text: /*
   * $Id$
   * PortAudio Portable Real-Time Audio Library
   * Latest Version at: http://www.portaudio.com
   * ALSA implementation by Joshua Haberman and Arve Knudsen
   *
   * Copyright (c) 2002 Joshua Haberman <joshua@haberman.com>
   * Copyright (c) 2005-2009 Arve Knudsen <arve.knudsen@gmail.com>
   * Copyright (c) 2008 Kevin Kofler <kevin.kofler@chello.at>
   *
   * Based on the Open Source API proposed by Ross Bencina
   * Copyright (c) 1999-2002 Ross Bencina, Phil Burk
   *
   * Permission is hereby granted, free of charge, to any person obtaining
   * a copy of this software and associated documentation files
   * (the "Software"), to deal in the Software without restriction,
   * including without limitation the rights to use, copy, modify, merge,
   * publish, distribute, sublicense, and/or sell copies of the Software,
   * and to permit persons to whom the Software is furnished to do so,
   * subject to the following conditions:
   *
   * The above copyright notice and this permission notice shall be
   * included in all copies or substantial portions of the Software.
   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
   * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
   * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
   * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR
   * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF
   * CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
   * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
   */
  
  /*
   * The text above constitutes the entire PortAudio license; however,
   * the PortAudio community also makes the following non-binding requests:
   *
   * Any person wishing to distribute modifications to the Software is
   * requested to send the modifications to the original developer so that
   * they can be incorporated into the canonical version. It is also
   * requested that these non-binding requests be included along with the
   * license above.
   */
  
  /**
   @file
   @ingroup hostapi_src
  */
  
  #define ALSA_PCM_NEW_HW_PARAMS_API
  #define ALSA_PCM_NEW_SW_PARAMS_API
  #include <alsa/asoundlib.h>
  #undef ALSA_PCM_NEW_HW_PARAMS_API
  #undef ALSA_PCM_NEW_SW_PARAMS_API
  
  #include <sys/poll.h>
  #include <string.h> /* strlen() */
  #include <limits.h>
  #include <math.h>
  #include <pthread.h>
  #include <signal.h>
  #include <time.h>
  #include <sys/mman.h>
  #include <signal.h> /* For sig_atomic_t */
  #ifdef PA_ALSA_DYNAMIC
      #include <dlfcn.h> /* For dlXXX functions */
  #endif
  
  #include "portaudio.h"
  #include "pa_util.h"
  #include "pa_unix_util.h"
  #include "pa_allocation.h"
  #include "pa_hostapi.h"
  #include "pa_stream.h"
  #include "pa_cpuload.h"
  #include "pa_process.h"
  #include "pa_endianness.h"
  #include "pa_debugprint.h"
  
  #include "pa_linux_alsa.h"
  
  /* Add missing define (for compatibility with older ALSA versions) */
  #ifndef SND_PCM_TSTAMP_ENABLE
      #define SND_PCM_TSTAMP_ENABLE SND_PCM_TSTAMP_MMAP
  #endif
  
  /* Combine version elements into a single (unsigned) integer */
  #define ALSA_VERSION_INT(major, minor, subminor)  ((major << 16) | (minor << 8) | subminor)
  
  /* The acceptable tolerance of sample rate set, to that requested (as a ratio, eg 50 is 2%, 100 is 1%) */
  #define RATE_MAX_DEVIATE_RATIO 100
  
  /* Defines Alsa function types and pointers to these functions. */
  #define _PA_DEFINE_FUNC(x)  typedef typeof(x) x##_ft; static x##_ft *alsa_##x = 0
  
  /* Alloca helper. */
  #define __alsa_snd_alloca(ptr,type) do { size_t __alsa_alloca_size = alsa_##type##_sizeof(); (*ptr) = (type##_t *) alloca(__alsa_alloca_size); memset(*ptr, 0, __alsa_alloca_size); } while (0)
  
  _PA_DEFINE_FUNC(snd_pcm_open);
  _PA_DEFINE_FUNC(snd_pcm_close);
  _PA_DEFINE_FUNC(snd_pcm_nonblock);
  _PA_DEFINE_FUNC(snd_pcm_frames_to_bytes);
  _PA_DEFINE_FUNC(snd_pcm_prepare);
  _PA_DEFINE_FUNC(snd_pcm_start);
  _PA_DEFINE_FUNC(snd_pcm_resume);
  _PA_DEFINE_FUNC(snd_pcm_wait);
  _PA_DEFINE_FUNC(snd_pcm_state);
  _PA_DEFINE_FUNC(snd_pcm_avail_update);
  _PA_DEFINE_FUNC(snd_pcm_areas_silence);
  _PA_DEFINE_FUNC(snd_pcm_mmap_begin);
  _PA_DEFINE_FUNC(snd_pcm_mmap_commit);
  _PA_DEFINE_FUNC(snd_pcm_readi);
  _PA_DEFINE_FUNC(snd_pcm_readn);
  _PA_DEFINE_FUNC(snd_pcm_writei);
  _PA_DEFINE_FUNC(snd_pcm_writen);
  _PA_DEFINE_FUNC(snd_pcm_drain);
  _PA_DEFINE_FUNC(snd_pcm_recover);
  _PA_DEFINE_FUNC(snd_pcm_drop);
  _PA_DEFINE_FUNC(snd_pcm_area_copy);
  _PA_DEFINE_FUNC(snd_pcm_poll_descriptors);
  _PA_DEFINE_FUNC(snd_pcm_poll_descriptors_count);
  _PA_DEFINE_FUNC(snd_pcm_poll_descriptors_revents);
  _PA_DEFINE_FUNC(snd_pcm_format_size);
  _PA_DEFINE_FUNC(snd_pcm_link);
  _PA_DEFINE_FUNC(snd_pcm_delay);
  
  _PA_DEFINE_FUNC(snd_pcm_hw_params_sizeof);
  _PA_DEFINE_FUNC(snd_pcm_hw_params_malloc);
  _PA_DEFINE_FUNC(snd_pcm_hw_params_free);
  _PA_DEFINE_FUNC(snd_pcm_hw_params_any);
  _PA_DEFINE_FUNC(snd_pcm_hw_params_set_access);
  _PA_DEFINE_FUNC(snd_pcm_hw_params_set_format);
  _PA_DEFINE_FUNC(snd_pcm_hw_params_set_channels);
  //_PA_DEFINE_FUNC(snd_pcm_hw_params_set_periods_near);
  _PA_DEFINE_FUNC(snd_pcm_hw_params_set_rate_near); //!!!
  _PA_DEFINE_FUNC(snd_pcm_hw_params_set_rate);
  _PA_DEFINE_FUNC(snd_pcm_hw_params_set_rate_resample);
  //_PA_DEFINE_FUNC(snd_pcm_hw_params_set_buffer_time_near);
  _PA_DEFINE_FUNC(snd_pcm_hw_params_set_buffer_size);
  _PA_DEFINE_FUNC(snd_pcm_hw_params_set_buffer_size_near); //!!!
  _PA_DEFINE_FUNC(snd_pcm_hw_params_set_buffer_size_min);
  //_PA_DEFINE_FUNC(snd_pcm_hw_params_set_period_time_near);
  _PA_DEFINE_FUNC(snd_pcm_hw_params_set_period_size_near);
  _PA_DEFINE_FUNC(snd_pcm_hw_params_set_periods_integer);
  _PA_DEFINE_FUNC(snd_pcm_hw_params_set_periods_min);
  
  _PA_DEFINE_FUNC(snd_pcm_hw_params_get_buffer_size);
  //_PA_DEFINE_FUNC(snd_pcm_hw_params_get_period_size);
  //_PA_DEFINE_FUNC(snd_pcm_hw_params_get_access);
  //_PA_DEFINE_FUNC(snd_pcm_hw_params_get_periods);
  //_PA_DEFINE_FUNC(snd_pcm_hw_params_get_rate);
  _PA_DEFINE_FUNC(snd_pcm_hw_params_get_channels_min);
  _PA_DEFINE_FUNC(snd_pcm_hw_params_get_channels_max);
  
  _PA_DEFINE_FUNC(snd_pcm_hw_params_test_period_size);
  _PA_DEFINE_FUNC(snd_pcm_hw_params_test_format);
  _PA_DEFINE_FUNC(snd_pcm_hw_params_test_access);
  _PA_DEFINE_FUNC(snd_pcm_hw_params_dump);
  _PA_DEFINE_FUNC(snd_pcm_hw_params);
  
  _PA_DEFINE_FUNC(snd_pcm_hw_params_get_periods_min);
  _PA_DEFINE_FUNC(snd_pcm_hw_params_get_periods_max);
  _PA_DEFINE_FUNC(snd_pcm_hw_params_set_period_size);
  _PA_DEFINE_FUNC(snd_pcm_hw_params_get_period_size_min);
  _PA_DEFINE_FUNC(snd_pcm_hw_params_get_period_size_max);
  _PA_DEFINE_FUNC(snd_pcm_hw_params_get_buffer_size_max);
  _PA_DEFINE_FUNC(snd_pcm_hw_params_get_rate_min);
  _PA_DEFINE_FUNC(snd_pcm_hw_params_get_rate_max);
  _PA_DEFINE_FUNC(snd_pcm_hw_params_get_rate_numden);
  #define alsa_snd_pcm_hw_params_alloca(ptr) __alsa_snd_alloca(ptr, snd_pcm_hw_params)
  
  _PA_DEFINE_FUNC(snd_pcm_sw_params_sizeof);
  _PA_DEFINE_FUNC(snd_pcm_sw_params_malloc);
  _PA_DEFINE_FUNC(snd_pcm_sw_params_current);
  _PA_DEFINE_FUNC(snd_pcm_sw_params_set_avail_min);
  _PA_DEFINE_FUNC(snd_pcm_sw_params);
  _PA_DEFINE_FUNC(snd_pcm_sw_params_free);
  _PA_DEFINE_FUNC(snd_pcm_sw_params_set_start_threshold);
  _PA_DEFINE_FUNC(snd_pcm_sw_params_set_stop_threshold);
  _PA_DEFINE_FUNC(snd_pcm_sw_params_get_boundary);
  _PA_DEFINE_FUNC(snd_pcm_sw_params_set_silence_threshold);
  _PA_DEFINE_FUNC(snd_pcm_sw_params_set_silence_size);
  _PA_DEFINE_FUNC(snd_pcm_sw_params_set_xfer_align);
  _PA_DEFINE_FUNC(snd_pcm_sw_params_set_tstamp_mode);
  #define alsa_snd_pcm_sw_params_alloca(ptr) __alsa_snd_alloca(ptr, snd_pcm_sw_params)
  
  _PA_DEFINE_FUNC(snd_pcm_info);
  _PA_DEFINE_FUNC(snd_pcm_info_sizeof);
  _PA_DEFINE_FUNC(snd_pcm_info_malloc);
  _PA_DEFINE_FUNC(snd_pcm_info_free);
  _PA_DEFINE_FUNC(snd_pcm_info_set_device);
  _PA_DEFINE_FUNC(snd_pcm_info_set_subdevice);
  _PA_DEFINE_FUNC(snd_pcm_info_set_stream);
  _PA_DEFINE_FUNC(snd_pcm_info_get_name);
  _PA_DEFINE_FUNC(snd_pcm_info_get_card);
  #define alsa_snd_pcm_info_alloca(ptr) __alsa_snd_alloca(ptr, snd_pcm_info)
  
  _PA_DEFINE_FUNC(snd_ctl_pcm_next_device);
  _PA_DEFINE_FUNC(snd_ctl_pcm_info);
  _PA_DEFINE_FUNC(snd_ctl_open);
  _PA_DEFINE_FUNC(snd_ctl_close);
  _PA_DEFINE_FUNC(snd_ctl_card_info_malloc);
  _PA_DEFINE_FUNC(snd_ctl_card_info_free);
  _PA_DEFINE_FUNC(snd_ctl_card_info);
  _PA_DEFINE_FUNC(snd_ctl_card_info_sizeof);
  _PA_DEFINE_FUNC(snd_ctl_card_info_get_name);
  #define alsa_snd_ctl_card_info_alloca(ptr) __alsa_snd_alloca(ptr, snd_ctl_card_info)
  
  _PA_DEFINE_FUNC(snd_config);
  _PA_DEFINE_FUNC(snd_config_update);
  _PA_DEFINE_FUNC(snd_config_search);
  _PA_DEFINE_FUNC(snd_config_iterator_entry);
  _PA_DEFINE_FUNC(snd_config_iterator_first);
  _PA_DEFINE_FUNC(snd_config_iterator_end);
  _PA_DEFINE_FUNC(snd_config_iterator_next);
  _PA_DEFINE_FUNC(snd_config_get_string);
  _PA_DEFINE_FUNC(snd_config_get_id);
  _PA_DEFINE_FUNC(snd_config_update_free_global);
  
  _PA_DEFINE_FUNC(snd_pcm_status);
  _PA_DEFINE_FUNC(snd_pcm_status_sizeof);
  _PA_DEFINE_FUNC(snd_pcm_status_get_tstamp);
  _PA_DEFINE_FUNC(snd_pcm_status_get_htstamp);
  _PA_DEFINE_FUNC(snd_pcm_status_get_state);
  _PA_DEFINE_FUNC(snd_pcm_status_get_trigger_tstamp);
  _PA_DEFINE_FUNC(snd_pcm_status_get_trigger_htstamp);
  _PA_DEFINE_FUNC(snd_pcm_status_get_delay);
  #define alsa_snd_pcm_status_alloca(ptr) __alsa_snd_alloca(ptr, snd_pcm_status)
  
  _PA_DEFINE_FUNC(snd_card_next);
  _PA_DEFINE_FUNC(snd_asoundlib_version);
  _PA_DEFINE_FUNC(snd_strerror);
  _PA_DEFINE_FUNC(snd_output_stdio_attach);
  
  #define alsa_snd_config_for_each(pos, next, node)\
      for (pos = alsa_snd_config_iterator_first(node),\
           next = alsa_snd_config_iterator_next(pos);\
           pos != alsa_snd_config_iterator_end(node); pos = next, next = alsa_snd_config_iterator_next(pos))
  
  #undef _PA_DEFINE_FUNC
  
  /* Redefine 'PA_ALSA_PATHNAME' to a different Alsa library name if desired. */
  #ifndef PA_ALSA_PATHNAME
      #define PA_ALSA_PATHNAME "libasound.so"
  #endif
  static const char *g_AlsaLibName = PA_ALSA_PATHNAME;
  
  /* Handle to dynamically loaded library. */
  static void *g_AlsaLib = NULL;
  
  #ifdef PA_ALSA_DYNAMIC
  
  #define _PA_LOCAL_IMPL(x) __pa_local_##x
  
  int _PA_LOCAL_IMPL(snd_pcm_hw_params_set_rate_near) (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int *val, int *dir)
  {
      int ret;
  
      if(( ret = alsa_snd_pcm_hw_params_set_rate(pcm, params, (*val), (*dir)) ) < 0 )
          return ret;
  
      return 0;
  }
  
  int _PA_LOCAL_IMPL(snd_pcm_hw_params_set_buffer_size_near) (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, snd_pcm_uframes_t *val)
  {
      int ret;
  
      if(( ret = alsa_snd_pcm_hw_params_set_buffer_size(pcm, params, (*val)) ) < 0 )
          return ret;
  
      return 0;
  }
  
  int _PA_LOCAL_IMPL(snd_pcm_hw_params_set_period_size_near) (snd_pcm_t *pcm, snd_pcm_hw_params_t *params, snd_pcm_uframes_t *val, int *dir)
  {
      int ret;
  
      if(( ret = alsa_snd_pcm_hw_params_set_period_size(pcm, params, (*val), (*dir)) ) < 0 )
          return ret;
  
      return 0;
  }
  
  int _PA_LOCAL_IMPL(snd_pcm_hw_params_get_channels_min) (const snd_pcm_hw_params_t *params, unsigned int *val)
  {
      (*val) = 1;
      return 0;
  }
  
  int _PA_LOCAL_IMPL(snd_pcm_hw_params_get_channels_max) (const snd_pcm_hw_params_t *params, unsigned int *val)
  {
      (*val) = 2;
      return 0;
  }
  
  int _PA_LOCAL_IMPL(snd_pcm_hw_params_get_periods_min) (const snd_pcm_hw_params_t *params, unsigned int *val, int *dir)
  {
      (*val) = 2;
      return 0;
  }
  
  int _PA_LOCAL_IMPL(snd_pcm_hw_params_get_periods_max) (const snd_pcm_hw_params_t *params, unsigned int *val, int *dir)
  {
      (*val) = 8;
      return 0;
  }
  
  int _PA_LOCAL_IMPL(snd_pcm_hw_params_get_period_size_min) (const snd_pcm_hw_params_t *params, snd_pcm_uframes_t *frames, int *dir)
  {
      (*frames) = 64;
      return 0;
  }
  
  int _PA_LOCAL_IMPL(snd_pcm_hw_params_get_period_size_max) (const snd_pcm_hw_params_t *params, snd_pcm_uframes_t *frames, int *dir)
  {
      (*frames) = 512;
      return 0;
  }
  
  int _PA_LOCAL_IMPL(snd_pcm_hw_params_get_buffer_size_max) (const snd_pcm_hw_params_t *params, snd_pcm_uframes_t *val)
  {
      int ret;
      int dir                = 0;
      snd_pcm_uframes_t pmax = 0;
      unsigned int      pcnt = 0;
  
      dir = 0;
      if(( ret = _PA_LOCAL_IMPL(snd_pcm_hw_params_get_period_size_max)(params, &pmax, &dir) ) < 0 )
          return ret;
      dir = 0;
      if(( ret = _PA_LOCAL_IMPL(snd_pcm_hw_params_get_periods_max)(params, &pcnt, &dir) ) < 0 )
          return ret;
  
      (*val) = pmax * pcnt;
      return 0;
  }
  
  int _PA_LOCAL_IMPL(snd_pcm_hw_params_get_rate_min) (const snd_pcm_hw_params_t *params, unsigned int *val, int *dir)
  {
      (*val) = 44100;
      return 0;
  }
  
  int _PA_LOCAL_IMPL(snd_pcm_hw_params_get_rate_max) (const snd_pcm_hw_params_t *params, unsigned int *val, int *dir)
  {
      (*val) = 44100;
      return 0;
  }
  
  #endif // PA_ALSA_DYNAMIC
  
  /* Trying to load Alsa library dynamically if 'PA_ALSA_DYNAMIC' is defined, othervise
     will link during compilation.
  */
  static int PaAlsa_LoadLibrary()
  {
  #ifdef PA_ALSA_DYNAMIC
  
      PA_DEBUG(( "%s: loading ALSA library file - %s\n", __FUNCTION__, g_AlsaLibName ));
  
      dlerror();
      g_AlsaLib = dlopen(g_AlsaLibName, (RTLD_NOW|RTLD_GLOBAL) );
      if (g_AlsaLib == NULL)
      {
          PA_DEBUG(( "%s: failed dlopen() ALSA library file - %s, error: %s\n", __FUNCTION__, g_AlsaLibName, dlerror() ));
          return 0;
      }
  
      PA_DEBUG(( "%s: loading ALSA API\n", __FUNCTION__ ));
  
      #define _PA_LOAD_FUNC(x) do {             \
          alsa_##x = dlsym( g_AlsaLib, #x );      \
          if( alsa_##x == NULL ) {               \
              PA_DEBUG(( "%s: symbol [%s] not found in - %s, error: %s\n", __FUNCTION__, #x, g_AlsaLibName, dlerror() )); }\
          } while(0)
  
  #else
  
      #define _PA_LOAD_FUNC(x) alsa_##x = &x
  
  #endif
  
      _PA_LOAD_FUNC(snd_pcm_open);
      _PA_LOAD_FUNC(snd_pcm_close);
      _PA_LOAD_FUNC(snd_pcm_nonblock);
      _PA_LOAD_FUNC(snd_pcm_frames_to_bytes);
      _PA_LOAD_FUNC(snd_pcm_prepare);
      _PA_LOAD_FUNC(snd_pcm_start);
      _PA_LOAD_FUNC(snd_pcm_resume);
      _PA_LOAD_FUNC(snd_pcm_wait);
      _PA_LOAD_FUNC(snd_pcm_state);
      _PA_LOAD_FUNC(snd_pcm_avail_update);
      _PA_LOAD_FUNC(snd_pcm_areas_silence);
      _PA_LOAD_FUNC(snd_pcm_mmap_begin);
      _PA_LOAD_FUNC(snd_pcm_mmap_commit);
      _PA_LOAD_FUNC(snd_pcm_readi);
      _PA_LOAD_FUNC(snd_pcm_readn);
      _PA_LOAD_FUNC(snd_pcm_writei);
      _PA_LOAD_FUNC(snd_pcm_writen);
      _PA_LOAD_FUNC(snd_pcm_drain);
      _PA_LOAD_FUNC(snd_pcm_recover);
      _PA_LOAD_FUNC(snd_pcm_drop);
      _PA_LOAD_FUNC(snd_pcm_area_copy);
      _PA_LOAD_FUNC(snd_pcm_poll_descriptors);
      _PA_LOAD_FUNC(snd_pcm_poll_descriptors_count);
      _PA_LOAD_FUNC(snd_pcm_poll_descriptors_revents);
      _PA_LOAD_FUNC(snd_pcm_format_size);
      _PA_LOAD_FUNC(snd_pcm_link);
      _PA_LOAD_FUNC(snd_pcm_delay);
  
      _PA_LOAD_FUNC(snd_pcm_hw_params_sizeof);
      _PA_LOAD_FUNC(snd_pcm_hw_params_malloc);
      _PA_LOAD_FUNC(snd_pcm_hw_params_free);
      _PA_LOAD_FUNC(snd_pcm_hw_params_any);
      _PA_LOAD_FUNC(snd_pcm_hw_params_set_access);
      _PA_LOAD_FUNC(snd_pcm_hw_params_set_format);
      _PA_LOAD_FUNC(snd_pcm_hw_params_set_channels);
  //    _PA_LOAD_FUNC(snd_pcm_hw_params_set_periods_near);
      _PA_LOAD_FUNC(snd_pcm_hw_params_set_rate_near);
      _PA_LOAD_FUNC(snd_pcm_hw_params_set_rate);
      _PA_LOAD_FUNC(snd_pcm_hw_params_set_rate_resample);
  //    _PA_LOAD_FUNC(snd_pcm_hw_params_set_buffer_time_near);
      _PA_LOAD_FUNC(snd_pcm_hw_params_set_buffer_size);
      _PA_LOAD_FUNC(snd_pcm_hw_params_set_buffer_size_near);
      _PA_LOAD_FUNC(snd_pcm_hw_params_set_buffer_size_min);
  //    _PA_LOAD_FUNC(snd_pcm_hw_params_set_period_time_near);
      _PA_LOAD_FUNC(snd_pcm_hw_params_set_period_size_near);
      _PA_LOAD_FUNC(snd_pcm_hw_params_set_periods_integer);
      _PA_LOAD_FUNC(snd_pcm_hw_params_set_periods_min);
  
      _PA_LOAD_FUNC(snd_pcm_hw_params_get_buffer_size);
  //    _PA_LOAD_FUNC(snd_pcm_hw_params_get_period_size);
  //    _PA_LOAD_FUNC(snd_pcm_hw_params_get_access);
  //    _PA_LOAD_FUNC(snd_pcm_hw_params_get_periods);
  //    _PA_LOAD_FUNC(snd_pcm_hw_params_get_rate);
      _PA_LOAD_FUNC(snd_pcm_hw_params_get_channels_min);
      _PA_LOAD_FUNC(snd_pcm_hw_params_get_channels_max);
  
      _PA_LOAD_FUNC(snd_pcm_hw_params_test_period_size);
      _PA_LOAD_FUNC(snd_pcm_hw_params_test_format);
      _PA_LOAD_FUNC(snd_pcm_hw_params_test_access);
      _PA_LOAD_FUNC(snd_pcm_hw_params_dump);
      _PA_LOAD_FUNC(snd_pcm_hw_params);
  
      _PA_LOAD_FUNC(snd_pcm_hw_params_get_periods_min);
      _PA_LOAD_FUNC(snd_pcm_hw_params_get_periods_max);
      _PA_LOAD_FUNC(snd_pcm_hw_params_set_period_size);
      _PA_LOAD_FUNC(snd_pcm_hw_params_get_period_size_min);
      _PA_LOAD_FUNC(snd_pcm_hw_params_get_period_size_max);
      _PA_LOAD_FUNC(snd_pcm_hw_params_get_buffer_size_max);
      _PA_LOAD_FUNC(snd_pcm_hw_params_get_rate_min);
      _PA_LOAD_FUNC(snd_pcm_hw_params_get_rate_max);
      _PA_LOAD_FUNC(snd_pcm_hw_params_get_rate_numden);
  
      _PA_LOAD_FUNC(snd_pcm_sw_params_sizeof);
      _PA_LOAD_FUNC(snd_pcm_sw_params_malloc);
      _PA_LOAD_FUNC(snd_pcm_sw_params_current);
      _PA_LOAD_FUNC(snd_pcm_sw_params_set_avail_min);
      _PA_LOAD_FUNC(snd_pcm_sw_params);
      _PA_LOAD_FUNC(snd_pcm_sw_params_free);
      _PA_LOAD_FUNC(snd_pcm_sw_params_set_start_threshold);
      _PA_LOAD_FUNC(snd_pcm_sw_params_set_stop_threshold);
      _PA_LOAD_FUNC(snd_pcm_sw_params_get_boundary);
      _PA_LOAD_FUNC(snd_pcm_sw_params_set_silence_threshold);
      _PA_LOAD_FUNC(snd_pcm_sw_params_set_silence_size);
      _PA_LOAD_FUNC(snd_pcm_sw_params_set_xfer_align);
      _PA_LOAD_FUNC(snd_pcm_sw_params_set_tstamp_mode);
  
      _PA_LOAD_FUNC(snd_pcm_info);
      _PA_LOAD_FUNC(snd_pcm_info_sizeof);
      _PA_LOAD_FUNC(snd_pcm_info_malloc);
      _PA_LOAD_FUNC(snd_pcm_info_free);
      _PA_LOAD_FUNC(snd_pcm_info_set_device);
      _PA_LOAD_FUNC(snd_pcm_info_set_subdevice);
      _PA_LOAD_FUNC(snd_pcm_info_set_stream);
      _PA_LOAD_FUNC(snd_pcm_info_get_name);
      _PA_LOAD_FUNC(snd_pcm_info_get_card);
  
      _PA_LOAD_FUNC(snd_ctl_pcm_next_device);
      _PA_LOAD_FUNC(snd_ctl_pcm_info);
      _PA_LOAD_FUNC(snd_ctl_open);
      _PA_LOAD_FUNC(snd_ctl_close);
      _PA_LOAD_FUNC(snd_ctl_card_info_malloc);
      _PA_LOAD_FUNC(snd_ctl_card_info_free);
      _PA_LOAD_FUNC(snd_ctl_card_info);
      _PA_LOAD_FUNC(snd_ctl_card_info_sizeof);
      _PA_LOAD_FUNC(snd_ctl_card_info_get_name);
  
      _PA_LOAD_FUNC(snd_config);
      _PA_LOAD_FUNC(snd_config_update);
      _PA_LOAD_FUNC(snd_config_search);
      _PA_LOAD_FUNC(snd_config_iterator_entry);
      _PA_LOAD_FUNC(snd_config_iterator_first);
      _PA_LOAD_FUNC(snd_config_iterator_end);
      _PA_LOAD_FUNC(snd_config_iterator_next);
      _PA_LOAD_FUNC(snd_config_get_string);
      _PA_LOAD_FUNC(snd_config_get_id);
      _PA_LOAD_FUNC(snd_config_update_free_global);
  
      _PA_LOAD_FUNC(snd_pcm_status);
      _PA_LOAD_FUNC(snd_pcm_status_sizeof);
      _PA_LOAD_FUNC(snd_pcm_status_get_tstamp);
      _PA_LOAD_FUNC(snd_pcm_status_get_htstamp);
      _PA_LOAD_FUNC(snd_pcm_status_get_state);
      _PA_LOAD_FUNC(snd_pcm_status_get_trigger_tstamp);
      _PA_LOAD_FUNC(snd_pcm_status_get_trigger_htstamp);
      _PA_LOAD_FUNC(snd_pcm_status_get_delay);
  
      _PA_LOAD_FUNC(snd_card_next);
      _PA_LOAD_FUNC(snd_asoundlib_version);
      _PA_LOAD_FUNC(snd_strerror);
      _PA_LOAD_FUNC(snd_output_stdio_attach);
  #undef _PA_LOAD_FUNC
  
  #ifdef PA_ALSA_DYNAMIC
      PA_DEBUG(( "%s: loaded ALSA API - ok\n", __FUNCTION__ ));
  
  #define _PA_VALIDATE_LOAD_REPLACEMENT(x)\
      do {\
          if( alsa_##x == NULL )\
          {\
              alsa_##x = &_PA_LOCAL_IMPL(x);\
              PA_DEBUG(( "%s: replacing [%s] with local implementation\n", __FUNCTION__, #x ));\
          }\
      } while (0)
  
      _PA_VALIDATE_LOAD_REPLACEMENT(snd_pcm_hw_params_set_rate_near);
      _PA_VALIDATE_LOAD_REPLACEMENT(snd_pcm_hw_params_set_buffer_size_near);
      _PA_VALIDATE_LOAD_REPLACEMENT(snd_pcm_hw_params_set_period_size_near);
      _PA_VALIDATE_LOAD_REPLACEMENT(snd_pcm_hw_params_get_channels_min);
      _PA_VALIDATE_LOAD_REPLACEMENT(snd_pcm_hw_params_get_channels_max);
      _PA_VALIDATE_LOAD_REPLACEMENT(snd_pcm_hw_params_get_periods_min);
      _PA_VALIDATE_LOAD_REPLACEMENT(snd_pcm_hw_params_get_periods_max);
      _PA_VALIDATE_LOAD_REPLACEMENT(snd_pcm_hw_params_get_period_size_min);
      _PA_VALIDATE_LOAD_REPLACEMENT(snd_pcm_hw_params_get_period_size_max);
      _PA_VALIDATE_LOAD_REPLACEMENT(snd_pcm_hw_params_get_buffer_size_max);
      _PA_VALIDATE_LOAD_REPLACEMENT(snd_pcm_hw_params_get_rate_min);
      _PA_VALIDATE_LOAD_REPLACEMENT(snd_pcm_hw_params_get_rate_max);
  
  #undef _PA_LOCAL_IMPL
  #undef _PA_VALIDATE_LOAD_REPLACEMENT
  
  #endif // PA_ALSA_DYNAMIC
  
      return 1;
  }
  
  void PaAlsa_SetLibraryPathName( const char *pathName )
  {
  #ifdef PA_ALSA_DYNAMIC
      g_AlsaLibName = pathName;
  #else
      (void)pathName;
  #endif
  }
  
  /* Close handle to Alsa library. */
  static void PaAlsa_CloseLibrary()
  {
  #ifdef PA_ALSA_DYNAMIC
      dlclose(g_AlsaLib);
      g_AlsaLib = NULL;
  #endif
  }
  
  /* Check return value of ALSA function, and map it to PaError */
  #define ENSURE_(expr, code) \
      do { \
          int __pa_unsure_error_id;\
          if( UNLIKELY( (__pa_unsure_error_id = (expr)) < 0 ) ) \
          { \
              /* PaUtil_SetLastHostErrorInfo should only be used in the main thread */ \
              if( (code) == paUnanticipatedHostError && pthread_equal( pthread_self(), paUnixMainThread) ) \
              { \
                  PaUtil_SetLastHostErrorInfo( paALSA, __pa_unsure_error_id, alsa_snd_strerror( __pa_unsure_error_id ) ); \
              } \
              PaUtil_DebugPrint( "Expression '" #expr "' failed in '" __FILE__ "', line: " PA_STRINGIZE( __LINE__ ) "\n" ); \
              if( (code) == paUnanticipatedHostError ) \
                  PA_DEBUG(( "Host error description: %s\n", alsa_snd_strerror( __pa_unsure_error_id ) )); \
              result = (code); \
              goto error; \
          } \
      } while (0)
  
  #define ASSERT_CALL_(expr, success) \
      do {\
          int __pa_assert_error_id;\
          __pa_assert_error_id = (expr);\
          assert( success == __pa_assert_error_id );\
      } while (0)
  
  static int numPeriods_ = 4;
  static int busyRetries_ = 100;
  
  int PaAlsa_SetNumPeriods( int numPeriods )
  {
      numPeriods_ = numPeriods;
      return paNoError;
  }
  
  typedef enum
  {
      StreamDirection_In,
      StreamDirection_Out
  } StreamDirection;
  
  typedef struct
  {
      PaSampleFormat hostSampleFormat;
      int numUserChannels, numHostChannels;
      int userInterleaved, hostInterleaved;
      int canMmap;
      void *nonMmapBuffer;
      unsigned int nonMmapBufferSize;
      PaDeviceIndex device;     /* Keep the device index */
      int deviceIsPlug; /* Distinguish plug types from direct 'hw:' devices */
      int useReventFix; /* Alsa older than 1.0.16, plug devices need a fix */
  
      snd_pcm_t *pcm;
      snd_pcm_uframes_t framesPerPeriod, alsaBufferSize;
      snd_pcm_format_t nativeFormat;
      unsigned int nfds;
      int ready;  /* Marked ready from poll */
      void **userBuffers;
      snd_pcm_uframes_t offset;
      StreamDirection streamDir;
  
      snd_pcm_channel_area_t *channelAreas;  /* Needed for channel adaption */
  } PaAlsaStreamComponent;
  
  /* Implementation specific stream structure */
  typedef struct PaAlsaStream
  {
      PaUtilStreamRepresentation streamRepresentation;
      PaUtilCpuLoadMeasurer cpuLoadMeasurer;
      PaUtilBufferProcessor bufferProcessor;
      PaUnixThread thread;
  
      unsigned long framesPerUserBuffer, maxFramesPerHostBuffer;
  
      int primeBuffers;
      int callbackMode;              /* bool: are we running in callback mode? */
      int pcmsSynced;                /* Have we successfully synced pcms */
      int rtSched;
  
      /* the callback thread uses these to poll the sound device(s), waiting
       * for data to be ready/available */
      struct pollfd* pfds;
      int pollTimeout;
  
      /* Used in communication between threads */
      volatile sig_atomic_t callback_finished; /* bool: are we in the "callback finished" state? */
      volatile sig_atomic_t callbackAbort;    /* Drop frames? */
      volatile sig_atomic_t isActive;         /* Is stream in active state? (Between StartStream and StopStream || !paContinue) */
      PaUnixMutex stateMtx;                   /* Used to synchronize access to stream state */
  
      int neverDropInput;
  
      PaTime underrun;
      PaTime overrun;
  
      PaAlsaStreamComponent capture, playback;
  }
  PaAlsaStream;
  
  /* PaAlsaHostApiRepresentation - host api datastructure specific to this implementation */
  
  typedef struct PaAlsaHostApiRepresentation
  {
      PaUtilHostApiRepresentation baseHostApiRep;
      PaUtilStreamInterface callbackStreamInterface;
      PaUtilStreamInterface blockingStreamInterface;
  
      PaUtilAllocationGroup *allocations;
  
      PaHostApiIndex hostApiIndex;
      PaUint32 alsaLibVersion; /* Retrieved from the library at run-time */
  }
  PaAlsaHostApiRepresentation;
  
  typedef struct PaAlsaDeviceInfo
  {
      PaDeviceInfo baseDeviceInfo;
      char *alsaName;
      int isPlug;
      int minInputChannels;
      int minOutputChannels;
  }
  PaAlsaDeviceInfo;
  
  /* prototypes for functions declared in this file */
  
  static void Terminate( struct PaUtilHostApiRepresentation *hostApi );
  static PaError IsFormatSupported( struct PaUtilHostApiRepresentation *hostApi,
                                    const PaStreamParameters *inputParameters,
                                    const PaStreamParameters *outputParameters,
                                    double sampleRate );
  static PaError OpenStream( struct PaUtilHostApiRepresentation *hostApi,
                             PaStream** s,
                             const PaStreamParameters *inputParameters,
                             const PaStreamParameters *outputParameters,
                             double sampleRate,
                             unsigned long framesPerBuffer,
                             PaStreamFlags streamFlags,
                             PaStreamCallback *callback,
                             void *userData );
  static PaError CloseStream( PaStream* stream );
  static PaError StartStream( PaStream *stream );
  static PaError StopStream( PaStream *stream );
  static PaError AbortStream( PaStream *stream );
  static PaError IsStreamStopped( PaStream *s );
  static PaError IsStreamActive( PaStream *stream );
  static PaTime GetStreamTime( PaStream *stream );
  static double GetStreamCpuLoad( PaStream* stream );
  static PaError BuildDeviceList( PaAlsaHostApiRepresentation *hostApi );
  static int SetApproximateSampleRate( snd_pcm_t *pcm, snd_pcm_hw_params_t *hwParams, double sampleRate );
  static int GetExactSampleRate( snd_pcm_hw_params_t *hwParams, double *sampleRate );
  static PaUint32 PaAlsaVersionNum(void);
  
  /* Callback prototypes */
  static void *CallbackThreadFunc( void *userData );
  
  /* Blocking prototypes */
  static signed long GetStreamReadAvailable( PaStream* s );
  static signed long GetStreamWriteAvailable( PaStream* s );
  static PaError ReadStream( PaStream* stream, void *buffer, unsigned long frames );
  static PaError WriteStream( PaStream* stream, const void *buffer, unsigned long frames );
  
  
  static const PaAlsaDeviceInfo *GetDeviceInfo( const PaUtilHostApiRepresentation *hostApi, int device )
  {
      return (const PaAlsaDeviceInfo *)hostApi->deviceInfos[device];
  }
  
  /** Uncommented because AlsaErrorHandler is unused for anything good yet. If AlsaErrorHandler is
      to be used, do not forget to register this callback in PaAlsa_Initialize, and unregister in Terminate.
  */
  /*static void AlsaErrorHandler(const char *file, int line, const char *function, int err, const char *fmt, ...)
  {
  }*/
  
  PaError PaAlsa_Initialize( PaUtilHostApiRepresentation **hostApi, PaHostApiIndex hostApiIndex )
  {
      PaError result = paNoError;
      PaAlsaHostApiRepresentation *alsaHostApi = NULL;
  
      /* Try loading Alsa library. */
      if (!PaAlsa_LoadLibrary())
          return paHostApiNotFound;
  
      PA_UNLESS( alsaHostApi = (PaAlsaHostApiRepresentation*) PaUtil_AllocateMemory(
                  sizeof(PaAlsaHostApiRepresentation) ), paInsufficientMemory );
      PA_UNLESS( alsaHostApi->allocations = PaUtil_CreateAllocationGroup(), paInsufficientMemory );
      alsaHostApi->hostApiIndex = hostApiIndex;
      alsaHostApi->alsaLibVersion = PaAlsaVersionNum();
  
      *hostApi = (PaUtilHostApiRepresentation*)alsaHostApi;
      (*hostApi)->info.structVersion = 1;
      (*hostApi)->info.type = paALSA;
      (*hostApi)->info.name = "ALSA";
  
      (*hostApi)->Terminate = Terminate;
      (*hostApi)->OpenStream = OpenStream;
      (*hostApi)->IsFormatSupported = IsFormatSupported;
  
      /** If AlsaErrorHandler is to be used, do not forget to unregister callback pointer in
          Terminate function.
      */
      /*ENSURE_( snd_lib_error_set_handler(AlsaErrorHandler), paUnanticipatedHostError );*/
  
      PA_ENSURE( BuildDeviceList( alsaHostApi ) );
  
      PaUtil_InitializeStreamInterface( &alsaHostApi->callbackStreamInterface,
                                        CloseStream, StartStream,
                                        StopStream, AbortStream,
                                        IsStreamStopped, IsStreamActive,
                                        GetStreamTime, GetStreamCpuLoad,
                                        PaUtil_DummyRead, PaUtil_DummyWrite,
                                        PaUtil_DummyGetReadAvailable,
                                        PaUtil_DummyGetWriteAvailable );
  
      PaUtil_InitializeStreamInterface( &alsaHostApi->blockingStreamInterface,
                                        CloseStream, StartStream,
                                        StopStream, AbortStream,
                                        IsStreamStopped, IsStreamActive,
                                        GetStreamTime, PaUtil_DummyGetCpuLoad,
                                        ReadStream, WriteStream,
                                        GetStreamReadAvailable,
                                        GetStreamWriteAvailable );
  
      PA_ENSURE( PaUnixThreading_Initialize() );
  
      return result;
  
  error:
      if( alsaHostApi )
      {
          if( alsaHostApi->allocations )
          {
              PaUtil_FreeAllAllocations( alsaHostApi->allocations );
              PaUtil_DestroyAllocationGroup( alsaHostApi->allocations );
          }
  
          PaUtil_FreeMemory( alsaHostApi );
      }
  
      return result;
  }
  
  static void Terminate( struct PaUtilHostApiRepresentation *hostApi )
  {
      PaAlsaHostApiRepresentation *alsaHostApi = (PaAlsaHostApiRepresentation*)hostApi;
  
      assert( hostApi );
  
      /** See AlsaErrorHandler and PaAlsa_Initialize for details.
      */
      /*snd_lib_error_set_handler(NULL);*/
  
      if( alsaHostApi->allocations )
      {
          PaUtil_FreeAllAllocations( alsaHostApi->allocations );
          PaUtil_DestroyAllocationGroup( alsaHostApi->allocations );
      }
  
      PaUtil_FreeMemory( alsaHostApi );
      alsa_snd_config_update_free_global();
  
      /* Close Alsa library. */
      PaAlsa_CloseLibrary();
  }
  
  /** Determine max channels and default latencies.
   *
   * This function provides functionality to grope an opened (might be opened for capture or playback) pcm device for
   * traits like max channels, suitable default latencies and default sample rate. Upon error, max channels is set to zero,
   * and a suitable result returned. The device is closed before returning.
   */
  static PaError GropeDevice( snd_pcm_t* pcm, int isPlug, StreamDirection mode, int openBlocking,
          PaAlsaDeviceInfo* devInfo )
  {
      PaError result = paNoError;
      snd_pcm_hw_params_t *hwParams;
      snd_pcm_uframes_t alsaBufferFrames, alsaPeriodFrames;
      unsigned int minChans, maxChans;
      int* minChannels, * maxChannels;
      double * defaultLowLatency, * defaultHighLatency, * defaultSampleRate =
          &devInfo->baseDeviceInfo.defaultSampleRate;
      double defaultSr = *defaultSampleRate;
  
      assert( pcm );
  
      PA_DEBUG(( "%s: collecting info ..\n", __FUNCTION__ ));
  
      if( StreamDirection_In == mode )
      {
          minChannels = &devInfo->minInputChannels;
          maxChannels = &devInfo->baseDeviceInfo.maxInputChannels;
          defaultLowLatency = &devInfo->baseDeviceInfo.defaultLowInputLatency;
          defaultHighLatency = &devInfo->baseDeviceInfo.defaultHighInputLatency;
      }
      else
      {
          minChannels = &devInfo->minOutputChannels;
          maxChannels = &devInfo->baseDeviceInfo.maxOutputChannels;
          defaultLowLatency = &devInfo->baseDeviceInfo.defaultLowOutputLatency;
          defaultHighLatency = &devInfo->baseDeviceInfo.defaultHighOutputLatency;
      }
  
      ENSURE_( alsa_snd_pcm_nonblock( pcm, 0 ), paUnanticipatedHostError );
  
      alsa_snd_pcm_hw_params_alloca( &hwParams );
      alsa_snd_pcm_hw_params_any( pcm, hwParams );
  
      if( defaultSr >= 0 )
      {
          /* Could be that the device opened in one mode supports samplerates that the other mode wont have,
           * so try again .. */
          if( SetApproximateSampleRate( pcm, hwParams, defaultSr ) < 0 )
          {
              defaultSr = -1.;
              alsa_snd_pcm_hw_params_any( pcm, hwParams ); /* Clear any params (rate) that might have been set */
              PA_DEBUG(( "%s: Original default samplerate failed, trying again ..\n", __FUNCTION__ ));
          }
      }
  
      if( defaultSr < 0. )           /* Default sample rate not set */
      {
          unsigned int sampleRate = 44100;        /* Will contain approximate rate returned by alsa-lib */
  
          /* Don't allow rate resampling when probing for the default rate (but ignore if this call fails) */
          alsa_snd_pcm_hw_params_set_rate_resample( pcm, hwParams, 0 );
          if( alsa_snd_pcm_hw_params_set_rate_near( pcm, hwParams, &sampleRate, NULL ) < 0 )
          {
              result = paUnanticipatedHostError;
              goto error;
          }
          ENSURE_( GetExactSampleRate( hwParams, &defaultSr ), paUnanticipatedHostError );
      }
  
      ENSURE_( alsa_snd_pcm_hw_params_get_channels_min( hwParams, &minChans ), paUnanticipatedHostError );
      ENSURE_( alsa_snd_pcm_hw_params_get_channels_max( hwParams, &maxChans ), paUnanticipatedHostError );
      assert( maxChans <= INT_MAX );
      assert( maxChans > 0 );    /* Weird linking issue could cause wrong version of ALSA symbols to be called,
                                     resulting in zeroed values */
  
      /* XXX: Limit to sensible number (ALSA plugins accept a crazy amount of channels)? */
      if( isPlug && maxChans > 128 )
      {
          maxChans = 128;
          PA_DEBUG(( "%s: Limiting number of plugin channels to %u\n", __FUNCTION__, maxChans ));
      }
  
      /* TWEAKME:
       * Giving values for default min and max latency is not straightforward.
       *  * for low latency, we want to give the lowest value that will work reliably.
       *      This varies based on the sound card, kernel, CPU, etc.  Better to give
       *      sub-optimal latency than to give a number too low and cause dropouts.
       *  * for high latency we want to give a large enough value that dropouts are basically impossible.
       *      This doesn't really require as much tweaking, since providing too large a number will
       *      just cause us to select the nearest setting that will work at stream config time.
       */
      /* Try low latency values, (sometimes the buffer & period that result are larger) */
      alsaBufferFrames = 512;
      alsaPeriodFrames = 128;
      ENSURE_( alsa_snd_pcm_hw_params_set_buffer_size_near( pcm, hwParams, &alsaBufferFrames ), paUnanticipatedHostError );
      ENSURE_( alsa_snd_pcm_hw_params_set_period_size_near( pcm, hwParams, &alsaPeriodFrames, NULL ), paUnanticipatedHostError );
      *defaultLowLatency = (double) (alsaBufferFrames - alsaPeriodFrames) / defaultSr;
  
      /* Base the high latency case on values four times larger */
      alsaBufferFrames = 2048;
      alsaPeriodFrames = 512;
      /* Have to reset hwParams, to set new buffer size; need to also set sample rate again */
      ENSURE_( alsa_snd_pcm_hw_params_any( pcm, hwParams ), paUnanticipatedHostError );
      ENSURE_( SetApproximateSampleRate( pcm, hwParams, defaultSr ), paUnanticipatedHostError );
      ENSURE_( alsa_snd_pcm_hw_params_set_buffer_size_near( pcm, hwParams, &alsaBufferFrames ), paUnanticipatedHostError );
      ENSURE_( alsa_snd_pcm_hw_params_set_period_size_near( pcm, hwParams, &alsaPeriodFrames, NULL ), paUnanticipatedHostError );
      *defaultHighLatency = (double) (alsaBufferFrames - alsaPeriodFrames) / defaultSr;
  
      *minChannels = (int)minChans;
      *maxChannels = (int)maxChans;
      *defaultSampleRate = defaultSr;
  
  end:
      alsa_snd_pcm_close( pcm );
      return result;
  
  error:
      goto end;
  }
  
  /* Initialize device info with invalid values (maxInputChannels and maxOutputChannels are set to zero since these indicate
   * whether input/output is available) */
  static void InitializeDeviceInfo( PaDeviceInfo *deviceInfo )
  {
      deviceInfo->structVersion = -1;
      deviceInfo->name = NULL;
      deviceInfo->hostApi = -1;
      deviceInfo->maxInputChannels = 0;
      deviceInfo->maxOutputChannels = 0;
      deviceInfo->defaultLowInputLatency = -1.;
      deviceInfo->defaultLowOutputLatency = -1.;
      deviceInfo->defaultHighInputLatency = -1.;
      deviceInfo->defaultHighOutputLatency = -1.;
      deviceInfo->defaultSampleRate = -1.;
  }
  
  
  /* Retrieve the version of the runtime Alsa-lib, as a single number equivalent to
   * SND_LIB_VERSION.  Only a version string is available ("a.b.c") so this has to be converted.
   * Assume 'a' and 'b' are single digits only.
   */
  static PaUint32 PaAlsaVersionNum(void)
  {
      char* verStr;
      PaUint32 verNum;
  
      verStr = (char*) alsa_snd_asoundlib_version();
      verNum = ALSA_VERSION_INT( atoi(verStr), atoi(verStr + 2), atoi(verStr + 4) );
      PA_DEBUG(( "ALSA version (build): " SND_LIB_VERSION_STR "\nALSA version (runtime): %s\n", verStr ));
  
      return verNum;
  }
  
  
  /* Helper struct */
  typedef struct
  {
      char *alsaName;
      char *name;
      int isPlug;
      int hasPlayback;
      int hasCapture;
  } HwDevInfo;
  
  
  HwDevInfo predefinedNames[] = {
      { "center_lfe", NULL, 0, 1, 0 },
  /* { "default", NULL, 0, 1, 1 }, */
      { "dmix", NULL, 0, 1, 0 },
  /* { "dpl", NULL, 0, 1, 0 }, */
  /* { "dsnoop", NULL, 0, 0, 1 }, */
      { "front", NULL, 0, 1, 0 },
      { "iec958", NULL, 0, 1, 0 },
  /* { "modem", NULL, 0, 1, 0 }, */
      { "rear", NULL, 0, 1, 0 },
      { "side", NULL, 0, 1, 0 },
  /*     { "spdif", NULL, 0, 0, 0 }, */
      { "surround40", NULL, 0, 1, 0 },
      { "surround41", NULL, 0, 1, 0 },
      { "surround50", NULL, 0, 1, 0 },
      { "surround51", NULL, 0, 1, 0 },
      { "surround71", NULL, 0, 1, 0 },
  
      { "AndroidPlayback_Earpiece_normal",         NULL, 0, 1, 0 },
      { "AndroidPlayback_Speaker_normal",          NULL, 0, 1, 0 },
      { "AndroidPlayback_Bluetooth_normal",        NULL, 0, 1, 0 },
      { "AndroidPlayback_Headset_normal",          NULL, 0, 1, 0 },
      { "AndroidPlayback_Speaker_Headset_normal",  NULL, 0, 1, 0 },
      { "AndroidPlayback_Bluetooth-A2DP_normal",   NULL, 0, 1, 0 },
      { "AndroidPlayback_ExtraDockSpeaker_normal", NULL, 0, 1, 0 },
      { "AndroidPlayback_TvOut_normal",            NULL, 0, 1, 0 },
  
      { "AndroidRecord_Microphone",                NULL, 0, 0, 1 },
      { "AndroidRecord_Earpiece_normal",           NULL, 0, 0, 1 },
      { "AndroidRecord_Speaker_normal",            NULL, 0, 0, 1 },
      { "AndroidRecord_Headset_normal",            NULL, 0, 0, 1 },
      { "AndroidRecord_Bluetooth_normal",          NULL, 0, 0, 1 },
      { "AndroidRecord_Speaker_Headset_normal",    NULL, 0, 0, 1 },
  
      { NULL, NULL, 0, 1, 0 }
  };
  
  static const HwDevInfo *FindDeviceName( const char *name )
  {
      int i;
  
      for( i = 0; predefinedNames[i].alsaName; i++ )
      {
          if( strcmp( name, predefinedNames[i].alsaName ) == 0 )
          {
              return &predefinedNames[i];
          }
      }
  
      return NULL;
  }
  
  static PaError PaAlsa_StrDup( PaAlsaHostApiRepresentation *alsaApi,
          char **dst,
          const char *src)
  {
      PaError result = paNoError;
      int len = strlen( src ) + 1;
  
      /* PA_DEBUG(("PaStrDup %s %d\n", src, len)); */
  
      PA_UNLESS( *dst = (char *)PaUtil_GroupAllocateMemory( alsaApi->allocations, len ),
              paInsufficientMemory );
      strncpy( *dst, src, len );
  
  error:
      return result;
  }
  
  /* Disregard some standard plugins
   */
  static int IgnorePlugin( const char *pluginId )
  {
      static const char *ignoredPlugins[] = {"hw", "plughw", "plug", "dsnoop", "tee",
          "file", "null", "shm", "cards", "rate_convert", NULL};
      int i = 0;
  
      if( getenv( "PA_ALSA_IGNORE_ALL_PLUGINS" ) && atoi( getenv( "PA_ALSA_IGNORE_ALL_PLUGINS") ) )
          return 1;
  
      while( ignoredPlugins[i] )
      {
          if( !strcmp( pluginId, ignoredPlugins[i] ) )
          {
              return 1;
          }
          ++i;
      }
  
      return 0;
  }
  
  /* Skip past parts at the beginning of a (pcm) info name that are already in the card name, to avoid duplication */
  static char *SkipCardDetailsInName( char *infoSkipName, char *cardRefName )
  {
      char *lastSpacePosn = infoSkipName;
  
      /* Skip matching chars; but only in chunks separated by ' ' (not part words etc), so track lastSpacePosn */
      while( *cardRefName )
      {
          while( *infoSkipName && *cardRefName && *infoSkipName == *cardRefName)
          {
              infoSkipName++;
              cardRefName++;
              if( *infoSkipName == ' ' || *infoSkipName == '\0' )
                  lastSpacePosn = infoSkipName;
          }
          infoSkipName = lastSpacePosn;
          /* Look for another chunk; post-increment means ends pointing to next char */
          while( *cardRefName && ( *cardRefName++ != ' ' ));
      }
      if( *infoSkipName == '\0' )
          return "-"; /* The 2 names were identical; instead of a nul-string, return a marker string */
  
      /* Now want to move to the first char after any spaces */
      while( *lastSpacePosn && *lastSpacePosn == ' ' )
          lastSpacePosn++;
      /* Skip a single separator char if present in the remaining pcm name; (pa will add its own) */
      if(( *lastSpacePosn == '-' || *lastSpacePosn == ':' ) && *(lastSpacePosn + 1) == ' ' )
          lastSpacePosn += 2;
  
      return lastSpacePosn;
  }
  
  /** Open PCM device.
   *
   * Wrapper around alsa_snd_pcm_open which may repeatedly retry opening a device if it is busy, for
   * a certain time. This is because dmix may temporarily hold on to a device after it (dmix)
   * has been opened and closed.
   * @param mode: Open mode (e.g., SND_PCM_BLOCKING).
   * @param waitOnBusy: Retry opening busy device for up to one second?
   **/
  static int OpenPcm( snd_pcm_t **pcmp, const char *name, snd_pcm_stream_t stream, int mode, int waitOnBusy )
  {
      int ret, tries = 0, maxTries = waitOnBusy ? busyRetries_ : 0;
  
      ret = alsa_snd_pcm_open( pcmp, name, stream, mode );
  
      for( tries = 0; tries < maxTries && -EBUSY == ret; ++tries )
      {
          Pa_Sleep( 10 );
          ret = alsa_snd_pcm_open( pcmp, name, stream, mode );
          if( -EBUSY != ret )
          {
              PA_DEBUG(( "%s: Successfully opened initially busy device after %d tries\n", __FUNCTION__, tries ));
          }
      }
      if( -EBUSY == ret )
      {
          PA_DEBUG(( "%s: Failed to open busy device '%s'\n", __FUNCTION__, name ));
      }
      else
      {
          if( ret < 0 )
              PA_DEBUG(( "%s: Opened device '%s' ptr[%p] - result: [%d:%s]\n", __FUNCTION__, name, *pcmp, ret, alsa_snd_strerror(ret) ));
      }
  
      return ret;
  }
  
  static PaError FillInDevInfo( PaAlsaHostApiRepresentation *alsaApi, HwDevInfo* deviceHwInfo, int blocking,
          PaAlsaDeviceInfo* devInfo, int* devIdx )
  {
      PaError result = 0;
      PaDeviceInfo *baseDeviceInfo = &devInfo->baseDeviceInfo;
      snd_pcm_t *pcm = NULL;
      PaUtilHostApiRepresentation *baseApi = &alsaApi->baseHostApiRep;
  
      PA_DEBUG(( "%s: Filling device info for: %s\n", __FUNCTION__, deviceHwInfo->name ));
  
      /* Zero fields */
      InitializeDeviceInfo( baseDeviceInfo );
  
      /* To determine device capabilities, we must open the device and query the
       * hardware parameter configuration space */
  
      /* Query capture */
      if( deviceHwInfo->hasCapture &&
          OpenPcm( &pcm, deviceHwInfo->alsaName, SND_PCM_STREAM_CAPTURE, blocking, 0 ) >= 0 )
      {
          if( GropeDevice( pcm, deviceHwInfo->isPlug, StreamDirection_In, blocking, devInfo ) != paNoError )
          {
              /* Error */
              PA_DEBUG(( "%s: Failed groping %s for capture\n", __FUNCTION__, deviceHwInfo->alsaName ));
              goto end;
          }
      }
  
      /* Query playback */
      if( deviceHwInfo->hasPlayback &&
          OpenPcm( &pcm, deviceHwInfo->alsaName, SND_PCM_STREAM_PLAYBACK, blocking, 0 ) >= 0 )
      {
          if( GropeDevice( pcm, deviceHwInfo->isPlug, StreamDirection_Out, blocking, devInfo ) != paNoError )
          {
              /* Error */
              PA_DEBUG(( "%s: Failed groping %s for playback\n", __FUNCTION__, deviceHwInfo->alsaName ));
              goto end;
          }
      }
  
      baseDeviceInfo->structVersion = 2;
      baseDeviceInfo->hostApi = alsaApi->hostApiIndex;
      baseDeviceInfo->name = deviceHwInfo->name;
      devInfo->alsaName = deviceHwInfo->alsaName;
      devInfo->isPlug = deviceHwInfo->isPlug;
  
      /* A: Storing pointer to PaAlsaDeviceInfo object as pointer to PaDeviceInfo object.
       * Should now be safe to add device info, unless the device supports neither capture nor playback
       */
      if( baseDeviceInfo->maxInputChannels > 0 || baseDeviceInfo->maxOutputChannels > 0 )
      {
          /* Make device default if there isn't already one or it is the ALSA "default" device */
          if( ( baseApi->info.defaultInputDevice == paNoDevice ||
              !strcmp( deviceHwInfo->alsaName, "default" ) ) && baseDeviceInfo->maxInputChannels > 0 )
          {
              baseApi->info.defaultInputDevice = *devIdx;
              PA_DEBUG(( "Default input device: %s\n", deviceHwInfo->name ));
          }
          if( ( baseApi->info.defaultOutputDevice == paNoDevice ||
              !strcmp( deviceHwInfo->alsaName, "default" ) ) && baseDeviceInfo->maxOutputChannels > 0 )
          {
              baseApi->info.defaultOutputDevice = *devIdx;
              PA_DEBUG(( "Default output device: %s\n", deviceHwInfo->name ));
          }
          PA_DEBUG(( "%s: Adding device %s: %d\n", __FUNCTION__, deviceHwInfo->name, *devIdx ));
          baseApi->deviceInfos[*devIdx] = (PaDeviceInfo *) devInfo;
          (*devIdx) += 1;
      }
      else
      {
          PA_DEBUG(( "%s: Skipped device: %s, all channels == 0\n", __FUNCTION__, deviceHwInfo->name ));
      }
  
  end:
      return result;
  }
  
  /* Build PaDeviceInfo list, ignore devices for which we cannot determine capabilities (possibly busy, sigh) */
  static PaError BuildDeviceList( PaAlsaHostApiRepresentation *alsaApi )
  {
      PaUtilHostApiRepresentation *baseApi = &alsaApi->baseHostApiRep;
      PaAlsaDeviceInfo *deviceInfoArray;
      int cardIdx = -1, devIdx = 0;
      snd_ctl_card_info_t *cardInfo;
      PaError result = paNoError;
      size_t numDeviceNames = 0, maxDeviceNames = 1, i;
      HwDevInfo *hwDevInfos = NULL;
      snd_config_t *topNode = NULL;
      snd_pcm_info_t *pcmInfo;
      int res;
      int blocking = SND_PCM_NONBLOCK;
      int usePlughw = 0;
      char *hwPrefix = "";
      char alsaCardName[50];
  #ifdef PA_ENABLE_DEBUG_OUTPUT
      PaTime startTime = PaUtil_GetTime();
  #endif
  
      if( getenv( "PA_ALSA_INITIALIZE_BLOCK" ) && atoi( getenv( "PA_ALSA_INITIALIZE_BLOCK" ) ) )
          blocking = 0;
  
      /* If PA_ALSA_PLUGHW is 1 (non-zero), use the plughw: pcm throughout instead of hw: */
      if( getenv( "PA_ALSA_PLUGHW" ) && atoi( getenv( "PA_ALSA_PLUGHW" ) ) )
      {
          usePlughw = 1;
          hwPrefix = "plug";
          PA_DEBUG(( "%s: Using Plughw\n", __FUNCTION__ ));
      }
  
      /* These two will be set to the first working input and output device, respectively */
      baseApi->info.defaultInputDevice = paNoDevice;
      baseApi->info.defaultOutputDevice = paNoDevice;
  
      /* Gather info about hw devices
  
       * alsa_snd_card_next() modifies the integer passed to it to be:
       *      the index of the first card if the parameter is -1
       *      the index of the next card if the parameter is the index of a card
       *      -1 if there are no more cards
       *
       * The function itself returns 0 if it succeeded. */
      cardIdx = -1;
      alsa_snd_ctl_card_info_alloca( &cardInfo );
      alsa_snd_pcm_info_alloca( &pcmInfo );
      while( alsa_snd_card_next( &cardIdx ) == 0 && cardIdx >= 0 )
      {
          char *cardName;
          int devIdx = -1;
          snd_ctl_t *ctl;
          char buf[66];
  
          snprintf( alsaCardName, sizeof (alsaCardName), "hw:%d", cardIdx );
  
          /* Acquire name of card */
          if( alsa_snd_ctl_open( &ctl, alsaCardName, 0 ) < 0 )
          {
              /* Unable to open card :( */
              PA_DEBUG(( "%s: Unable to open device %s\n", __FUNCTION__, alsaCardName ));
              continue;
          }
          alsa_snd_ctl_card_info( ctl, cardInfo );
  
          PA_ENSURE( PaAlsa_StrDup( alsaApi, &cardName, alsa_snd_ctl_card_info_get_name( cardInfo )) );
  
          while( alsa_snd_ctl_pcm_next_device( ctl, &devIdx ) == 0 && devIdx >= 0 )
          {
              char *alsaDeviceName, *deviceName, *infoName;
              size_t len;
              int hasPlayback = 0, hasCapture = 0;
  
              snprintf( buf, sizeof (buf), "%s%s,%d", hwPrefix, alsaCardName, devIdx );
  
              /* Obtain info about this particular device */
              alsa_snd_pcm_info_set_device( pcmInfo, devIdx );
              alsa_snd_pcm_info_set_subdevice( pcmInfo, 0 );
              alsa_snd_pcm_info_set_stream( pcmInfo, SND_PCM_STREAM_CAPTURE );
              if( alsa_snd_ctl_pcm_info( ctl, pcmInfo ) >= 0 )
              {
                  hasCapture = 1;
              }
  
              alsa_snd_pcm_info_set_stream( pcmInfo, SND_PCM_STREAM_PLAYBACK );
              if( alsa_snd_ctl_pcm_info( ctl, pcmInfo ) >= 0 )
              {
                  hasPlayback = 1;
              }
  
              if( !hasPlayback && !hasCapture )
              {
                  /* Error */
                  continue;
              }
  
              infoName = SkipCardDetailsInName( (char *)alsa_snd_pcm_info_get_name( pcmInfo ), cardName );
  
              /* The length of the string written by snprintf plus terminating 0 */
              len = snprintf( NULL, 0, "%s: %s (%s)", cardName, infoName, buf ) + 1;
              PA_UNLESS( deviceName = (char *)PaUtil_GroupAllocateMemory( alsaApi->allocations, len ),
                      paInsufficientMemory );
              snprintf( deviceName, len, "%s: %s (%s)", cardName, infoName, buf );
  
              PA_DEBUG(( "%s: Found device [%d]: %s\n", __FUNCTION__, numDeviceNames, deviceName ));
  
              ++numDeviceNames;
              if( !hwDevInfos || numDeviceNames > maxDeviceNames )
              {
                  maxDeviceNames *= 2;
                  PA_UNLESS( hwDevInfos = (HwDevInfo *) realloc( hwDevInfos, maxDeviceNames * sizeof (HwDevInfo) ),
                          paInsufficientMemory );
              }
  
              PA_ENSURE( PaAlsa_StrDup( alsaApi, &alsaDeviceName, buf ) );
  
              hwDevInfos[ numDeviceNames - 1 ].alsaName = alsaDeviceName;
              hwDevInfos[ numDeviceNames - 1 ].name = deviceName;
              hwDevInfos[ numDeviceNames - 1 ].isPlug = usePlughw;
              hwDevInfos[ numDeviceNames - 1 ].hasPlayback = hasPlayback;
              hwDevInfos[ numDeviceNames - 1 ].hasCapture = hasCapture;
          }
          alsa_snd_ctl_close( ctl );
      }
  
      /* Iterate over plugin devices */
      if( NULL == (*alsa_snd_config) )
      {
          /* alsa_snd_config_update is called implicitly by some functions, if this hasn't happened snd_config will be NULL (bleh) */
          ENSURE_( alsa_snd_config_update(), paUnanticipatedHostError );
          PA_DEBUG(( "Updating snd_config\n" ));
      }
      assert( *alsa_snd_config );
      if( ( res = alsa_snd_config_search( *alsa_snd_config, "pcm", &topNode ) ) >= 0 )
      {
          snd_config_iterator_t i, next;
  
          alsa_snd_config_for_each( i, next, topNode )
          {
              const char *tpStr = "unknown", *idStr = NULL;
              int err = 0;
  
              char *alsaDeviceName, *deviceName;
              const HwDevInfo *predefined = NULL;
              snd_config_t *n = alsa_snd_config_iterator_entry( i ), * tp = NULL;;
  
              if( (err = alsa_snd_config_search( n, "type", &tp )) < 0 )
              {
                  if( -ENOENT != err )
                  {
                      ENSURE_(err, paUnanticipatedHostError);
                  }
              }
              else
              {
                  ENSURE_( alsa_snd_config_get_string( tp, &tpStr ), paUnanticipatedHostError );
              }
              ENSURE_( alsa_snd_config_get_id( n, &idStr ), paUnanticipatedHostError );
              if( IgnorePlugin( idStr ) )
              {
                  PA_DEBUG(( "%s: Ignoring ALSA plugin device [%s] of type [%s]\n", __FUNCTION__, idStr, tpStr ));
                  continue;
              }
              PA_DEBUG(( "%s: Found plugin [%s] of type [%s]\n", __FUNCTION__, idStr, tpStr ));
  
              PA_UNLESS( alsaDeviceName = (char*)PaUtil_GroupAllocateMemory( alsaApi->allocations,
                                                              strlen(idStr) + 6 ), paInsufficientMemory );
              strcpy( alsaDeviceName, idStr );
              PA_UNLESS( deviceName = (char*)PaUtil_GroupAllocateMemory( alsaApi->allocations,
                                                              strlen(idStr) + 1 ), paInsufficientMemory );
              strcpy( deviceName, idStr );
  
              ++numDeviceNames;
              if( !hwDevInfos || numDeviceNames > maxDeviceNames )
              {
                  maxDeviceNames *= 2;
                  PA_UNLESS( hwDevInfos = (HwDevInfo *) realloc( hwDevInfos, maxDeviceNames * sizeof (HwDevInfo) ),
                          paInsufficientMemory );
              }
  
              predefined = FindDeviceName( alsaDeviceName );
  
              hwDevInfos[numDeviceNames - 1].alsaName = alsaDeviceName;
              hwDevInfos[numDeviceNames - 1].name     = deviceName;
              hwDevInfos[numDeviceNames - 1].isPlug   = 1;
  
              if( predefined )
              {
                  hwDevInfos[numDeviceNames - 1].hasPlayback = predefined->hasPlayback;
                  hwDevInfos[numDeviceNames - 1].hasCapture  = predefined->hasCapture;
              }
              else
              {
                  hwDevInfos[numDeviceNames - 1].hasPlayback = 1;
                  hwDevInfos[numDeviceNames - 1].hasCapture  = 1;
              }
          }
      }
      else
          PA_DEBUG(( "%s: Iterating over ALSA plugins failed: %s\n", __FUNCTION__, alsa_snd_strerror( res ) ));
  
      /* allocate deviceInfo memory based on the number of devices */
      PA_UNLESS( baseApi->deviceInfos = (PaDeviceInfo**)PaUtil_GroupAllocateMemory(
              alsaApi->allocations, sizeof(PaDeviceInfo*) * (numDeviceNames) ), paInsufficientMemory );
  
      /* allocate all device info structs in a contiguous block */
      PA_UNLESS( deviceInfoArray = (PaAlsaDeviceInfo*)PaUtil_GroupAllocateMemory(
              alsaApi->allocations, sizeof(PaAlsaDeviceInfo) * numDeviceNames ), paInsufficientMemory );
  
      /* Loop over list of cards, filling in info. If a device is deemed unavailable (can't get name),
       * it's ignored.
       *
       * Note that we do this in two stages. This is a workaround owing to the fact that the 'dmix'
       * plugin may cause the underlying hardware device to be busy for a short while even after it
       * (dmix) is closed. The 'default' plugin may also point to the dmix plugin, so the same goes
       * for this.
       */
      PA_DEBUG(( "%s: Filling device info for %d devices\n", __FUNCTION__, numDeviceNames ));
      for( i = 0, devIdx = 0; i < numDeviceNames; ++i )
      {
          PaAlsaDeviceInfo* devInfo = &deviceInfoArray[i];
          HwDevInfo* hwInfo = &hwDevInfos[i];
          if( !strcmp( hwInfo->name, "dmix" ) || !strcmp( hwInfo->name, "default" ) )
          {
              continue;
          }
  
          PA_ENSURE( FillInDevInfo( alsaApi, hwInfo, blocking, devInfo, &devIdx ) );
      }
      assert( devIdx <= numDeviceNames );
      /* Now inspect 'dmix' and 'default' plugins */
      for( i = 0; i < numDeviceNames; ++i )
      {
          PaAlsaDeviceInfo* devInfo = &deviceInfoArray[i];
          HwDevInfo* hwInfo = &hwDevInfos[i];
          if( strcmp( hwInfo->name, "dmix" ) && strcmp( hwInfo->name, "default" ) )
          {
              continue;
          }
  
          PA_ENSURE( FillInDevInfo( alsaApi, hwInfo, blocking, devInfo, &devIdx ) );
      }
      free( hwDevInfos );
  
      baseApi->info.deviceCount = devIdx;   /* Number of successfully queried devices */
  
  #ifdef PA_ENABLE_DEBUG_OUTPUT
      PA_DEBUG(( "%s: Building device list took %f seconds\n", __FUNCTION__, PaUtil_GetTime() - startTime ));
  #endif
  
  end:
      return result;
  
  error:
      /* No particular action */
      goto end;
  }
  
  /* Check against known device capabilities */
  static PaError ValidateParameters( const PaStreamParameters *parameters, PaUtilHostApiRepresentation *hostApi, StreamDirection mode )
  {
      PaError result = paNoError;
      int maxChans;
      const PaAlsaDeviceInfo *deviceInfo = NULL;
      assert( parameters );
  
      if( parameters->device != paUseHostApiSpecificDeviceSpecification )
      {
          assert( parameters->device < hostApi->info.deviceCount );
          PA_UNLESS( parameters->hostApiSpecificStreamInfo == NULL, paBadIODeviceCombination );
          deviceInfo = GetDeviceInfo( hostApi, parameters->device );
      }
      else
      {
          const PaAlsaStreamInfo *streamInfo = parameters->hostApiSpecificStreamInfo;
  
          PA_UNLESS( parameters->device == paUseHostApiSpecificDeviceSpecification, paInvalidDevice );
          PA_UNLESS( streamInfo->size == sizeof (PaAlsaStreamInfo) && streamInfo->version == 1,
                  paIncompatibleHostApiSpecificStreamInfo );
          PA_UNLESS( streamInfo->deviceString != NULL, paInvalidDevice );
  
          /* Skip further checking */
          return paNoError;
      }
  
      assert( deviceInfo );
      assert( parameters->hostApiSpecificStreamInfo == NULL );
      maxChans = ( StreamDirection_In == mode ? deviceInfo->baseDeviceInfo.maxInputChannels :
          deviceInfo->baseDeviceInfo.maxOutputChannels );
      PA_UNLESS( parameters->channelCount <= maxChans, paInvalidChannelCount );
  
  error:
      return result;
  }
  
  /* Given an open stream, what sample formats are available? */
  static PaSampleFormat GetAvailableFormats( snd_pcm_t *pcm )
  {
      PaSampleFormat available = 0;
      snd_pcm_hw_params_t *hwParams;
      alsa_snd_pcm_hw_params_alloca( &hwParams );
  
      alsa_snd_pcm_hw_params_any( pcm, hwParams );
  
      if( alsa_snd_pcm_hw_params_test_format( pcm, hwParams, SND_PCM_FORMAT_FLOAT ) >= 0)
          available |= paFloat32;
  
      if( alsa_snd_pcm_hw_params_test_format( pcm, hwParams, SND_PCM_FORMAT_S32 ) >= 0)
          available |= paInt32;
  
  #ifdef PA_LITTLE_ENDIAN
      if( alsa_snd_pcm_hw_params_test_format( pcm, hwParams, SND_PCM_FORMAT_S24_3LE ) >= 0)
          available |= paInt24;
  #elif defined PA_BIG_ENDIAN
      if( alsa_snd_pcm_hw_params_test_format( pcm, hwParams, SND_PCM_FORMAT_S24_3BE ) >= 0)
          available |= paInt24;
  #endif
  
      if( alsa_snd_pcm_hw_params_test_format( pcm, hwParams, SND_PCM_FORMAT_S16 ) >= 0)
          available |= paInt16;
  
      if( alsa_snd_pcm_hw_params_test_format( pcm, hwParams, SND_PCM_FORMAT_U8 ) >= 0)
          available |= paUInt8;
  
      if( alsa_snd_pcm_hw_params_test_format( pcm, hwParams, SND_PCM_FORMAT_S8 ) >= 0)
          available |= paInt8;
  
      return available;
  }
  
  /* Output to console all formats supported by device */
  static void LogAllAvailableFormats( snd_pcm_t *pcm )
  {
      PaSampleFormat available = 0;
      snd_pcm_hw_params_t *hwParams;
      alsa_snd_pcm_hw_params_alloca( &hwParams );
  
      alsa_snd_pcm_hw_params_any( pcm, hwParams );
  
      PA_DEBUG(( " --- Supported Formats ---\n" ));
  
      if( alsa_snd_pcm_hw_params_test_format( pcm, hwParams, SND_PCM_FORMAT_S8 ) >= 0)
          PA_DEBUG(( "SND_PCM_FORMAT_S8\n" ));
      if( alsa_snd_pcm_hw_params_test_format( pcm, hwParams, SND_PCM_FORMAT_U8 ) >= 0)
          PA_DEBUG(( "SND_PCM_FORMAT_U8\n" ));
  
      if( alsa_snd_pcm_hw_params_test_format( pcm, hwParams, SND_PCM_FORMAT_S16_LE ) >= 0)
          PA_DEBUG(( "SND_PCM_FORMAT_S16_LE\n" ));
      if( alsa_snd_pcm_hw_params_test_format( pcm, hwParams, SND_PCM_FORMAT_S16_BE ) >= 0)
          PA_DEBUG(( "SND_PCM_FORMAT_S16_BE\n" ));
  
      if( alsa_snd_pcm_hw_params_test_format( pcm, hwParams, SND_PCM_FORMAT_U16_LE ) >= 0)
          PA_DEBUG(( "SND_PCM_FORMAT_U16_LE\n" ));
      if( alsa_snd_pcm_hw_params_test_format( pcm, hwParams, SND_PCM_FORMAT_U16_BE ) >= 0)
          PA_DEBUG(( "SND_PCM_FORMAT_U16_BE\n" ));
  
      if( alsa_snd_pcm_hw_params_test_format( pcm, hwParams, SND_PCM_FORMAT_S24_LE ) >= 0)
          PA_DEBUG(( "SND_PCM_FORMAT_S24_LE\n" ));
      if( alsa_snd_pcm_hw_params_test_format( pcm, hwParams, SND_PCM_FORMAT_S24_BE ) >= 0)
          PA_DEBUG(( "SND_PCM_FORMAT_S24_BE\n" ));
  
      if( alsa_snd_pcm_hw_params_test_format( pcm, hwParams, SND_PCM_FORMAT_U24_LE ) >= 0)
          PA_DEBUG(( "SND_PCM_FORMAT_U24_LE\n" ));
      if( alsa_snd_pcm_hw_params_test_format( pcm, hwParams, SND_PCM_FORMAT_U24_BE ) >= 0)
          PA_DEBUG(( "SND_PCM_FORMAT_U24_BE\n" ));
  
      if( alsa_snd_pcm_hw_params_test_format( pcm, hwParams, SND_PCM_FORMAT_FLOAT_LE ) >= 0)
          PA_DEBUG(( "SND_PCM_FORMAT_FLOAT_LE\n" ));
      if( alsa_snd_pcm_hw_params_test_format( pcm, hwParams, SND_PCM_FORMAT_FLOAT_BE ) >= 0)
          PA_DEBUG(( "SND_PCM_FORMAT_FLOAT_BE\n" ));
  
      if( alsa_snd_pcm_hw_params_test_format( pcm, hwParams, SND_PCM_FORMAT_FLOAT64_LE ) >= 0)
          PA_DEBUG(( "SND_PCM_FORMAT_FLOAT64_LE\n" ));
      if( alsa_snd_pcm_hw_params_test_format( pcm, hwParams, SND_PCM_FORMAT_FLOAT64_BE ) >= 0)
          PA_DEBUG(( "SND_PCM_FORMAT_FLOAT64_BE\n" ));
  
      if( alsa_snd_pcm_hw_params_test_format( pcm, hwParams, SND_PCM_FORMAT_IEC958_SUBFRAME_LE ) >= 0)
          PA_DEBUG(( "SND_PCM_FORMAT_IEC958_SUBFRAME_LE\n" ));
      if( alsa_snd_pcm_hw_params_test_format( pcm, hwParams, SND_PCM_FORMAT_IEC958_SUBFRAME_BE ) >= 0)
          PA_DEBUG(( "SND_PCM_FORMAT_IEC958_SUBFRAME_BE\n" ));
  
      if( alsa_snd_pcm_hw_params_test_format( pcm, hwParams, SND_PCM_FORMAT_MU_LAW ) >= 0)
          PA_DEBUG(( "SND_PCM_FORMAT_MU_LAW\n" ));
      if( alsa_snd_pcm_hw_params_test_format( pcm, hwParams, SND_PCM_FORMAT_A_LAW ) >= 0)
          PA_DEBUG(( "SND_PCM_FORMAT_A_LAW\n" ));
  
      if( alsa_snd_pcm_hw_params_test_format( pcm, hwParams, SND_PCM_FORMAT_IMA_ADPCM ) >= 0)
          PA_DEBUG(( "SND_PCM_FORMAT_IMA_ADPCM\n" ));
      if( alsa_snd_pcm_hw_params_test_format( pcm, hwParams, SND_PCM_FORMAT_MPEG ) >= 0)
          PA_DEBUG(( "SND_PCM_FORMAT_MPEG\n" ));
  
      if( alsa_snd_pcm_hw_params_test_format( pcm, hwParams, SND_PCM_FORMAT_GSM ) >= 0)
          PA_DEBUG(( "SND_PCM_FORMAT_GSM\n" ));
      if( alsa_snd_pcm_hw_params_test_format( pcm, hwParams, SND_PCM_FORMAT_SPECIAL ) >= 0)
          PA_DEBUG(( "SND_PCM_FORMAT_SPECIAL\n" ));
  
      if( alsa_snd_pcm_hw_params_test_format( pcm, hwParams, SND_PCM_FORMAT_S24_3LE ) >= 0)
          PA_DEBUG(( "SND_PCM_FORMAT_S24_3LE\n" ));
      if( alsa_snd_pcm_hw_params_test_format( pcm, hwParams, SND_PCM_FORMAT_S24_3BE ) >= 0)
          PA_DEBUG(( "SND_PCM_FORMAT_S24_3BE\n" ));
  
      if( alsa_snd_pcm_hw_params_test_format( pcm, hwParams, SND_PCM_FORMAT_U24_3LE ) >= 0)
          PA_DEBUG(( "SND_PCM_FORMAT_U24_3LE\n" ));
      if( alsa_snd_pcm_hw_params_test_format( pcm, hwParams, SND_PCM_FORMAT_U24_3BE ) >= 0)
          PA_DEBUG(( "SND_PCM_FORMAT_U24_3BE\n" ));
  
      if( alsa_snd_pcm_hw_params_test_format( pcm, hwParams, SND_PCM_FORMAT_S20_3LE ) >= 0)
          PA_DEBUG(( "SND_PCM_FORMAT_S20_3LE\n" ));
      if( alsa_snd_pcm_hw_params_test_format( pcm, hwParams, SND_PCM_FORMAT_S20_3BE ) >= 0)
          PA_DEBUG(( "SND_PCM_FORMAT_S20_3BE\n" ));
  
      if( alsa_snd_pcm_hw_params_test_format( pcm, hwParams, SND_PCM_FORMAT_U20_3LE ) >= 0)
          PA_DEBUG(( "SND_PCM_FORMAT_U20_3LE\n" ));
      if( alsa_snd_pcm_hw_params_test_format( pcm, hwParams, SND_PCM_FORMAT_U20_3BE ) >= 0)
          PA_DEBUG(( "SND_PCM_FORMAT_U20_3BE\n" ));
  
      if( alsa_snd_pcm_hw_params_test_format( pcm, hwParams, SND_PCM_FORMAT_S18_3LE ) >= 0)
          PA_DEBUG(( "SND_PCM_FORMAT_S18_3LE\n" ));
      if( alsa_snd_pcm_hw_params_test_format( pcm, hwParams, SND_PCM_FORMAT_S18_3BE ) >= 0)
          PA_DEBUG(( "SND_PCM_FORMAT_S18_3BE\n" ));
  
      if( alsa_snd_pcm_hw_params_test_format( pcm, hwParams, SND_PCM_FORMAT_U18_3LE ) >= 0)
          PA_DEBUG(( "SND_PCM_FORMAT_U18_3LE\n" ));
      if( alsa_snd_pcm_hw_params_test_format( pcm, hwParams, SND_PCM_FORMAT_U18_3BE ) >= 0)
          PA_DEBUG(( "SND_PCM_FORMAT_U18_3BE\n" ));
  
      if( alsa_snd_pcm_hw_params_test_format( pcm, hwParams, SND_PCM_FORMAT_S16 ) >= 0)
          PA_DEBUG(( "SND_PCM_FORMAT_S16\n" ));
      if( alsa_snd_pcm_hw_params_test_format( pcm, hwParams, SND_PCM_FORMAT_U16 ) >= 0)
          PA_DEBUG(( "SND_PCM_FORMAT_U16\n" ));
  
      if( alsa_snd_pcm_hw_params_test_format( pcm, hwParams, SND_PCM_FORMAT_S24 ) >= 0)
          PA_DEBUG(( "SND_PCM_FORMAT_S24\n" ));
      if( alsa_snd_pcm_hw_params_test_format( pcm, hwParams, SND_PCM_FORMAT_U24 ) >= 0)
          PA_DEBUG(( "SND_PCM_FORMAT_U24\n" ));
  
      if( alsa_snd_pcm_hw_params_test_format( pcm, hwParams, SND_PCM_FORMAT_S32 ) >= 0)
          PA_DEBUG(( "SND_PCM_FORMAT_S32\n" ));
      if( alsa_snd_pcm_hw_params_test_format( pcm, hwParams, SND_PCM_FORMAT_U32 ) >= 0)
          PA_DEBUG(( "SND_PCM_FORMAT_U32\n" ));
  
      if( alsa_snd_pcm_hw_params_test_format( pcm, hwParams, SND_PCM_FORMAT_FLOAT ) >= 0)
          PA_DEBUG(( "SND_PCM_FORMAT_FLOAT\n" ));
      if( alsa_snd_pcm_hw_params_test_format( pcm, hwParams, SND_PCM_FORMAT_FLOAT64 ) >= 0)
          PA_DEBUG(( "SND_PCM_FORMAT_FLOAT64\n" ));
  
      if( alsa_snd_pcm_hw_params_test_format( pcm, hwParams, SND_PCM_FORMAT_IEC958_SUBFRAME ) >= 0)
          PA_DEBUG(( "SND_PCM_FORMAT_IEC958_SUBFRAME\n" ));
  
      PA_DEBUG(( " -------------------------\n" ));
  }
  
  static snd_pcm_format_t Pa2AlsaFormat( PaSampleFormat paFormat )
  {
      switch( paFormat )
      {
          case paFloat32:
              return SND_PCM_FORMAT_FLOAT;
  
          case paInt16:
              return SND_PCM_FORMAT_S16;
  
          case paInt24:
  #ifdef PA_LITTLE_ENDIAN
              return SND_PCM_FORMAT_S24_3LE;
  #elif defined PA_BIG_ENDIAN
              return SND_PCM_FORMAT_S24_3BE;
  #endif
  
          case paInt32:
              return SND_PCM_FORMAT_S32;
  
          case paInt8:
              return SND_PCM_FORMAT_S8;
  
          case paUInt8:
              return SND_PCM_FORMAT_U8;
  
          default:
              return SND_PCM_FORMAT_UNKNOWN;
      }
  }
  
  /** Open an ALSA pcm handle.
   *
   * The device to be open can be specified by name in a custom PaAlsaStreamInfo struct, or it will be by
   * the Portaudio device number supplied in the stream parameters.
   */
  static PaError AlsaOpen( const PaUtilHostApiRepresentation *hostApi, const PaStreamParameters *params, StreamDirection
          streamDir, snd_pcm_t **pcm )
  {
      PaError result = paNoError;
      int ret;
      const char* deviceName = "";
      const PaAlsaDeviceInfo *deviceInfo = NULL;
      PaAlsaStreamInfo *streamInfo = (PaAlsaStreamInfo *)params->hostApiSpecificStreamInfo;
  
      if( !streamInfo )
      {
          deviceInfo = GetDeviceInfo( hostApi, params->device );
          deviceName = deviceInfo->alsaName;
      }
      else
          deviceName = streamInfo->deviceString;
  
      PA_DEBUG(( "%s: Opening device %s\n", __FUNCTION__, deviceName ));
      if( (ret = OpenPcm( pcm, deviceName, streamDir == StreamDirection_In ? SND_PCM_STREAM_CAPTURE : SND_PCM_STREAM_PLAYBACK,
                      SND_PCM_NONBLOCK, 1 )) < 0 )
      {
          /* Not to be closed */
          *pcm = NULL;
          ENSURE_( ret, -EBUSY == ret ? paDeviceUnavailable : paBadIODeviceCombination );
      }
      ENSURE_( alsa_snd_pcm_nonblock( *pcm, 0 ), paUnanticipatedHostError );
  
  end:
      return result;
  
  error:
      goto end;
  }
  
  static PaError TestParameters( const PaUtilHostApiRepresentation *hostApi, const PaStreamParameters *parameters,
          double sampleRate, StreamDirection streamDir )
  {
      PaError result = paNoError;
      snd_pcm_t *pcm = NULL;
      PaSampleFormat availableFormats;
      /* We are able to adapt to a number of channels less than what the device supports */
      unsigned int numHostChannels;
      PaSampleFormat hostFormat;
      snd_pcm_hw_params_t *hwParams;
      alsa_snd_pcm_hw_params_alloca( &hwParams );
  
      if( !parameters->hostApiSpecificStreamInfo )
      {
          const PaAlsaDeviceInfo *devInfo = GetDeviceInfo( hostApi, parameters->device );
          numHostChannels = PA_MAX( parameters->channelCount, StreamDirection_In == streamDir ?
                  devInfo->minInputChannels : devInfo->minOutputChannels );
      }
      else
          numHostChannels = parameters->channelCount;
  
      PA_ENSURE( AlsaOpen( hostApi, parameters, streamDir, &pcm ) );
  
      alsa_snd_pcm_hw_params_any( pcm, hwParams );
  
      if( SetApproximateSampleRate( pcm, hwParams, sampleRate ) < 0 )
      {
          result = paInvalidSampleRate;
          goto error;
      }
  
      if( alsa_snd_pcm_hw_params_set_channels( pcm, hwParams, numHostChannels ) < 0 )
      {
          result = paInvalidChannelCount;
          goto error;
      }
  
      /* See if we can find a best possible match */
      availableFormats = GetAvailableFormats( pcm );
      PA_ENSURE( hostFormat = PaUtil_SelectClosestAvailableFormat( availableFormats, parameters->sampleFormat ) );
  
      /* Some specific hardware (reported: Audio8 DJ) can fail with assertion during this step. */
      ENSURE_( alsa_snd_pcm_hw_params_set_format( pcm, hwParams, Pa2AlsaFormat( hostFormat ) ), paUnanticipatedHostError );
  
      {
          /* It happens that this call fails because the device is busy */
          int ret = 0;
          if( ( ret = alsa_snd_pcm_hw_params( pcm, hwParams ) ) < 0 )
          {
              if( -EINVAL == ret )
              {
                  /* Don't know what to return here */
                  result = paBadIODeviceCombination;
                  goto error;
              }
              else if( -EBUSY == ret )
              {
                  result = paDeviceUnavailable;
                  PA_DEBUG(( "%s: Device is busy\n", __FUNCTION__ ));
              }
              else
              {
                  result = paUnanticipatedHostError;
              }
  
              ENSURE_( ret, result );
          }
      }
  
  end:
      if( pcm )
      {
          alsa_snd_pcm_close( pcm );
      }
      return result;
  
  error:
      goto end;
  }
  
  static PaError IsFormatSupported( struct PaUtilHostApiRepresentation *hostApi,
                                    const PaStreamParameters *inputParameters,
                                    const PaStreamParameters *outputParameters,
                                    double sampleRate )
  {
      int inputChannelCount = 0, outputChannelCount = 0;
      PaSampleFormat inputSampleFormat, outputSampleFormat;
      PaError result = paFormatIsSupported;
  
      if( inputParameters )
      {
          PA_ENSURE( ValidateParameters( inputParameters, hostApi, StreamDirection_In ) );
  
          inputChannelCount = inputParameters->channelCount;
          inputSampleFormat = inputParameters->sampleFormat;
      }
  
      if( outputParameters )
      {
          PA_ENSURE( ValidateParameters( outputParameters, hostApi, StreamDirection_Out ) );
  
          outputChannelCount = outputParameters->channelCount;
          outputSampleFormat = outputParameters->sampleFormat;
      }
  
      if( inputChannelCount )
      {
          if( ( result = TestParameters( hostApi, inputParameters, sampleRate, StreamDirection_In ) )
                  != paNoError )
              goto error;
      }
      if ( outputChannelCount )
      {
          if( ( result = TestParameters( hostApi, outputParameters, sampleRate, StreamDirection_Out ) )
                  != paNoError )
              goto error;
      }
  
      return paFormatIsSupported;
  
  error:
      return result;
  }
  
  
  static PaError PaAlsaStreamComponent_Initialize( PaAlsaStreamComponent *self, PaAlsaHostApiRepresentation *alsaApi,
          const PaStreamParameters *params, StreamDirection streamDir, int callbackMode )
  {
      PaError result = paNoError;
      PaSampleFormat userSampleFormat = params->sampleFormat, hostSampleFormat = paNoError;
      assert( params->channelCount > 0 );
  
      /* Make sure things have an initial value */
      memset( self, 0, sizeof (PaAlsaStreamComponent) );
  
      if( NULL == params->hostApiSpecificStreamInfo )
      {
          const PaAlsaDeviceInfo *devInfo = GetDeviceInfo( &alsaApi->baseHostApiRep, params->device );
          self->numHostChannels = PA_MAX( params->channelCount, StreamDirection_In == streamDir ? devInfo->minInputChannels
                  : devInfo->minOutputChannels );
          self->deviceIsPlug = devInfo->isPlug;
          PA_DEBUG(( "%s: Host Chans %c %i\n", __FUNCTION__, streamDir == StreamDirection_In ? 'C' : 'P', self->numHostChannels ));
      }
      else
      {
          /* We're blissfully unaware of the minimum channelCount */
          self->numHostChannels = params->channelCount;
          /* Check if device name does not start with hw: to determine if it is a 'plug' device */
          if( strncmp( "hw:", ((PaAlsaStreamInfo *)params->hostApiSpecificStreamInfo)->deviceString, 3 ) != 0  )
              self->deviceIsPlug = 1; /* An Alsa plug device, not a direct hw device */
      }
      if( self->deviceIsPlug && alsaApi->alsaLibVersion < ALSA_VERSION_INT( 1, 0, 16 ) )
          self->useReventFix = 1; /* Prior to Alsa1.0.16, plug devices may stutter without this fix */
  
      self->device = params->device;
  
      PA_ENSURE( AlsaOpen( &alsaApi->baseHostApiRep, params, streamDir, &self->pcm ) );
      self->nfds = alsa_snd_pcm_poll_descriptors_count( self->pcm );
  
      PA_ENSURE( hostSampleFormat = PaUtil_SelectClosestAvailableFormat( GetAvailableFormats( self->pcm ), userSampleFormat ) );
  
      self->hostSampleFormat = hostSampleFormat;
      self->nativeFormat = Pa2AlsaFormat( hostSampleFormat );
      self->hostInterleaved = self->userInterleaved = !( userSampleFormat & paNonInterleaved );
      self->numUserChannels = params->channelCount;
      self->streamDir = streamDir;
      self->canMmap = 0;
      self->nonMmapBuffer = NULL;
      self->nonMmapBufferSize = 0;
  
      if( !callbackMode && !self->userInterleaved )
      {
          /* Pre-allocate non-interleaved user provided buffers */
          PA_UNLESS( self->userBuffers = PaUtil_AllocateMemory( sizeof (void *) * self->numUserChannels ),
                  paInsufficientMemory );
      }
  
  error:
  
      /* Log all available formats. */
      if ( hostSampleFormat == paSampleFormatNotSupported )
      {
          LogAllAvailableFormats( self->pcm );
          PA_DEBUG(( "%s: Please provide the log output to PortAudio developers, your hardware does not have any sample format implemented yet.\n", __FUNCTION__ ));
      }
  
      return result;
  }
  
  static void PaAlsaStreamComponent_Terminate( PaAlsaStreamComponent *self )
  {
      alsa_snd_pcm_close( self->pcm );
      PaUtil_FreeMemory( self->userBuffers ); /* (Ptr can be NULL; PaUtil_FreeMemory includes a NULL check) */
      PaUtil_FreeMemory( self->nonMmapBuffer );
  }
  
  /*
  static int nearbyint_(float value) {
      if(  value - (int)value > .5 )
          return (int)ceil( value );
      return (int)floor( value );
  }
  */
  
  /** Initiate configuration, preparing for determining a period size suitable for both capture and playback components.
   *
   */
  static PaError PaAlsaStreamComponent_InitialConfigure( PaAlsaStreamComponent *self, const PaStreamParameters *params,
          int primeBuffers, snd_pcm_hw_params_t *hwParams, double *sampleRate )
  {
      /* Configuration consists of setting all of ALSA's parameters.
       * These parameters come in two flavors: hardware parameters
       * and software parameters.  Hardware parameters will affect
       * the way the device is initialized, software parameters
       * affect the way ALSA interacts with me, the user-level client.
       */
  
      PaError result = paNoError;
      snd_pcm_access_t accessMode, alternateAccessMode;
      int dir = 0;
      snd_pcm_t *pcm = self->pcm;
      double sr = *sampleRate;
      unsigned int minPeriods = 2;
  
      /* self->framesPerPeriod = framesPerHostBuffer; */
  
      /* ... fill up the configuration space with all possible
       * combinations of parameters this device will accept */
      ENSURE_( alsa_snd_pcm_hw_params_any( pcm, hwParams ), paUnanticipatedHostError );
  
      ENSURE_( alsa_snd_pcm_hw_params_set_periods_integer( pcm, hwParams ), paUnanticipatedHostError );
      /* I think there should be at least 2 periods (even though ALSA doesn't appear to enforce this) */
      dir = 0;
      ENSURE_( alsa_snd_pcm_hw_params_set_periods_min( pcm, hwParams, &minPeriods, &dir ), paUnanticipatedHostError );
  
      if( self->userInterleaved )
      {
          accessMode          = SND_PCM_ACCESS_MMAP_INTERLEAVED;
          alternateAccessMode = SND_PCM_ACCESS_MMAP_NONINTERLEAVED;
  
          /* test if MMAP supported */
          self->canMmap = alsa_snd_pcm_hw_params_test_access( pcm, hwParams, accessMode ) >= 0 ||
                          alsa_snd_pcm_hw_params_test_access( pcm, hwParams, alternateAccessMode ) >= 0;
  
          PA_DEBUG(( "%s: device MMAP SND_PCM_ACCESS_MMAP_INTERLEAVED: %s\n", __FUNCTION__, ( alsa_snd_pcm_hw_params_test_access( pcm, hwParams, accessMode ) >= 0 ? "YES" : "NO" ) ));
          PA_DEBUG(( "%s: device MMAP SND_PCM_ACCESS_MMAP_NONINTERLEAVED: %s\n", __FUNCTION__, ( alsa_snd_pcm_hw_params_test_access( pcm, hwParams, alternateAccessMode ) >= 0 ? "YES" : "NO" ) ));
  
          if( !self->canMmap )
          {
              accessMode          = SND_PCM_ACCESS_RW_INTERLEAVED;
              alternateAccessMode = SND_PCM_ACCESS_RW_NONINTERLEAVED;
          }
      }
      else
      {
          accessMode          = SND_PCM_ACCESS_MMAP_NONINTERLEAVED;
          alternateAccessMode = SND_PCM_ACCESS_MMAP_INTERLEAVED;
  
          /* test if MMAP supported */
          self->canMmap = alsa_snd_pcm_hw_params_test_access( pcm, hwParams, accessMode ) >= 0 ||
                          alsa_snd_pcm_hw_params_test_access( pcm, hwParams, alternateAccessMode ) >= 0;
  
          PA_DEBUG((" %s: device MMAP SND_PCM_ACCESS_MMAP_NONINTERLEAVED: %s\n", __FUNCTION__, ( alsa_snd_pcm_hw_params_test_access( pcm, hwParams, accessMode ) >= 0 ? "YES" : "NO" ) ));
          PA_DEBUG(( "%s: device MMAP SND_PCM_ACCESS_MMAP_INTERLEAVED: %s\n", __FUNCTION__, ( alsa_snd_pcm_hw_params_test_access( pcm, hwParams, alternateAccessMode ) >= 0 ? "YES" : "NO" ) ));
  
          if( !self->canMmap )
          {
              accessMode          = SND_PCM_ACCESS_RW_NONINTERLEAVED;
              alternateAccessMode = SND_PCM_ACCESS_RW_INTERLEAVED;
          }
      }
  
      PA_DEBUG(( "%s: device can MMAP: %s\n", __FUNCTION__, ( self->canMmap ? "YES" : "NO" ) ));
  
      /* If requested access mode fails, try alternate mode */
      if( alsa_snd_pcm_hw_params_set_access( pcm, hwParams, accessMode ) < 0 )
      {
          int err = 0;
          if( ( err = alsa_snd_pcm_hw_params_set_access( pcm, hwParams, alternateAccessMode )) < 0 )
          {
              result = paUnanticipatedHostError;
              PaUtil_SetLastHostErrorInfo( paALSA, err, alsa_snd_strerror( err ) );
              goto error;
          }
          /* Flip mode */
          self->hostInterleaved = !self->userInterleaved;
      }
  
      /* Some specific hardware (reported: Audio8 DJ) can fail with assertion during this step. */
      ENSURE_( alsa_snd_pcm_hw_params_set_format( pcm, hwParams, self->nativeFormat ), paUnanticipatedHostError );
  
      if( ( result = SetApproximateSampleRate( pcm, hwParams, sr )) != paUnanticipatedHostError )
      {
          ENSURE_( GetExactSampleRate( hwParams, &sr ), paUnanticipatedHostError );
          if( result == paInvalidSampleRate ) /* From the SetApproximateSampleRate() call above */
          { /* The sample rate was returned as 'out of tolerance' of the one requested */
              PA_DEBUG(( "%s: Wanted %.3f, closest sample rate was %.3f\n", __FUNCTION__, sampleRate, sr ));
              PA_ENSURE( paInvalidSampleRate );
          }
      }
      else
      {
          PA_ENSURE( paUnanticipatedHostError );
      }
  
      ENSURE_( alsa_snd_pcm_hw_params_set_channels( pcm, hwParams, self->numHostChannels ), paInvalidChannelCount );
  
      *sampleRate = sr;
  
  end:
      return result;
  
  error:
      /* No particular action */
      goto end;
  }
  
  /** Finish the configuration of the component's ALSA device.
   *
   * As part of this method, the component's alsaBufferSize attribute will be set.
   * @param latency: The latency for this component.
   */
  static PaError PaAlsaStreamComponent_FinishConfigure( PaAlsaStreamComponent *self, snd_pcm_hw_params_t* hwParams,
          const PaStreamParameters *params, int primeBuffers, double sampleRate, PaTime* latency )
  {
      PaError result = paNoError;
      snd_pcm_sw_params_t* swParams;
      snd_pcm_uframes_t bufSz = 0;
      *latency = -1.;
  
      alsa_snd_pcm_sw_params_alloca( &swParams );
  
      bufSz = params->suggestedLatency * sampleRate + self->framesPerPeriod;
      ENSURE_( alsa_snd_pcm_hw_params_set_buffer_size_near( self->pcm, hwParams, &bufSz ), paUnanticipatedHostError );
  
      /* Set the parameters! */
      {
          int r = alsa_snd_pcm_hw_params( self->pcm, hwParams );
  #ifdef PA_ENABLE_DEBUG_OUTPUT
          if( r < 0 )
          {
              snd_output_t *output = NULL;
              alsa_snd_output_stdio_attach( &output, stderr, 0 );
              alsa_snd_pcm_hw_params_dump( hwParams, output );
          }
  #endif
          ENSURE_( r, paUnanticipatedHostError );
      }
      if( alsa_snd_pcm_hw_params_get_buffer_size != NULL )
      {
          ENSURE_( alsa_snd_pcm_hw_params_get_buffer_size( hwParams, &self->alsaBufferSize ), paUnanticipatedHostError );
      }
      else
      {
          self->alsaBufferSize = bufSz;
      }
  
      /* Latency in seconds */
      *latency = (self->alsaBufferSize - self->framesPerPeriod) / sampleRate;
  
      /* Now software parameters... */
      ENSURE_( alsa_snd_pcm_sw_params_current( self->pcm, swParams ), paUnanticipatedHostError );
  
      ENSURE_( alsa_snd_pcm_sw_params_set_start_threshold( self->pcm, swParams, self->framesPerPeriod ), paUnanticipatedHostError );
      ENSURE_( alsa_snd_pcm_sw_params_set_stop_threshold( self->pcm, swParams, self->alsaBufferSize ), paUnanticipatedHostError );
  
      /* Silence buffer in the case of underrun */
      if( !primeBuffers ) /* XXX: Make sense? */
      {
          snd_pcm_uframes_t boundary;
          ENSURE_( alsa_snd_pcm_sw_params_get_boundary( swParams, &boundary ), paUnanticipatedHostError );
          ENSURE_( alsa_snd_pcm_sw_params_set_silence_threshold( self->pcm, swParams, 0 ), paUnanticipatedHostError );
          ENSURE_( alsa_snd_pcm_sw_params_set_silence_size( self->pcm, swParams, boundary ), paUnanticipatedHostError );
      }
  
      ENSURE_( alsa_snd_pcm_sw_params_set_avail_min( self->pcm, swParams, self->framesPerPeriod ), paUnanticipatedHostError );
      ENSURE_( alsa_snd_pcm_sw_params_set_xfer_align( self->pcm, swParams, 1 ), paUnanticipatedHostError );
      ENSURE_( alsa_snd_pcm_sw_params_set_tstamp_mode( self->pcm, swParams, SND_PCM_TSTAMP_ENABLE ), paUnanticipatedHostError );
  
      /* Set the parameters! */
      ENSURE_( alsa_snd_pcm_sw_params( self->pcm, swParams ), paUnanticipatedHostError );
  
  error:
      return result;
  }
  
  static PaError PaAlsaStream_Initialize( PaAlsaStream *self, PaAlsaHostApiRepresentation *alsaApi, const PaStreamParameters *inParams,
          const PaStreamParameters *outParams, double sampleRate, unsigned long framesPerUserBuffer, PaStreamCallback callback,
          PaStreamFlags streamFlags, void *userData )
  {
      PaError result = paNoError;
      assert( self );
  
      memset( self, 0, sizeof( PaAlsaStream ) );
  
      if( NULL != callback )
      {
          PaUtil_InitializeStreamRepresentation( &self->streamRepresentation,
                                                 &alsaApi->callbackStreamInterface,
                                                 callback, userData );
          self->callbackMode = 1;
      }
      else
      {
          PaUtil_InitializeStreamRepresentation( &self->streamRepresentation,
                                                 &alsaApi->blockingStreamInterface,
                                                 NULL, userData );
      }
  
      self->framesPerUserBuffer = framesPerUserBuffer;
      self->neverDropInput = streamFlags & paNeverDropInput;
      /* XXX: Ignore paPrimeOutputBuffersUsingStreamCallback until buffer priming is fully supported in pa_process.c */
      /*
      if( outParams & streamFlags & paPrimeOutputBuffersUsingStreamCallback )
          self->primeBuffers = 1;
          */
      memset( &self->capture, 0, sizeof (PaAlsaStreamComponent) );
      memset( &self->playback, 0, sizeof (PaAlsaStreamComponent) );
      if( inParams )
      {
          PA_ENSURE( PaAlsaStreamComponent_Initialize( &self->capture, alsaApi, inParams, StreamDirection_In, NULL != callback ) );
      }
      if( outParams )
      {
          PA_ENSURE( PaAlsaStreamComponent_Initialize( &self->playback, alsaApi, outParams, StreamDirection_Out, NULL != callback ) );
      }
  
      assert( self->capture.nfds || self->playback.nfds );
  
      PA_UNLESS( self->pfds = (struct pollfd*)PaUtil_AllocateMemory( ( self->capture.nfds +
                      self->playback.nfds ) * sizeof( struct pollfd ) ), paInsufficientMemory );
  
      PaUtil_InitializeCpuLoadMeasurer( &self->cpuLoadMeasurer, sampleRate );
      ASSERT_CALL_( PaUnixMutex_Initialize( &self->stateMtx ), paNoError );
  
  error:
      return result;
  }
  
  /** Free resources associated with stream, and eventually stream itself.
   *
   * Frees allocated memory, and terminates individual StreamComponents.
   */
  static void PaAlsaStream_Terminate( PaAlsaStream *self )
  {
      assert( self );
  
      if( self->capture.pcm )
      {
          PaAlsaStreamComponent_Terminate( &self->capture );
      }
      if( self->playback.pcm )
      {
          PaAlsaStreamComponent_Terminate( &self->playback );
      }
  
      PaUtil_FreeMemory( self->pfds );
      ASSERT_CALL_( PaUnixMutex_Terminate( &self->stateMtx ), paNoError );
  
      PaUtil_FreeMemory( self );
  }
  
  /** Calculate polling timeout
   *
   * @param frames Time to wait
   * @return Polling timeout in milliseconds
   */
  static int CalculatePollTimeout( const PaAlsaStream *stream, unsigned long frames )
  {
      assert( stream->streamRepresentation.streamInfo.sampleRate > 0.0 );
      /* Period in msecs, rounded up */
      return (int)ceil( 1000 * frames / stream->streamRepresentation.streamInfo.sampleRate );
  }
  
  /** Align value in backward direction.
   *
   * @param v: Value to align.
   * @param align: Alignment.
   */
  static unsigned long PaAlsa_AlignBackward(unsigned long v, unsigned long align)
  {
      return ( v - ( align ? v % align : 0 ) );
  }
  
  /** Align value in forward direction.
   *
   * @param v: Value to align.
   * @param align: Alignment.
   */
  static unsigned long PaAlsa_AlignForward(unsigned long v, unsigned long align)
  {
      unsigned long remainder = ( align ? ( v % align ) : 0);
      return ( remainder != 0 ? v + ( align - remainder ) : v );
  }
  
  /** Get size of host buffer maintained from the number of user frames, sample rate and suggested latency. Minimum double buffering
   *  is maintained to allow 100% CPU usage inside user callback.
   *
   * @param userFramesPerBuffer: User buffer size in number of frames.
   * @param suggestedLatency: User provided desired latency.
   * @param sampleRate: Sample rate.
   */
  static unsigned long PaAlsa_GetFramesPerHostBuffer(unsigned long userFramesPerBuffer, PaTime suggestedLatency, double sampleRate)
  {
      unsigned long frames = userFramesPerBuffer + PA_MAX( userFramesPerBuffer, (unsigned long)( suggestedLatency * sampleRate ) );
      return frames;
  }
  
  /** Determine size per host buffer.
   *
   * During this method call, the component's framesPerPeriod attribute gets computed, and the corresponding period size
   * gets configured for the device.
   * @param accurate: If the configured period size is non-integer, this will be set to 0.
   */
  static PaError PaAlsaStreamComponent_DetermineFramesPerBuffer( PaAlsaStreamComponent* self, const PaStreamParameters* params,
          unsigned long framesPerUserBuffer, double sampleRate, snd_pcm_hw_params_t* hwParams, int* accurate )
  {
      PaError result = paNoError;
      unsigned long bufferSize, framesPerHostBuffer;
      int dir = 0;
  
      /* Calculate host buffer size */
      bufferSize = PaAlsa_GetFramesPerHostBuffer(framesPerUserBuffer, params->suggestedLatency, sampleRate);
  
      /* Log */
      PA_DEBUG(( "%s: user-buffer (frames)           = %lu\n", __FUNCTION__, framesPerUserBuffer ));
      PA_DEBUG(( "%s: user-buffer (sec)              = %f\n",  __FUNCTION__, (double)(framesPerUserBuffer / sampleRate) ));
      PA_DEBUG(( "%s: suggested latency (sec)        = %f\n",  __FUNCTION__, params->suggestedLatency ));
      PA_DEBUG(( "%s: suggested host buffer (frames) = %lu\n", __FUNCTION__, bufferSize ));
      PA_DEBUG(( "%s: suggested host buffer (sec)    = %f\n",  __FUNCTION__, (double)(bufferSize / sampleRate) ));
  
  #ifdef PA_ALSA_USE_OBSOLETE_HOST_BUFFER_CALC
  
      if( framesPerUserBuffer != paFramesPerBufferUnspecified )
      {
          /* Preferably the host buffer size should be a multiple of the user buffer size */
  
          if( bufferSize > framesPerUserBuffer )
          {
              snd_pcm_uframes_t remainder = bufferSize % framesPerUserBuffer;
              if( remainder > framesPerUserBuffer / 2. )
                  bufferSize += framesPerUserBuffer - remainder;
              else
                  bufferSize -= remainder;
  
              assert( bufferSize % framesPerUserBuffer == 0 );
          }
          else if( framesPerUserBuffer % bufferSize != 0 )
          {
              /*  Find a good compromise between user specified latency and buffer size */
              if( bufferSize > framesPerUserBuffer * .75 )
              {
                  bufferSize = framesPerUserBuffer;
              }
              else
              {
                  snd_pcm_uframes_t newSz = framesPerUserBuffer;
                  while( newSz / 2 >= bufferSize )
                  {
                      if( framesPerUserBuffer % (newSz / 2) != 0 )
                      {
                          /* No use dividing any further */
                          break;
                      }
                      newSz /= 2;
                  }
                  bufferSize = newSz;
              }
  
              assert( framesPerUserBuffer % bufferSize == 0 );
          }
      }
  
  #endif
  
      {
          unsigned numPeriods = numPeriods_, maxPeriods = 0, minPeriods = numPeriods_;
  
          /* It may be that the device only supports 2 periods for instance */
          dir = 0;
          ENSURE_( alsa_snd_pcm_hw_params_get_periods_min( hwParams, &minPeriods, &dir ), paUnanticipatedHostError );
          dir = 0;
          ENSURE_( alsa_snd_pcm_hw_params_get_periods_max( hwParams, &maxPeriods, &dir ), paUnanticipatedHostError );
          assert( maxPeriods > 1 );
  
          /* Clamp to min/max */
          numPeriods = PA_MIN(maxPeriods, PA_MAX(minPeriods, numPeriods));
  
          PA_DEBUG(( "%s: periods min = %lu, max = %lu, req = %lu \n", __FUNCTION__, minPeriods, maxPeriods, numPeriods ));
  
  #ifndef PA_ALSA_USE_OBSOLETE_HOST_BUFFER_CALC
  
          /* Calculate period size */
          framesPerHostBuffer = (bufferSize / numPeriods);
  
          /* Align & test size */
          if( framesPerUserBuffer != paFramesPerBufferUnspecified )
          {
              /* Align to user buffer size */
              framesPerHostBuffer = PaAlsa_AlignForward(framesPerHostBuffer, framesPerUserBuffer);
  
              /* Test (borrowed from older implementation) */
              if( framesPerHostBuffer < framesPerUserBuffer )
              {
                  assert( framesPerUserBuffer % framesPerHostBuffer == 0 );
                  if( alsa_snd_pcm_hw_params_test_period_size( self->pcm, hwParams, framesPerHostBuffer, 0 ) < 0 )
                  {
                      if( alsa_snd_pcm_hw_params_test_period_size( self->pcm, hwParams, framesPerHostBuffer * 2, 0 ) == 0 )
                          framesPerHostBuffer *= 2;
                      else if( alsa_snd_pcm_hw_params_test_period_size( self->pcm, hwParams, framesPerHostBuffer / 2, 0 ) == 0 )
                          framesPerHostBuffer /= 2;
                  }
              }
              else
              {
                  assert( framesPerHostBuffer % framesPerUserBuffer == 0 );
                  if( alsa_snd_pcm_hw_params_test_period_size( self->pcm, hwParams, framesPerHostBuffer, 0 ) < 0 )
                  {
                      if( alsa_snd_pcm_hw_params_test_period_size( self->pcm, hwParams, framesPerHostBuffer + framesPerUserBuffer, 0 ) == 0 )
                          framesPerHostBuffer += framesPerUserBuffer;
                      else if( alsa_snd_pcm_hw_params_test_period_size( self->pcm, hwParams, framesPerHostBuffer - framesPerUserBuffer, 0 ) == 0 )
                          framesPerHostBuffer -= framesPerUserBuffer;
                  }
              }
          }
  #endif
  
  #ifdef PA_ALSA_USE_OBSOLETE_HOST_BUFFER_CALC
  
          if( framesPerUserBuffer != paFramesPerBufferUnspecified )
          {
              /* Try to get a power-of-two of the user buffer size. */
              framesPerHostBuffer = framesPerUserBuffer;
              if( framesPerHostBuffer < bufferSize )
              {
                  while( bufferSize / framesPerHostBuffer > numPeriods )
                  {
                      framesPerHostBuffer *= 2;
                  }
                  /* One extra period is preferable to one less (should be more robust) */
                  if( bufferSize / framesPerHostBuffer < numPeriods )
                  {
                      framesPerHostBuffer /= 2;
                  }
              }
              else
              {
                  while( bufferSize / framesPerHostBuffer < numPeriods )
                  {
                      if( framesPerUserBuffer % ( framesPerHostBuffer / 2 ) != 0 )
                      {
                          /* Can't be divided any further */
                          break;
                      }
                      framesPerHostBuffer /= 2;
                  }
              }
  
              if( framesPerHostBuffer < framesPerUserBuffer )
              {
                  assert( framesPerUserBuffer % framesPerHostBuffer == 0 );
                  if( alsa_snd_pcm_hw_params_test_period_size( self->pcm, hwParams, framesPerHostBuffer, 0 ) < 0 )
                  {
                      if( alsa_snd_pcm_hw_params_test_period_size( self->pcm, hwParams, framesPerHostBuffer * 2, 0 ) == 0 )
                          framesPerHostBuffer *= 2;
                      else if( alsa_snd_pcm_hw_params_test_period_size( self->pcm, hwParams, framesPerHostBuffer / 2, 0 ) == 0 )
                          framesPerHostBuffer /= 2;
                  }
              }
              else
              {
                  assert( framesPerHostBuffer % framesPerUserBuffer == 0 );
                  if( alsa_snd_pcm_hw_params_test_period_size( self->pcm, hwParams, framesPerHostBuffer, 0 ) < 0 )
                  {
                      if( alsa_snd_pcm_hw_params_test_period_size( self->pcm, hwParams, framesPerHostBuffer + framesPerUserBuffer, 0 ) == 0 )
                          framesPerHostBuffer += framesPerUserBuffer;
                      else if( alsa_snd_pcm_hw_params_test_period_size( self->pcm, hwParams, framesPerHostBuffer - framesPerUserBuffer, 0 ) == 0 )
                          framesPerHostBuffer -= framesPerUserBuffer;
                  }
              }
          }
          else
          {
              framesPerHostBuffer = bufferSize / numPeriods;
          }
  
          /* non-mmap mode needs a reasonably-sized buffer or it'll stutter */
          if( !self->canMmap && framesPerHostBuffer < 2048 )
              framesPerHostBuffer = 2048;
  #endif
          PA_DEBUG(( "%s: suggested host buffer period   = %lu \n", __FUNCTION__, framesPerHostBuffer ));
      }
  
      {
          /* Get min/max period sizes and adjust our chosen */
          snd_pcm_uframes_t min = 0, max = 0, minmax_diff;
          ENSURE_( alsa_snd_pcm_hw_params_get_period_size_min( hwParams, &min, NULL ), paUnanticipatedHostError );
          ENSURE_( alsa_snd_pcm_hw_params_get_period_size_max( hwParams, &max, NULL ), paUnanticipatedHostError );
          minmax_diff = max - min;
  
          if( framesPerHostBuffer < min )
          {
              PA_DEBUG(( "%s: The determined period size (%lu) is less than minimum (%lu)\n", __FUNCTION__, framesPerHostBuffer, min ));
              framesPerHostBuffer = (( minmax_diff == 2 ) ? min + 1 : min );
          }
          else if( framesPerHostBuffer > max )
          {
              PA_DEBUG(( "%s: The determined period size (%lu) is greater than maximum (%lu)\n", __FUNCTION__, framesPerHostBuffer, max ));
              framesPerHostBuffer = (( minmax_diff == 2 ) ? max - 1 : max );
          }
  
          PA_DEBUG(( "%s: device period minimum          = %lu\n", __FUNCTION__, min ));
          PA_DEBUG(( "%s: device period maximum          = %lu\n", __FUNCTION__, max ));
          PA_DEBUG(( "%s: host buffer period             = %lu\n", __FUNCTION__, framesPerHostBuffer ));
          PA_DEBUG(( "%s: host buffer period latency     = %f\n", __FUNCTION__, (double)( framesPerHostBuffer / sampleRate ) ));
  
          /* Try setting period size */
          dir = 0;
          ENSURE_( alsa_snd_pcm_hw_params_set_period_size_near( self->pcm, hwParams, &framesPerHostBuffer, &dir ), paUnanticipatedHostError );
          if( dir != 0 )
          {
              PA_DEBUG(( "%s: The configured period size is non-integer.\n", __FUNCTION__, dir ));
              *accurate = 0;
          }
      }
  
      /* Set result */
      self->framesPerPeriod = framesPerHostBuffer;
  
  error:
      return result;
  }
  
  /* We need to determine how many frames per host buffer (period) to use.  Our
   * goals are to provide the best possible performance, but also to
   * honor the requested latency settings as closely as we can. Therefore this
   * decision is based on:
   *
   *   - the period sizes that playback and/or capture support.  The
   *     host buffer size has to be one of these.
   *   - the number of periods that playback and/or capture support.
   *
   * We want to make period_size*(num_periods-1) to be as close as possible
   * to latency*rate for both playback and capture.
   *
   * This method will determine suitable period sizes for capture and playback handles, and report the maximum number of
   * frames per host buffer. The latter is relevant, in case we should be so unfortunate that the period size differs
   * between capture and playback. If this should happen, the stream's hostBufferSizeMode attribute will be set to
   * paUtilBoundedHostBufferSize, because the best we can do is limit the size of individual host buffers to the upper
   * bound. The size of host buffers scheduled for processing should only matter if the user has specified a buffer size,
   * but when he/she does we must strive for an optimal configuration. By default we'll opt for a fixed host buffer size,
   * which should be fine if the period size is the same for capture and playback. In general, if there is a specified user
   * buffer size, this method tries it best to determine a period size which is a multiple of the user buffer size.
   *
   * The framesPerPeriod attributes of the individual capture and playback components of the stream are set to corresponding
   * values determined here. Since these should be reported as
   *
   * This is one of those blocks of code that will just take a lot of
   * refinement to be any good.
   *
   * In the full-duplex case it is possible that the routine was unable
   * to find a number of frames per buffer acceptable to both devices
   * TODO: Implement an algorithm to find the value closest to acceptance
   * by both devices, to minimize difference between period sizes?
   *
   * @param determinedFramesPerHostBuffer: The determined host buffer size.
   */
  static PaError PaAlsaStream_DetermineFramesPerBuffer( PaAlsaStream* self, double sampleRate, const PaStreamParameters* inputParameters,
          const PaStreamParameters* outputParameters, unsigned long framesPerUserBuffer, snd_pcm_hw_params_t* hwParamsCapture,
          snd_pcm_hw_params_t* hwParamsPlayback, PaUtilHostBufferSizeMode* hostBufferSizeMode )
  {
      PaError result = paNoError;
      unsigned long framesPerHostBuffer = 0;
      int dir = 0;
      int accurate = 1;
      unsigned numPeriods = numPeriods_;
  
      if( self->capture.pcm && self->playback.pcm )
      {
          if( framesPerUserBuffer == paFramesPerBufferUnspecified )
          {
              /* Come up with a common desired latency */
              snd_pcm_uframes_t desiredBufSz, e, minPeriodSize, maxPeriodSize, optimalPeriodSize, periodSize,
                                minCapture, minPlayback, maxCapture, maxPlayback;
  
              dir = 0;
              ENSURE_( alsa_snd_pcm_hw_params_get_period_size_min( hwParamsCapture, &minCapture, &dir ), paUnanticipatedHostError );
              dir = 0;
              ENSURE_( alsa_snd_pcm_hw_params_get_period_size_min( hwParamsPlayback, &minPlayback, &dir ), paUnanticipatedHostError );
              dir = 0;
              ENSURE_( alsa_snd_pcm_hw_params_get_period_size_max( hwParamsCapture, &maxCapture, &dir ), paUnanticipatedHostError );
              dir = 0;
              ENSURE_( alsa_snd_pcm_hw_params_get_period_size_max( hwParamsPlayback, &maxPlayback, &dir ), paUnanticipatedHostError );
              minPeriodSize = PA_MAX( minPlayback, minCapture );
              maxPeriodSize = PA_MIN( maxPlayback, maxCapture );
              PA_UNLESS( minPeriodSize <= maxPeriodSize, paBadIODeviceCombination );
  
              desiredBufSz = (snd_pcm_uframes_t)( PA_MIN( outputParameters->suggestedLatency, inputParameters->suggestedLatency )
                      * sampleRate );
              /* Clamp desiredBufSz */
              {
                  snd_pcm_uframes_t maxBufferSize;
                  snd_pcm_uframes_t maxBufferSizeCapture, maxBufferSizePlayback;
                  ENSURE_( alsa_snd_pcm_hw_params_get_buffer_size_max( hwParamsCapture, &maxBufferSizeCapture ), paUnanticipatedHostError );
                  ENSURE_( alsa_snd_pcm_hw_params_get_buffer_size_max( hwParamsPlayback, &maxBufferSizePlayback ), paUnanticipatedHostError );
                  maxBufferSize = PA_MIN( maxBufferSizeCapture, maxBufferSizePlayback );
  
                  desiredBufSz = PA_MIN( desiredBufSz, maxBufferSize );
              }
  
              /* Find the closest power of 2 */
              e = ilogb( minPeriodSize );
              if( minPeriodSize & ( minPeriodSize - 1 ) )
                  e += 1;
              periodSize = (snd_pcm_uframes_t)pow( 2, e );
  
              while( periodSize <= maxPeriodSize )
              {
                  if( alsa_snd_pcm_hw_params_test_period_size( self->playback.pcm, hwParamsPlayback, periodSize, 0 ) >= 0 &&
                          alsa_snd_pcm_hw_params_test_period_size( self->capture.pcm, hwParamsCapture, periodSize, 0 ) >= 0 )
                  {
                      /* OK! */
                      break;
                  }
  
                  periodSize *= 2;
              }
  
              optimalPeriodSize = PA_MAX( desiredBufSz / numPeriods, minPeriodSize );
              optimalPeriodSize = PA_MIN( optimalPeriodSize, maxPeriodSize );
  
              /* Find the closest power of 2 */
              e = ilogb( optimalPeriodSize );
              if( optimalPeriodSize & (optimalPeriodSize - 1) )
                  e += 1;
              optimalPeriodSize = (snd_pcm_uframes_t)pow( 2, e );
  
              while( optimalPeriodSize >= periodSize )
              {
                  if( alsa_snd_pcm_hw_params_test_period_size( self->capture.pcm, hwParamsCapture, optimalPeriodSize, 0 )
                          >= 0 && alsa_snd_pcm_hw_params_test_period_size( self->playback.pcm, hwParamsPlayback,
                              optimalPeriodSize, 0 ) >= 0 )
                  {
                      break;
                  }
                  optimalPeriodSize /= 2;
              }
  
              if( optimalPeriodSize > periodSize )
                  periodSize = optimalPeriodSize;
  
              if( periodSize <= maxPeriodSize )
              {
                  /* Looks good, the periodSize _should_ be acceptable by both devices */
                  ENSURE_( alsa_snd_pcm_hw_params_set_period_size( self->capture.pcm, hwParamsCapture, periodSize, 0 ),
                          paUnanticipatedHostError );
                  ENSURE_( alsa_snd_pcm_hw_params_set_period_size( self->playback.pcm, hwParamsPlayback, periodSize, 0 ),
                          paUnanticipatedHostError );
                  self->capture.framesPerPeriod = self->playback.framesPerPeriod = periodSize;
                  framesPerHostBuffer = periodSize;
              }
              else
              {
                  /* Unable to find a common period size, oh well */
                  optimalPeriodSize = PA_MAX( desiredBufSz / numPeriods, minPeriodSize );
                  optimalPeriodSize = PA_MIN( optimalPeriodSize, maxPeriodSize );
  
                  self->capture.framesPerPeriod = optimalPeriodSize;
                  dir = 0;
                  ENSURE_( alsa_snd_pcm_hw_params_set_period_size_near( self->capture.pcm, hwParamsCapture, &self->capture.framesPerPeriod, &dir ),
                          paUnanticipatedHostError );
                  self->playback.framesPerPeriod = optimalPeriodSize;
                  dir = 0;
                  ENSURE_( alsa_snd_pcm_hw_params_set_period_size_near( self->playback.pcm, hwParamsPlayback, &self->playback.framesPerPeriod, &dir ),
                          paUnanticipatedHostError );
                  framesPerHostBuffer = PA_MAX( self->capture.framesPerPeriod, self->playback.framesPerPeriod );
                  *hostBufferSizeMode = paUtilBoundedHostBufferSize;
              }
          }
          else
          {
              /* We choose the simple route and determine a suitable number of frames per buffer for one component of
               * the stream, then we hope that this will work for the other component too (it should!).
               */
  
              unsigned maxPeriods = 0;
              PaAlsaStreamComponent* first = &self->capture, * second = &self->playback;
              const PaStreamParameters* firstStreamParams = inputParameters;
              snd_pcm_hw_params_t* firstHwParams = hwParamsCapture, * secondHwParams = hwParamsPlayback;
  
              dir = 0;
              ENSURE_( alsa_snd_pcm_hw_params_get_periods_max( hwParamsPlayback, &maxPeriods, &dir ), paUnanticipatedHostError );
              if( maxPeriods < numPeriods )
              {
                  /* The playback component is trickier to get right, try that first */
                  first = &self->playback;
                  second = &self->capture;
                  firstStreamParams = outputParameters;
                  firstHwParams = hwParamsPlayback;
                  secondHwParams = hwParamsCapture;
              }
  
              PA_ENSURE( PaAlsaStreamComponent_DetermineFramesPerBuffer( first, firstStreamParams, framesPerUserBuffer,
                          sampleRate, firstHwParams, &accurate ) );
  
              second->framesPerPeriod = first->framesPerPeriod;
              dir = 0;
              ENSURE_( alsa_snd_pcm_hw_params_set_period_size_near( second->pcm, secondHwParams, &second->framesPerPeriod, &dir ),
                      paUnanticipatedHostError );
              if( self->capture.framesPerPeriod == self->playback.framesPerPeriod )
              {
                  framesPerHostBuffer = self->capture.framesPerPeriod;
              }
              else
              {
                  framesPerHostBuffer = PA_MAX( self->capture.framesPerPeriod, self->playback.framesPerPeriod );
                  *hostBufferSizeMode = paUtilBoundedHostBufferSize;
              }
          }
      }
      else    /* half-duplex is a slightly simpler case */
      {
          if( self->capture.pcm )
          {
              PA_ENSURE( PaAlsaStreamComponent_DetermineFramesPerBuffer( &self->capture, inputParameters, framesPerUserBuffer,
                          sampleRate, hwParamsCapture, &accurate) );
              framesPerHostBuffer = self->capture.framesPerPeriod;
          }
          else
          {
              assert( self->playback.pcm );
              PA_ENSURE( PaAlsaStreamComponent_DetermineFramesPerBuffer( &self->playback, outputParameters, framesPerUserBuffer,
                          sampleRate, hwParamsPlayback, &accurate ) );
              framesPerHostBuffer = self->playback.framesPerPeriod;
          }
      }
  
      PA_UNLESS( framesPerHostBuffer != 0, paInternalError );
      self->maxFramesPerHostBuffer = framesPerHostBuffer;
  
      if( !self->playback.canMmap || !accurate )
      {
          /* Don't know the exact size per host buffer */
          *hostBufferSizeMode = paUtilBoundedHostBufferSize;
          /* Raise upper bound */
          if( !accurate )
              ++self->maxFramesPerHostBuffer;
      }
  
  error:
      return result;
  }
  
  /** Set up ALSA stream parameters.
   *
   */
  static PaError PaAlsaStream_Configure( PaAlsaStream *self, const PaStreamParameters *inParams, const PaStreamParameters*
          outParams, double sampleRate, unsigned long framesPerUserBuffer, double* inputLatency, double* outputLatency,
          PaUtilHostBufferSizeMode* hostBufferSizeMode )
  {
      PaError result = paNoError;
      double realSr = sampleRate;
      snd_pcm_hw_params_t* hwParamsCapture, * hwParamsPlayback;
  
      alsa_snd_pcm_hw_params_alloca( &hwParamsCapture );
      alsa_snd_pcm_hw_params_alloca( &hwParamsPlayback );
  
      if( self->capture.pcm )
          PA_ENSURE( PaAlsaStreamComponent_InitialConfigure( &self->capture, inParams, self->primeBuffers, hwParamsCapture,
                      &realSr ) );
      if( self->playback.pcm )
          PA_ENSURE( PaAlsaStreamComponent_InitialConfigure( &self->playback, outParams, self->primeBuffers, hwParamsPlayback,
                      &realSr ) );
  
      PA_ENSURE( PaAlsaStream_DetermineFramesPerBuffer( self, realSr, inParams, outParams, framesPerUserBuffer,
                  hwParamsCapture, hwParamsPlayback, hostBufferSizeMode ) );
  
      if( self->capture.pcm )
      {
          assert( self->capture.framesPerPeriod != 0 );
          PA_ENSURE( PaAlsaStreamComponent_FinishConfigure( &self->capture, hwParamsCapture, inParams, self->primeBuffers, realSr,
                      inputLatency ) );
          PA_DEBUG(( "%s: Capture period size: %lu, latency: %f\n", __FUNCTION__, self->capture.framesPerPeriod, *inputLatency ));
      }
      if( self->playback.pcm )
      {
          assert( self->playback.framesPerPeriod != 0 );
          PA_ENSURE( PaAlsaStreamComponent_FinishConfigure( &self->playback, hwParamsPlayback, outParams, self->primeBuffers, realSr,
                      outputLatency ) );
          PA_DEBUG(( "%s: Playback period size: %lu, latency: %f\n", __FUNCTION__, self->playback.framesPerPeriod, *outputLatency ));
      }
  
      /* Should be exact now */
      self->streamRepresentation.streamInfo.sampleRate = realSr;
  
      /* this will cause the two streams to automatically start/stop/prepare in sync.
       * We only need to execute these operations on one of the pair.
       * A: We don't want to do this on a blocking stream.
       */
      if( self->callbackMode && self->capture.pcm && self->playback.pcm )
      {
          int err = alsa_snd_pcm_link( self->capture.pcm, self->playback.pcm );
          if( err == 0 )
              self->pcmsSynced = 1;
          else
              PA_DEBUG(( "%s: Unable to sync pcms: %s\n", __FUNCTION__, alsa_snd_strerror( err ) ));
      }
  
      {
          unsigned long minFramesPerHostBuffer = PA_MIN( self->capture.pcm ? self->capture.framesPerPeriod : ULONG_MAX,
              self->playback.pcm ? self->playback.framesPerPeriod : ULONG_MAX );
          self->pollTimeout = CalculatePollTimeout( self, minFramesPerHostBuffer );    /* Period in msecs, rounded up */
  
          /* Time before watchdog unthrottles realtime thread == 1/4 of period time in msecs */
          /* self->threading.throttledSleepTime = (unsigned long) (minFramesPerHostBuffer / sampleRate / 4 * 1000); */
      }
  
      if( self->callbackMode )
      {
          /* If the user expects a certain number of frames per callback we will either have to rely on block adaption
           * (framesPerHostBuffer is not an integer multiple of framesPerPeriod) or we can simply align the number
           * of host buffer frames with what the user specified */
          if( self->framesPerUserBuffer != paFramesPerBufferUnspecified )
          {
              /* self->alignFrames = 1; */
  
              /* Unless the ratio between number of host and user buffer frames is an integer we will have to rely
               * on block adaption */
          /*
              if( framesPerHostBuffer % framesPerPeriod != 0 || (self->capture.pcm && self->playback.pcm &&
                          self->capture.framesPerPeriod != self->playback.framesPerPeriod) )
                  self->useBlockAdaption = 1;
              else
                  self->alignFrames = 1;
          */
          }
      }
  
  error:
      return result;
  }
  
  static PaError OpenStream( struct PaUtilHostApiRepresentation *hostApi,
                             PaStream** s,
                             const PaStreamParameters *inputParameters,
                             const PaStreamParameters *outputParameters,
                             double sampleRate,
                             unsigned long framesPerBuffer,
                             PaStreamFlags streamFlags,
                             PaStreamCallback* callback,
                             void *userData )
  {
      PaError result = paNoError;
      PaAlsaHostApiRepresentation *alsaHostApi = (PaAlsaHostApiRepresentation*)hostApi;
      PaAlsaStream *stream = NULL;
      PaSampleFormat hostInputSampleFormat = 0, hostOutputSampleFormat = 0;
      PaSampleFormat inputSampleFormat = 0, outputSampleFormat = 0;
      int numInputChannels = 0, numOutputChannels = 0;
      PaTime inputLatency, outputLatency;
      /* Operate with fixed host buffer size by default, since other modes will invariably lead to block adaption */
      /* XXX: Use Bounded by default? Output tends to get stuttery with Fixed ... */
      PaUtilHostBufferSizeMode hostBufferSizeMode = paUtilFixedHostBufferSize;
  
      if( ( streamFlags & paPlatformSpecificFlags ) != 0 )
          return paInvalidFlag;
  
      if( inputParameters )
      {
          PA_ENSURE( ValidateParameters( inputParameters, hostApi, StreamDirection_In ) );
  
          numInputChannels = inputParameters->channelCount;
          inputSampleFormat = inputParameters->sampleFormat;
      }
      if( outputParameters )
      {
          PA_ENSURE( ValidateParameters( outputParameters, hostApi, StreamDirection_Out ) );
  
          numOutputChannels = outputParameters->channelCount;
          outputSampleFormat = outputParameters->sampleFormat;
      }
  
      /* XXX: Why do we support this anyway? */
      if( framesPerBuffer == paFramesPerBufferUnspecified && getenv( "PA_ALSA_PERIODSIZE" ) != NULL )
      {
          PA_DEBUG(( "%s: Getting framesPerBuffer (Alsa period-size) from environment\n", __FUNCTION__ ));
          framesPerBuffer = atoi( getenv("PA_ALSA_PERIODSIZE") );
      }
  
      PA_UNLESS( stream = (PaAlsaStream*)PaUtil_AllocateMemory( sizeof(PaAlsaStream) ), paInsufficientMemory );
      PA_ENSURE( PaAlsaStream_Initialize( stream, alsaHostApi, inputParameters, outputParameters, sampleRate,
                  framesPerBuffer, callback, streamFlags, userData ) );
  
      PA_ENSURE( PaAlsaStream_Configure( stream, inputParameters, outputParameters, sampleRate, framesPerBuffer,
                  &inputLatency, &outputLatency, &hostBufferSizeMode ) );
      hostInputSampleFormat = stream->capture.hostSampleFormat | (!stream->capture.hostInterleaved ? paNonInterleaved : 0);
      hostOutputSampleFormat = stream->playback.hostSampleFormat | (!stream->playback.hostInterleaved ? paNonInterleaved : 0);
  
      PA_ENSURE( PaUtil_InitializeBufferProcessor( &stream->bufferProcessor,
                      numInputChannels, inputSampleFormat, hostInputSampleFormat,
                      numOutputChannels, outputSampleFormat, hostOutputSampleFormat,
                      sampleRate, streamFlags, framesPerBuffer, stream->maxFramesPerHostBuffer,
                      hostBufferSizeMode, callback, userData ) );
  
      /* Ok, buffer processor is initialized, now we can deduce it's latency */
      if( numInputChannels > 0 )
          stream->streamRepresentation.streamInfo.inputLatency = inputLatency + (PaTime)(
                  PaUtil_GetBufferProcessorInputLatencyFrames( &stream->bufferProcessor ) / sampleRate);
      if( numOutputChannels > 0 )
          stream->streamRepresentation.streamInfo.outputLatency = outputLatency + (PaTime)(
                  PaUtil_GetBufferProcessorOutputLatencyFrames( &stream->bufferProcessor ) / sampleRate);
  
      PA_DEBUG(( "%s: Stream: framesPerBuffer = %lu, maxFramesPerHostBuffer = %lu, latency i=%f, o=%f\n", __FUNCTION__, framesPerBuffer, stream->maxFramesPerHostBuffer, stream->streamRepresentation.streamInfo.inputLatency, stream->streamRepresentation.streamInfo.outputLatency));
  
      *s = (PaStream*)stream;
  
      return result;
  
  error:
      if( stream )
      {
          PA_DEBUG(( "%s: Stream in error, terminating\n", __FUNCTION__ ));
          PaAlsaStream_Terminate( stream );
      }
  
      return result;
  }
  
  static PaError CloseStream( PaStream* s )
  {
      PaError result = paNoError;
      PaAlsaStream *stream = (PaAlsaStream*)s;
  
      PaUtil_TerminateBufferProcessor( &stream->bufferProcessor );
      PaUtil_TerminateStreamRepresentation( &stream->streamRepresentation );
  
      PaAlsaStream_Terminate( stream );
  
      return result;
  }
  
  static void SilenceBuffer( PaAlsaStream *stream )
  {
      const snd_pcm_channel_area_t *areas;
      snd_pcm_uframes_t frames = (snd_pcm_uframes_t)alsa_snd_pcm_avail_update( stream->playback.pcm ), offset;
  
      alsa_snd_pcm_mmap_begin( stream->playback.pcm, &areas, &offset, &frames );
      alsa_snd_pcm_areas_silence( areas, offset, stream->playback.numHostChannels, frames, stream->playback.nativeFormat );
      alsa_snd_pcm_mmap_commit( stream->playback.pcm, offset, frames );
  }
  
  /** Start/prepare pcm(s) for streaming.
   *
   * Depending on whether the stream is in callback or blocking mode, we will respectively start or simply
   * prepare the playback pcm. If the buffer has _not_ been primed, we will in callback mode prepare and
   * silence the buffer before starting playback. In blocking mode we simply prepare, as the playback will
   * be started automatically as the user writes to output.
   *
   * The capture pcm, however, will simply be prepared and started.
   */
  static PaError AlsaStart( PaAlsaStream *stream, int priming )
  {
      PaError result = paNoError;
  
      if( stream->playback.pcm )
      {
          if( stream->callbackMode )
          {
              if( !priming )
              {
                  /* Buffer isn't primed, so prepare and silence */
                  ENSURE_( alsa_snd_pcm_prepare( stream->playback.pcm ), paUnanticipatedHostError );
                  if( stream->playback.canMmap )
                      SilenceBuffer( stream );
              }
              if( stream->playback.canMmap )
                  ENSURE_( alsa_snd_pcm_start( stream->playback.pcm ), paUnanticipatedHostError );
          }
          else
              ENSURE_( alsa_snd_pcm_prepare( stream->playback.pcm ), paUnanticipatedHostError );
      }
      if( stream->capture.pcm && !stream->pcmsSynced )
      {
          ENSURE_( alsa_snd_pcm_prepare( stream->capture.pcm ), paUnanticipatedHostError );
          /* For a blocking stream we want to start capture as well, since nothing will happen otherwise */
          ENSURE_( alsa_snd_pcm_start( stream->capture.pcm ), paUnanticipatedHostError );
      }
  
  end:
      return result;
  error:
      goto end;
  }
  
  /** Utility function for determining if pcms are in running state.
   *
   */
  #if 0
  static int IsRunning( PaAlsaStream *stream )
  {
      int result = 0;
  
      PA_ENSURE( PaUnixMutex_Lock( &stream->stateMtx ) );
      if( stream->capture.pcm )
      {
          snd_pcm_state_t capture_state = alsa_snd_pcm_state( stream->capture.pcm );
  
          if( capture_state == SND_PCM_STATE_RUNNING || capture_state == SND_PCM_STATE_XRUN
                  || capture_state == SND_PCM_STATE_DRAINING )
          {
              result = 1;
              goto end;
          }
      }
  
      if( stream->playback.pcm )
      {
          snd_pcm_state_t playback_state = alsa_snd_pcm_state( stream->playback.pcm );
  
          if( playback_state == SND_PCM_STATE_RUNNING || playback_state == SND_PCM_STATE_XRUN
                  || playback_state == SND_PCM_STATE_DRAINING )
          {
              result = 1;
              goto end;
          }
      }
  
  end:
      ASSERT_CALL_( PaUnixMutex_Unlock( &stream->stateMtx ), paNoError );
      return result;
  error:
      goto error;
  }
  #endif
  
  static PaError StartStream( PaStream *s )
  {
      PaError result = paNoError;
      PaAlsaStream* stream = (PaAlsaStream*)s;
      int streamStarted = 0;  /* So we can know whether we need to take the stream down */
  
      /* Ready the processor */
      PaUtil_ResetBufferProcessor( &stream->bufferProcessor );
  
      /* Set now, so we can test for activity further down */
      stream->isActive = 1;
  
      if( stream->callbackMode )
      {
          PA_ENSURE( PaUnixThread_New( &stream->thread, &CallbackThreadFunc, stream, 1., stream->rtSched ) );
      }
      else
      {
          PA_ENSURE( AlsaStart( stream, 0 ) );
          streamStarted = 1;
      }
  
  end:
      return result;
  error:
      if( streamStarted )
      {
          AbortStream( stream );
      }
      stream->isActive = 0;
  
      goto end;
  }
  
  /** Stop PCM handle, either softly or abruptly.
   */
  static PaError AlsaStop( PaAlsaStream *stream, int abort )
  {
      PaError result = paNoError;
      /* XXX: alsa_snd_pcm_drain tends to lock up, avoid it until we find out more */
      abort = 1;
      /*
      if( stream->capture.pcm && !strcmp( Pa_GetDeviceInfo( stream->capture.device )->name,
                  "dmix" ) )
      {
          abort = 1;
      }
      else if( stream->playback.pcm && !strcmp( Pa_GetDeviceInfo( stream->playback.device )->name,
                  "dmix" ) )
      {
          abort = 1;
      }
      */
  
      if( abort )
      {
          if( stream->playback.pcm )
          {
              ENSURE_( alsa_snd_pcm_drop( stream->playback.pcm ), paUnanticipatedHostError );
          }
          if( stream->capture.pcm && !stream->pcmsSynced )
          {
              ENSURE_( alsa_snd_pcm_drop( stream->capture.pcm ), paUnanticipatedHostError );
          }
  
          PA_DEBUG(( "%s: Dropped frames\n", __FUNCTION__ ));
      }
      else
      {
          if( stream->playback.pcm )
          {
              ENSURE_( alsa_snd_pcm_nonblock( stream->playback.pcm, 0 ), paUnanticipatedHostError );
              if( alsa_snd_pcm_drain( stream->playback.pcm ) < 0 )
              {
                  PA_DEBUG(( "%s: Draining playback handle failed!\n", __FUNCTION__ ));
              }
          }
          if( stream->capture.pcm && !stream->pcmsSynced )
          {
              /* We don't need to retrieve any remaining frames */
              if( alsa_snd_pcm_drain( stream->capture.pcm ) < 0 )
              {
                  PA_DEBUG(( "%s: Draining capture handle failed!\n", __FUNCTION__ ));
              }
          }
      }
  
  end:
      return result;
  error:
      goto end;
  }
  
  /** Stop or abort stream.
   *
   * If a stream is in callback mode we will have to inspect whether the background thread has
   * finished, or we will have to take it out. In either case we join the thread before
   * returning. In blocking mode, we simply tell ALSA to stop abruptly (abort) or finish
   * buffers (drain)
   *
   * Stream will be considered inactive (!PaAlsaStream::isActive) after a call to this function
   */
  static PaError RealStop( PaAlsaStream *stream, int abort )
  {
      PaError result = paNoError;
  
      /* First deal with the callback thread, cancelling and/or joining
       * it if necessary
       */
      if( stream->callbackMode )
      {
          PaError threadRes;
          stream->callbackAbort = abort;
  
          if( !abort )
          {
              PA_DEBUG(( "Stopping callback\n" ));
          }
          PA_ENSURE( PaUnixThread_Terminate( &stream->thread, !abort, &threadRes ) );
          if( threadRes != paNoError )
          {
              PA_DEBUG(( "Callback thread returned: %d\n", threadRes ));
          }
  #if 0
          if( watchdogRes != paNoError )
              PA_DEBUG(( "Watchdog thread returned: %d\n", watchdogRes ));
  #endif
  
          stream->callback_finished = 0;
      }
      else
      {
          PA_ENSURE( AlsaStop( stream, abort ) );
      }
  
      stream->isActive = 0;
  
  end:
      return result;
  
  error:
      goto end;
  }
  
  static PaError StopStream( PaStream *s )
  {
      return RealStop( (PaAlsaStream *) s, 0 );
  }
  
  static PaError AbortStream( PaStream *s )
  {
      return RealStop( (PaAlsaStream * ) s, 1 );
  }
  
  /** The stream is considered stopped before StartStream, or AFTER a call to Abort/StopStream (callback
   * returning !paContinue is not considered)
   *
   */
  static PaError IsStreamStopped( PaStream *s )
  {
      PaAlsaStream *stream = (PaAlsaStream *)s;
  
      /* callback_finished indicates we need to join callback thread (ie. in Abort/StopStream) */
      return !IsStreamActive( s ) && !stream->callback_finished;
  }
  
  static PaError IsStreamActive( PaStream *s )
  {
      PaAlsaStream *stream = (PaAlsaStream*)s;
      return stream->isActive;
  }
  
  /** Extract audio/trigger htstamp from status and convert into PaTime (seconds).
   *
   * trigger is boolean:  trigger stampstamp vs audio timestamp.  If delay is non-NULL, return delay in
   * frames.  */
  static PaTime StatusToTime( const snd_pcm_status_t *status, int trigger, snd_pcm_uframes_t* delay )
  {
      snd_htimestamp_t timestamp;
      if ( trigger )
      {
          alsa_snd_pcm_status_get_trigger_htstamp( status, &timestamp );
      }
      else
      {
          alsa_snd_pcm_status_get_htstamp( status, &timestamp );
      }
      if ( delay )
      {
          *delay = alsa_snd_pcm_status_get_delay( status );
      }
      return timestamp.tv_sec + ( (PaTime)timestamp.tv_nsec * 1e-9 );
  }
  
  static PaTime GetStreamTime( PaStream *s )
  {
      PaAlsaStream *stream = (PaAlsaStream*)s;
  
      snd_timestamp_t timestamp;
      snd_pcm_status_t* status;
      alsa_snd_pcm_status_alloca( &status );
  
      /* TODO: what if we have both?  does it really matter? */
  
      /* TODO: if running in callback mode, this will mean
       * libasound routines are being called from multiple threads.
       * need to verify that libasound is thread-safe. */
  
      if( stream->capture.pcm )
      {
          alsa_snd_pcm_status( stream->capture.pcm, status );
      }
      else if( stream->playback.pcm )
      {
          alsa_snd_pcm_status( stream->playback.pcm, status );
      }
  
      return StatusToTime( status, 0, NULL );
  }
  
  static double GetStreamCpuLoad( PaStream* s )
  {
      PaAlsaStream *stream = (PaAlsaStream*)s;
  
      return PaUtil_GetCpuLoad( &stream->cpuLoadMeasurer );
  }
  
  /* Set the stream sample rate to a nominal value requested; allow only a defined tolerance range */
  static int SetApproximateSampleRate( snd_pcm_t *pcm, snd_pcm_hw_params_t *hwParams, double sampleRate )
  {
      PaError result = paNoError;
      unsigned int reqRate, setRate, deviation;
  
      assert( pcm && hwParams );
  
      /* The Alsa sample rate is set by integer value; also the actual rate may differ */
      reqRate = setRate = (unsigned int) sampleRate;
  
      ENSURE_( alsa_snd_pcm_hw_params_set_rate_near( pcm, hwParams, &setRate, NULL ), paUnanticipatedHostError );
      /* The value actually set will be put in 'setRate' (may be way off); check the deviation as a proportion
       * of the requested-rate with reference to the max-deviate-ratio (larger values allow less deviation) */
      deviation = abs( (int)setRate - (int)reqRate );
      if( deviation > 0 && deviation * RATE_MAX_DEVIATE_RATIO > reqRate )
          result = paInvalidSampleRate;
  
  end:
      return result;
  
  error:
      /* Log */
      {
          unsigned int _min = 0, _max = 0;
          int _dir = 0;
          ENSURE_( alsa_snd_pcm_hw_params_get_rate_min( hwParams, &_min, &_dir ), paUnanticipatedHostError );
          _dir = 0;
          ENSURE_( alsa_snd_pcm_hw_params_get_rate_max( hwParams, &_max, &_dir ), paUnanticipatedHostError );
          PA_DEBUG(( "%s: SR min = %u, max = %u, req = %u\n", __FUNCTION__, _min, _max, reqRate ));
      }
      goto end;
  }
  
  /* Return exact sample rate in param sampleRate */
  static int GetExactSampleRate( snd_pcm_hw_params_t *hwParams, double *sampleRate )
  {
      unsigned int num, den = 1;
      int err;
  
      assert( hwParams );
  
      err = alsa_snd_pcm_hw_params_get_rate_numden( hwParams, &num, &den );
      *sampleRate = (double) num / den;
  
      return err;
  }
  
  /* Utility functions for blocking/callback interfaces */
  
  /* Atomic restart of stream (we don't want the intermediate state visible) */
  static PaError AlsaRestart( PaAlsaStream *stream )
  {
      PaError result = paNoError;
  
      PA_ENSURE( PaUnixMutex_Lock( &stream->stateMtx ) );
      PA_ENSURE( AlsaStop( stream, 0 ) );
      PA_ENSURE( AlsaStart( stream, 0 ) );
  
      PA_DEBUG(( "%s: Restarted audio\n", __FUNCTION__ ));
  
  error:
      PA_ENSURE( PaUnixMutex_Unlock( &stream->stateMtx ) );
  
      return result;
  }
  
  /** Recover from xrun state.
   *
   */
  static PaError PaAlsaStream_HandleXrun( PaAlsaStream *self )
  {
      PaError result = paNoError;
      snd_pcm_status_t *st;
      PaTime now = PaUtil_GetTime();
      snd_timestamp_t t;
      int restartAlsa = 0; /* do not restart Alsa by default */
  
      alsa_snd_pcm_status_alloca( &st );
  
      if( self->playback.pcm )
      {
          alsa_snd_pcm_status( self->playback.pcm, st );
          if( alsa_snd_pcm_status_get_state( st ) == SND_PCM_STATE_XRUN )
          {
              alsa_snd_pcm_status_get_trigger_tstamp( st, &t );
              self->underrun = ( now - StatusToTime( st, 1, NULL ) ) * 1000;
  
              if( !self->playback.canMmap )
              {
                  if( alsa_snd_pcm_recover( self->playback.pcm, -EPIPE, 0 ) < 0 )
                  {
                      PA_DEBUG(( "%s: [playback] non-MMAP-PCM failed recovering from XRUN, will restart Alsa\n", __FUNCTION__ ));
                      ++ restartAlsa; /* did not manage to recover */
                  }
              }
              else
                  ++ restartAlsa; /* always restart MMAPed device */
          }
      }
      if( self->capture.pcm )
      {
          alsa_snd_pcm_status( self->capture.pcm, st );
          if( alsa_snd_pcm_status_get_state( st ) == SND_PCM_STATE_XRUN )
          {
              self->overrun = ( now - StatusToTime( st, 1, NULL ) ) * 1000;
  
              if (!self->capture.canMmap)
              {
                  if (alsa_snd_pcm_recover( self->capture.pcm, -EPIPE, 0 ) < 0)
                  {
                      PA_DEBUG(( "%s: [capture] non-MMAP-PCM failed recovering from XRUN, will restart Alsa\n", __FUNCTION__ ));
                      ++ restartAlsa; /* did not manage to recover */
                  }
              }
              else
                  ++ restartAlsa; /* always restart MMAPed device */
          }
      }
  
      if( restartAlsa )
      {
          PA_DEBUG(( "%s: restarting Alsa to recover from XRUN\n", __FUNCTION__ ));
          PA_ENSURE( AlsaRestart( self ) );
      }
  
  end:
      return result;
  error:
      goto end;
  }
  
  /** Decide if we should continue polling for specified direction, eventually adjust the poll timeout.
   *
   */
  static PaError ContinuePoll( const PaAlsaStream *stream, StreamDirection streamDir, int *pollTimeout, int *continuePoll )
  {
      PaError result = paNoError;
      snd_pcm_sframes_t delay, margin;
      int err;
      const PaAlsaStreamComponent *component = NULL, *otherComponent = NULL;
  
      *continuePoll = 1;
  
      if( StreamDirection_In == streamDir )
      {
          component = &stream->capture;
          otherComponent = &stream->playback;
      }
      else
      {
          component = &stream->playback;
          otherComponent = &stream->capture;
      }
  
      /* ALSA docs say that negative delay should indicate xrun, but in my experience alsa_snd_pcm_delay returns -EPIPE */
      if( ( err = alsa_snd_pcm_delay( otherComponent->pcm, &delay ) ) < 0 )
      {
          if( err == -EPIPE )
          {
              /* Xrun */
              *continuePoll = 0;
              goto error;
          }
  
          ENSURE_( err, paUnanticipatedHostError );
      }
  
      if( StreamDirection_Out == streamDir )
      {
          /* Number of eligible frames before capture overrun */
          delay = otherComponent->alsaBufferSize - delay;
      }
      margin = delay - otherComponent->framesPerPeriod / 2;
  
      if( margin < 0 )
      {
          PA_DEBUG(( "%s: Stopping poll for %s\n", __FUNCTION__, StreamDirection_In == streamDir ? "capture" : "playback" ));
          *continuePoll = 0;
      }
      else if( margin < otherComponent->framesPerPeriod )
      {
          *pollTimeout = CalculatePollTimeout( stream, margin );
          PA_DEBUG(( "%s: Trying to poll again for %s frames, pollTimeout: %d\n",
                      __FUNCTION__, StreamDirection_In == streamDir ? "capture" : "playback", *pollTimeout ));
      }
  
  error:
      return result;
  }
  
  /* Callback interface */
  
  static void OnExit( void *data )
  {
      PaAlsaStream *stream = (PaAlsaStream *) data;
  
      assert( data );
  
      PaUtil_ResetCpuLoadMeasurer( &stream->cpuLoadMeasurer );
  
      stream->callback_finished = 1;  /* Let the outside world know stream was stopped in callback */
      PA_DEBUG(( "%s: Stopping ALSA handles\n", __FUNCTION__ ));
      AlsaStop( stream, stream->callbackAbort );
  
      PA_DEBUG(( "%s: Stoppage\n", __FUNCTION__ ));
  
      /* Eventually notify user all buffers have played */
      if( stream->streamRepresentation.streamFinishedCallback )
      {
          stream->streamRepresentation.streamFinishedCallback( stream->streamRepresentation.userData );
      }
      stream->isActive = 0;
  }
  
  static void CalculateTimeInfo( PaAlsaStream *stream, PaStreamCallbackTimeInfo *timeInfo )
  {
      snd_pcm_status_t *status;
      PaTime capture_time = 0., playback_time = 0.;
  
      alsa_snd_pcm_status_alloca( &status );
  
      if( stream->capture.pcm )
      {
          snd_pcm_sframes_t capture_delay;
  
          alsa_snd_pcm_status( stream->capture.pcm, status );
          capture_time = StatusToTime( status, 0, &capture_delay );
  
          timeInfo->currentTime = capture_time;
          timeInfo->inputBufferAdcTime = capture_time -
              (PaTime)capture_delay / stream->streamRepresentation.streamInfo.sampleRate;
      }
      if( stream->playback.pcm )
      {
          snd_pcm_sframes_t playback_delay;
          PaTime playback_time;
  
          alsa_snd_pcm_status( stream->playback.pcm, status );
          playback_time = StatusToTime( status, 0, &playback_delay );
  
          if( stream->capture.pcm ) /* Full duplex */
          {
              /* Hmm, we have both a playback and a capture timestamp.
               * Hopefully they are the same... */
              if( fabs( capture_time - playback_time ) > 0.01 )
                  PA_DEBUG(( "Capture time and playback time differ by %f\n", fabs( capture_time-playback_time ) ));
          }
          else
              timeInfo->currentTime = playback_time;
  
          timeInfo->outputBufferDacTime = timeInfo->currentTime +
              (PaTime)playback_delay / stream->streamRepresentation.streamInfo.sampleRate;
      }
  }
  
  /** Called after buffer processing is finished.
   *
   * A number of mmapped frames is committed, it is possible that an xrun has occurred in the meantime.
   *
   * @param numFrames The number of frames that has been processed
   * @param xrun Return whether an xrun has occurred
   */
  static PaError PaAlsaStreamComponent_EndProcessing( PaAlsaStreamComponent *self, unsigned long numFrames, int *xrun )
  {
      PaError result = paNoError;
      int res = 0;
  
      /* @concern FullDuplex It is possible that only one direction is marked ready after polling, and processed
       * afterwards
       */
      if( !self->ready )
          goto end;
  
      if( !self->canMmap && StreamDirection_Out == self->streamDir )
      {
          /* Play sound */
          if( self->hostInterleaved )
              res = alsa_snd_pcm_writei( self->pcm, self->nonMmapBuffer, numFrames );
          else
          {
              void *bufs[self->numHostChannels];
              int bufsize = alsa_snd_pcm_format_size( self->nativeFormat, self->framesPerPeriod + 1 );
              unsigned char *buffer = self->nonMmapBuffer;
              int i;
              for( i = 0; i < self->numHostChannels; ++i )
              {
                  bufs[i] = buffer;
                  buffer += bufsize;
              }
              res = alsa_snd_pcm_writen( self->pcm, bufs, numFrames );
          }
      }
  
      if( self->canMmap )
          res = alsa_snd_pcm_mmap_commit( self->pcm, self->offset, numFrames );
  
      if( res == -EPIPE )
      {
          *xrun = 1;
      }
      // ESTRPIPE is provided by the Linux kernel headers, and is unavailable
      // on the BSDs, which can still use alsalib.
  #if defined(ESTRPIPE) && ESTRPIPE != EPIPE
      else if( res == -ESTRPIPE )
      {
          *xrun = 1;
      }
  #endif
      else
      {
          ENSURE_( res, paUnanticipatedHostError );
      }
  
  end:
  error:
      return result;
  }
  
  /* Extract buffer from channel area */
  static unsigned char *ExtractAddress( const snd_pcm_channel_area_t *area, snd_pcm_uframes_t offset )
  {
      return (unsigned char *) area->addr + ( area->first + offset * area->step ) / 8;
  }
  
  /** Do necessary adaption between user and host channels.
   *
      @concern ChannelAdaption Adapting between user and host channels can involve silencing unused channels and
      duplicating mono information if host outputs come in pairs.
   */
  static PaError PaAlsaStreamComponent_DoChannelAdaption( PaAlsaStreamComponent *self, PaUtilBufferProcessor *bp, int numFrames )
  {
      PaError result = paNoError;
      unsigned char *p;
      int i;
      int unusedChans = self->numHostChannels - self->numUserChannels;
      unsigned char *src, *dst;
      int convertMono = ( self->numHostChannels % 2 ) == 0 && ( self->numUserChannels % 2 ) != 0;
  
      assert( StreamDirection_Out == self->streamDir );
  
      if( self->hostInterleaved )
      {
          int swidth = alsa_snd_pcm_format_size( self->nativeFormat, 1 );
          unsigned char *buffer = self->canMmap ? ExtractAddress( self->channelAreas, self->offset ) : self->nonMmapBuffer;
  
          /* Start after the last user channel */
          p = buffer + self->numUserChannels * swidth;
  
          if( convertMono )
          {
              /* Convert the last user channel into stereo pair */
              src = buffer + ( self->numUserChannels - 1 ) * swidth;
              for( i = 0; i < numFrames; ++i )
              {
                  dst = src + swidth;
                  memcpy( dst, src, swidth );
                  src += self->numHostChannels * swidth;
              }
  
              /* Don't touch the channel we just wrote to */
              p += swidth;
              --unusedChans;
          }
  
          if( unusedChans > 0 )
          {
              /* Silence unused output channels */
              for( i = 0; i < numFrames; ++i )
              {
                  memset( p, 0, swidth * unusedChans );
                  p += self->numHostChannels * swidth;
              }
          }
      }
      else
      {
          /* We extract the last user channel */
          if( convertMono )
          {
              ENSURE_( alsa_snd_pcm_area_copy( self->channelAreas + self->numUserChannels, self->offset, self->channelAreas +
                      ( self->numUserChannels - 1 ), self->offset, numFrames, self->nativeFormat ), paUnanticipatedHostError );
              --unusedChans;
          }
          if( unusedChans > 0 )
          {
              alsa_snd_pcm_areas_silence( self->channelAreas + ( self->numHostChannels - unusedChans ), self->offset, unusedChans, numFrames,
                      self->nativeFormat );
          }
      }
  
  error:
      return result;
  }
  
  static PaError PaAlsaStream_EndProcessing( PaAlsaStream *self, unsigned long numFrames, int *xrunOccurred )
  {
      PaError result = paNoError;
      int xrun = 0;
  
      if( self->capture.pcm )
      {
          PA_ENSURE( PaAlsaStreamComponent_EndProcessing( &self->capture, numFrames, &xrun ) );
      }
      if( self->playback.pcm )
      {
          if( self->playback.numHostChannels > self->playback.numUserChannels )
          {
              PA_ENSURE( PaAlsaStreamComponent_DoChannelAdaption( &self->playback, &self->bufferProcessor, numFrames ) );
          }
          PA_ENSURE( PaAlsaStreamComponent_EndProcessing( &self->playback, numFrames, &xrun ) );
      }
  
  error:
      *xrunOccurred = xrun;
      return result;
  }
  
  /** Update the number of available frames.
   *
   */
  static PaError PaAlsaStreamComponent_GetAvailableFrames( PaAlsaStreamComponent *self, unsigned long *numFrames, int *xrunOccurred )
  {
      PaError result = paNoError;
      snd_pcm_sframes_t framesAvail = alsa_snd_pcm_avail_update( self->pcm );
      *xrunOccurred = 0;
  
      if( -EPIPE == framesAvail )
      {
          *xrunOccurred = 1;
          framesAvail = 0;
      }
      else
      {
          ENSURE_( framesAvail, paUnanticipatedHostError );
      }
  
      *numFrames = framesAvail;
  
  error:
      return result;
  }
  
  /** Fill in pollfd objects.
   */
  static PaError PaAlsaStreamComponent_BeginPolling( PaAlsaStreamComponent* self, struct pollfd* pfds )
  {
      int nfds = alsa_snd_pcm_poll_descriptors( self->pcm, pfds, self->nfds );
      /* If alsa returns anything else, like -EPIPE return */
      if( nfds != self->nfds )
      {
          return paUnanticipatedHostError;
      }
      self->ready = 0;
  
      return paNoError;
  }
  
  /** Examine results from poll().
   *
   * @param pfds pollfds to inspect
   * @param shouldPoll Should we continue to poll
   * @param xrun Has an xrun occurred
   */
  static PaError PaAlsaStreamComponent_EndPolling( PaAlsaStreamComponent* self, struct pollfd* pfds, int* shouldPoll, int* xrun )
  {
      PaError result = paNoError;
      unsigned short revents;
  
      ENSURE_( alsa_snd_pcm_poll_descriptors_revents( self->pcm, pfds, self->nfds, &revents ), paUnanticipatedHostError );
      if( revents != 0 )
      {
          if( revents & POLLERR )
          {
              *xrun = 1;
          }
          else if( revents & POLLHUP )
          {
              *xrun = 1;
              PA_DEBUG(( "%s: revents has POLLHUP, processing as XRUN\n", __FUNCTION__ ));
          }
          else
              self->ready = 1;
  
          *shouldPoll = 0;
      }
      else /* (A zero revent occurred) */
          /* Work around an issue with Alsa older than 1.0.16 using some plugins (eg default with plug + dmix) where
           * POLLIN or POLLOUT are zeroed by Alsa-lib if _mmap_avail() is a few frames short of avail_min at period
           * boundary, possibly due to erratic dma interrupts at period boundary?  Treat as a valid event.
           */
          if( self->useReventFix )
          {
              self->ready = 1;
              *shouldPoll = 0;
          }
  
  error:
      return result;
  }
  
  /** Return the number of available frames for this stream.
   *
   * @concern FullDuplex The minimum available for the two directions is calculated, it might be desirable to ignore
   * one direction however (not marked ready from poll), so this is controlled by queryCapture and queryPlayback.
   *
   * @param queryCapture Check available for capture
   * @param queryPlayback Check available for playback
   * @param available The returned number of frames
   * @param xrunOccurred Return whether an xrun has occurred
   */
  static PaError PaAlsaStream_GetAvailableFrames( PaAlsaStream *self, int queryCapture, int queryPlayback, unsigned long
          *available, int *xrunOccurred )
  {
      PaError result = paNoError;
      unsigned long captureFrames, playbackFrames;
      *xrunOccurred = 0;
  
      assert( queryCapture || queryPlayback );
  
      if( queryCapture )
      {
          assert( self->capture.pcm );
          PA_ENSURE( PaAlsaStreamComponent_GetAvailableFrames( &self->capture, &captureFrames, xrunOccurred ) );
          if( *xrunOccurred )
          {
              goto end;
          }
      }
      if( queryPlayback )
      {
          assert( self->playback.pcm );
          PA_ENSURE( PaAlsaStreamComponent_GetAvailableFrames( &self->playback, &playbackFrames, xrunOccurred ) );
          if( *xrunOccurred )
          {
              goto end;
          }
      }
  
      if( queryCapture && queryPlayback )
      {
          *available = PA_MIN( captureFrames, playbackFrames );
          /*PA_DEBUG(("capture: %lu, playback: %lu, combined: %lu\n", captureFrames, playbackFrames, *available));*/
      }
      else if( queryCapture )
      {
          *available = captureFrames;
      }
      else
      {
          *available = playbackFrames;
      }
  
  end:
  error:
      return result;
  }
  
  /** Wait for and report available buffer space from ALSA.
   *
   * Unless ALSA reports a minimum of frames available for I/O, we poll the ALSA filedescriptors for more.
   * Both of these operations can uncover xrun conditions.
   *
   * @concern Xruns Both polling and querying available frames can report an xrun condition.
   *
   * @param framesAvail Return the number of available frames
   * @param xrunOccurred Return whether an xrun has occurred
   */
  static PaError PaAlsaStream_WaitForFrames( PaAlsaStream *self, unsigned long *framesAvail, int *xrunOccurred )
  {
      PaError result = paNoError;
      int pollPlayback = self->playback.pcm != NULL, pollCapture = self->capture.pcm != NULL;
      int pollTimeout = self->pollTimeout;
      int xrun = 0, timeouts = 0;
      int pollResults;
  
      assert( self );
      assert( framesAvail );
  
      if( !self->callbackMode )
      {
          /* In blocking mode we will only wait if necessary */
          PA_ENSURE( PaAlsaStream_GetAvailableFrames( self, self->capture.pcm != NULL, self->playback.pcm != NULL,
                      framesAvail, &xrun ) );
          if( xrun )
          {
              goto end;
          }
  
          if( *framesAvail > 0 )
          {
              /* Mark pcms ready from poll */
              if( self->capture.pcm )
                  self->capture.ready = 1;
              if( self->playback.pcm )
                  self->playback.ready = 1;
  
              goto end;
          }
      }
  
      while( pollPlayback || pollCapture )
      {
          int totalFds = 0;
          struct pollfd *capturePfds = NULL, *playbackPfds = NULL;
  
  #ifdef PTHREAD_CANCELED
          pthread_testcancel();
  #endif
          if( pollCapture )
          {
              capturePfds = self->pfds;
              PaError res = PaAlsaStreamComponent_BeginPolling( &self->capture, capturePfds );
              if( res != paNoError)
              {
                  xrun = 1;
                  goto end;
              }
              totalFds += self->capture.nfds;
          }
          if( pollPlayback )
          {
              /* self->pfds is in effect an array of fds; if necessary, index past the capture fds */
              playbackPfds = self->pfds + (pollCapture ? self->capture.nfds : 0);
              PaError res = PaAlsaStreamComponent_BeginPolling( &self->playback, playbackPfds );
              if( res != paNoError)
              {
                  xrun = 1;
                  goto end;
              }
              totalFds += self->playback.nfds;
          }
  
  #ifdef PTHREAD_CANCELED
          if( self->callbackMode )
          {
              /* To allow 'Abort' to terminate the callback thread, enable cancelability just for poll() (& disable after) */
              pthread_setcancelstate( PTHREAD_CANCEL_ENABLE, NULL );
          }
  #endif
  
          pollResults = poll( self->pfds, totalFds, pollTimeout );
  
  #ifdef PTHREAD_CANCELED
          if( self->callbackMode )
          {
              pthread_setcancelstate( PTHREAD_CANCEL_DISABLE, NULL );
          }
  #endif
  
          if( pollResults < 0 )
          {
              /*  XXX: Depend on preprocessor condition? */
              if( errno == EINTR )
              {
                  /* gdb */
                  Pa_Sleep( 1 ); /* avoid hot loop */
                  continue;
              }
  
              /* TODO: Add macro for checking system calls */
              PA_ENSURE( paInternalError );
          }
          else if( pollResults == 0 )
          {
             /* Suspended, paused or failed device can provide 0 poll results. To avoid deadloop in such situation
              * we simply run counter 'timeouts' which detects 0 poll result and accumulates. As soon as 2048 timouts (around 2 seconds)
              * are achieved we simply fail function with paTimedOut to notify waiting methods that device is not capable
              * of providing audio data anymore and needs some corresponding recovery action.
              * Note that 'timeouts' is reset to 0 if poll() managed to return non 0 results.
              */
  
              /*PA_DEBUG(( "%s: poll == 0 results, timed out, %d times left\n", __FUNCTION__, 2048 - timeouts ));*/
              ++ timeouts;
              if( timeouts > 1 ) /* sometimes device times out, but normally once, so we do not sleep any time */
              {
                  Pa_Sleep( 1 ); /* avoid hot loop */
              }
              /* not else ! */
              if( timeouts >= 2048 ) /* audio device not working, shall return error to notify waiters */
              {
                  *framesAvail = 0; /* no frames available for processing */
                  xrun = 1; /* try recovering device */
  
                  PA_DEBUG(( "%s: poll timed out\n", __FUNCTION__, timeouts ));
                  goto end;/*PA_ENSURE( paTimedOut );*/
              }
          }
          else if( pollResults > 0 )
          {
              /* reset timouts counter */
              timeouts = 0;
  
              /* check the return status of our pfds */
              if( pollCapture )
              {
                  PA_ENSURE( PaAlsaStreamComponent_EndPolling( &self->capture, capturePfds, &pollCapture, &xrun ) );
              }
              if( pollPlayback )
              {
                  PA_ENSURE( PaAlsaStreamComponent_EndPolling( &self->playback, playbackPfds, &pollPlayback, &xrun ) );
              }
              if( xrun )
              {
                  break;
              }
          }
  
          /* @concern FullDuplex If only one of two pcms is ready we may want to compromise between the two.
           * If there is less than half a period's worth of samples left of frames in the other pcm's buffer we will
           * stop polling.
           */
          if( self->capture.pcm && self->playback.pcm )
          {
              if( pollCapture && !pollPlayback )
              {
                  PA_ENSURE( ContinuePoll( self, StreamDirection_In, &pollTimeout, &pollCapture ) );
              }
              else if( pollPlayback && !pollCapture )
              {
                  PA_ENSURE( ContinuePoll( self, StreamDirection_Out, &pollTimeout, &pollPlayback ) );
              }
          }
      }
  
      if( !xrun )
      {
          /* Get the number of available frames for the pcms that are marked ready.
           * @concern FullDuplex If only one direction is marked ready (from poll), the number of frames available for
           * the other direction is returned. Output is normally preferred over capture however, so capture frames may be
           * discarded to avoid overrun unless paNeverDropInput is specified.
           */
          int captureReady = self->capture.pcm ? self->capture.ready : 0,
              playbackReady = self->playback.pcm ? self->playback.ready : 0;
          PA_ENSURE( PaAlsaStream_GetAvailableFrames( self, captureReady, playbackReady, framesAvail, &xrun ) );
  
          if( self->capture.pcm && self->playback.pcm )
          {
              if( !self->playback.ready && !self->neverDropInput )
              {
                  /* Drop input, a period's worth */
                  assert( self->capture.ready );
                  PaAlsaStreamComponent_EndProcessing( &self->capture, PA_MIN( self->capture.framesPerPeriod,
                              *framesAvail ), &xrun );
                  *framesAvail = 0;
                  self->capture.ready = 0;
              }
          }
          else if( self->capture.pcm )
              assert( self->capture.ready );
          else
              assert( self->playback.ready );
      }
  
  end:
  error:
      if( xrun )
      {
          /* Recover from the xrun state */
          PA_ENSURE( PaAlsaStream_HandleXrun( self ) );
          *framesAvail = 0;
      }
      else
      {
          if( 0 != *framesAvail )
          {
              /* If we're reporting frames eligible for processing, one of the handles better be ready */
              PA_UNLESS( self->capture.ready || self->playback.ready, paInternalError );
          }
      }
      *xrunOccurred = xrun;
  
      return result;
  }
  
  /** Register per-channel ALSA buffer information with buffer processor.
   *
   * Mmapped buffer space is acquired from ALSA, and registered with the buffer processor. Differences between the
   * number of host and user channels is taken into account.
   *
   * @param numFrames On entrance the number of requested frames, on exit the number of contiguously accessible frames.
   */
  static PaError PaAlsaStreamComponent_RegisterChannels( PaAlsaStreamComponent* self, PaUtilBufferProcessor* bp,
          unsigned long* numFrames, int* xrun )
  {
      PaError result = paNoError;
      const snd_pcm_channel_area_t *areas, *area;
      void (*setChannel)(PaUtilBufferProcessor *, unsigned int, void *, unsigned int) =
          StreamDirection_In == self->streamDir ? PaUtil_SetInputChannel : PaUtil_SetOutputChannel;
      unsigned char *buffer, *p;
      int i;
      unsigned long framesAvail;
  
      /* This _must_ be called before mmap_begin */
      PA_ENSURE( PaAlsaStreamComponent_GetAvailableFrames( self, &framesAvail, xrun ) );
      if( *xrun )
      {
          *numFrames = 0;
          goto end;
      }
  
      if( self->canMmap )
      {
          ENSURE_( alsa_snd_pcm_mmap_begin( self->pcm, &areas, &self->offset, numFrames ), paUnanticipatedHostError );
          /* @concern ChannelAdaption Buffer address is recorded so we can do some channel adaption later */
          self->channelAreas = (snd_pcm_channel_area_t *)areas;
      }
      else
      {
          unsigned int bufferSize = self->numHostChannels * alsa_snd_pcm_format_size( self->nativeFormat, *numFrames );
          if( bufferSize > self->nonMmapBufferSize )
          {
              self->nonMmapBuffer = realloc( self->nonMmapBuffer, ( self->nonMmapBufferSize = bufferSize ) );
              if( !self->nonMmapBuffer )
              {
                  result = paInsufficientMemory;
                  goto error;
              }
          }
      }
  
      if( self->hostInterleaved )
      {
          int swidth = alsa_snd_pcm_format_size( self->nativeFormat, 1 );
  
          p = buffer = self->canMmap ? ExtractAddress( areas, self->offset ) : self->nonMmapBuffer;
          for( i = 0; i < self->numUserChannels; ++i )
          {
              /* We're setting the channels up to userChannels, but the stride will be hostChannels samples */
              setChannel( bp, i, p, self->numHostChannels );
              p += swidth;
          }
      }
      else
      {
          if( self->canMmap )
          {
              for( i = 0; i < self->numUserChannels; ++i )
              {
                  area = areas + i;
                  buffer = ExtractAddress( area, self->offset );
                  setChannel( bp, i, buffer, 1 );
              }
          }
          else
          {
              unsigned int buf_per_ch_size = self->nonMmapBufferSize / self->numHostChannels;
              buffer = self->nonMmapBuffer;
              for( i = 0; i < self->numUserChannels; ++i )
              {
                  setChannel( bp, i, buffer, 1 );
                  buffer += buf_per_ch_size;
              }
          }
      }
  
      if( !self->canMmap && StreamDirection_In == self->streamDir )
      {
          /* Read sound */
          int res;
          if( self->hostInterleaved )
              res = alsa_snd_pcm_readi( self->pcm, self->nonMmapBuffer, *numFrames );
          else
          {
              void *bufs[self->numHostChannels];
              unsigned int buf_per_ch_size = self->nonMmapBufferSize / self->numHostChannels;
              unsigned char *buffer = self->nonMmapBuffer;
              int i;
              for( i = 0; i < self->numHostChannels; ++i )
              {
                  bufs[i] = buffer;
                  buffer += buf_per_ch_size;
              }
              res = alsa_snd_pcm_readn( self->pcm, bufs, *numFrames );
          }
          if( res == -EPIPE )
          {
              *xrun = 1;
              *numFrames = 0;
          }
          // ESTRPIPE is provided by the Linux kernel headers, and is unavailable
          // on the BSDs, which can still use alsalib.
  #if defined(ESTRPIPE) && ESTRPIPE != EPIPE
          else if( res == -ESTRPIPE )
          {
              *xrun = 1;
              *numFrames = 0;
          }
  #endif
      }
  
  end:
  error:
      return result;
  }
  
  /** Initiate buffer processing.
   *
   * ALSA buffers are registered with the PA buffer processor and the buffer size (in frames) set.
   *
   * @concern FullDuplex If both directions are being processed, the minimum amount of frames for the two directions is
   * calculated.
   *
   * @param numFrames On entrance the number of available frames, on exit the number of received frames
   * @param xrunOccurred Return whether an xrun has occurred
   */
  static PaError PaAlsaStream_SetUpBuffers( PaAlsaStream* self, unsigned long* numFrames, int* xrunOccurred )
  {
      PaError result = paNoError;
      unsigned long captureFrames = ULONG_MAX, playbackFrames = ULONG_MAX, commonFrames = 0;
      int xrun = 0;
  
      if( *xrunOccurred )
      {
          *numFrames = 0;
          return result;
      }
      /* If we got here at least one of the pcm's should be marked ready */
      PA_UNLESS( self->capture.ready || self->playback.ready, paInternalError );
  
      /* Extract per-channel ALSA buffer pointers and register them with the buffer processor.
       * It is possible that a direction is not marked ready however, because it is out of sync with the other.
       */
      if( self->capture.pcm && self->capture.ready )
      {
          captureFrames = *numFrames;
          PA_ENSURE( PaAlsaStreamComponent_RegisterChannels( &self->capture, &self->bufferProcessor, &captureFrames,
                      &xrun ) );
      }
      if( self->playback.pcm && self->playback.ready )
      {
          playbackFrames = *numFrames;
          PA_ENSURE( PaAlsaStreamComponent_RegisterChannels( &self->playback, &self->bufferProcessor, &playbackFrames,
                      &xrun ) );
      }
      if( xrun )
      {
          /* Nothing more to do */
          assert( 0 == commonFrames );
          goto end;
      }
  
      commonFrames = PA_MIN( captureFrames, playbackFrames );
      /* assert( commonFrames <= *numFrames ); */
      if( commonFrames > *numFrames )
      {
          /* Hmmm ... how come there are more frames available than we requested!? Blah. */
          PA_DEBUG(( "%s: Common available frames are reported to be more than number requested: %lu, %lu, callbackMode: %d\n", __FUNCTION__,
                      commonFrames, *numFrames, self->callbackMode ));
          if( self->capture.pcm )
          {
              PA_DEBUG(( "%s: captureFrames: %lu, capture.ready: %d\n", __FUNCTION__, captureFrames, self->capture.ready ));
          }
          if( self->playback.pcm )
          {
              PA_DEBUG(( "%s: playbackFrames: %lu, playback.ready: %d\n", __FUNCTION__, playbackFrames, self->playback.ready ));
          }
  
          commonFrames = 0;
          goto end;
      }
  
      /* Inform PortAudio of the number of frames we got.
       * @concern FullDuplex We might be experiencing underflow in either end; if its an input underflow, we go on
       * with output. If its output underflow however, depending on the paNeverDropInput flag, we may want to simply
       * discard the excess input or call the callback with paOutputOverflow flagged.
       */
      if( self->capture.pcm )
      {
          if( self->capture.ready )
          {
              PaUtil_SetInputFrameCount( &self->bufferProcessor, commonFrames );
          }
          else
          {
              /* We have input underflow */
              PaUtil_SetNoInput( &self->bufferProcessor );
          }
      }
      if( self->playback.pcm )
      {
          if( self->playback.ready )
          {
              PaUtil_SetOutputFrameCount( &self->bufferProcessor, commonFrames );
          }
          else
          {
              /* We have output underflow, but keeping input data (paNeverDropInput) */
              assert( self->neverDropInput );
              assert( self->capture.pcm != NULL );
              PA_DEBUG(( "%s: Setting output buffers to NULL\n", __FUNCTION__ ));
              PaUtil_SetNoOutput( &self->bufferProcessor );
          }
      }
  
  end:
      *numFrames = commonFrames;
  error:
      if( xrun )
      {
          PA_ENSURE( PaAlsaStream_HandleXrun( self ) );
          *numFrames = 0;
      }
      *xrunOccurred = xrun;
  
      return result;
  }
  
  /** Callback thread's function.
   *
   * Roughly, the workflow can be described in the following way: The number of available frames that can be processed
   * directly is obtained from ALSA, we then request as much directly accessible memory as possible within this amount
   * from ALSA. The buffer memory is registered with the PA buffer processor and processing is carried out with
   * PaUtil_EndBufferProcessing. Finally, the number of processed frames is reported to ALSA. The processing can
   * happen in several iterations until we have consumed the known number of available frames (or an xrun is detected).
   */
  static void *CallbackThreadFunc( void *userData )
  {
      PaError result = paNoError;
      PaAlsaStream *stream = (PaAlsaStream*) userData;
      PaStreamCallbackTimeInfo timeInfo = {0, 0, 0};
      snd_pcm_sframes_t startThreshold = 0;
      int callbackResult = paContinue;
      PaStreamCallbackFlags cbFlags = 0;  /* We might want to keep state across iterations */
      int streamStarted = 0;
  
      assert( stream );
      /* Not implemented */
      assert( !stream->primeBuffers );
  
      /* Execute OnExit when exiting */
      pthread_cleanup_push( &OnExit, stream );
  #ifdef PTHREAD_CANCELED
      /* 'Abort' will use thread cancellation to terminate the callback thread, but the Alsa-lib functions
       * are NOT cancel-safe, (and can end up in an inconsistent state).  So, disable cancelability for
       * the thread here, and just re-enable it for the poll() in PaAlsaStream_WaitForFrames(). */
      pthread_testcancel();
      pthread_setcancelstate( PTHREAD_CANCEL_DISABLE, NULL );
  #endif
  
      /* @concern StreamStart If the output is being primed the output pcm needs to be prepared, otherwise the
       * stream is started immediately. The latter involves signaling the waiting main thread.
       */
      if( stream->primeBuffers )
      {
          snd_pcm_sframes_t avail;
  
          if( stream->playback.pcm )
              ENSURE_( alsa_snd_pcm_prepare( stream->playback.pcm ), paUnanticipatedHostError );
          if( stream->capture.pcm && !stream->pcmsSynced )
              ENSURE_( alsa_snd_pcm_prepare( stream->capture.pcm ), paUnanticipatedHostError );
  
          /* We can't be certain that the whole ring buffer is available for priming, but there should be
           * at least one period */
          avail = alsa_snd_pcm_avail_update( stream->playback.pcm );
          startThreshold = avail - (avail % stream->playback.framesPerPeriod);
          assert( startThreshold >= stream->playback.framesPerPeriod );
      }
      else
      {
          PA_ENSURE( PaUnixThread_PrepareNotify( &stream->thread ) );
          /* Buffer will be zeroed */
          PA_ENSURE( AlsaStart( stream, 0 ) );
          PA_ENSURE( PaUnixThread_NotifyParent( &stream->thread ) );
  
          streamStarted = 1;
      }
  
      while( 1 )
      {
          unsigned long framesAvail, framesGot;
          int xrun = 0;
  
  #ifdef PTHREAD_CANCELED
          pthread_testcancel();
  #endif
  
          /* @concern StreamStop if the main thread has requested a stop and the stream has not been effectively
           * stopped we signal this condition by modifying callbackResult (we'll want to flush buffered output).
           */
          if( PaUnixThread_StopRequested( &stream->thread ) && paContinue == callbackResult )
          {
              PA_DEBUG(( "Setting callbackResult to paComplete\n" ));
              callbackResult = paComplete;
          }
  
          if( paContinue != callbackResult )
          {
              stream->callbackAbort = ( paAbort == callbackResult );
              if( stream->callbackAbort ||
                      /** @concern BlockAdaption: Go on if adaption buffers are empty */
                      PaUtil_IsBufferProcessorOutputEmpty( &stream->bufferProcessor ) )
              {
                  goto end;
              }
  
              PA_DEBUG(( "%s: Flushing buffer processor\n", __FUNCTION__ ));
              /* There is still buffered output that needs to be processed */
          }
  
          /* Wait for data to become available, this comes down to polling the ALSA file descriptors until we have
           * a number of available frames.
           */
          PA_ENSURE( PaAlsaStream_WaitForFrames( stream, &framesAvail, &xrun ) );
          if( xrun )
          {
              assert( 0 == framesAvail );
              continue;
  
              /* XXX: Report xruns to the user? A situation is conceivable where the callback is never invoked due
               * to constant xruns, it might be desirable to notify the user of this.
               */
          }
  
          /* Consume buffer space. Once we have a number of frames available for consumption we must retrieve the
           * mmapped buffers from ALSA, this is contiguously accessible memory however, so we may receive smaller
           * portions at a time than is available as a whole. Therefore we should be prepared to process several
           * chunks successively. The buffers are passed to the PA buffer processor.
           */
          while( framesAvail > 0 )
          {
              xrun = 0;
  
              /** @concern Xruns Under/overflows are to be reported to the callback */
              if( stream->underrun > 0.0 )
              {
                  cbFlags |= paOutputUnderflow;
                  stream->underrun = 0.0;
              }
              if( stream->overrun > 0.0 )
              {
                  cbFlags |= paInputOverflow;
                  stream->overrun = 0.0;
              }
              if( stream->capture.pcm && stream->playback.pcm )
              {
                  /** @concern FullDuplex It's possible that only one direction is being processed to avoid an
                   * under- or overflow, this should be reported correspondingly */
                  if( !stream->capture.ready )
                  {
                      cbFlags |= paInputUnderflow;
                      PA_DEBUG(( "%s: Input underflow\n", __FUNCTION__ ));
                  }
                  else if( !stream->playback.ready )
                  {
                      cbFlags |= paOutputOverflow;
                      PA_DEBUG(( "%s: Output overflow\n", __FUNCTION__ ));
                  }
              }
  
  #if 0
              CallbackUpdate( &stream->threading );
  #endif
  
              CalculateTimeInfo( stream, &timeInfo );
              PaUtil_BeginBufferProcessing( &stream->bufferProcessor, &timeInfo, cbFlags );
              cbFlags = 0;
  
              /* CPU load measurement should include processing activity external to the stream callback */
              PaUtil_BeginCpuLoadMeasurement( &stream->cpuLoadMeasurer );
  
              framesGot = framesAvail;
              if( paUtilFixedHostBufferSize == stream->bufferProcessor.hostBufferSizeMode )
              {
                  /* We've committed to a fixed host buffer size, stick to that */
                  framesGot = framesGot >= stream->maxFramesPerHostBuffer ? stream->maxFramesPerHostBuffer : 0;
              }
              else
              {
                  /* We've committed to an upper bound on the size of host buffers */
                  assert( paUtilBoundedHostBufferSize == stream->bufferProcessor.hostBufferSizeMode );
                  framesGot = PA_MIN( framesGot, stream->maxFramesPerHostBuffer );
              }
              PA_ENSURE( PaAlsaStream_SetUpBuffers( stream, &framesGot, &xrun ) );
              /* Check the host buffer size against the buffer processor configuration */
              framesAvail -= framesGot;
  
              if( framesGot > 0 )
              {
                  assert( !xrun );
                  PaUtil_EndBufferProcessing( &stream->bufferProcessor, &callbackResult );
                  PA_ENSURE( PaAlsaStream_EndProcessing( stream, framesGot, &xrun ) );
              }
              PaUtil_EndCpuLoadMeasurement( &stream->cpuLoadMeasurer, framesGot );
  
              if( 0 == framesGot )
              {
                  /* Go back to polling for more frames */
                  break;
              }
  
              if( paContinue != callbackResult )
                  break;
          }
      }
  
  end:
      ; /* Hack to fix "label at end of compound statement" error caused by pthread_cleanup_pop(1) macro. */
      /* Match pthread_cleanup_push */
      pthread_cleanup_pop( 1 );
  
      PA_DEBUG(( "%s: Thread %d exiting\n ", __FUNCTION__, pthread_self() ));
      PaUnixThreading_EXIT( result );
  
  error:
      PA_DEBUG(( "%s: Thread %d is canceled due to error %d\n ", __FUNCTION__, pthread_self(), result ));
      goto end;
  }
  
  /* Blocking interface */
  
  static PaError ReadStream( PaStream* s, void *buffer, unsigned long frames )
  {
      PaError result = paNoError;
      PaAlsaStream *stream = (PaAlsaStream*)s;
      unsigned long framesGot, framesAvail;
      void *userBuffer;
      snd_pcm_t *save = stream->playback.pcm;
  
      assert( stream );
  
      PA_UNLESS( stream->capture.pcm, paCanNotReadFromAnOutputOnlyStream );
  
      /* Disregard playback */
      stream->playback.pcm = NULL;
  
      if( stream->overrun > 0. )
      {
          result = paInputOverflowed;
          stream->overrun = 0.0;
      }
  
      if( stream->capture.userInterleaved )
      {
          userBuffer = buffer;
      }
      else
      {
          /* Copy channels into local array */
          userBuffer = stream->capture.userBuffers;
          memcpy( userBuffer, buffer, sizeof (void *) * stream->capture.numUserChannels );
      }
  
      /* Start stream if in prepared state */
      if( alsa_snd_pcm_state( stream->capture.pcm ) == SND_PCM_STATE_PREPARED )
      {
          ENSURE_( alsa_snd_pcm_start( stream->capture.pcm ), paUnanticipatedHostError );
      }
  
      while( frames > 0 )
      {
          int xrun = 0;
          PA_ENSURE( PaAlsaStream_WaitForFrames( stream, &framesAvail, &xrun ) );
          framesGot = PA_MIN( framesAvail, frames );
  
          PA_ENSURE( PaAlsaStream_SetUpBuffers( stream, &framesGot, &xrun ) );
          if( framesGot > 0 )
          {
              framesGot = PaUtil_CopyInput( &stream->bufferProcessor, &userBuffer, framesGot );
              PA_ENSURE( PaAlsaStream_EndProcessing( stream, framesGot, &xrun ) );
              frames -= framesGot;
          }
      }
  
  end:
      stream->playback.pcm = save;
      return result;
  error:
      goto end;
  }
  
  static PaError WriteStream( PaStream* s, const void *buffer, unsigned long frames )
  {
      PaError result = paNoError;
      signed long err;
      PaAlsaStream *stream = (PaAlsaStream*)s;
      snd_pcm_uframes_t framesGot, framesAvail;
      const void *userBuffer;
      snd_pcm_t *save = stream->capture.pcm;
  
      assert( stream );
  
      PA_UNLESS( stream->playback.pcm, paCanNotWriteToAnInputOnlyStream );
  
      /* Disregard capture */
      stream->capture.pcm = NULL;
  
      if( stream->underrun > 0. )
      {
          result = paOutputUnderflowed;
          stream->underrun = 0.0;
      }
  
      if( stream->playback.userInterleaved )
          userBuffer = buffer;
      else /* Copy channels into local array */
      {
          userBuffer = stream->playback.userBuffers;
          memcpy( (void *)userBuffer, buffer, sizeof (void *) * stream->playback.numUserChannels );
      }
  
      while( frames > 0 )
      {
          int xrun = 0;
          snd_pcm_uframes_t hwAvail;
  
          PA_ENSURE( PaAlsaStream_WaitForFrames( stream, &framesAvail, &xrun ) );
          framesGot = PA_MIN( framesAvail, frames );
  
          PA_ENSURE( PaAlsaStream_SetUpBuffers( stream, &framesGot, &xrun ) );
          if( framesGot > 0 )
          {
              framesGot = PaUtil_CopyOutput( &stream->bufferProcessor, &userBuffer, framesGot );
              PA_ENSURE( PaAlsaStream_EndProcessing( stream, framesGot, &xrun ) );
              frames -= framesGot;
          }
  
          /* Start stream after one period of samples worth */
  
          /* Frames residing in buffer */
          PA_ENSURE( err = GetStreamWriteAvailable( stream ) );
          framesAvail = err;
          hwAvail = stream->playback.alsaBufferSize - framesAvail;
  
          if( alsa_snd_pcm_state( stream->playback.pcm ) == SND_PCM_STATE_PREPARED &&
                  hwAvail >= stream->playback.framesPerPeriod )
          {
              ENSURE_( alsa_snd_pcm_start( stream->playback.pcm ), paUnanticipatedHostError );
          }
      }
  
  end:
      stream->capture.pcm = save;
      return result;
  error:
      goto end;
  }
  
  /* Return frames available for reading. In the event of an overflow, the capture pcm will be restarted */
  static signed long GetStreamReadAvailable( PaStream* s )
  {
      PaError result = paNoError;
      PaAlsaStream *stream = (PaAlsaStream*)s;
      unsigned long avail;
      int xrun;
  
      PA_ENSURE( PaAlsaStreamComponent_GetAvailableFrames( &stream->capture, &avail, &xrun ) );
      if( xrun )
      {
          PA_ENSURE( PaAlsaStream_HandleXrun( stream ) );
          PA_ENSURE( PaAlsaStreamComponent_GetAvailableFrames( &stream->capture, &avail, &xrun ) );
          if( xrun )
              PA_ENSURE( paInputOverflowed );
      }
  
      return (signed long)avail;
  
  error:
      return result;
  }
  
  static signed long GetStreamWriteAvailable( PaStream* s )
  {
      PaError result = paNoError;
      PaAlsaStream *stream = (PaAlsaStream*)s;
      unsigned long avail;
      int xrun;
  
      PA_ENSURE( PaAlsaStreamComponent_GetAvailableFrames( &stream->playback, &avail, &xrun ) );
      if( xrun )
      {
          snd_pcm_sframes_t savail;
  
          PA_ENSURE( PaAlsaStream_HandleXrun( stream ) );
          savail = alsa_snd_pcm_avail_update( stream->playback.pcm );
  
          /* savail should not contain -EPIPE now, since PaAlsaStream_HandleXrun will only prepare the pcm */
          ENSURE_( savail, paUnanticipatedHostError );
  
          avail = (unsigned long) savail;
      }
  
      return (signed long)avail;
  
  error:
      return result;
  }
  
  /* Extensions */
  
  void PaAlsa_InitializeStreamInfo( PaAlsaStreamInfo *info )
  {
      info->size = sizeof (PaAlsaStreamInfo);
      info->hostApiType = paALSA;
      info->version = 1;
      info->deviceString = NULL;
  }
  
  void PaAlsa_EnableRealtimeScheduling( PaStream *s, int enable )
  {
      PaAlsaStream *stream = (PaAlsaStream *) s;
      stream->rtSched = enable;
  }
  
  #if 0
  void PaAlsa_EnableWatchdog( PaStream *s, int enable )
  {
      PaAlsaStream *stream = (PaAlsaStream *) s;
      stream->thread.useWatchdog = enable;
  }
  #endif
  
  static PaError GetAlsaStreamPointer( PaStream* s, PaAlsaStream** stream )
  {
      PaError result = paNoError;
      PaUtilHostApiRepresentation* hostApi;
      PaAlsaHostApiRepresentation* alsaHostApi;
  
      PA_ENSURE( PaUtil_ValidateStreamPointer( s ) );
      PA_ENSURE( PaUtil_GetHostApiRepresentation( &hostApi, paALSA ) );
      alsaHostApi = (PaAlsaHostApiRepresentation*)hostApi;
  
      PA_UNLESS( PA_STREAM_REP( s )->streamInterface == &alsaHostApi->callbackStreamInterface
              || PA_STREAM_REP( s )->streamInterface == &alsaHostApi->blockingStreamInterface,
          paIncompatibleStreamHostApi );
  
      *stream = (PaAlsaStream*)s;
  error:
      return paNoError;
  }
  
  PaError PaAlsa_GetStreamInputCard( PaStream* s, int* card )
  {
      PaAlsaStream *stream;
      PaError result = paNoError;
      snd_pcm_info_t* pcmInfo;
  
      stream = NULL;
      PA_ENSURE( GetAlsaStreamPointer( s, &stream ) );
  
      /* XXX: More descriptive error? */
      PA_UNLESS( stream->capture.pcm, paDeviceUnavailable );
  
      alsa_snd_pcm_info_alloca( &pcmInfo );
      PA_ENSURE( alsa_snd_pcm_info( stream->capture.pcm, pcmInfo ) );
      *card = alsa_snd_pcm_info_get_card( pcmInfo );
  
  error:
      return result;
  }
  
  PaError PaAlsa_GetStreamOutputCard( PaStream* s, int* card )
  {
      PaAlsaStream *stream;
      PaError result = paNoError;
      snd_pcm_info_t* pcmInfo;
  
      stream = NULL;
      PA_ENSURE( GetAlsaStreamPointer( s, &stream ) );
  
      /* XXX: More descriptive error? */
      PA_UNLESS( stream->playback.pcm, paDeviceUnavailable );
  
      alsa_snd_pcm_info_alloca( &pcmInfo );
      PA_ENSURE( alsa_snd_pcm_info( stream->playback.pcm, pcmInfo ) );
      *card = alsa_snd_pcm_info_get_card( pcmInfo );
  
  error:
      return result;
  }
  
  PaError PaAlsa_SetRetriesBusy( int retries )
  {
      busyRetries_ = retries;
      return paNoError;
  }
  