chmaps(chmap);
|
|
Packit |
4a16fb |
return err;
|
|
Packit |
4a16fb |
}
|
|
Packit |
4a16fb |
|
|
Packit |
4a16fb |
null = (*pcmp)->private_data;
|
|
Packit |
4a16fb |
null->chmap = chmap;
|
|
Packit |
4a16fb |
return 0;
|
|
Packit |
4a16fb |
}
|
|
Packit |
4a16fb |
#ifndef DOC_HIDDEN
|
|
Packit |
4a16fb |
SND_DLSYM_BUILD_VERSION(_snd_pcm_null_open, SND_PCM_DLSYM_VERSION);
|
|
Packit |
4a16fb |
#endif
|