path: root/portaudio/src/hostapi/alsa/pa_linux_alsa.c

/*
 * $Id$
 * 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_state);
_PA_DEFINE_FUNC(snd_pcm_status_get_trigger_tstamp);
_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_state);
    _PA_LOAD_FUNC(snd_pcm_status_get_trigger_tstamp);
    _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: " 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[50];

        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;
}

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 );
    }

    alsa_snd_pcm_status_get_tstamp( status, &timestamp );
    return timestamp.tv_sec + (PaTime)timestamp.tv_usec / 1e6;
}

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 * 1000 - ( (PaTime)t.tv_sec * 1000 + (PaTime)t.tv_usec / 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 )
        {
            alsa_snd_pcm_status_get_trigger_tstamp( st, &t );
            self->overrun = now * 1000 - ((PaTime) t.tv_sec * 1000 + (PaTime) t.tv_usec / 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 *capture_status, *playback_status;
    snd_timestamp_t capture_timestamp, playback_timestamp;
    PaTime capture_time = 0., playback_time = 0.;

    alsa_snd_pcm_status_alloca( &capture_status );
    alsa_snd_pcm_status_alloca( &playback_status );

    if( stream->capture.pcm )
    {
        snd_pcm_sframes_t capture_delay;

        alsa_snd_pcm_status( stream->capture.pcm, capture_status );
        alsa_snd_pcm_status_get_tstamp( capture_status, &capture_timestamp );

        capture_time = capture_timestamp.tv_sec +
            ( (PaTime)capture_timestamp.tv_usec / 1000000.0 );
        timeInfo->currentTime = capture_time;

        capture_delay = alsa_snd_pcm_status_get_delay( capture_status );
        timeInfo->inputBufferAdcTime = timeInfo->currentTime -
            (PaTime)capture_delay / stream->streamRepresentation.streamInfo.sampleRate;
    }
    if( stream->playback.pcm )
    {
        snd_pcm_sframes_t playback_delay;

        alsa_snd_pcm_status( stream->playback.pcm, playback_status );
        alsa_snd_pcm_status_get_tstamp( playback_status, &playback_timestamp );

        playback_time = playback_timestamp.tv_sec +
            ((PaTime)playback_timestamp.tv_usec / 1000000.0);

        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;

        playback_delay = alsa_snd_pcm_status_get_delay( playback_status );
        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 || res == -ESTRPIPE )
    {
        *xrun = 1;
    }
    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 || res == -ESTRPIPE )
        {
            *xrun = 1;
            *numFrames = 0;
        }
    }

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;

    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;

    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;
}