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pcm_dsnoop.c

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/**
 * \file pcm/pcm_dsnoop.c
 * \ingroup PCM_Plugins
 * \brief PCM Capture Stream Snooping (dsnoop) Plugin Interface
 * \author Jaroslav Kysela <perex@suse.cz>
 * \date 2003
 */
/*
 *  PCM - Capture Stream Snooping
 *  Copyright (c) 2003 by Jaroslav Kysela <perex@suse.cz>
 *
 *
 *   This library is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU Lesser General Public License as
 *   published by the Free Software Foundation; either version 2.1 of
 *   the License, or (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU Lesser General Public License for more details.
 *
 *   You should have received a copy of the GNU Lesser General Public
 *   License along with this library; if not, write to the Free Software
 *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
 *
 */
  
#include <stdio.h>
#include <stdlib.h>
#include <stddef.h>
#include <unistd.h>
#include <signal.h>
#include <string.h>
#include <fcntl.h>
#include <ctype.h>
#include <grp.h>
#include <sys/ioctl.h>
#include <sys/mman.h>
#include <sys/shm.h>
#include <sys/sem.h>
#include <sys/wait.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <sys/mman.h>
#include "pcm_direct.h"

#ifndef PIC
/* entry for static linking */
const char *_snd_module_pcm_dsnoop = "";
#endif

/*
 *
 */

static void snoop_areas(snd_pcm_direct_t *dsnoop,
                  const snd_pcm_channel_area_t *src_areas,
                  const snd_pcm_channel_area_t *dst_areas,
                  snd_pcm_uframes_t src_ofs,
                  snd_pcm_uframes_t dst_ofs,
                  snd_pcm_uframes_t size)
{
      unsigned int chn, schn, channels;
      snd_pcm_format_t format;

      channels = dsnoop->channels;
      format = dsnoop->shmptr->s.format;
      if (dsnoop->interleaved) {
            unsigned int fbytes = snd_pcm_format_physical_width(format) / 8;
            memcpy(((char *)dst_areas[0].addr) + (dst_ofs * channels * fbytes),
                   ((char *)src_areas[0].addr) + (src_ofs * channels * fbytes),
                   size * channels * fbytes);
      } else {
            for (chn = 0; chn < channels; chn++) {
                  schn = dsnoop->bindings ? dsnoop->bindings[chn] : chn;
                  snd_pcm_area_copy(&dst_areas[chn], dst_ofs, &src_areas[schn], src_ofs, size, format);
            }
      }
}

/*
 *  synchronize shm ring buffer with hardware
 */
static void snd_pcm_dsnoop_sync_area(snd_pcm_t *pcm, snd_pcm_uframes_t slave_hw_ptr, snd_pcm_uframes_t size)
{
      snd_pcm_direct_t *dsnoop = pcm->private_data;
      snd_pcm_uframes_t hw_ptr = dsnoop->hw_ptr;
      snd_pcm_uframes_t transfer;
      const snd_pcm_channel_area_t *src_areas, *dst_areas;
      
      /* add sample areas here */
      dst_areas = snd_pcm_mmap_areas(pcm);
      src_areas = snd_pcm_mmap_areas(dsnoop->spcm);
      hw_ptr %= pcm->buffer_size;
      slave_hw_ptr %= dsnoop->slave_buffer_size;
      while (size > 0) {
            transfer = hw_ptr + size > pcm->buffer_size ? pcm->buffer_size - hw_ptr : size;
            transfer = slave_hw_ptr + transfer > dsnoop->slave_buffer_size ?
                  dsnoop->slave_buffer_size - slave_hw_ptr : transfer;
            size -= transfer;
            snoop_areas(dsnoop, src_areas, dst_areas, slave_hw_ptr, hw_ptr, transfer);
            slave_hw_ptr += transfer;
            slave_hw_ptr %= dsnoop->slave_buffer_size;
            hw_ptr += transfer;
            hw_ptr %= pcm->buffer_size;
      }
}

/*
 *  synchronize hardware pointer (hw_ptr) with ours
 */
static int snd_pcm_dsnoop_sync_ptr(snd_pcm_t *pcm)
{
      snd_pcm_direct_t *dsnoop = pcm->private_data;
      snd_pcm_uframes_t slave_hw_ptr, old_slave_hw_ptr, avail;
      snd_pcm_sframes_t diff;
      
      switch (snd_pcm_state(dsnoop->spcm)) {
      case SND_PCM_STATE_DISCONNECTED:
            dsnoop->state = SNDRV_PCM_STATE_DISCONNECTED;
            return -ENOTTY;
      default:
            break;
      }
      if (dsnoop->slowptr)
            snd_pcm_hwsync(dsnoop->spcm);
      old_slave_hw_ptr = dsnoop->slave_hw_ptr;
      slave_hw_ptr = dsnoop->slave_hw_ptr = *dsnoop->spcm->hw.ptr;
      diff = slave_hw_ptr - old_slave_hw_ptr;
      if (diff == 0)          /* fast path */
            return 0;
      if (diff < 0) {
            slave_hw_ptr += dsnoop->slave_boundary;
            diff = slave_hw_ptr - old_slave_hw_ptr;
      }
      snd_pcm_dsnoop_sync_area(pcm, old_slave_hw_ptr, diff);
      dsnoop->hw_ptr += diff;
      dsnoop->hw_ptr %= pcm->boundary;
      // printf("sync ptr diff = %li\n", diff);
      if (pcm->stop_threshold >= pcm->boundary) /* don't care */
            return 0;
      if ((avail = snd_pcm_mmap_capture_hw_avail(pcm)) >= pcm->stop_threshold) {
            struct timeval tv;
            gettimeofday(&tv, 0);
            dsnoop->trigger_tstamp.tv_sec = tv.tv_sec;
            dsnoop->trigger_tstamp.tv_nsec = tv.tv_usec * 1000L;
            dsnoop->state = SND_PCM_STATE_XRUN;
            dsnoop->avail_max = avail;
            return -EPIPE;
      }
      if (avail > dsnoop->avail_max)
            dsnoop->avail_max = avail;
      return 0;
}

/*
 *  plugin implementation
 */

static int snd_pcm_dsnoop_status(snd_pcm_t *pcm, snd_pcm_status_t * status)
{
      snd_pcm_direct_t *dsnoop = pcm->private_data;
      snd_pcm_state_t state;

      switch(dsnoop->state) {
      case SNDRV_PCM_STATE_DRAINING:
      case SNDRV_PCM_STATE_RUNNING:
            snd_pcm_dsnoop_sync_ptr(pcm);
            break;
      default:
            break;
      }
      memset(status, 0, sizeof(*status));
      state = snd_pcm_state(dsnoop->spcm);
      status->state = state == SND_PCM_STATE_RUNNING ? dsnoop->state : state;
      status->trigger_tstamp = dsnoop->trigger_tstamp;
      status->tstamp = snd_pcm_hw_fast_tstamp(dsnoop->spcm);
      status->avail = snd_pcm_mmap_capture_avail(pcm);
      status->avail_max = status->avail > dsnoop->avail_max ? status->avail : dsnoop->avail_max;
      dsnoop->avail_max = 0;
      return 0;
}

static snd_pcm_state_t snd_pcm_dsnoop_state(snd_pcm_t *pcm)
{
      snd_pcm_direct_t *dsnoop = pcm->private_data;
      switch (snd_pcm_state(dsnoop->spcm)) {
      case SND_PCM_STATE_SUSPENDED:
            return SND_PCM_STATE_SUSPENDED;
      case SND_PCM_STATE_DISCONNECTED:
            dsnoop->state = SNDRV_PCM_STATE_DISCONNECTED;
            return -ENOTTY;
      default:
            break;
      }
      return dsnoop->state;
}

static int snd_pcm_dsnoop_delay(snd_pcm_t *pcm, snd_pcm_sframes_t *delayp)
{
      snd_pcm_direct_t *dsnoop = pcm->private_data;
      int err;
      
      switch(dsnoop->state) {
      case SNDRV_PCM_STATE_DRAINING:
      case SNDRV_PCM_STATE_RUNNING:
            err = snd_pcm_dsnoop_sync_ptr(pcm);
            if (err < 0)
                  return err;
      case SNDRV_PCM_STATE_PREPARED:
      case SNDRV_PCM_STATE_SUSPENDED:
            *delayp = snd_pcm_mmap_capture_hw_avail(pcm);
            return 0;
      case SNDRV_PCM_STATE_XRUN:
            return -EPIPE;
      case SNDRV_PCM_STATE_DISCONNECTED:
            return -ENOTTY;
      default:
            return -EBADFD;
      }
}

static int snd_pcm_dsnoop_hwsync(snd_pcm_t *pcm)
{
      snd_pcm_direct_t *dsnoop = pcm->private_data;

      switch(dsnoop->state) {
      case SNDRV_PCM_STATE_DRAINING:
      case SNDRV_PCM_STATE_RUNNING:
            return snd_pcm_dsnoop_sync_ptr(pcm);
      case SNDRV_PCM_STATE_PREPARED:
      case SNDRV_PCM_STATE_SUSPENDED:
            return 0;
      case SNDRV_PCM_STATE_XRUN:
            return -EPIPE;
      case SNDRV_PCM_STATE_DISCONNECTED:
            return -ENOTTY;
      default:
            return -EBADFD;
      }
}

static int snd_pcm_dsnoop_prepare(snd_pcm_t *pcm)
{
      snd_pcm_direct_t *dsnoop = pcm->private_data;

      snd_pcm_direct_check_interleave(dsnoop, pcm);
      dsnoop->state = SND_PCM_STATE_PREPARED;
      dsnoop->appl_ptr = 0;
      dsnoop->hw_ptr = 0;
      return snd_pcm_direct_set_timer_params(dsnoop);
}

static int snd_pcm_dsnoop_reset(snd_pcm_t *pcm)
{
      snd_pcm_direct_t *dsnoop = pcm->private_data;
      dsnoop->hw_ptr %= pcm->period_size;
      dsnoop->appl_ptr = dsnoop->hw_ptr;
      dsnoop->slave_appl_ptr = dsnoop->slave_hw_ptr = *dsnoop->spcm->hw.ptr;
      return 0;
}

static int snd_pcm_dsnoop_start(snd_pcm_t *pcm)
{
      snd_pcm_direct_t *dsnoop = pcm->private_data;
      struct timeval tv;
      int err;
      
      if (dsnoop->state != SND_PCM_STATE_PREPARED)
            return -EBADFD;
      snd_pcm_hwsync(dsnoop->spcm);
      dsnoop->slave_appl_ptr = dsnoop->slave_hw_ptr = *dsnoop->spcm->hw.ptr;
      err = snd_timer_start(dsnoop->timer);
      if (err < 0)
            return err;
      dsnoop->state = SND_PCM_STATE_RUNNING;
      gettimeofday(&tv, 0);
      dsnoop->trigger_tstamp.tv_sec = tv.tv_sec;
      dsnoop->trigger_tstamp.tv_nsec = tv.tv_usec * 1000L;
      return 0;
}

static int snd_pcm_dsnoop_drop(snd_pcm_t *pcm)
{
      snd_pcm_direct_t *dsnoop = pcm->private_data;
      if (dsnoop->state == SND_PCM_STATE_OPEN)
            return -EBADFD;
      snd_timer_stop(dsnoop->timer);
      dsnoop->state = SND_PCM_STATE_SETUP;
      return 0;
}

static int snd_pcm_dsnoop_drain(snd_pcm_t *pcm)
{
      snd_pcm_direct_t *dsnoop = pcm->private_data;
      snd_pcm_uframes_t stop_threshold;
      int err;

      if (dsnoop->state == SND_PCM_STATE_OPEN)
            return -EBADFD;
      stop_threshold = pcm->stop_threshold;
      if (pcm->stop_threshold > pcm->buffer_size)
            pcm->stop_threshold = pcm->buffer_size;
      while (dsnoop->state == SND_PCM_STATE_RUNNING) {
            err = snd_pcm_dsnoop_sync_ptr(pcm);
            if (err < 0)
                  break;
            if (pcm->mode & SND_PCM_NONBLOCK)
                  return -EAGAIN;
            snd_pcm_wait(pcm, -1);
      }
      pcm->stop_threshold = stop_threshold;
      return snd_pcm_dsnoop_drop(pcm);
}

static int snd_pcm_dsnoop_pause(snd_pcm_t *pcm ATTRIBUTE_UNUSED, int enable ATTRIBUTE_UNUSED)
{
      return -EIO;
}

static snd_pcm_sframes_t snd_pcm_dsnoop_rewind(snd_pcm_t *pcm, snd_pcm_uframes_t frames)
{
      snd_pcm_mmap_appl_backward(pcm, frames);
      return frames;
}

static snd_pcm_sframes_t snd_pcm_dsnoop_forward(snd_pcm_t *pcm, snd_pcm_uframes_t frames)
{
      snd_pcm_sframes_t avail;

      avail = snd_pcm_mmap_capture_hw_avail(pcm);
      if (avail < 0)
            return 0;
      if (frames > (snd_pcm_uframes_t)avail)
            frames = avail;
      snd_pcm_mmap_appl_forward(pcm, frames);
      return frames;
}

static snd_pcm_sframes_t snd_pcm_dsnoop_writei(snd_pcm_t *pcm ATTRIBUTE_UNUSED, const void *buffer ATTRIBUTE_UNUSED, snd_pcm_uframes_t size ATTRIBUTE_UNUSED)
{
      return -ENODEV;
}

static snd_pcm_sframes_t snd_pcm_dsnoop_writen(snd_pcm_t *pcm ATTRIBUTE_UNUSED, void **bufs ATTRIBUTE_UNUSED, snd_pcm_uframes_t size ATTRIBUTE_UNUSED)
{
      return -ENODEV;
}

static int snd_pcm_dsnoop_close(snd_pcm_t *pcm)
{
      snd_pcm_direct_t *dsnoop = pcm->private_data;

      if (dsnoop->timer)
            snd_timer_close(dsnoop->timer);
      snd_pcm_direct_semaphore_down(dsnoop, DIRECT_IPC_SEM_CLIENT);
      snd_pcm_close(dsnoop->spcm);
      if (dsnoop->server)
            snd_pcm_direct_server_discard(dsnoop);
      if (dsnoop->client)
            snd_pcm_direct_client_discard(dsnoop);
      snd_pcm_direct_shm_discard(dsnoop);
      snd_pcm_direct_semaphore_up(dsnoop, DIRECT_IPC_SEM_CLIENT);
      if (dsnoop->bindings)
            free(dsnoop->bindings);
      pcm->private_data = NULL;
      free(dsnoop);
      return 0;
}

static snd_pcm_sframes_t snd_pcm_dsnoop_mmap_commit(snd_pcm_t *pcm,
                                        snd_pcm_uframes_t offset ATTRIBUTE_UNUSED,
                                        snd_pcm_uframes_t size)
{
      snd_pcm_direct_t *dsnoop = pcm->private_data;
      int err;

      switch (snd_pcm_state(dsnoop->spcm)) {
      case SND_PCM_STATE_XRUN:
            return -EPIPE;
      case SND_PCM_STATE_SUSPENDED:
            return -ESTRPIPE;
      default:
            break;
      }
      if (dsnoop->state == SND_PCM_STATE_RUNNING) {
            err = snd_pcm_dsnoop_sync_ptr(pcm);
            if (err < 0)
                  return err;
      }
      snd_pcm_mmap_appl_forward(pcm, size);
      /* clear timer queue to avoid a bogus return from poll */
      if (snd_pcm_mmap_capture_avail(pcm) < pcm->avail_min)
            snd_pcm_direct_clear_timer_queue(dsnoop);
      return size;
}

static snd_pcm_sframes_t snd_pcm_dsnoop_avail_update(snd_pcm_t *pcm ATTRIBUTE_UNUSED)
{
      snd_pcm_direct_t *dsnoop = pcm->private_data;
      int err;
      
      if (dsnoop->state == SND_PCM_STATE_RUNNING) {
            err = snd_pcm_dsnoop_sync_ptr(pcm);
            if (err < 0)
                  return err;
      }
      return snd_pcm_mmap_capture_avail(pcm);
}

static void snd_pcm_dsnoop_dump(snd_pcm_t *pcm, snd_output_t *out)
{
      snd_pcm_direct_t *dsnoop = pcm->private_data;

      snd_output_printf(out, "Direct Snoop PCM\n");
      if (pcm->setup) {
            snd_output_printf(out, "\nIts setup is:\n");
            snd_pcm_dump_setup(pcm, out);
      }
      if (dsnoop->spcm)
            snd_pcm_dump(dsnoop->spcm, out);
}

static snd_pcm_ops_t snd_pcm_dsnoop_ops = {
      .close = snd_pcm_dsnoop_close,
      .info = snd_pcm_direct_info,
      .hw_refine = snd_pcm_direct_hw_refine,
      .hw_params = snd_pcm_direct_hw_params,
      .hw_free = snd_pcm_direct_hw_free,
      .sw_params = snd_pcm_direct_sw_params,
      .channel_info = snd_pcm_direct_channel_info,
      .dump = snd_pcm_dsnoop_dump,
      .nonblock = snd_pcm_direct_nonblock,
      .async = snd_pcm_direct_async,
      .mmap = snd_pcm_direct_mmap,
      .munmap = snd_pcm_direct_munmap,
};

static snd_pcm_fast_ops_t snd_pcm_dsnoop_fast_ops = {
      .status = snd_pcm_dsnoop_status,
      .state = snd_pcm_dsnoop_state,
      .hwsync = snd_pcm_dsnoop_hwsync,
      .delay = snd_pcm_dsnoop_delay,
      .prepare = snd_pcm_dsnoop_prepare,
      .reset = snd_pcm_dsnoop_reset,
      .start = snd_pcm_dsnoop_start,
      .drop = snd_pcm_dsnoop_drop,
      .drain = snd_pcm_dsnoop_drain,
      .pause = snd_pcm_dsnoop_pause,
      .rewind = snd_pcm_dsnoop_rewind,
      .forward = snd_pcm_dsnoop_forward,
      .resume = snd_pcm_direct_resume,
      .link_fd = NULL,
      .link = NULL,
      .unlink = NULL,
      .writei = snd_pcm_dsnoop_writei,
      .writen = snd_pcm_dsnoop_writen,
      .readi = snd_pcm_mmap_readi,
      .readn = snd_pcm_mmap_readn,
      .avail_update = snd_pcm_dsnoop_avail_update,
      .mmap_commit = snd_pcm_dsnoop_mmap_commit,
      .poll_descriptors = NULL,
      .poll_descriptors_count = NULL,
      .poll_revents = snd_pcm_direct_poll_revents,
};

/**
 * \brief Creates a new dsnoop PCM
 * \param pcmp Returns created PCM handle
 * \param name Name of PCM
 * \param ipc_key IPC key for semaphore and shared memory
 * \param ipc_perm IPC permissions for semaphore and shared memory
 * \param ipc_gid IPC group ID for semaphore and shared memory
 * \param params Parameters for slave
 * \param bindings Channel bindings
 * \param slowptr Slow but more precise pointer updates
 * \param root Configuration root
 * \param sconf Slave configuration
 * \param stream PCM Direction (stream)
 * \param mode PCM Mode
 * \retval zero on success otherwise a negative error code
 * \warning Using of this function might be dangerous in the sense
 *          of compatibility reasons. The prototype might be freely
 *          changed in future.
 */
00487 int snd_pcm_dsnoop_open(snd_pcm_t **pcmp, const char *name,
                  key_t ipc_key, mode_t ipc_perm, int ipc_gid,
                  struct slave_params *params,
                  snd_config_t *bindings,
                  int slowptr,
                  snd_config_t *root, snd_config_t *sconf,
                  snd_pcm_stream_t stream, int mode)
{
      snd_pcm_t *pcm = NULL, *spcm = NULL;
      snd_pcm_direct_t *dsnoop = NULL;
      int ret, first_instance, fail_sem_loop = 10;

      assert(pcmp);

      if (stream != SND_PCM_STREAM_CAPTURE) {
            SNDERR("The dsnoop plugin supports only capture stream");
            return -EINVAL;
      }

      dsnoop = calloc(1, sizeof(snd_pcm_direct_t));
      if (!dsnoop) {
            ret = -ENOMEM;
            goto _err_nosem;
      }
      
      ret = snd_pcm_direct_parse_bindings(dsnoop, bindings);
      if (ret < 0)
            goto _err_nosem;
      
      dsnoop->ipc_key = ipc_key;
      dsnoop->ipc_perm = ipc_perm;
      dsnoop->ipc_gid = ipc_gid;
      dsnoop->semid = -1;
      dsnoop->shmid = -1;

      ret = snd_pcm_new(&pcm, dsnoop->type = SND_PCM_TYPE_DSNOOP, name, stream, mode);
      if (ret < 0)
            goto _err_nosem;

      while (1) {
            ret = snd_pcm_direct_semaphore_create_or_connect(dsnoop);
            if (ret < 0) {
                  SNDERR("unable to create IPC semaphore");
                  goto _err_nosem;
            }
      
            ret = snd_pcm_direct_semaphore_down(dsnoop, DIRECT_IPC_SEM_CLIENT);
            if (ret < 0) {
                  snd_pcm_direct_semaphore_discard(dsnoop);
                  if (--fail_sem_loop <= 0)
                        goto _err_nosem;
                  continue;
            }
            break;
      }
            
      first_instance = ret = snd_pcm_direct_shm_create_or_connect(dsnoop);
      if (ret < 0) {
            SNDERR("unable to create IPC shm instance");
            goto _err;
      }
            
      pcm->ops = &snd_pcm_dsnoop_ops;
      pcm->fast_ops = &snd_pcm_dsnoop_fast_ops;
      pcm->private_data = dsnoop;
      dsnoop->state = SND_PCM_STATE_OPEN;
      dsnoop->slowptr = slowptr;
      dsnoop->sync_ptr = snd_pcm_dsnoop_sync_ptr;

      if (first_instance) {
            ret = snd_pcm_open_slave(&spcm, root, sconf, stream, mode | SND_PCM_NONBLOCK);
            if (ret < 0) {
                  SNDERR("unable to open slave");
                  goto _err;
            }
      
            if (snd_pcm_type(spcm) != SND_PCM_TYPE_HW) {
                  SNDERR("dsnoop plugin can be only connected to hw plugin");
                  goto _err;
            }
            
            ret = snd_pcm_direct_initialize_slave(dsnoop, spcm, params);
            if (ret < 0) {
                  SNDERR("unable to initialize slave");
                  goto _err;
            }

            dsnoop->spcm = spcm;
            
            ret = snd_pcm_direct_server_create(dsnoop);
            if (ret < 0) {
                  SNDERR("unable to create server");
                  goto _err;
            }

            dsnoop->shmptr->type = spcm->type;
      } else {
            /* up semaphore to avoid deadlock */
            snd_pcm_direct_semaphore_up(dsnoop, DIRECT_IPC_SEM_CLIENT);
            ret = snd_pcm_direct_client_connect(dsnoop);
            if (ret < 0) {
                  SNDERR("unable to connect client");
                  goto _err_nosem;
            }
                  
            snd_pcm_direct_semaphore_down(dsnoop, DIRECT_IPC_SEM_CLIENT);

            ret = snd_pcm_direct_open_secondary_client(&spcm, dsnoop, "dsnoop_client");
            if (ret < 0)
                  goto _err;
            dsnoop->spcm = spcm;
      }

      ret = snd_pcm_direct_initialize_poll_fd(dsnoop);
      if (ret < 0) {
            SNDERR("unable to initialize poll_fd");
            goto _err;
      }

      pcm->poll_fd = dsnoop->poll_fd;
      pcm->poll_events = POLLIN;    /* it's different than other plugins */
            
      pcm->mmap_rw = 1;
      snd_pcm_set_hw_ptr(pcm, &dsnoop->hw_ptr, -1, 0);
      snd_pcm_set_appl_ptr(pcm, &dsnoop->appl_ptr, -1, 0);
      
      if (dsnoop->channels == UINT_MAX)
            dsnoop->channels = dsnoop->shmptr->s.channels;
      
      snd_pcm_direct_semaphore_up(dsnoop, DIRECT_IPC_SEM_CLIENT);

      *pcmp = pcm;
      return 0;
      
 _err:
      if (dsnoop->timer)
            snd_timer_close(dsnoop->timer);
      if (dsnoop->server)
            snd_pcm_direct_server_discard(dsnoop);
      if (dsnoop->client)
            snd_pcm_direct_client_discard(dsnoop);
      if (spcm)
            snd_pcm_close(spcm);
      if (dsnoop->shmid >= 0)
            snd_pcm_direct_shm_discard(dsnoop);
      if (snd_pcm_direct_semaphore_discard(dsnoop) < 0)
            snd_pcm_direct_semaphore_up(dsnoop, DIRECT_IPC_SEM_CLIENT);
 _err_nosem:
      if (dsnoop) {
            if (dsnoop->bindings)
                  free(dsnoop->bindings);
            free(dsnoop);
      }
      if (pcm)
            snd_pcm_free(pcm);
      return ret;
}

/*! \page pcm_plugins

\section pcm_plugins_dsnoop Plugin: dsnoop

This plugin splits one capture stream to more.
It works the reverse way of \ref pcm_plugins_dmix "dmix plugin",
reading the shared capture buffer from many clients concurrently.
The meaning of parameters below are almost identical with
dmix plugin.

\code
pcm.name {
      type dsnoop       # Direct snoop
      ipc_key INT       # unique IPC key
      ipc_key_add_uid BOOL    # add current uid to unique IPC key
      ipc_perm INT            # IPC permissions (octal, default 0600)
      slave STR
      # or
      slave {                 # Slave definition
            pcm STR           # slave PCM name
            # or
            pcm { }           # slave PCM definition
            format STR  # format definition
            rate INT    # rate definition
            channels INT
            period_time INT   # in usec
            # or
            period_size INT   # in bytes
            buffer_time INT   # in usec
            # or
            buffer_size INT # in bytes
            periods INT # when buffer_size or buffer_time is not specified
      }
      bindings {        # note: this is client independent!!!
            N INT       # maps slave channel to client channel N
      }
      slowptr BOOL            # slow but more precise pointer updates
}
\endcode

\subsection pcm_plugins_dsnoop_funcref Function reference

<UL>
  <LI>snd_pcm_dsnoop_open()
  <LI>_snd_pcm_dsnoop_open()
</UL>

*/

/**
 * \brief Creates a new dsnoop PCM
 * \param pcmp Returns created PCM handle
 * \param name Name of PCM
 * \param root Root configuration node
 * \param conf Configuration node with dsnoop PCM description
 * \param stream PCM Stream
 * \param mode PCM Mode
 * \warning Using of this function might be dangerous in the sense
 *          of compatibility reasons. The prototype might be freely
 *          changed in future.
 */
00706 int _snd_pcm_dsnoop_open(snd_pcm_t **pcmp, const char *name,
                   snd_config_t *root, snd_config_t *conf,
                   snd_pcm_stream_t stream, int mode)
{
      snd_config_iterator_t i, next;
      snd_config_t *slave = NULL, *bindings = NULL, *sconf;
      struct slave_params params;
      int bsize, psize, ipc_key_add_uid = 0, slowptr = 0;
      key_t ipc_key = 0;
      mode_t ipc_perm = 0600;
      int ipc_gid = -1;
      int err;

      snd_config_for_each(i, next, conf) {
            snd_config_t *n = snd_config_iterator_entry(i);
            const char *id;
            if (snd_config_get_id(n, &id) < 0)
                  continue;
            if (snd_pcm_conf_generic_id(id))
                  continue;
            if (strcmp(id, "ipc_key") == 0) {
                  long key;
                  err = snd_config_get_integer(n, &key);
                  if (err < 0) {
                        SNDERR("The field ipc_key must be an integer type");
                        return err;
                  }
                  ipc_key = key;
                  continue;
            }
            if (strcmp(id, "ipc_perm") == 0) {
                  char *perm;
                  char *endp;
                  err = snd_config_get_ascii(n, &perm);
                  if (err < 0) {
                        SNDERR("The field ipc_perm must be a valid file permission");
                        return err;
                  }
                  if (isdigit(*perm) == 0) {
                        SNDERR("The field ipc_perm must be a valid file permission");
                        free(perm);
                        return -EINVAL;
                  }
                  ipc_perm = strtol(perm, &endp, 8);
                  free(perm);
                  continue;
            }
            if (strcmp(id, "ipc_gid") == 0) {
                  char *group;
                  char *endp;
                  err = snd_config_get_ascii(n, &group);
                  if (err < 0) {
                        SNDERR("The field ipc_gid must be a valid group");
                        return err;
                  }
                  if (isdigit(*group) == 0) {
                        struct group *grp = getgrnam(group);
                        if (group == NULL) {
                              SNDERR("The field ipc_gid must be a valid group (create group %s)", group);
                              free(group);
                              return -EINVAL;
                        }
                        ipc_gid = grp->gr_gid;
                  } else {
                        ipc_perm = strtol(group, &endp, 10);
                  }
                  free(group);
                  continue;
            }
            if (strcmp(id, "ipc_key_add_uid") == 0) {
                  err = snd_config_get_bool(n);
                  if (err < 0) {
                        SNDERR("The field ipc_key_add_uid must be a boolean type");
                        return err;
                  }
                  ipc_key_add_uid = err;
                  continue;
            }
            if (strcmp(id, "slave") == 0) {
                  slave = n;
                  continue;
            }
            if (strcmp(id, "bindings") == 0) {
                  bindings = n;
                  continue;
            }
            if (strcmp(id, "slowptr") == 0) {
                  err = snd_config_get_bool(n);
                  if (err < 0) {
                        SNDERR("The field slowptr must be a boolean type");
                        return err;
                  }
                  slowptr = err;
                  continue;
            }
            SNDERR("Unknown field %s", id);
            return -EINVAL;
      }
      if (!slave) {
            SNDERR("slave is not defined");
            return -EINVAL;
      }
      if (ipc_key_add_uid)
            ipc_key += getuid();
      if (!ipc_key) {
            SNDERR("Unique IPC key is not defined");
            return -EINVAL;
      }
      /* the default settings, it might be invalid for some hardware */
      params.format = SND_PCM_FORMAT_S16;
      params.rate = 48000;
      params.channels = 2;
      params.period_time = -1;
      params.buffer_time = -1;
      bsize = psize = -1;
      params.periods = 3;
      err = snd_pcm_slave_conf(root, slave, &sconf, 8,
                         SND_PCM_HW_PARAM_FORMAT, 0, &params.format,
                         SND_PCM_HW_PARAM_RATE, 0, &params.rate,
                         SND_PCM_HW_PARAM_CHANNELS, 0, &params.channels,
                         SND_PCM_HW_PARAM_PERIOD_TIME, 0, &params.period_time,
                         SND_PCM_HW_PARAM_BUFFER_TIME, 0, &params.buffer_time,
                         SND_PCM_HW_PARAM_PERIOD_SIZE, 0, &psize,
                         SND_PCM_HW_PARAM_BUFFER_SIZE, 0, &bsize,
                         SND_PCM_HW_PARAM_PERIODS, 0, &params.periods);
      if (err < 0)
            return err;

      /* set a reasonable default */  
      if (psize == -1 && params.period_time == -1)
            params.period_time = 125000;    /* 0.125 seconds */

      params.period_size = psize;
      params.buffer_size = bsize;
      err = snd_pcm_dsnoop_open(pcmp, name, ipc_key, ipc_perm, ipc_gid, &params, bindings, slowptr, root, sconf, stream, mode);
      if (err < 0)
            snd_config_delete(sconf);
      return err;
}
#ifndef DOC_HIDDEN
SND_DLSYM_BUILD_VERSION(_snd_pcm_dsnoop_open, SND_PCM_DLSYM_VERSION);
#endif

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