Release v1.0.27.1

[alsa-lib.git] / src / pcm / pcm.c

/**
 * \file pcm/pcm.c
 * \ingroup PCM
 * \brief PCM Interface
 * \author Jaroslav Kysela <perex@perex.cz>
 * \author Abramo Bagnara <abramo@alsa-project.org>
 * \date 2000-2001
 *
 * PCM Interface is designed to write or read digital audio frames. A
 * frame is the data unit converted into/from sound in one time unit
 * (1/rate seconds), by example if you set your playback PCM rate to
 * 44100 you'll hear 44100 frames per second. The size in bytes of a
 * frame may be obtained from bits needed to store a sample and
 * channels count.
 *
 * See the \ref pcm page for more details.
 */
/*
 *  PCM Interface - main file
 *  Copyright (c) 1998 by Jaroslav Kysela <perex@perex.cz>
 *  Copyright (c) 2000 by Abramo Bagnara <abramo@alsa-project.org>
 *
 *   This library is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU Lesser General Public License as
 *   published by the Free Software Foundation; either version 2.1 of
 *   the License, or (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU Lesser General Public License for more details.
 *
 *   You should have received a copy of the GNU Lesser General Public
 *   License along with this library; if not, write to the Free Software
 *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
 *
 */

/*! \page pcm PCM (digital audio) interface

<P>Although abbreviation PCM stands for Pulse Code Modulation, we are
understanding it as general digital audio processing with volume samples
generated in continuous time periods.</P>

<P>The analog signal is recorded via analog to digital converters (ADC).
The digital value (de-facto a volume at a specific time) obtained
from ADC can be further processed. The following picture shows a perfect
sinus waveform:</P>

<BR>
\image html wave1.gif

<P>Next image shows digitized representation:</P>

<BR>
\image html wave2.gif

<P>As you may see, the quality of digital audio signal depends on the time
(recording rate) and voltage resolution (usually in an linear integer
representation with basic unit one bit).</P>

<P>The stored digital signal can be converted back to voltage (analog)
representation via digital to analog converters (DAC).</P>

<P>One digital value is called sample. More samples are collected to frames
(frame is terminology for ALSA) depending on count of converters used at one
specific time. One frame might contain one sample (when only one converter is
used - mono) or more samples (for example: stereo has signals from two converters
recorded at same time). Digital audio stream contains collection of frames
recorded at boundaries of continuous time periods.</P>

\section pcm_general_overview General overview

ALSA uses the ring buffer to store outgoing (playback) and incoming (capture,
record) samples. There are two pointers being maintained to allow
a precise communication between application and device pointing to current
processed sample by hardware and last processed sample by application.
The modern audio chips allow to program the transfer time periods.
It means that the stream of samples is divided to small chunks. Device
acknowledges to application when the transfer of a chunk is complete.

\section pcm_transfer Transfer methods in UNIX environments

In the UNIX environment, data chunk acknowledges are received via standard I/O
calls or event waiting routines (poll or select function). To accomplish
this list, the asynchronous notification of acknowledges should be listed
here. The ALSA implementation for these methods is described in
the \ref alsa_transfers section.

\subsection pcm_transfer_io Standard I/O transfers

The standard I/O transfers are using the read (see 'man 2 read') and write
(see 'man 2 write') C functions. There are two basic behaviours of these
functions - blocked and non-blocked (see the O_NONBLOCK flag for the
standard C open function - see 'man 2 open'). In non-blocked behaviour,
these I/O functions never stops, they return -EAGAIN error code, when no
data can be transferred (the ring buffer is full in our case). In blocked
behaviour, these I/O functions stop and wait until there is a room in the
ring buffer (playback) or until there are a new samples (capture). The ALSA
implementation can be found in the \ref alsa_pcm_rw section.

\subsection pcm_transfer_event Event waiting routines

The poll or select functions (see 'man 2 poll' or 'man 2 select' for further
details) allows to receive requests/events from the device while
an application is waiting on events from other sources (like keyboard, screen,
network etc.), too. \ref snd_pcm_poll_descriptors can be used to get a file
descriptor to poll or select on. The implemented
transfer routines can be found in the \ref alsa_transfers section.

\subsection pcm_transfer_async Asynchronous notification

ALSA driver and library knows to handle the asynchronous notifications over
the SIGIO signal. This signal allows to interrupt application and transfer
data in the signal handler. For further details see the sigaction function
('man 2 sigaction'). The section \ref pcm_async describes the ALSA API for
this extension. The implemented transfer routines can be found in the
\ref alsa_transfers section.

\section pcm_open_behaviour Blocked and non-blocked open

The ALSA PCM API uses a different behaviour when the device is opened
with blocked or non-blocked mode. The mode can be specified with
\a mode argument in #snd_pcm_open() function.
The blocked mode is the default (without #SND_PCM_NONBLOCK mode).
In this mode, the behaviour is that if the resources have already used
with another application, then it blocks the caller, until resources are
free. The non-blocked behaviour (with #SND_PCM_NONBLOCK)
doesn't block the caller in any way and returns -EBUSY error when the
resources are not available. Note that the mode also determines the
behaviour of standard I/O calls, returning -EAGAIN when non-blocked mode is
used and the ring buffer is full (playback) or empty (capture).
The operation mode for I/O calls can be changed later with
the #snd_pcm_nonblock() function.

\section pcm_async Asynchronous mode

There is also possibility to receive asynchronous notification after
specified time periods. You may see the #SND_PCM_ASYNC
mode for #snd_pcm_open() function and
#snd_async_add_pcm_handler() function for further details.

\section pcm_handshake Handshake between application and library

The ALSA PCM API design uses the states to determine the communication
phase between application and library. The actual state can be determined
using #snd_pcm_state() call. There are these states:

\par SND_PCM_STATE_OPEN
The PCM device is in the open state. After the #snd_pcm_open() open call,
the device is in this state. Also, when #snd_pcm_hw_params() call fails,
then this state is entered to force application calling 
#snd_pcm_hw_params() function to set right communication
parameters.

\par SND_PCM_STATE_SETUP
The PCM device has accepted communication parameters and it is waiting
for #snd_pcm_prepare() call to prepare the hardware for
selected operation (playback or capture).

\par SND_PCM_STATE_PREPARE
The PCM device is prepared for operation. Application can use
#snd_pcm_start() call, write or read data to start
the operation.

\par SND_PCM_STATE_RUNNING
The PCM device is running. It processes the samples. The stream can
be stopped using the #snd_pcm_drop() or
#snd_pcm_drain calls.

\par SND_PCM_STATE_XRUN
The PCM device reached overrun (capture) or underrun (playback).
You can use the -EPIPE return code from I/O functions
(#snd_pcm_writei(), #snd_pcm_writen(), #snd_pcm_readi(), #snd_pcm_readn())
to determine this state without checking
the actual state via #snd_pcm_state() call. You can recover from
this state with #snd_pcm_prepare(),
#snd_pcm_drop() or #snd_pcm_drain() calls.

\par SND_PCM_STATE_DRAINING
The device is in this state when application using the capture mode
called #snd_pcm_drain() function. Until all data are
read from the internal ring buffer using I/O routines
(#snd_pcm_readi(), #snd_pcm_readn()),
then the device stays in this state.

\par SND_PCM_STATE_PAUSED
The device is in this state when application called
the #snd_pcm_pause() function until the pause is released.
Not all hardware supports this feature. Application should check the
capability with the #snd_pcm_hw_params_can_pause().

\par SND_PCM_STATE_SUSPENDED
The device is in the suspend state provoked with the power management
system. The stream can be resumed using #snd_pcm_resume()
call, but not all hardware supports this feature. Application should check
the capability with the #snd_pcm_hw_params_can_resume().
In other case, the calls #snd_pcm_prepare(),
#snd_pcm_drop(), #snd_pcm_drain() can be used
to leave this state.

\par SND_PCM_STATE_DISCONNECTED
The device is physicaly disconnected. It does not accept any I/O calls in this state.

\section pcm_formats PCM formats

The full list of formats present the #snd_pcm_format_t type.
The 24-bit linear samples uses 32-bit physical space, but the sample is
stored in low three bits. Some hardware does not support processing of full
range, thus you may get the significant bits for linear samples via
#snd_pcm_hw_params_get_sbits() function. The example: ICE1712
chips support 32-bit sample processing, but low byte is ignored (playback)
or zero (capture). The function snd_pcm_hw_params_get_sbits()
returns 24 in the case.

\section alsa_transfers ALSA transfers

There are two methods to transfer samples in application. The first method
is the standard read / write one. The second method, uses the direct audio
buffer to communicate with the device while ALSA library manages this space
itself. You can find examples of all communication schemes for playback
in \ref example_test_pcm "Sine-wave generator example". To complete the
list, we should note that #snd_pcm_wait() function contains
embedded poll waiting implementation.

\subsection alsa_pcm_rw Read / Write transfer

There are two versions of read / write routines. The first expects the
interleaved samples at input (#SND_PCM_ACCESS_RW_INTERLEAVED access method),
and the second one expects non-interleaved (samples in separated buffers -
#SND_PCM_ACCESS_RW_NONINTERLEAVED access method) at input. There are these
functions for interleaved transfers: #snd_pcm_writei()
#snd_pcm_readi(). For non-interleaved transfers, there are
these functions: #snd_pcm_writen() and #snd_pcm_readn().

\subsection alsa_mmap_rw Direct Read / Write transfer (via mmap'ed areas)

Three kinds of organization of ring buffer memory areas exist in ALSA API.
Access #SND_PCM_ACCESS_MMAP_INTERLEAVED has interleaved samples. Access
#SND_PCM_ACCESS_MMAP_NONINTERLEAVED expects continous sample areas for
one channel. Access #SND_PCM_ACCESS_MMAP_COMPLEX does not fit to interleaved
and non-interleaved ring buffer organization.

There are two functions for this kind of transfer. Application can get an
access to memory areas via #snd_pcm_mmap_begin() function.
This function returns the areas (single area is equal to a channel)
containing the direct pointers to memory and sample position description
in #snd_pcm_channel_area_t structure. After application
transfers the data in the memory areas, then it must be acknowledged
the end of transfer via #snd_pcm_mmap_commit() function
to allow the ALSA library update the pointers to ring buffer. This kind of
communication is also called "zero-copy", because the device does not require
to copy the samples from application to another place in system memory.

If you like to use the compatibility functions in mmap mode, there are
read / write routines equaling to standard read / write transfers. Using
these functions discards the benefits of direct access to memory region.
See the #snd_pcm_mmap_readi(),
#snd_pcm_writei(), #snd_pcm_readn()
and #snd_pcm_writen() functions.

\section pcm_errors Error codes

\par -EPIPE

This error means xrun (underrun for playback or overrun for capture).
The underrun can happen when an application does not feed new samples
in time to alsa-lib (due CPU usage). The overrun can happen when
an application does not take new captured samples in time from alsa-lib.

\par -ESTRPIPE

This error means that system has suspended drivers. The application
should wait in loop when snd_pcm_resume() != -EAGAIN and then
call snd_pcm_prepare() when snd_pcm_resume() return an error code.
If snd_pcm_resume() does not fail (a zero value is returned), driver
supports resume and the snd_pcm_prepare() call can be ommited.

\par -EBADFD

This error means that the device is in a bad state. It means that
the handskahe between application and alsa-lib is corrupted.

\par -ENOTTY, -ENODEV

This error can happen when device is physically removed (for example
some hotplug devices like USB or PCMCIA, CardBus or ExpressCard
can be removed on the fly).

\section pcm_params Managing parameters

The ALSA PCM device uses two groups of PCM related parameters. The hardware
parameters contains the stream description like format, rate, count of
channels, ring buffer size etc. The software parameters contains the
software (driver) related parameters. The communication behaviour can be
controlled via these parameters, like automatic start, automatic stop,
interrupting (chunk acknowledge) etc. The software parameters can be
modified at any time (when valid hardware parameters are set). It includes
the running state as well.

\subsection pcm_hw_params Hardware related parameters

The ALSA PCM devices use the parameter refining system for hardware
parameters - #snd_pcm_hw_params_t. It means, that
application choose the full-range of configurations at first and then
application sets single parameters until all parameters are elementary
(definite).

\par Access modes

ALSA knows about five access modes. The first three can be used for direct
communication. The access mode #SND_PCM_ACCESS_MMAP_INTERLEAVED
determines the direct memory area and interleaved sample organization.
Interleaved organization means, that samples from channels are mixed together.
The access mode #SND_PCM_ACCESS_MMAP_NONINTERLEAVED
determines the direct memory area and non-interleaved sample organization.
Each channel has a separate buffer in the case. The complex direct memory
organization represents the #SND_PCM_ACCESS_MMAP_COMPLEX
access mode. The sample organization does not fit the interleaved or
non-interleaved access modes in the case. The last two access modes
describes the read / write access methods.
The #SND_PCM_ACCESS_RW_INTERLEAVED access represents the read /
write interleaved access and the #SND_PCM_ACCESS_RW_NONINTERLEAVED
represents the non-interleaved access.

\par Formats

The full list of formats is available in #snd_pcm_format_t
enumeration.

\subsection pcm_sw_params Software related parameters

These parameters - #snd_pcm_sw_params_t can be modified at
any time including the running state.

\par Minimum available count of samples

This parameter controls the wakeup point. If the count of available samples
is equal or greater than this value, then application will be activated.

\par Timestamp mode

The timestamp mode specifies, if timestamps are activated. Currently, only
#SND_PCM_TSTAMP_NONE and #SND_PCM_TSTAMP_MMAP
modes are known. The mmap mode means that timestamp is taken
on every period time boundary. Corresponding position in the ring buffer
assigned to timestamp can be obtained using #snd_pcm_htimestamp() function.

\par Transfer align

The read / write transfers can be aligned to this sample count. The modulo
is ignored by device. Usually, this value is set to one (no align).

\par Start threshold

The start threshold parameter is used to determine the start point in
stream. For playback, if samples in ring buffer is equal or greater than
the start threshold parameters and the stream is not running, the stream will
be started automatically from the device. For capture, if the application wants
to read count of samples equal or greater then the stream will be started.
If you want to use explicit start (#snd_pcm_start), you can
set this value greater than ring buffer size (in samples), but use the
constant MAXINT is not a bad idea.

\par Stop threshold

Similarly, the stop threshold parameter is used to automatically stop
the running stream, when the available samples crosses this boundary.
It means, for playback, the empty samples in ring buffer and for capture,
the filled (used) samples in ring buffer.

\par Silence threshold

The silence threshold specifies count of samples filled with silence
ahead of the current application pointer for playback. It is usable
for applications when an overrun is possible (like tasks depending on
network I/O etc.). If application wants to manage the ahead samples itself,
the #snd_pcm_rewind() function allows to forget the last
samples in the stream.

\section pcm_status Obtaining stream status

The stream status is stored in #snd_pcm_status_t structure.
These parameters can be obtained: the current stream state -
#snd_pcm_status_get_state(), timestamp of trigger -
#snd_pcm_status_get_trigger_tstamp(), timestamp of last
pointer update #snd_pcm_status_get_tstamp(), delay in samples -
#snd_pcm_status_get_delay(), available count in samples -
#snd_pcm_status_get_avail(), maximum available samples -
#snd_pcm_status_get_avail_max(), ADC over-range count in
samples - #snd_pcm_status_get_overrange(). The last two
parameters - avail_max and overrange are reset to zero after the status
call.

\subsection pcm_status_fast Obtaining stream state fast and update r/w pointer

<p>
The function #snd_pcm_avail_update() updates the current
available count of samples for writing (playback) or filled samples for
reading (capture). This call is mandatory for updating actual r/w pointer.
Using standalone, it is a light method to obtain current stream position,
because it does not require the user <-> kernel context switch, but the value
is less accurate, because ring buffer pointers are updated in kernel drivers
only when an interrupt occurs. If you want to get accurate stream state,
use functions #snd_pcm_avail(), #snd_pcm_delay() or #snd_pcm_avail_delay().
</p>
<p>
The function #snd_pcm_avail() reads the current hardware pointer
in the ring buffer from hardware and calls #snd_pcm_avail_update() then.
</p>
<p>
The function #snd_pcm_delay() returns the delay in samples.
For playback, it means count of samples in the ring buffer before
the next sample will be sent to DAC. For capture, it means count of samples
in the ring buffer before the next sample will be captured from ADC. It works
only when the stream is in the running or draining (playback only) state.
Note that this function does not update the current r/w pointer for applications,
so the function #snd_pcm_avail_update() must be called afterwards
before any read/write begin+commit operations.
</p>
<p>
The function #snd_pcm_avail_delay() combines #snd_pcm_avail() and
#snd_pcm_delay() and returns both values in sync.
</p>

\section pcm_action Managing the stream state

The following functions directly and indirectly affect the stream state:

\par snd_pcm_hw_params
The #snd_pcm_hw_params() function brings the stream state
to #SND_PCM_STATE_SETUP
if successfully finishes, otherwise the state #SND_PCM_STATE_OPEN
is entered.
When it is brought to SETUP state, this function automatically
calls #snd_pcm_prepare() function to bring to the PREPARE state
as below.

\par snd_pcm_prepare
The #snd_pcm_prepare() function enters from #SND_PCM_STATE_SETUP
to the #SND_PCM_STATE_PREPARED after a successful finish.

\par snd_pcm_start
The #snd_pcm_start() function enters
the #SND_PCM_STATE_RUNNING after a successful finish.

\par snd_pcm_drop
The #snd_pcm_drop() function enters the
#SND_PCM_STATE_SETUP state.

\par snd_pcm_drain
The #snd_pcm_drain() function enters the
#SND_PCM_STATE_DRAINING, if
the capture device has some samples in the ring buffer otherwise
#SND_PCM_STATE_SETUP state is entered.

\par snd_pcm_pause
The #snd_pcm_pause() function enters the
#SND_PCM_STATE_PAUSED or #SND_PCM_STATE_RUNNING.

\par snd_pcm_writei, snd_pcm_writen
The #snd_pcm_writei() and #snd_pcm_writen()
functions can conditionally start the stream -
#SND_PCM_STATE_RUNNING. They depend on the start threshold
software parameter.

\par snd_pcm_readi, snd_pcm_readn
The #snd_pcm_readi() and #snd_pcm_readn()
functions can conditionally start the stream -
#SND_PCM_STATE_RUNNING. They depend on the start threshold
software parameter.

\section pcm_sync Streams synchronization

There are two functions allowing link multiple streams together. In the
case, the linking means that all operations are synchronized. Because the
drivers cannot guarantee the synchronization (sample resolution) on hardware
lacking this feature, the #snd_pcm_info_get_sync() function
returns synchronization ID - #snd_pcm_sync_id_t, which is equal
for hardware synchronized streams. When the #snd_pcm_link()
function is called, all operations managing the stream state for these two
streams are joined. The opposite function is #snd_pcm_unlink().

\section pcm_dev_names PCM naming conventions

The ALSA library uses a generic string representation for names of devices.
The devices might be virtual, physical or a mix of both. The generic string
is passed to #snd_pcm_open() or #snd_pcm_open_lconf().
It contains two parts: device name and arguments. Devices and arguments are described
in configuration files. The usual place for default definitions is at /usr/share/alsa/alsa.conf.
For detailed descriptions about integrated PCM plugins look to \ref pcm_plugins.

\subsection pcm_dev_names_default Default device

The default device is equal to plug plugin with hw plugin as slave. The defaults are
used:

\code
defaults.pcm.card 0
defaults.pcm.device 0
defaults.pcm.subdevice -1
\endcode

These defaults can be freely overwritten in local configuration files.

Example:

\code
default
\endcode

\subsection pcm_dev_names_hw HW device

The hw device description uses the hw plugin. The three arguments (in order: CARD,DEV,SUBDEV)
specify card number or identifier, device number and subdevice number (-1 means any).

Example:

\code
hw
hw:0
hw:0,0
hw:supersonic,1
hw:soundwave,1,2
hw:DEV=1,CARD=soundwave,SUBDEV=2
\endcode

\subsection pcm_dev_names_plughw Plug->HW device

The plughw device description uses the plug plugin and hw plugin as slave. The arguments
are same as for hw device.

Example:

\code
plughw
plughw:0
plughw:0,0
plughw:supersonic,1
plughw:soundwave,1,2
plughw:DEV=1,CARD=soundwave,SUBDEV=2
\endcode

\subsection pcm_dev_names_plug Plug device

The plug device uses the plug plugin. The one SLAVE argument specifies the slave plugin.

Example:

\code
plug:mypcmdef
plug:hw
plug:'hw:0,0'
plug:SLAVE=hw
\endcode

\subsection pcm_dev_names_shm Shared memory device

The shm device uses the shm plugin. The two arguments (in order: SOCKET,PCM) specify
UNIX socket name (for example /tmp/alsa.socket) for server communication and server's PCM name.

Example:

\code
shm:'/tmp/alsa.sock',default
shm:SOCKET='/tmp/alsa.sock',PCM=default
\endcode

\subsection pcm_dev_names_tee Tee device

The tee device stores contents of a stream to given file plus transfers it to given slave plugin.
The three arguments (in order: SLAVE,FILE,FORMAT) specify slave plugin, filename and file format.

Example:

\code
tee:hw,'/tmp/out.raw',raw
\endcode

\subsection pcm_dev_names_file File device

The file device is file plugin with null plugin as slave. The arguments (in order: FILE,FORMAT)
specify filename and file format.

Example:

\code
file:'/tmp/out.raw',raw
\endcode

\subsection pcm_dev_names_null Null device

The null device is null plugin. This device has not any arguments.


\section pcm_examples Examples

The full featured examples with cross-links can be found in Examples section
(see top of page):

\anchor example_test_pcm
\par Sine-wave generator
\par
alsa-lib/test/pcm.c example shows various transfer methods for the playback direction.

\par Minimalistic PCM playback code
\par
alsa-lib/test/pcm_min.c example shows the minimal code to produce a sound.

\par Latency measuring tool
\par
alsa-lib/test/latency.c example shows the measuring of minimal latency between capture and
playback devices.

*/

/**
\example ../../test/pcm.c
*/
/**
\example ../../test/pcm_min.c
*/
/**
\example ../../test/latency.c
*/

#include <stdio.h>
#include <string.h>
#include <malloc.h>
#include <stdarg.h>
#include <signal.h>
#include <sys/poll.h>
#include <sys/shm.h>
#include <sys/mman.h>
#include <limits.h>
#include "pcm_local.h"

/**
 * \brief get identifier of PCM handle
 * \param pcm PCM handle
 * \return ascii identifier of PCM handle
 *
 * Returns the ASCII identifier of given PCM handle. It's the same
 * identifier specified in snd_pcm_open().
 */
const char *snd_pcm_name(snd_pcm_t *pcm)
{
        assert(pcm);
        return pcm->name;
}

/**
 * \brief get type of PCM handle
 * \param pcm PCM handle
 * \return type of PCM handle
 *
 * Returns the type #snd_pcm_type_t of given PCM handle.
 */
snd_pcm_type_t snd_pcm_type(snd_pcm_t *pcm)
{
        assert(pcm);
        return pcm->type;
}

/**
 * \brief get stream for a PCM handle
 * \param pcm PCM handle
 * \return stream of PCM handle
 *
 * Returns the type #snd_pcm_stream_t of given PCM handle.
 */
snd_pcm_stream_t snd_pcm_stream(snd_pcm_t *pcm)
{
        assert(pcm);
        return pcm->stream;
}

/**
 * \brief close PCM handle
 * \param pcm PCM handle
 * \return 0 on success otherwise a negative error code
 *
 * Closes the specified PCM handle and frees all associated
 * resources.
 */
int snd_pcm_close(snd_pcm_t *pcm)
{
        int res = 0, err;
        assert(pcm);
        if (pcm->setup && !pcm->donot_close) {
                snd_pcm_drop(pcm);
                err = snd_pcm_hw_free(pcm);
                if (err < 0)
                        res = err;
        }
        if (pcm->mmap_channels)
                snd_pcm_munmap(pcm);
        while (!list_empty(&pcm->async_handlers)) {
                snd_async_handler_t *h = list_entry(pcm->async_handlers.next, snd_async_handler_t, hlist);
                snd_async_del_handler(h);
        }
        err = pcm->ops->close(pcm->op_arg);
        if (err < 0)
                res = err;
        err = snd_pcm_free(pcm);
        if (err < 0)
                res = err;
        return res;
}       

/**
 * \brief set nonblock mode
 * \param pcm PCM handle
 * \param nonblock 0 = block, 1 = nonblock mode
 * \return 0 on success otherwise a negative error code
 */
int snd_pcm_nonblock(snd_pcm_t *pcm, int nonblock)
{
        int err;
        assert(pcm);
        if ((err = pcm->ops->nonblock(pcm->op_arg, nonblock)) < 0)
                return err;
        if (nonblock)
                pcm->mode |= SND_PCM_NONBLOCK;
        else
                pcm->mode &= ~SND_PCM_NONBLOCK;
        return 0;
}

#ifndef DOC_HIDDEN
/**
 * \brief set async mode
 * \param pcm PCM handle
 * \param sig Signal to raise: < 0 disable, 0 default (SIGIO)
 * \param pid Process ID to signal: 0 current
 * \return 0 on success otherwise a negative error code
 *
 * A signal is raised every period.
 */
int snd_pcm_async(snd_pcm_t *pcm, int sig, pid_t pid)
{
        assert(pcm);
        if (sig == 0)
                sig = SIGIO;
        if (pid == 0)
                pid = getpid();
        return pcm->ops->async(pcm->op_arg, sig, pid);
}
#endif

/**
 * \brief Obtain general (static) information for PCM handle
 * \param pcm PCM handle
 * \param info Information container
 * \return 0 on success otherwise a negative error code
 */
int snd_pcm_info(snd_pcm_t *pcm, snd_pcm_info_t *info)
{
        assert(pcm && info);
        return pcm->ops->info(pcm->op_arg, info);
}

/** \brief Retreive current PCM hardware configuration chosen with #snd_pcm_hw_params
 * \param pcm PCM handle
 * \param params Configuration space definition container
 * \return 0 on success otherwise a negative error code
 */
int snd_pcm_hw_params_current(snd_pcm_t *pcm, snd_pcm_hw_params_t *params)
{
        unsigned int frame_bits;

        assert(pcm && params);
        if (!pcm->setup)
                return -EBADFD;
        memset(params, 0, snd_pcm_hw_params_sizeof());
        params->flags = pcm->hw_flags;
        snd_mask_set(&params->masks[SND_PCM_HW_PARAM_ACCESS - SND_PCM_HW_PARAM_FIRST_MASK], pcm->access);
        snd_mask_set(&params->masks[SND_PCM_HW_PARAM_FORMAT - SND_PCM_HW_PARAM_FIRST_MASK], pcm->format);
        snd_mask_set(&params->masks[SND_PCM_HW_PARAM_SUBFORMAT - SND_PCM_HW_PARAM_FIRST_MASK], pcm->subformat);
        frame_bits = snd_pcm_format_physical_width(pcm->format) * pcm->channels;
        snd_interval_set_value(&params->intervals[SND_PCM_HW_PARAM_FRAME_BITS - SND_PCM_HW_PARAM_FIRST_INTERVAL], frame_bits);
        snd_interval_set_value(&params->intervals[SND_PCM_HW_PARAM_CHANNELS - SND_PCM_HW_PARAM_FIRST_INTERVAL], pcm->channels);
        snd_interval_set_value(&params->intervals[SND_PCM_HW_PARAM_RATE - SND_PCM_HW_PARAM_FIRST_INTERVAL], pcm->rate);
        snd_interval_set_value(&params->intervals[SND_PCM_HW_PARAM_PERIOD_TIME - SND_PCM_HW_PARAM_FIRST_INTERVAL], pcm->period_time);
        snd_interval_set_value(&params->intervals[SND_PCM_HW_PARAM_PERIOD_SIZE - SND_PCM_HW_PARAM_FIRST_INTERVAL], pcm->period_size);
        snd_interval_copy(&params->intervals[SND_PCM_HW_PARAM_PERIODS - SND_PCM_HW_PARAM_FIRST_INTERVAL], &pcm->periods);
        snd_interval_copy(&params->intervals[SND_PCM_HW_PARAM_BUFFER_TIME - SND_PCM_HW_PARAM_FIRST_INTERVAL], &pcm->buffer_time);
        snd_interval_set_value(&params->intervals[SND_PCM_HW_PARAM_BUFFER_SIZE - SND_PCM_HW_PARAM_FIRST_INTERVAL], pcm->buffer_size);
        snd_interval_set_value(&params->intervals[SND_PCM_HW_PARAM_BUFFER_BYTES - SND_PCM_HW_PARAM_FIRST_INTERVAL], (pcm->buffer_size * frame_bits) / 8);
        params->info = pcm->info;
        params->msbits = pcm->msbits;
        params->rate_num = pcm->rate_num;
        params->rate_den = pcm->rate_den;
        params->fifo_size = pcm->fifo_size;
        return 0;
} 

/** \brief Install one PCM hardware configuration chosen from a configuration space and #snd_pcm_prepare it
 * \param pcm PCM handle
 * \param params Configuration space definition container
 * \return 0 on success otherwise a negative error code
 *
 * The configuration is chosen fixing single parameters in this order:
 * first access, first format, first subformat, min channels, min rate, 
 * min period time, max buffer size, min tick time
 *
 * After this call, #snd_pcm_prepare() is called automatically and
 * the stream is brought to \c #SND_PCM_STATE_PREPARED state.
 *
 * The hardware parameters cannot be changed when the stream is
 * running (active). The software parameters can be changed
 * at any time.
 */
int snd_pcm_hw_params(snd_pcm_t *pcm, snd_pcm_hw_params_t *params)
{
        int err;
        assert(pcm && params);
        err = _snd_pcm_hw_params(pcm, params);
        if (err < 0)
                return err;
        err = snd_pcm_prepare(pcm);
        return err;
}

/** \brief Remove PCM hardware configuration and free associated resources
 * \param pcm PCM handle
 * \return 0 on success otherwise a negative error code
 */
int snd_pcm_hw_free(snd_pcm_t *pcm)
{
        int err;
        if (! pcm->setup)
                return 0;
        if (pcm->mmap_channels) {
                err = snd_pcm_munmap(pcm);
                if (err < 0)
                        return err;
        }
        // assert(snd_pcm_state(pcm) == SND_PCM_STATE_SETUP ||
        //        snd_pcm_state(pcm) == SND_PCM_STATE_PREPARED);
        err = pcm->ops->hw_free(pcm->op_arg);
        pcm->setup = 0;
        if (err < 0)
                return err;
        return 0;
}

/** \brief Install PCM software configuration defined by params
 * \param pcm PCM handle
 * \param params Configuration container
 * \return 0 on success otherwise a negative error code
 *
 * The software parameters can be changed at any time.
 * The hardware parameters cannot be changed when the stream is
 * running (active).
 */
int snd_pcm_sw_params(snd_pcm_t *pcm, snd_pcm_sw_params_t *params)
{
        int err;
        /* the hw_params must be set at first!!! */
        if (CHECK_SANITY(! pcm->setup)) {
                SNDMSG("PCM not set up");
                return -EIO;
        }
        if (! params->avail_min) {
                SNDMSG("params->avail_min is 0");
                return -EINVAL;
        }
#if 0
        /* disable the check below - it looks too restrictive
         * (start_threshold is basically independent from avail_min)
         */
        if (params->start_threshold <= pcm->buffer_size &&
            params->start_threshold > (pcm->buffer_size / params->avail_min) * params->avail_min) {
                SNDMSG("params->avail_min problem for start_threshold");
                return -EINVAL;
        }
#endif
        err = pcm->ops->sw_params(pcm->op_arg, params);
        if (err < 0)
                return err;
        pcm->tstamp_mode = params->tstamp_mode;
        pcm->period_step = params->period_step;
        pcm->avail_min = params->avail_min;
        pcm->period_event = params->period_event;
        pcm->start_threshold = params->start_threshold;
        pcm->stop_threshold = params->stop_threshold;
        pcm->silence_threshold = params->silence_threshold;
        pcm->silence_size = params->silence_size;
        pcm->boundary = params->boundary;
        return 0;
}

/**
 * \brief Obtain status (runtime) information for PCM handle
 * \param pcm PCM handle
 * \param status Status container
 * \return 0 on success otherwise a negative error code
 */
int snd_pcm_status(snd_pcm_t *pcm, snd_pcm_status_t *status)
{
        assert(pcm && status);
        return pcm->fast_ops->status(pcm->fast_op_arg, status);
}

/**
 * \brief Return PCM state
 * \param pcm PCM handle
 * \return PCM state #snd_pcm_state_t of given PCM handle
 *
 * This is a faster way to obtain only the PCM state without calling
 * \link ::snd_pcm_status() \endlink.
 */
snd_pcm_state_t snd_pcm_state(snd_pcm_t *pcm)
{
        assert(pcm);
        return pcm->fast_ops->state(pcm->fast_op_arg);
}

/**
 * \brief (DEPRECATED) Synchronize stream position with hardware
 * \param pcm PCM handle
 * \return 0 on success otherwise a negative error code
 *
 * Note this function does not update the actual r/w pointer
 * for applications. The function #snd_pcm_avail_update()
 * have to be called before any mmap begin+commit operation.
 */
int snd_pcm_hwsync(snd_pcm_t *pcm)
{
        assert(pcm);
        if (CHECK_SANITY(! pcm->setup)) {
                SNDMSG("PCM not set up");
                return -EIO;
        }
        return pcm->fast_ops->hwsync(pcm->fast_op_arg);
}
#ifndef DOC_HIDDEN
link_warning(snd_pcm_hwsync, "Warning: snd_pcm_hwsync() is deprecated, consider to use snd_pcm_avail()");
#endif

/**
 * \brief Obtain delay for a running PCM handle
 * \param pcm PCM handle
 * \param delayp Returned delay in frames
 * \return 0 on success otherwise a negative error code
 *
 * For playback the delay is defined as the time that a frame that is written
 * to the PCM stream shortly after this call will take to be actually
 * audible. It is as such the overall latency from the write call to the final
 * DAC.
 *
 * For capture the delay is defined as the time that a frame that was
 * digitized by the audio device takes until it can be read from the PCM
 * stream shortly after this call returns. It is as such the overall latency
 * from the initial ADC to the read call.
 *
 * Please note that hence in case of a playback underrun this value will not
 * necessarily got down to 0.
 *
 * If the application is interested in the fill level of the playback buffer
 * of the device, it should use #snd_pcm_avail*() functions. The
 * value returned by that call is not directly related to the delay, since the
 * latter might include some additional, fixed latencies the former does not.
 *
 * Note this function does not update the actual r/w pointer
 * for applications. The function #snd_pcm_avail_update()
 * have to be called before any begin+commit operation.
 */
int snd_pcm_delay(snd_pcm_t *pcm, snd_pcm_sframes_t *delayp)
{
        assert(pcm);
        if (CHECK_SANITY(! pcm->setup)) {
                SNDMSG("PCM not set up");
                return -EIO;
        }
        return pcm->fast_ops->delay(pcm->fast_op_arg, delayp);
}

/**
 * \brief Resume from suspend, no samples are lost
 * \param pcm PCM handle
 * \return 0 on success otherwise a negative error code
 * \retval -EAGAIN resume can't be proceed immediately (audio hardware is probably still suspended)
 * \retval -ENOSYS hardware doesn't support this feature
 *
 * This function can be used when the stream is in the suspend state
 * to do the fine resume from this state. Not all hardware supports
 * this feature, when an -ENOSYS error is returned, use the \link ::snd_pcm_prepare() \endlink
 * function to recovery.
 */
int snd_pcm_resume(snd_pcm_t *pcm)
{
        assert(pcm);
        if (CHECK_SANITY(! pcm->setup)) {
                SNDMSG("PCM not set up");
                return -EIO;
        }
        return pcm->fast_ops->resume(pcm->fast_op_arg);
}

/**
 * \brief Obtain last position update hi-res timestamp
 * \param pcm PCM handle
 * \param avail Number of available frames when timestamp was grabbed
 * \param tstamp Hi-res timestamp
 * \return 0 on success otherwise a negative error code
 *
 * Note this function does not update the actual r/w pointer
 * for applications.
 */
int snd_pcm_htimestamp(snd_pcm_t *pcm, snd_pcm_uframes_t *avail, snd_htimestamp_t *tstamp)
{
        assert(pcm);
        if (CHECK_SANITY(! pcm->setup)) {
                SNDMSG("PCM not set up");
                return -EIO;
        }
        return pcm->fast_ops->htimestamp(pcm->fast_op_arg, avail, tstamp);
}

/**
 * \brief Prepare PCM for use
 * \param pcm PCM handle
 * \return 0 on success otherwise a negative error code
 */
int snd_pcm_prepare(snd_pcm_t *pcm)
{
        assert(pcm);
        if (CHECK_SANITY(! pcm->setup)) {
                SNDMSG("PCM not set up");
                return -EIO;
        }
        return pcm->fast_ops->prepare(pcm->fast_op_arg);
}

/**
 * \brief Reset PCM position
 * \param pcm PCM handle
 * \return 0 on success otherwise a negative error code
 *
 * Reduce PCM delay to 0.
 */
int snd_pcm_reset(snd_pcm_t *pcm)
{
        assert(pcm);
        if (CHECK_SANITY(! pcm->setup)) {
                SNDMSG("PCM not set up");
                return -EIO;
        }
        return pcm->fast_ops->reset(pcm->fast_op_arg);
}

/**
 * \brief Start a PCM
 * \param pcm PCM handle
 * \return 0 on success otherwise a negative error code
 */
int snd_pcm_start(snd_pcm_t *pcm)
{
        assert(pcm);
        if (CHECK_SANITY(! pcm->setup)) {
                SNDMSG("PCM not set up");
                return -EIO;
        }
        return pcm->fast_ops->start(pcm->fast_op_arg);
}

/**
 * \brief Stop a PCM dropping pending frames
 * \param pcm PCM handle
 * \return 0 on success otherwise a negative error code
 *
 * This function stops the PCM <i>immediately</i>.
 * The pending samples on the buffer are ignored.
 *
 * For processing all pending samples, use \link ::snd_pcm_drain() \endlink
 * instead.
 */
int snd_pcm_drop(snd_pcm_t *pcm)
{
        assert(pcm);
        if (CHECK_SANITY(! pcm->setup)) {
                SNDMSG("PCM not set up");
                return -EIO;
        }
        return pcm->fast_ops->drop(pcm->fast_op_arg);
}

/**
 * \brief Stop a PCM preserving pending frames
 * \param pcm PCM handle
 * \return 0 on success otherwise a negative error code
 * \retval -ESTRPIPE a suspend event occurred
 *
 * For playback wait for all pending frames to be played and then stop
 * the PCM.
 * For capture stop PCM permitting to retrieve residual frames.
 *
 * For stopping the PCM stream immediately, use \link ::snd_pcm_drop() \endlink
 * instead.
 */
int snd_pcm_drain(snd_pcm_t *pcm)
{
        assert(pcm);
        if (CHECK_SANITY(! pcm->setup)) {
                SNDMSG("PCM not set up");
                return -EIO;
        }
        return pcm->fast_ops->drain(pcm->fast_op_arg);
}

/**
 * \brief Pause/resume PCM
 * \param pcm PCM handle
 * \param enable 0 = resume, 1 = pause
 * \return 0 on success otherwise a negative error code
 *
 * Note that this function works only on the hardware which supports
 * pause feature.  You can check it via \link ::snd_pcm_hw_params_can_pause() \endlink
 * function.
 */
int snd_pcm_pause(snd_pcm_t *pcm, int enable)
{
        assert(pcm);
        if (CHECK_SANITY(! pcm->setup)) {
                SNDMSG("PCM not set up");
                return -EIO;
        }
        return pcm->fast_ops->pause(pcm->fast_op_arg, enable);
}

/**
 * \brief Get safe count of frames which can be rewinded
 * \param pcm PCM handle
 * \return a positive number of frames or negative error code
 *
 * Note: The snd_pcm_rewind() can accept bigger value than returned
 * by this function. But it is not guaranteed that output stream
 * will be consistent with bigger value.
 */
snd_pcm_sframes_t snd_pcm_rewindable(snd_pcm_t *pcm)
{
        assert(pcm);
        if (CHECK_SANITY(! pcm->setup)) {
                SNDMSG("PCM not set up");
                return -EIO;
        }
        return pcm->fast_ops->rewindable(pcm->fast_op_arg);
}

/**
 * \brief Move application frame position backward
 * \param pcm PCM handle
 * \param frames wanted displacement in frames
 * \return a positive number for actual displacement otherwise a
 * negative error code
 */
snd_pcm_sframes_t snd_pcm_rewind(snd_pcm_t *pcm, snd_pcm_uframes_t frames)
{
        assert(pcm);
        if (CHECK_SANITY(! pcm->setup)) {
                SNDMSG("PCM not set up");
                return -EIO;
        }
        if (frames == 0)
                return 0;
        return pcm->fast_ops->rewind(pcm->fast_op_arg, frames);
}

/**
 * \brief Get safe count of frames which can be forwarded
 * \param pcm PCM handle
 * \return a positive number of frames or negative error code
 *
 * Note: The snd_pcm_forward() can accept bigger value than returned
 * by this function. But it is not guaranteed that output stream
 * will be consistent with bigger value.
 */
snd_pcm_sframes_t snd_pcm_forwardable(snd_pcm_t *pcm)
{
        assert(pcm);
        if (CHECK_SANITY(! pcm->setup)) {
                SNDMSG("PCM not set up");
                return -EIO;
        }
        return pcm->fast_ops->forwardable(pcm->fast_op_arg);
}

/**
 * \brief Move application frame position forward
 * \param pcm PCM handle
 * \param frames wanted skip in frames
 * \return a positive number for actual skip otherwise a negative error code
 * \retval 0 means no action
 */
#ifndef DOXYGEN
snd_pcm_sframes_t INTERNAL(snd_pcm_forward)(snd_pcm_t *pcm, snd_pcm_uframes_t frames)
#else
snd_pcm_sframes_t snd_pcm_forward(snd_pcm_t *pcm, snd_pcm_uframes_t frames)
#endif
{
        assert(pcm);
        if (CHECK_SANITY(! pcm->setup)) {
                SNDMSG("PCM not set up");
                return -EIO;
        }
        if (frames == 0)
                return 0;
        return pcm->fast_ops->forward(pcm->fast_op_arg, frames);
}
use_default_symbol_version(__snd_pcm_forward, snd_pcm_forward, ALSA_0.9.0rc8);

/**
 * \brief Write interleaved frames to a PCM
 * \param pcm PCM handle
 * \param buffer frames containing buffer
 * \param size frames to be written
 * \return a positive number of frames actually written otherwise a
 * negative error code
 * \retval -EBADFD PCM is not in the right state (#SND_PCM_STATE_PREPARED or #SND_PCM_STATE_RUNNING)
 * \retval -EPIPE an underrun occurred
 * \retval -ESTRPIPE a suspend event occurred (stream is suspended and waiting for an application recovery)
 *
 * If the blocking behaviour is selected, then routine waits until
 * all requested bytes are played or put to the playback ring buffer.
 * The count of bytes can be less only if a signal or underrun occurred.
 *
 * If the non-blocking behaviour is selected, then routine doesn't wait at all.
 */ 
snd_pcm_sframes_t snd_pcm_writei(snd_pcm_t *pcm, const void *buffer, snd_pcm_uframes_t size)
{
        assert(pcm);
        assert(size == 0 || buffer);
        if (CHECK_SANITY(! pcm->setup)) {
                SNDMSG("PCM not set up");
                return -EIO;
        }
        if (pcm->access != SND_PCM_ACCESS_RW_INTERLEAVED) {
                SNDMSG("invalid access type %s", snd_pcm_access_name(pcm->access));
                return -EINVAL;
        }
        return _snd_pcm_writei(pcm, buffer, size);
}

/**
 * \brief Write non interleaved frames to a PCM
 * \param pcm PCM handle
 * \param bufs frames containing buffers (one for each channel)
 * \param size frames to be written
 * \return a positive number of frames actually written otherwise a
 * negative error code
 * \retval -EBADFD PCM is not in the right state (#SND_PCM_STATE_PREPARED or #SND_PCM_STATE_RUNNING)
 * \retval -EPIPE an underrun occurred
 * \retval -ESTRPIPE a suspend event occurred (stream is suspended and waiting for an application recovery)
 *
 * If the blocking behaviour is selected, then routine waits until
 * all requested bytes are played or put to the playback ring buffer.
 * The count of bytes can be less only if a signal or underrun occurred.
 *
 * If the non-blocking behaviour is selected, then routine doesn't wait at all.
 */ 
snd_pcm_sframes_t snd_pcm_writen(snd_pcm_t *pcm, void **bufs, snd_pcm_uframes_t size)
{
        assert(pcm);
        assert(size == 0 || bufs);
        if (CHECK_SANITY(! pcm->setup)) {
                SNDMSG("PCM not set up");
                return -EIO;
        }
        if (pcm->access != SND_PCM_ACCESS_RW_NONINTERLEAVED) {
                SNDMSG("invalid access type %s", snd_pcm_access_name(pcm->access));
                return -EINVAL;
        }
        return _snd_pcm_writen(pcm, bufs, size);
}

/**
 * \brief Read interleaved frames from a PCM
 * \param pcm PCM handle
 * \param buffer frames containing buffer
 * \param size frames to be read
 * \return a positive number of frames actually read otherwise a
 * negative error code
 * \retval -EBADFD PCM is not in the right state (#SND_PCM_STATE_PREPARED or #SND_PCM_STATE_RUNNING)
 * \retval -EPIPE an overrun occurred
 * \retval -ESTRPIPE a suspend event occurred (stream is suspended and waiting for an application recovery)
 *
 * If the blocking behaviour was selected, then routine waits until
 * all requested bytes are filled. The count of bytes can be less only
 * if a signal or underrun occurred.
 *
 * If the non-blocking behaviour is selected, then routine doesn't wait at all.
 */ 
snd_pcm_sframes_t snd_pcm_readi(snd_pcm_t *pcm, void *buffer, snd_pcm_uframes_t size)
{
        assert(pcm);
        assert(size == 0 || buffer);
        if (CHECK_SANITY(! pcm->setup)) {
                SNDMSG("PCM not set up");
                return -EIO;
        }
        if (pcm->access != SND_PCM_ACCESS_RW_INTERLEAVED) {
                SNDMSG("invalid access type %s", snd_pcm_access_name(pcm->access));
                return -EINVAL;
        }
        return _snd_pcm_readi(pcm, buffer, size);
}

/**
 * \brief Read non interleaved frames to a PCM
 * \param pcm PCM handle
 * \param bufs frames containing buffers (one for each channel)
 * \param size frames to be read
 * \return a positive number of frames actually read otherwise a
 * negative error code
 * \retval -EBADFD PCM is not in the right state (#SND_PCM_STATE_PREPARED or #SND_PCM_STATE_RUNNING)
 * \retval -EPIPE an overrun occurred
 * \retval -ESTRPIPE a suspend event occurred (stream is suspended and waiting for an application recovery)
 *
 * If the blocking behaviour was selected, then routine waits until
 * all requested bytes are filled. The count of bytes can be less only
 * if a signal or underrun occurred.
 *
 * If the non-blocking behaviour is selected, then routine doesn't wait at all.
 */ 
snd_pcm_sframes_t snd_pcm_readn(snd_pcm_t *pcm, void **bufs, snd_pcm_uframes_t size)
{
        assert(pcm);
        assert(size == 0 || bufs);
        if (CHECK_SANITY(! pcm->setup)) {
                SNDMSG("PCM not set up");
                return -EIO;
        }
        if (pcm->access != SND_PCM_ACCESS_RW_NONINTERLEAVED) {
                SNDMSG("invalid access type %s", snd_pcm_access_name(pcm->access));
                return -EINVAL;
        }
        return _snd_pcm_readn(pcm, bufs, size);
}

/**
 * \brief Link two PCMs
 * \param pcm1 first PCM handle
 * \param pcm2 first PCM handle
 * \return 0 on success otherwise a negative error code
 *
 * The two PCMs will start/stop/prepare in sync.
 */ 
int snd_pcm_link(snd_pcm_t *pcm1, snd_pcm_t *pcm2)
{
        assert(pcm1);
        assert(pcm2);
        if (pcm1->fast_ops->link)
                return pcm1->fast_ops->link(pcm1, pcm2);
        return -ENOSYS;
}

/**
 * \brief Remove a PCM from a linked group
 * \param pcm PCM handle
 * \return 0 on success otherwise a negative error code
 */
int snd_pcm_unlink(snd_pcm_t *pcm)
{
        assert(pcm);
        if (pcm->fast_ops->unlink)
                return pcm->fast_ops->unlink(pcm);
        return -ENOSYS;
}

/**
 * \brief get count of poll descriptors for PCM handle
 * \param pcm PCM handle
 * \return count of poll descriptors
 */
int snd_pcm_poll_descriptors_count(snd_pcm_t *pcm)
{
        assert(pcm);
        if (pcm->fast_ops->poll_descriptors_count)
                return pcm->fast_ops->poll_descriptors_count(pcm->fast_op_arg);
        return pcm->poll_fd_count;
}


/**
 * \brief get poll descriptors
 * \param pcm PCM handle
 * \param pfds array of poll descriptors
 * \param space space in the poll descriptor array
 * \return count of filled descriptors
 *
 * This function fills the given poll descriptor structs for the specified
 * PCM handle.  The poll desctiptor array should have the size returned by
 * \link ::snd_pcm_poll_descriptors_count() \endlink function.
 *
 * The result is intended for direct use with the poll() syscall.
 *
 * For reading the returned events of poll descriptor after poll() system
 * call, use \link ::snd_pcm_poll_descriptors_revents() \endlink function.
 * The field values in pollfd structs may be bogus regarding the stream
 * direction from the application perspective (POLLIN might not imply read
 * direction and POLLOUT might not imply write), but
 * the \link ::snd_pcm_poll_descriptors_revents() \endlink function
 * does the right "demangling".
 *
 * You can use output from this function as arguments for the select()
 * syscall, too.
 */
int snd_pcm_poll_descriptors(snd_pcm_t *pcm, struct pollfd *pfds, unsigned int space)
{
        assert(pcm && pfds);
        if (pcm->fast_ops->poll_descriptors)
                return pcm->fast_ops->poll_descriptors(pcm->fast_op_arg, pfds, space);
        if (pcm->poll_fd < 0) {
                SNDMSG("poll_fd < 0");
                return -EIO;
        }
        if (space >= 1 && pfds) {
                pfds->fd = pcm->poll_fd;
                pfds->events = pcm->poll_events | POLLERR | POLLNVAL;
        } else {
                return 0;
        }
        return 1;
}

/**
 * \brief get returned events from poll descriptors
 * \param pcm PCM handle
 * \param pfds array of poll descriptors
 * \param nfds count of poll descriptors
 * \param revents returned events
 * \return zero if success, otherwise a negative error code
 *
 * This function does "demangling" of the revents mask returned from
 * the poll() syscall to correct semantics (POLLIN = read, POLLOUT = write).
 *
 * Note: The null event also exists. Even if poll() or select()
 * syscall returned that some events are waiting, this function might
 * return empty set of events. In this case, application should
 * do next event waiting using poll() or select().
 */
int snd_pcm_poll_descriptors_revents(snd_pcm_t *pcm, struct pollfd *pfds, unsigned int nfds, unsigned short *revents)
{
        assert(pcm && pfds && revents);
        if (pcm->fast_ops->poll_revents)
                return pcm->fast_ops->poll_revents(pcm->fast_op_arg, pfds, nfds, revents);
        if (nfds == 1) {
                *revents = pfds->revents;
                return 0;
        }
        return -EINVAL;
}

#ifndef DOC_HIDDEN
#define PCMTYPE(v) [SND_PCM_TYPE_##v] = #v
#define STATE(v) [SND_PCM_STATE_##v] = #v
#define STREAM(v) [SND_PCM_STREAM_##v] = #v
#define READY(v) [SND_PCM_READY_##v] = #v
#define XRUN(v) [SND_PCM_XRUN_##v] = #v
#define SILENCE(v) [SND_PCM_SILENCE_##v] = #v
#define TSTAMP(v) [SND_PCM_TSTAMP_##v] = #v
#define ACCESS(v) [SND_PCM_ACCESS_##v] = #v
#define START(v) [SND_PCM_START_##v] = #v
#define HW_PARAM(v) [SND_PCM_HW_PARAM_##v] = #v
#define SW_PARAM(v) [SND_PCM_SW_PARAM_##v] = #v
#define FORMAT(v) [SND_PCM_FORMAT_##v] = #v
#define SUBFORMAT(v) [SND_PCM_SUBFORMAT_##v] = #v 

#define FORMATD(v, d) [SND_PCM_FORMAT_##v] = d
#define SUBFORMATD(v, d) [SND_PCM_SUBFORMAT_##v] = d 


static const char *const snd_pcm_stream_names[] = {
        STREAM(PLAYBACK),
        STREAM(CAPTURE),
};

static const char *const snd_pcm_state_names[] = {
        STATE(OPEN),
        STATE(SETUP),
        STATE(PREPARED),
        STATE(RUNNING),
        STATE(XRUN),
        STATE(DRAINING),
        STATE(PAUSED),
        STATE(SUSPENDED),
        STATE(DISCONNECTED),
};

static const char *const snd_pcm_access_names[] = {
        ACCESS(MMAP_INTERLEAVED), 
        ACCESS(MMAP_NONINTERLEAVED),
        ACCESS(MMAP_COMPLEX),
        ACCESS(RW_INTERLEAVED),
        ACCESS(RW_NONINTERLEAVED),
};

static const char *const snd_pcm_format_names[] = {
        FORMAT(S8),
        FORMAT(U8),
        FORMAT(S16_LE),
        FORMAT(S16_BE),
        FORMAT(U16_LE),
        FORMAT(U16_BE),
        FORMAT(S24_LE),
        FORMAT(S24_BE),
        FORMAT(U24_LE),
        FORMAT(U24_BE),
        FORMAT(S32_LE),
        FORMAT(S32_BE),
        FORMAT(U32_LE),
        FORMAT(U32_BE),
        FORMAT(FLOAT_LE),
        FORMAT(FLOAT_BE),
        FORMAT(FLOAT64_LE),
        FORMAT(FLOAT64_BE),
        FORMAT(IEC958_SUBFRAME_LE),
        FORMAT(IEC958_SUBFRAME_BE),
        FORMAT(MU_LAW),
        FORMAT(A_LAW),
        FORMAT(IMA_ADPCM),
        FORMAT(MPEG),
        FORMAT(GSM),
        FORMAT(SPECIAL),
        FORMAT(S24_3LE),
        FORMAT(S24_3BE),
        FORMAT(U24_3LE),
        FORMAT(U24_3BE),
        FORMAT(S20_3LE),
        FORMAT(S20_3BE),
        FORMAT(U20_3LE),
        FORMAT(U20_3BE),
        FORMAT(S18_3LE),
        FORMAT(S18_3BE),
        FORMAT(U18_3LE),
        FORMAT(U18_3BE),
};

static const char *const snd_pcm_format_aliases[SND_PCM_FORMAT_LAST+1] = {
        FORMAT(S16),
        FORMAT(U16),
        FORMAT(S24),
        FORMAT(U24),
        FORMAT(S32),
        FORMAT(U32),
        FORMAT(FLOAT),
        FORMAT(FLOAT64),
        FORMAT(IEC958_SUBFRAME),
};

static const char *const snd_pcm_format_descriptions[] = {
        FORMATD(S8, "Signed 8 bit"), 
        FORMATD(U8, "Unsigned 8 bit"),
        FORMATD(S16_LE, "Signed 16 bit Little Endian"),
        FORMATD(S16_BE, "Signed 16 bit Big Endian"),
        FORMATD(U16_LE, "Unsigned 16 bit Little Endian"),
        FORMATD(U16_BE, "Unsigned 16 bit Big Endian"),
        FORMATD(S24_LE, "Signed 24 bit Little Endian"),
        FORMATD(S24_BE, "Signed 24 bit Big Endian"),
        FORMATD(U24_LE, "Unsigned 24 bit Little Endian"),
        FORMATD(U24_BE, "Unsigned 24 bit Big Endian"),
        FORMATD(S32_LE, "Signed 32 bit Little Endian"),
        FORMATD(S32_BE, "Signed 32 bit Big Endian"),
        FORMATD(U32_LE, "Unsigned 32 bit Little Endian"),
        FORMATD(U32_BE, "Unsigned 32 bit Big Endian"),
        FORMATD(FLOAT_LE, "Float 32 bit Little Endian"),
        FORMATD(FLOAT_BE, "Float 32 bit Big Endian"),
        FORMATD(FLOAT64_LE, "Float 64 bit Little Endian"),
        FORMATD(FLOAT64_BE, "Float 64 bit Big Endian"),
        FORMATD(IEC958_SUBFRAME_LE, "IEC-958 Little Endian"),
        FORMATD(IEC958_SUBFRAME_BE, "IEC-958 Big Endian"),
        FORMATD(MU_LAW, "Mu-Law"),
        FORMATD(A_LAW, "A-Law"),
        FORMATD(IMA_ADPCM, "Ima-ADPCM"),
        FORMATD(MPEG, "MPEG"),
        FORMATD(GSM, "GSM"),
        FORMATD(SPECIAL, "Special"),
        FORMATD(S24_3LE, "Signed 24 bit Little Endian in 3bytes"),
        FORMATD(S24_3BE, "Signed 24 bit Big Endian in 3bytes"),
        FORMATD(U24_3LE, "Unsigned 24 bit Little Endian in 3bytes"),
        FORMATD(U24_3BE, "Unsigned 24 bit Big Endian in 3bytes"),
        FORMATD(S20_3LE, "Signed 20 bit Little Endian in 3bytes"),
        FORMATD(S20_3BE, "Signed 20 bit Big Endian in 3bytes"),
        FORMATD(U20_3LE, "Unsigned 20 bit Little Endian in 3bytes"),
        FORMATD(U20_3BE, "Unsigned 20 bit Big Endian in 3bytes"),
        FORMATD(S18_3LE, "Signed 18 bit Little Endian in 3bytes"),
        FORMATD(S18_3BE, "Signed 18 bit Big Endian in 3bytes"),
        FORMATD(U18_3LE, "Unsigned 18 bit Little Endian in 3bytes"),
        FORMATD(U18_3BE, "Unsigned 18 bit Big Endian in 3bytes"),
};

static const char *const snd_pcm_type_names[] = {
        PCMTYPE(HW), 
        PCMTYPE(HOOKS), 
        PCMTYPE(MULTI), 
        PCMTYPE(FILE), 
        PCMTYPE(NULL), 
        PCMTYPE(SHM), 
        PCMTYPE(INET), 
        PCMTYPE(COPY), 
        PCMTYPE(LINEAR), 
        PCMTYPE(ALAW), 
        PCMTYPE(MULAW), 
        PCMTYPE(ADPCM), 
        PCMTYPE(RATE), 
        PCMTYPE(ROUTE), 
        PCMTYPE(PLUG), 
        PCMTYPE(SHARE), 
        PCMTYPE(METER), 
        PCMTYPE(MIX), 
        PCMTYPE(DROUTE), 
        PCMTYPE(LBSERVER), 
        PCMTYPE(LINEAR_FLOAT), 
        PCMTYPE(LADSPA), 
        PCMTYPE(DMIX), 
        PCMTYPE(JACK),
        PCMTYPE(DSNOOP),
        PCMTYPE(IEC958),
        PCMTYPE(SOFTVOL),
        PCMTYPE(IOPLUG),
        PCMTYPE(EXTPLUG),
};

static const char *const snd_pcm_subformat_names[] = {
        SUBFORMAT(STD), 
};

static const char *const snd_pcm_subformat_descriptions[] = {
        SUBFORMATD(STD, "Standard"), 
};

static const char *const snd_pcm_start_mode_names[] = {
        START(EXPLICIT),
        START(DATA),
};

static const char *const snd_pcm_xrun_mode_names[] = {
        XRUN(NONE),
        XRUN(STOP),
};

static const char *const snd_pcm_tstamp_mode_names[] = {
        TSTAMP(NONE),
        TSTAMP(ENABLE),
};
#endif

/**
 * \brief get name of PCM stream type
 * \param stream PCM stream type
 * \return ascii name of PCM stream type
 */
const char *snd_pcm_stream_name(snd_pcm_stream_t stream)
{
        if (stream > SND_PCM_STREAM_LAST)
                return NULL;
        return snd_pcm_stream_names[stream];
}

/**
 * \brief get name of PCM access type
 * \param acc PCM access type
 * \return ascii name of PCM access type
 */
const char *snd_pcm_access_name(snd_pcm_access_t acc)
{
        if (acc > SND_PCM_ACCESS_LAST)
                return NULL;
        return snd_pcm_access_names[acc];
}

/**
 * \brief get name of PCM sample format
 * \param format PCM sample format
 * \return ascii name of PCM sample format
 */
const char *snd_pcm_format_name(snd_pcm_format_t format)
{
        if (format > SND_PCM_FORMAT_LAST)
                return NULL;
        return snd_pcm_format_names[format];
}

/**
 * \brief get description of PCM sample format
 * \param format PCM sample format
 * \return ascii description of PCM sample format
 */
const char *snd_pcm_format_description(snd_pcm_format_t format)
{
        if (format > SND_PCM_FORMAT_LAST)
                return NULL;
        return snd_pcm_format_descriptions[format];
}

/**
 * \brief get PCM sample format from name
 * \param name PCM sample format name (case insensitive)
 * \return PCM sample format
 */
snd_pcm_format_t snd_pcm_format_value(const char* name)
{
        snd_pcm_format_t format;
        for (format = 0; format <= SND_PCM_FORMAT_LAST; format++) {
                if (snd_pcm_format_names[format] &&
                    strcasecmp(name, snd_pcm_format_names[format]) == 0) {
                        return format;
                }
                if (snd_pcm_format_aliases[format] &&
                    strcasecmp(name, snd_pcm_format_aliases[format]) == 0) {
                        return format;
                }
        }
        for (format = 0; format <= SND_PCM_FORMAT_LAST; format++) {
                if (snd_pcm_format_descriptions[format] &&
                    strcasecmp(name, snd_pcm_format_descriptions[format]) == 0) {
                        return format;
                }
        }
        return SND_PCM_FORMAT_UNKNOWN;
}

/**
 * \brief get name of PCM sample subformat
 * \param subformat PCM sample subformat
 * \return ascii name of PCM sample subformat
 */
const char *snd_pcm_subformat_name(snd_pcm_subformat_t subformat)
{
        if (subformat > SND_PCM_SUBFORMAT_LAST)
                return NULL;
        return snd_pcm_subformat_names[subformat];
}

/**
 * \brief get description of PCM sample subformat
 * \param subformat PCM sample subformat
 * \return ascii description of PCM sample subformat
 */
const char *snd_pcm_subformat_description(snd_pcm_subformat_t subformat)
{
        if (subformat > SND_PCM_SUBFORMAT_LAST)
                return NULL;
        return snd_pcm_subformat_descriptions[subformat];
}

/**
 * \brief (DEPRECATED) get name of PCM start mode setting
 * \param mode PCM start mode
 * \return ascii name of PCM start mode setting
 */
const char *snd_pcm_start_mode_name(snd_pcm_start_t mode)
{
        if (mode > SND_PCM_START_LAST)
                return NULL;
        return snd_pcm_start_mode_names[mode];
}

#ifndef DOC_HIDDEN
link_warning(snd_pcm_start_mode_name, "Warning: start_mode is deprecated, consider to use start_threshold");
#endif

/**
 * \brief (DEPRECATED) get name of PCM xrun mode setting
 * \param mode PCM xrun mode
 * \return ascii name of PCM xrun mode setting
 */
const char *snd_pcm_xrun_mode_name(snd_pcm_xrun_t mode)
{
        if (mode > SND_PCM_XRUN_LAST)
                return NULL;
        return snd_pcm_xrun_mode_names[mode];
}

#ifndef DOC_HIDDEN
link_warning(snd_pcm_xrun_mode_name, "Warning: xrun_mode is deprecated, consider to use stop_threshold");
#endif

/**
 * \brief get name of PCM tstamp mode setting
 * \param mode PCM tstamp mode
 * \return ascii name of PCM tstamp mode setting
 */
const char *snd_pcm_tstamp_mode_name(snd_pcm_tstamp_t mode)
{
        if (mode > SND_PCM_TSTAMP_LAST)
                return NULL;
        return snd_pcm_tstamp_mode_names[mode];
}

/**
 * \brief get name of PCM state
 * \param state PCM state
 * \return ascii name of PCM state
 */
const char *snd_pcm_state_name(snd_pcm_state_t state)
{
        if (state > SND_PCM_STATE_LAST)
                return NULL;
        return snd_pcm_state_names[state];
}

/**
 * \brief get name of PCM type
 * \param type PCM type
 * \return ascii name of PCM type
 */
#ifndef DOXYGEN
const char *INTERNAL(snd_pcm_type_name)(snd_pcm_type_t type)
#else
const char *snd_pcm_type_name(snd_pcm_type_t type)
#endif
{
        if (type > SND_PCM_TYPE_LAST)
                return NULL;
        return snd_pcm_type_names[type];
}
use_default_symbol_version(__snd_pcm_type_name, snd_pcm_type_name, ALSA_0.9.0);

/**
 * \brief Dump current hardware setup for PCM
 * \param pcm PCM handle
 * \param out Output handle
 * \return 0 on success otherwise a negative error code
 */
int snd_pcm_dump_hw_setup(snd_pcm_t *pcm, snd_output_t *out)
{
        assert(pcm);
        assert(out);
        if (CHECK_SANITY(! pcm->setup)) {
                SNDMSG("PCM not set up");
                return -EIO;
        }
        snd_output_printf(out, "  stream       : %s\n", snd_pcm_stream_name(pcm->stream));
        snd_output_printf(out, "  access       : %s\n", snd_pcm_access_name(pcm->access));
        snd_output_printf(out, "  format       : %s\n", snd_pcm_format_name(pcm->format));
        snd_output_printf(out, "  subformat    : %s\n", snd_pcm_subformat_name(pcm->subformat));
        snd_output_printf(out, "  channels     : %u\n", pcm->channels);
        snd_output_printf(out, "  rate         : %u\n", pcm->rate);
        snd_output_printf(out, "  exact rate   : %g (%u/%u)\n",
                          (pcm->rate_den ? ((double) pcm->rate_num / pcm->rate_den) : 0.0),
                          pcm->rate_num, pcm->rate_den);
        snd_output_printf(out, "  msbits       : %u\n", pcm->msbits);
        snd_output_printf(out, "  buffer_size  : %lu\n", pcm->buffer_size);
        snd_output_printf(out, "  period_size  : %lu\n", pcm->period_size);
        snd_output_printf(out, "  period_time  : %u\n", pcm->period_time);
        return 0;
}

/**
 * \brief Dump current software setup for PCM
 * \param pcm PCM handle
 * \param out Output handle
 * \return 0 on success otherwise a negative error code
 */
int snd_pcm_dump_sw_setup(snd_pcm_t *pcm, snd_output_t *out)
{
        assert(pcm);
        assert(out);
        if (CHECK_SANITY(! pcm->setup)) {
                SNDMSG("PCM not set up");
                return -EIO;
        }
        snd_output_printf(out, "  tstamp_mode  : %s\n", snd_pcm_tstamp_mode_name(pcm->tstamp_mode));
        snd_output_printf(out, "  period_step  : %d\n", pcm->period_step);
        snd_output_printf(out, "  avail_min    : %ld\n", pcm->avail_min);
        snd_output_printf(out, "  period_event : %i\n", pcm->period_event);
        snd_output_printf(out, "  start_threshold  : %ld\n", pcm->start_threshold);
        snd_output_printf(out, "  stop_threshold   : %ld\n", pcm->stop_threshold);
        snd_output_printf(out, "  silence_threshold: %ld\n", pcm->silence_threshold);
        snd_output_printf(out, "  silence_size : %ld\n", pcm->silence_size);
        snd_output_printf(out, "  boundary     : %ld\n", pcm->boundary);
        return 0;
}

/**
 * \brief Dump current setup (hardware and software) for PCM
 * \param pcm PCM handle
 * \param out Output handle
 * \return 0 on success otherwise a negative error code
 */
int snd_pcm_dump_setup(snd_pcm_t *pcm, snd_output_t *out)
{
        snd_pcm_dump_hw_setup(pcm, out);
        snd_pcm_dump_sw_setup(pcm, out);
        return 0;
}

/**
 * \brief Dump status
 * \param status Status container
 * \param out Output handle
 * \return 0 on success otherwise a negative error code
 */
int snd_pcm_status_dump(snd_pcm_status_t *status, snd_output_t *out)
{
        assert(status);
        snd_output_printf(out, "  state       : %s\n", snd_pcm_state_name((snd_pcm_state_t) status->state));
        snd_output_printf(out, "  trigger_time: %ld.%06ld\n",
                status->trigger_tstamp.tv_sec, status->trigger_tstamp.tv_nsec);
        snd_output_printf(out, "  tstamp      : %ld.%06ld\n",
                status->tstamp.tv_sec, status->tstamp.tv_nsec);
        snd_output_printf(out, "  delay       : %ld\n", (long)status->delay);
        snd_output_printf(out, "  avail       : %ld\n", (long)status->avail);
        snd_output_printf(out, "  avail_max   : %ld\n", (long)status->avail_max);
        return 0;
}

/**
 * \brief Dump PCM info
 * \param pcm PCM handle
 * \param out Output handle
 * \return 0 on success otherwise a negative error code
 */
int snd_pcm_dump(snd_pcm_t *pcm, snd_output_t *out)
{
        assert(pcm);
        assert(out);
        pcm->ops->dump(pcm->op_arg, out);
        return 0;
}

/**
 * \brief Convert bytes in frames for a PCM
 * \param pcm PCM handle
 * \param bytes quantity in bytes
 * \return quantity expressed in frames
 */
snd_pcm_sframes_t snd_pcm_bytes_to_frames(snd_pcm_t *pcm, ssize_t bytes)
{
        assert(pcm);
        if (CHECK_SANITY(! pcm->setup)) {
                SNDMSG("PCM not set up");
                return -EIO;
        }
        return bytes * 8 / pcm->frame_bits;
}

/**
 * \brief Convert frames in bytes for a PCM
 * \param pcm PCM handle
 * \param frames quantity in frames
 * \return quantity expressed in bytes
 */
ssize_t snd_pcm_frames_to_bytes(snd_pcm_t *pcm, snd_pcm_sframes_t frames)
{
        assert(pcm);
        if (CHECK_SANITY(! pcm->setup)) {
                SNDMSG("PCM not set up");
                return -EIO;
        }
        return frames * pcm->frame_bits / 8;
}

/**
 * \brief Convert bytes in samples for a PCM
 * \param pcm PCM handle
 * \param bytes quantity in bytes
 * \return quantity expressed in samples
 */
long snd_pcm_bytes_to_samples(snd_pcm_t *pcm, ssize_t bytes)
{
        assert(pcm);
        if (CHECK_SANITY(! pcm->setup)) {
                SNDMSG("PCM not set up");
                return -EIO;
        }
        return bytes * 8 / pcm->sample_bits;
}

/**
 * \brief Convert samples in bytes for a PCM
 * \param pcm PCM handle
 * \param samples quantity in samples
 * \return quantity expressed in bytes
 */
ssize_t snd_pcm_samples_to_bytes(snd_pcm_t *pcm, long samples)
{
        assert(pcm);
        if (CHECK_SANITY(! pcm->setup)) {
                SNDMSG("PCM not set up");
                return -EIO;
        }
        return samples * pcm->sample_bits / 8;
}

/**
 * \brief Add an async handler for a PCM
 * \param handler Returned handler handle
 * \param pcm PCM handle
 * \param callback Callback function
 * \param private_data Callback private data
 * \return 0 otherwise a negative error code on failure
 *
 * The asynchronous callback is called when period boundary elapses.
 */
int snd_async_add_pcm_handler(snd_async_handler_t **handler, snd_pcm_t *pcm, 
                              snd_async_callback_t callback, void *private_data)
{
        int err;
        int was_empty;
        snd_async_handler_t *h;
        err = snd_async_add_handler(&h, _snd_pcm_async_descriptor(pcm),
                                    callback, private_data);
        if (err < 0)
                return err;
        h->type = SND_ASYNC_HANDLER_PCM;
        h->u.pcm = pcm;
        was_empty = list_empty(&pcm->async_handlers);
        list_add_tail(&h->hlist, &pcm->async_handlers);
        if (was_empty) {
                err = snd_pcm_async(pcm, snd_async_handler_get_signo(h), getpid());
                if (err < 0) {
                        snd_async_del_handler(h);
                        return err;
                }
        }
        *handler = h;
        return 0;
}

/**
 * \brief Return PCM handle related to an async handler
 * \param handler Async handler handle
 * \return PCM handle
 */
snd_pcm_t *snd_async_handler_get_pcm(snd_async_handler_t *handler)
{
        if (handler->type != SND_ASYNC_HANDLER_PCM) {
                SNDMSG("invalid handler type %d", handler->type);
                return NULL;
        }
        return handler->u.pcm;
}

static const char *const build_in_pcms[] = {
        "adpcm", "alaw", "copy", "dmix", "file", "hooks", "hw", "ladspa", "lfloat",
        "linear", "meter", "mulaw", "multi", "null", "empty", "plug", "rate", "route", "share",
        "shm", "dsnoop", "dshare", "asym", "iec958", "softvol", "mmap_emul",
        NULL
};

static int snd_pcm_open_conf(snd_pcm_t **pcmp, const char *name,
                             snd_config_t *pcm_root, snd_config_t *pcm_conf,
                             snd_pcm_stream_t stream, int mode)
{
        const char *str;
        char *buf = NULL, *buf1 = NULL;
        int err;
        snd_config_t *conf, *type_conf = NULL;
        snd_config_iterator_t i, next;
        const char *id;
        const char *lib = NULL, *open_name = NULL;
        int (*open_func)(snd_pcm_t **, const char *, 
                         snd_config_t *, snd_config_t *, 
                         snd_pcm_stream_t, int) = NULL;
#ifndef PIC
        extern void *snd_pcm_open_symbols(void);
#endif
        void *h = NULL;
        if (snd_config_get_type(pcm_conf) != SND_CONFIG_TYPE_COMPOUND) {
                char *val;
                id = NULL;
                snd_config_get_id(pcm_conf, &id);
                val = NULL;
                snd_config_get_ascii(pcm_conf, &val);
                SNDERR("Invalid type for PCM %s%sdefinition (id: %s, value: %s)", name ? name : "", name ? " " : "", id, val);
                free(val);
                return -EINVAL;
        }
        err = snd_config_search(pcm_conf, "type", &conf);
        if (err < 0) {
                SNDERR("type is not defined");
                return err;
        }
        err = snd_config_get_id(conf, &id);
        if (err < 0) {
                SNDERR("unable to get id");
                return err;
        }
        err = snd_config_get_string(conf, &str);
        if (err < 0) {
                SNDERR("Invalid type for %s", id);
                return err;
        }
        err = snd_config_search_definition(pcm_root, "pcm_type", str, &type_conf);
        if (err >= 0) {
                if (snd_config_get_type(type_conf) != SND_CONFIG_TYPE_COMPOUND) {
                        SNDERR("Invalid type for PCM type %s definition", str);
                        goto _err;
                }
                snd_config_for_each(i, next, type_conf) {
                        snd_config_t *n = snd_config_iterator_entry(i);
                        const char *id;
                        if (snd_config_get_id(n, &id) < 0)
                                continue;
                        if (strcmp(id, "comment") == 0)
                                continue;
                        if (strcmp(id, "lib") == 0) {
                                err = snd_config_get_string(n, &lib);
                                if (err < 0) {
                                        SNDERR("Invalid type for %s", id);
                                        goto _err;
                                }
                                continue;
                        }
                        if (strcmp(id, "open") == 0) {
                                err = snd_config_get_string(n, &open_name);
                                if (err < 0) {
                                        SNDERR("Invalid type for %s", id);
                                        goto _err;
                                }
                                continue;
                        }
                        SNDERR("Unknown field %s", id);
                        err = -EINVAL;
                        goto _err;
                }
        }
        if (!open_name) {
                buf = malloc(strlen(str) + 32);
                if (buf == NULL) {
                        err = -ENOMEM;
                        goto _err;
                }
                open_name = buf;
                sprintf(buf, "_snd_pcm_%s_open", str);
        }
        if (!lib) {
                const char *const *build_in = build_in_pcms;
                while (*build_in) {
                        if (!strcmp(*build_in, str))
                                break;
                        build_in++;
                }
                if (*build_in == NULL) {
                        buf1 = malloc(strlen(str) + sizeof(ALSA_PLUGIN_DIR) + 32);
                        if (buf1 == NULL) {
                                err = -ENOMEM;
                                goto _err;
                        }
                        lib = buf1;
                        sprintf(buf1, "%s/libasound_module_pcm_%s.so", ALSA_PLUGIN_DIR, str);
                }
        }
#ifndef PIC
        snd_pcm_open_symbols(); /* this call is for static linking only */
#endif
        open_func = snd_dlobj_cache_lookup(open_name);
        if (open_func) {
                err = 0;
                goto _err;
        }
        h = snd_dlopen(lib, RTLD_NOW);
        if (h)
                open_func = snd_dlsym(h, open_name, SND_DLSYM_VERSION(SND_PCM_DLSYM_VERSION));
        err = 0;
        if (!h) {
                SNDERR("Cannot open shared library %s",
                       lib ? lib : "[builtin]");
                err = -ENOENT;
        } else if (!open_func) {
                SNDERR("symbol %s is not defined inside %s", open_name,
                       lib ? lib : "[builtin]");
                snd_dlclose(h);
                err = -ENXIO;
        }
       _err:
        if (err >= 0) {
                err = open_func(pcmp, name, pcm_root, pcm_conf, stream, mode);
                if (err >= 0) {
                        if (h /*&& (mode & SND_PCM_KEEP_ALIVE)*/) {
                                snd_dlobj_cache_add(open_name, h, open_func);
                                h = NULL;
                        }
                        (*pcmp)->dl_handle = h;
                        err = 0;
                } else {
                        if (h)
                                snd_dlclose(h);
                }
        }
        if (type_conf)
                snd_config_delete(type_conf);
        free(buf);
        free(buf1);
        return err;
}

static int snd_pcm_open_noupdate(snd_pcm_t **pcmp, snd_config_t *root,
                                 const char *name, snd_pcm_stream_t stream,
                                 int mode, int hop)
{
        int err;
        snd_config_t *pcm_conf;
        const char *str;

        err = snd_config_search_definition(root, "pcm", name, &pcm_conf);
        if (err < 0) {
                SNDERR("Unknown PCM %s", name);
                return err;
        }
        if (snd_config_get_string(pcm_conf, &str) >= 0)
                err = snd_pcm_open_noupdate(pcmp, root, str, stream, mode,
                                            hop + 1);
        else {
                snd_config_set_hop(pcm_conf, hop);
                err = snd_pcm_open_conf(pcmp, name, root, pcm_conf, stream, mode);
        }
        snd_config_delete(pcm_conf);
        return err;
}

/**
 * \brief Opens a PCM
 * \param pcmp Returned PCM handle
 * \param name ASCII identifier of the PCM handle
 * \param stream Wanted stream
 * \param mode Open mode (see #SND_PCM_NONBLOCK, #SND_PCM_ASYNC)
 * \return 0 on success otherwise a negative error code
 */
int snd_pcm_open(snd_pcm_t **pcmp, const char *name, 
                 snd_pcm_stream_t stream, int mode)
{
        int err;
        assert(pcmp && name);
        err = snd_config_update();
        if (err < 0)
                return err;
        return snd_pcm_open_noupdate(pcmp, snd_config, name, stream, mode, 0);
}

/**
 * \brief Opens a PCM using local configuration
 * \param pcmp Returned PCM handle
 * \param name ASCII identifier of the PCM handle
 * \param stream Wanted stream
 * \param mode Open mode (see #SND_PCM_NONBLOCK, #SND_PCM_ASYNC)
 * \param lconf Local configuration
 * \return 0 on success otherwise a negative error code
 */
int snd_pcm_open_lconf(snd_pcm_t **pcmp, const char *name, 
                       snd_pcm_stream_t stream, int mode,
                       snd_config_t *lconf)
{
        assert(pcmp && name && lconf);
        return snd_pcm_open_noupdate(pcmp, lconf, name, stream, mode, 0);
}

#ifndef DOC_HIDDEN
int snd_pcm_new(snd_pcm_t **pcmp, snd_pcm_type_t type, const char *name,
                snd_pcm_stream_t stream, int mode)
{
        snd_pcm_t *pcm;
        pcm = calloc(1, sizeof(*pcm));
        if (!pcm)
                return -ENOMEM;
        pcm->type = type;
        if (name)
                pcm->name = strdup(name);
        pcm->stream = stream;
        pcm->mode = mode;
        pcm->poll_fd_count = 1;
        pcm->poll_fd = -1;
        pcm->op_arg = pcm;
        pcm->fast_op_arg = pcm;
        INIT_LIST_HEAD(&pcm->async_handlers);
        *pcmp = pcm;
        return 0;
}

int snd_pcm_free(snd_pcm_t *pcm)
{
        assert(pcm);
        free(pcm->name);
        free(pcm->hw.link_dst);
        free(pcm->appl.link_dst);
        if (pcm->dl_handle)
                snd_dlclose(pcm->dl_handle);
        free(pcm);
        return 0;
}

int snd_pcm_open_named_slave(snd_pcm_t **pcmp, const char *name,
                             snd_config_t *root,
                             snd_config_t *conf, snd_pcm_stream_t stream,
                             int mode, snd_config_t *parent_conf)
{
        const char *str;
        int hop;

        if ((hop = snd_config_check_hop(parent_conf)) < 0)
                return hop;
        if (snd_config_get_string(conf, &str) >= 0)
                return snd_pcm_open_noupdate(pcmp, root, str, stream, mode,
                                             hop + 1);
        return snd_pcm_open_conf(pcmp, name, root, conf, stream, mode);
}
#endif

/**
 * \brief Wait for a PCM to become ready
 * \param pcm PCM handle
 * \param timeout maximum time in milliseconds to wait,
 *        a negative value means infinity
 * \return a positive value on success otherwise a negative error code
 *         (-EPIPE for the xrun and -ESTRPIPE for the suspended status,
 *          others for general errors) 
 * \retval 0 timeout occurred
 * \retval 1 PCM stream is ready for I/O
 */
int snd_pcm_wait(snd_pcm_t *pcm, int timeout)
{
        if (snd_pcm_mmap_avail(pcm) >= pcm->avail_min) {
                /* check more precisely */
                switch (snd_pcm_state(pcm)) {
                case SND_PCM_STATE_XRUN:
                        return -EPIPE;
                case SND_PCM_STATE_SUSPENDED:
                        return -ESTRPIPE;
                case SND_PCM_STATE_DISCONNECTED:
                        return -ENODEV;
                default:
                        return 1;
                }
        }
        return snd_pcm_wait_nocheck(pcm, timeout);
}

#ifndef DOC_HIDDEN
/* 
 * like snd_pcm_wait() but doesn't check mmap_avail before calling poll()
 *
 * used in drain code in some plugins
 */
int snd_pcm_wait_nocheck(snd_pcm_t *pcm, int timeout)
{
        struct pollfd *pfd;
        unsigned short *revents;
        int i, npfds, pollio, err, err_poll;
        
        npfds = snd_pcm_poll_descriptors_count(pcm);
        if (npfds <= 0 || npfds >= 16) {
                SNDERR("Invalid poll_fds %d\n", npfds);
                return -EIO;
        }
        pfd = alloca(sizeof(*pfd) * npfds);
        revents = alloca(sizeof(*revents) * npfds);
        err = snd_pcm_poll_descriptors(pcm, pfd, npfds);
        if (err < 0)
                return err;
        if (err != npfds) {
                SNDMSG("invalid poll descriptors %d\n", err);
                return -EIO;
        }
        do {
                pollio = 0;
                err_poll = poll(pfd, npfds, timeout);
                if (err_poll < 0) {
                        if (errno == EINTR)
                                continue;
                        return -errno;
                }
                if (! err_poll)
                        break;
                err = snd_pcm_poll_descriptors_revents(pcm, pfd, npfds, revents);
                if (err < 0)
                        return err;
                for (i = 0; i < npfds; i++) {
                        if (revents[i] & (POLLERR | POLLNVAL)) {
                                /* check more precisely */
                                switch (snd_pcm_state(pcm)) {
                                case SND_PCM_STATE_XRUN:
                                        return -EPIPE;
                                case SND_PCM_STATE_SUSPENDED:
                                        return -ESTRPIPE;
                                case SND_PCM_STATE_DISCONNECTED:
                                        return -ENODEV;
                                default:
                                        return -EIO;
                                }
                        }
                        if ((revents[i] & (POLLIN | POLLOUT)) == 0)
                                continue;
                        pollio++;
                }
        } while (! pollio);
#if 0 /* very useful code to test poll related problems */
        {
                snd_pcm_sframes_t avail_update;
                snd_pcm_hwsync(pcm);
                avail_update = snd_pcm_avail_update(pcm);
                if (avail_update < (snd_pcm_sframes_t)pcm->avail_min) {
                        printf("*** snd_pcm_wait() FATAL ERROR!!!\n");
                        printf("avail_min = %li, avail_update = %li\n", pcm->avail_min, avail_update);
                }
        }
#endif
        return err_poll > 0 ? 1 : 0;
}
#endif

/**
 * \brief Return number of frames ready to be read (capture) / written (playback)
 * \param pcm PCM handle
 * \return a positive number of frames ready otherwise a negative
 * error code
 *
 * On capture does all the actions needed to transport to application
 * level all the ready frames across underlying layers.
 *
 * The position is not synced with hardware (driver) position in the sound
 * ring buffer in this function. This function is a light version of
 * #snd_pcm_avail() .
 *
 * Using this function is ideal after poll() or select() when audio
 * file descriptor made the event and when application expects just period
 * timing.
 *
 * Also this function might be called after #snd_pcm_delay() or
 * #snd_pcm_hwsync() functions to move private ring buffer pointers
 * in alsa-lib (the internal plugin chain).
 */
snd_pcm_sframes_t snd_pcm_avail_update(snd_pcm_t *pcm)
{
        return pcm->fast_ops->avail_update(pcm->fast_op_arg);
}

/**
 * \brief Return number of frames ready to be read (capture) / written (playback)
 * \param pcm PCM handle
 * \return a positive number of frames ready otherwise a negative
 * error code
 *
 * On capture does all the actions needed to transport to application
 * level all the ready frames across underlying layers.
 *
 * The position is synced with hardware (driver) position in the sound
 * ring buffer in this functions.
 */
snd_pcm_sframes_t snd_pcm_avail(snd_pcm_t *pcm)
{
        int err;

        assert(pcm);
        if (CHECK_SANITY(! pcm->setup)) {
                SNDMSG("PCM not set up");
                return -EIO;
        }
        err = pcm->fast_ops->hwsync(pcm->fast_op_arg);
        if (err < 0)
                return err;
        return pcm->fast_ops->avail_update(pcm->fast_op_arg);
}

/**
 * \brief Combine snd_pcm_avail and snd_pcm_delay functions
 * \param pcm PCM handle
 * \param avail Number of available frames in the ring buffer
 * \param delay Total I/O latency in frames
 * \return zero on success otherwise a negative error code
 *
 * The avail and delay values retuned are in sync.
 */
int snd_pcm_avail_delay(snd_pcm_t *pcm,
                        snd_pcm_sframes_t *availp,
                        snd_pcm_sframes_t *delayp)
{
        snd_pcm_sframes_t sf;

        assert(pcm && availp && delayp);
        if (CHECK_SANITY(! pcm->setup)) {
                SNDMSG("PCM not set up");
                return -EIO;
        }
        sf = pcm->fast_ops->delay(pcm->fast_op_arg, delayp);
        if (sf < 0)
                return (int)sf;
        sf = pcm->fast_ops->avail_update(pcm->fast_op_arg);
        if (sf < 0)
                return (int)sf;
        *availp = sf;
        return 0;
}

/**
 * \brief Silence an area
 * \param dst_area area specification
 * \param dst_offset offset in frames inside area
 * \param samples samples to silence
 * \param format PCM sample format
 * \return 0 on success otherwise a negative error code
 */
int snd_pcm_area_silence(const snd_pcm_channel_area_t *dst_area, snd_pcm_uframes_t dst_offset,
                         unsigned int samples, snd_pcm_format_t format)
{
        /* FIXME: sub byte resolution and odd dst_offset */
        char *dst;
        unsigned int dst_step;
        int width;
        u_int64_t silence;
        if (!dst_area->addr)
                return 0;
        dst = snd_pcm_channel_area_addr(dst_area, dst_offset);
        width = snd_pcm_format_physical_width(format);
        silence = snd_pcm_format_silence_64(format);
        if (dst_area->step == (unsigned int) width) {
                unsigned int dwords = samples * width / 64;
                u_int64_t *dstp = (u_int64_t *)dst;
                samples -= dwords * 64 / width;
                while (dwords-- > 0)
                        *dstp++ = silence;
                if (samples == 0)
                        return 0;
        }
        dst_step = dst_area->step / 8;
        switch (width) {
        case 4: {
                u_int8_t s0 = silence & 0xf0;
                u_int8_t s1 = silence & 0x0f;
                int dstbit = dst_area->first % 8;
                int dstbit_step = dst_area->step % 8;
                while (samples-- > 0) {
                        if (dstbit) {
                                *dst &= 0xf0;
                                *dst |= s1;
                        } else {
                                *dst &= 0x0f;
                                *dst |= s0;
                        }
                        dst += dst_step;
                        dstbit += dstbit_step;
                        if (dstbit == 8) {
                                dst++;
                                dstbit = 0;
                        }
                }
                break;
        }
        case 8: {
                u_int8_t sil = silence;
                while (samples-- > 0) {
                        *dst = sil;
                        dst += dst_step;
                }
                break;
        }
        case 16: {
                u_int16_t sil = silence;
                while (samples-- > 0) {
                        *(u_int16_t*)dst = sil;
                        dst += dst_step;
                }
                break;
        }
        case 24:
#ifdef SNDRV_LITTLE_ENDIAN
                *(dst + 0) = silence >> 0;
                *(dst + 1) = silence >> 8;
                *(dst + 2) = silence >> 16;
#else
                *(dst + 2) = silence >> 0;
                *(dst + 1) = silence >> 8;
                *(dst + 0) = silence >> 16;
#endif
                break;
        case 32: {
                u_int32_t sil = silence;
                while (samples-- > 0) {
                        *(u_int32_t*)dst = sil;
                        dst += dst_step;
                }
                break;
        }
        case 64: {
                while (samples-- > 0) {
                        *(u_int64_t*)dst = silence;
                        dst += dst_step;
                }
                break;
        }
        default:
                SNDMSG("invalid format width %d", width);
                return -EINVAL;
        }
        return 0;
}

/**
 * \brief Silence one or more areas
 * \param dst_areas areas specification (one for each channel)
 * \param dst_offset offset in frames inside area
 * \param channels channels count
 * \param frames frames to silence
 * \param format PCM sample format
 * \return 0 on success otherwise a negative error code
 */
int snd_pcm_areas_silence(const snd_pcm_channel_area_t *dst_areas, snd_pcm_uframes_t dst_offset,
                          unsigned int channels, snd_pcm_uframes_t frames, snd_pcm_format_t format)
{
        int width = snd_pcm_format_physical_width(format);
        while (channels > 0) {
                void *addr = dst_areas->addr;
                unsigned int step = dst_areas->step;
                const snd_pcm_channel_area_t *begin = dst_areas;
                int channels1 = channels;
                unsigned int chns = 0;
                int err;
                while (1) {
                        channels1--;
                        chns++;
                        dst_areas++;
                        if (channels1 == 0 ||
                            dst_areas->addr != addr ||
                            dst_areas->step != step ||
                            dst_areas->first != dst_areas[-1].first + width)
                                break;
                }
                if (chns > 1 && chns * width == step) {
                        /* Collapse the areas */
                        snd_pcm_channel_area_t d;
                        d.addr = begin->addr;
                        d.first = begin->first;
                        d.step = width;
                        err = snd_pcm_area_silence(&d, dst_offset * chns, frames * chns, format);
                        channels -= chns;
                } else {
                        err = snd_pcm_area_silence(begin, dst_offset, frames, format);
                        dst_areas = begin + 1;
                        channels--;
                }
                if (err < 0)
                        return err;
        }
        return 0;
}


/**
 * \brief Copy an area
 * \param dst_area destination area specification
 * \param dst_offset offset in frames inside destination area
 * \param src_area source area specification
 * \param src_offset offset in frames inside source area
 * \param samples samples to copy
 * \param format PCM sample format
 * \return 0 on success otherwise a negative error code
 */
int snd_pcm_area_copy(const snd_pcm_channel_area_t *dst_area, snd_pcm_uframes_t dst_offset,
                      const snd_pcm_channel_area_t *src_area, snd_pcm_uframes_t src_offset,
                      unsigned int samples, snd_pcm_format_t format)
{
        /* FIXME: sub byte resolution and odd dst_offset */
        const char *src;
        char *dst;
        int width;
        int src_step, dst_step;
        if (dst_area == src_area && dst_offset == src_offset)
                return 0;
        if (!src_area->addr)
                return snd_pcm_area_silence(dst_area, dst_offset, samples, format);
        src = snd_pcm_channel_area_addr(src_area, src_offset);
        if (!dst_area->addr)
                return 0;
        dst = snd_pcm_channel_area_addr(dst_area, dst_offset);
        width = snd_pcm_format_physical_width(format);
        if (src_area->step == (unsigned int) width &&
            dst_area->step == (unsigned int) width) {
                size_t bytes = samples * width / 8;
                samples -= bytes * 8 / width;
                memcpy(dst, src, bytes);
                if (samples == 0)
                        return 0;
        }
        src_step = src_area->step / 8;
        dst_step = dst_area->step / 8;
        switch (width) {
        case 4: {
                int srcbit = src_area->first % 8;
                int srcbit_step = src_area->step % 8;
                int dstbit = dst_area->first % 8;
                int dstbit_step = dst_area->step % 8;
                while (samples-- > 0) {
                        unsigned char srcval;
                        if (srcbit)
                                srcval = *src & 0x0f;
                        else
                                srcval = *src & 0xf0;
                        if (dstbit)
                                *dst &= 0xf0;
                        else
                                *dst &= 0x0f;
                        *dst |= srcval;
                        src += src_step;
                        srcbit += srcbit_step;
                        if (srcbit == 8) {
                                src++;
                                srcbit = 0;
                        }
                        dst += dst_step;
                        dstbit += dstbit_step;
                        if (dstbit == 8) {
                                dst++;
                                dstbit = 0;
                        }
                }
                break;
        }
        case 8: {
                while (samples-- > 0) {
                        *dst = *src;
                        src += src_step;
                        dst += dst_step;
                }
                break;
        }
        case 16: {
                while (samples-- > 0) {
                        *(u_int16_t*)dst = *(const u_int16_t*)src;
                        src += src_step;
                        dst += dst_step;
                }
                break;
        }
        case 24:
                while (samples-- > 0) {
                        *(dst + 0) = *(src + 0);
                        *(dst + 1) = *(src + 1);
                        *(dst + 2) = *(src + 2);
                        src += src_step;
                        dst += dst_step;
                }
                break;
        case 32: {
                while (samples-- > 0) {
                        *(u_int32_t*)dst = *(const u_int32_t*)src;
                        src += src_step;
                        dst += dst_step;
                }
                break;
        }
        case 64: {
                while (samples-- > 0) {
                        *(u_int64_t*)dst = *(const u_int64_t*)src;
                        src += src_step;
                        dst += dst_step;
                }
                break;
        }
        default:
                SNDMSG("invalid format width %d", width);
                return -EINVAL;
        }
        return 0;
}

/**
 * \brief Copy one or more areas
 * \param dst_areas destination areas specification (one for each channel)
 * \param dst_offset offset in frames inside destination area
 * \param src_areas source areas specification (one for each channel)
 * \param src_offset offset in frames inside source area
 * \param channels channels count
 * \param frames frames to copy
 * \param format PCM sample format
 * \return 0 on success otherwise a negative error code
 */
int snd_pcm_areas_copy(const snd_pcm_channel_area_t *dst_areas, snd_pcm_uframes_t dst_offset,
                       const snd_pcm_channel_area_t *src_areas, snd_pcm_uframes_t src_offset,
                       unsigned int channels, snd_pcm_uframes_t frames, snd_pcm_format_t format)
{
        int width = snd_pcm_format_physical_width(format);
        assert(dst_areas);
        assert(src_areas);
        if (! channels) {
                SNDMSG("invalid channels %d", channels);
                return -EINVAL;
        }
        if (! frames) {
                SNDMSG("invalid frames %ld", frames);
                return -EINVAL;
        }
        while (channels > 0) {
                unsigned int step = src_areas->step;
                void *src_addr = src_areas->addr;
                const snd_pcm_channel_area_t *src_start = src_areas;
                void *dst_addr = dst_areas->addr;
                const snd_pcm_channel_area_t *dst_start = dst_areas;
                int channels1 = channels;
                unsigned int chns = 0;
                while (dst_areas->step == step) {
                        channels1--;
                        chns++;
                        src_areas++;
                        dst_areas++;
                        if (channels1 == 0 ||
                            src_areas->step != step ||
                            src_areas->addr != src_addr ||
                            dst_areas->addr != dst_addr ||
                            src_areas->first != src_areas[-1].first + width ||
                            dst_areas->first != dst_areas[-1].first + width)
                                break;
                }
                if (chns > 1 && chns * width == step) {
                        /* Collapse the areas */
                        snd_pcm_channel_area_t s, d;
                        s.addr = src_start->addr;
                        s.first = src_start->first;
                        s.step = width;
                        d.addr = dst_start->addr;
                        d.first = dst_start->first;
                        d.step = width;
                        snd_pcm_area_copy(&d, dst_offset * chns,
                                          &s, src_offset * chns, 
                                          frames * chns, format);
                        channels -= chns;
                } else {
                        snd_pcm_area_copy(dst_start, dst_offset,
                                          src_start, src_offset,
                                          frames, format);
                        src_areas = src_start + 1;
                        dst_areas = dst_start + 1;
                        channels--;
                }
        }
        return 0;
}

static void dump_one_param(snd_pcm_hw_params_t *params, unsigned int k, snd_output_t *out)
{
        snd_output_printf(out, "%s: ", snd_pcm_hw_param_name(k));
        snd_pcm_hw_param_dump(params, k, out);
        snd_output_putc(out, '\n');
}

/**
 * \brief Dump a PCM hardware configuration space
 * \param params Configuration space
 * \param out Output handle
 * \return 0 on success otherwise a negative error code
 */
int snd_pcm_hw_params_dump(snd_pcm_hw_params_t *params, snd_output_t *out)
{
        unsigned int k;
        for (k = SND_PCM_HW_PARAM_FIRST_MASK; k <= SND_PCM_HW_PARAM_LAST_MASK; k++)
                dump_one_param(params, k, out);
        for (k = SND_PCM_HW_PARAM_FIRST_INTERVAL; k <= SND_PCM_HW_PARAM_LAST_INTERVAL; k++)
                dump_one_param(params, k, out);
        return 0;
}

/**
 * \brief Check, if hardware supports sample-resolution mmap for given configuration
 * \param params Configuration space
 * \return Boolean value
 * \retval 0 Hardware doesn't support sample-resolution mmap
 * \retval 1 Hardware supports sample-resolution mmap
 *
 * The return value is always one when given configuration is not exactly one.
 * Usually, #snd_pcm_hw_params() function chooses one configuration
 * from the configuration space.
 */
int snd_pcm_hw_params_can_mmap_sample_resolution(const snd_pcm_hw_params_t *params)
{
        assert(params);
        if (CHECK_SANITY(params->info == ~0U)) {
                SNDMSG("invalid PCM info field");
                return 0; /* FIXME: should be a negative error? */
        }
        return !!(params->info & SNDRV_PCM_INFO_MMAP_VALID);
}

/**
 * \brief Check, if hardware does double buffering for start/stop for given configuration
 * \param params Configuration space
 * \return Boolean value
 * \retval 0 Hardware doesn't do double buffering for start/stop
 * \retval 1 Hardware does double buffering for start/stop
 *
 * It is not allowed to call this function when given configuration is not exactly one.
 * Usually, #snd_pcm_hw_params() function chooses one configuration
 * from the configuration space.
 */
int snd_pcm_hw_params_is_double(const snd_pcm_hw_params_t *params)
{
        assert(params);
        if (CHECK_SANITY(params->info == ~0U)) {
                SNDMSG("invalid PCM info field");
                return 0; /* FIXME: should be a negative error? */
        }
        return !!(params->info & SNDRV_PCM_INFO_DOUBLE);
}

/**
 * \brief Check, if hardware does double buffering for data transfers for given configuration
 * \param params Configuration space
 * \return Boolean value
 * \retval 0 Hardware doesn't do double buffering for data transfers
 * \retval 1 Hardware does double buffering for data transfers
 *
 * It is not allowed to call this function when given configuration is not exactly one.
 * Usually, #snd_pcm_hw_params() function chooses one configuration
 * from the configuration space.
 */
int snd_pcm_hw_params_is_batch(const snd_pcm_hw_params_t *params)
{
        assert(params);
        if (CHECK_SANITY(params->info == ~0U)) {
                SNDMSG("invalid PCM info field");
                return 0; /* FIXME: should be a negative error? */
        }
        return !!(params->info & SNDRV_PCM_INFO_BATCH);
}

/**
 * \brief Check, if hardware does block transfers for samples for given configuration
 * \param params Configuration space
 * \return Boolean value
 * \retval 0 Hardware doesn't block transfers
 * \retval 1 Hardware does block transfers
 *
 * It is not allowed to call this function when given configuration is not exactly one.
 * Usually, #snd_pcm_hw_params() function chooses one configuration
 * from the configuration space.
 */
int snd_pcm_hw_params_is_block_transfer(const snd_pcm_hw_params_t *params)
{
        assert(params);
        if (CHECK_SANITY(params->info == ~0U)) {
                SNDMSG("invalid PCM info field");
                return 0; /* FIXME: should be a negative error? */
        }
        return !!(params->info & SNDRV_PCM_INFO_BLOCK_TRANSFER);
}

/**
 * \brief Check, if timestamps are monotonic for given configuration
 * \param params Configuration space
 * \return Boolean value
 * \retval 0 Device doesn't do monotomic timestamps
 * \retval 1 Device does monotonic timestamps
 *
 * It is not allowed to call this function when given configuration is not exactly one.
 * Usually, #snd_pcm_hw_params() function chooses one configuration
 * from the configuration space.
 */
int snd_pcm_hw_params_is_monotonic(const snd_pcm_hw_params_t *params)
{
        assert(params);
        if (CHECK_SANITY(params->info == ~0U)) {
                SNDMSG("invalid PCM info field");
                return 0; /* FIXME: should be a negative error? */
        }
        return !!(params->info & SND_PCM_INFO_MONOTONIC);
}

/**
 * \brief Check, if hardware supports overrange detection
 * \param params Configuration space
 * \return Boolean value
 * \retval 0 Hardware doesn't support overrange detection
 * \retval 1 Hardware supports overrange detection
 *
 * It is not allowed to call this function when given configuration is not exactly one.
 * Usually, #snd_pcm_hw_params() function chooses one configuration
 * from the configuration space.
 */
int snd_pcm_hw_params_can_overrange(const snd_pcm_hw_params_t *params)
{
        assert(params);
        if (CHECK_SANITY(params->info == ~0U)) {
                SNDMSG("invalid PCM info field");
                return 0; /* FIXME: should be a negative error? */
        }
        return !!(params->info & SNDRV_PCM_INFO_OVERRANGE);
}

/**
 * \brief Check, if hardware supports pause
 * \param params Configuration space
 * \return Boolean value
 * \retval 0 Hardware doesn't support pause
 * \retval 1 Hardware supports pause
 *
 * It is not allowed to call this function when given configuration is not exactly one.
 * Usually, #snd_pcm_hw_params() function chooses one configuration
 * from the configuration space.
 */
int snd_pcm_hw_params_can_pause(const snd_pcm_hw_params_t *params)
{
        assert(params);
        if (CHECK_SANITY(params->info == ~0U)) {
                SNDMSG("invalid PCM info field");
                return 0; /* FIXME: should be a negative error? */
        }
        return !!(params->info & SNDRV_PCM_INFO_PAUSE);
}

/**
 * \brief Check, if hardware supports resume
 * \param params Configuration space
 * \return Boolean value
 * \retval 0 Hardware doesn't support resume
 * \retval 1 Hardware supports resume
 *
 * It is not allowed to call this function when given configuration is not exactly one.
 * Usually, #snd_pcm_hw_params() function chooses one configuration
 * from the configuration space.
 */
int snd_pcm_hw_params_can_resume(const snd_pcm_hw_params_t *params)
{
        assert(params);
        if (CHECK_SANITY(params->info == ~0U)) {
                SNDMSG("invalid PCM info field");
                return 0; /* FIXME: should be a negative error? */
        }
        return !!(params->info & SNDRV_PCM_INFO_RESUME);
}

/**
 * \brief Check, if hardware does half-duplex only
 * \param params Configuration space
 * \return Boolean value
 * \retval 0 Hardware doesn't do half-duplex
 * \retval 1 Hardware does half-duplex
 *
 * It is not allowed to call this function when given configuration is not exactly one.
 * Usually, #snd_pcm_hw_params() function chooses one configuration
 * from the configuration space.
 */
int snd_pcm_hw_params_is_half_duplex(const snd_pcm_hw_params_t *params)
{
        assert(params);
        if (CHECK_SANITY(params->info == ~0U)) {
                SNDMSG("invalid PCM info field");
                return 0; /* FIXME: should be a negative error? */
        }
        return !!(params->info & SNDRV_PCM_INFO_HALF_DUPLEX);
}

/**
 * \brief Check, if hardware does joint-duplex (playback and capture are somewhat correlated)
 * \param params Configuration space
 * \return Boolean value
 * \retval 0 Hardware doesn't do joint-duplex
 * \retval 1 Hardware does joint-duplex
 *
 * It is not allowed to call this function when given configuration is not exactly one.
 * Usually, #snd_pcm_hw_params() function chooses one configuration
 * from the configuration space.
 */
int snd_pcm_hw_params_is_joint_duplex(const snd_pcm_hw_params_t *params)
{
        assert(params);
        if (CHECK_SANITY(params->info == ~0U)) {
                SNDMSG("invalid PCM info field");
                return 0; /* FIXME: should be a negative error? */
        }
        return !!(params->info & SNDRV_PCM_INFO_JOINT_DUPLEX);
}

/**
 * \brief Check, if hardware supports synchronized start with sample resolution
 * \param params Configuration space
 * \return Boolean value
 * \retval 0 Hardware doesn't support synchronized start
 * \retval 1 Hardware supports synchronized start
 *
 * It is not allowed to call this function when given configuration is not exactly one.
 * Usually, #snd_pcm_hw_params() function chooses one configuration
 * from the configuration space.
 */
int snd_pcm_hw_params_can_sync_start(const snd_pcm_hw_params_t *params)
{
        assert(params);
        if (CHECK_SANITY(params->info == ~0U)) {
                SNDMSG("invalid PCM info field");
                return 0; /* FIXME: should be a negative error? */
        }
        return !!(params->info & SNDRV_PCM_INFO_SYNC_START);
}

/**
 * \brief Get rate exact info from a configuration space
 * \param params Configuration space
 * \param rate_num Pointer to returned rate numerator
 * \param rate_den Pointer to returned rate denominator
 * \return 0 otherwise a negative error code if the info is not available
 *
 * It is not allowed to call this function when given configuration is not exactly one.
 * Usually, #snd_pcm_hw_params() function chooses one configuration
 * from the configuration space.
 */
int snd_pcm_hw_params_get_rate_numden(const snd_pcm_hw_params_t *params,
                                      unsigned int *rate_num, unsigned int *rate_den)
{
        assert(params);
        if (CHECK_SANITY(params->rate_den == 0)) {
                SNDMSG("invalid rate_den value");
                return -EINVAL;
        }
        *rate_num = params->rate_num;
        *rate_den = params->rate_den;
        return 0;
}

/**
 * \brief Get sample resolution info from a configuration space
 * \param params Configuration space
 * \return signification bits in sample otherwise a negative error code if the info is not available
 *
 * It is not allowed to call this function when given configuration is not exactly one.
 * Usually, #snd_pcm_hw_params() function chooses one configuration
 * from the configuration space.
 */
int snd_pcm_hw_params_get_sbits(const snd_pcm_hw_params_t *params)
{
        assert(params);
        if (CHECK_SANITY(params->msbits == 0)) {
                SNDMSG("invalid msbits value");
                return -EINVAL;
        }
        return params->msbits;
}

/**
 * \brief Get hard are FIFO size info from a configuration space
 * \param params Configuration space
 * \return FIFO size in frames otherwise a negative error code if the info is not available
 *
 * It is not allowed to call this function when given configuration is not exactly one.
 * Usually, #snd_pcm_hw_params() function chooses one configuration
 * from the configuration space.
 */
int snd_pcm_hw_params_get_fifo_size(const snd_pcm_hw_params_t *params)
{
        assert(params);
        if (CHECK_SANITY(params->info == ~0U)) {
                SNDMSG("invalid PCM info field");
                return -EINVAL;
        }
        return params->fifo_size;
}

/**
 * \brief Fill params with a full configuration space for a PCM
 * \param pcm PCM handle
 * \param params Configuration space
 */
int snd_pcm_hw_params_any(snd_pcm_t *pcm, snd_pcm_hw_params_t *params)
{
        _snd_pcm_hw_params_any(params);
        return snd_pcm_hw_refine(pcm, params);
}

/**
 * \brief get size of #snd_pcm_access_mask_t
 * \return size in bytes
 */
size_t snd_pcm_access_mask_sizeof()
{
        return sizeof(snd_pcm_access_mask_t);
}

/**
 * \brief allocate an empty #snd_pcm_access_mask_t using standard malloc
 * \param ptr returned pointer
 * \return 0 on success otherwise negative error code
 */
int snd_pcm_access_mask_malloc(snd_pcm_access_mask_t **ptr)
{
        assert(ptr);
        *ptr = calloc(1, sizeof(snd_pcm_access_mask_t));
        if (!*ptr)
                return -ENOMEM;
        return 0;
}

/**
 * \brief frees a previously allocated #snd_pcm_access_mask_t
 * \param obj pointer to object to free
 */
void snd_pcm_access_mask_free(snd_pcm_access_mask_t *obj)
{
        free(obj);
}

/**
 * \brief copy one #snd_pcm_access_mask_t to another
 * \param dst pointer to destination
 * \param src pointer to source
 */
void snd_pcm_access_mask_copy(snd_pcm_access_mask_t *dst, const snd_pcm_access_mask_t *src)
{
        assert(dst && src);
        *dst = *src;
}

/**
 * \brief reset all bits in a #snd_pcm_access_mask_t
 * \param mask pointer to mask
 */
void snd_pcm_access_mask_none(snd_pcm_access_mask_t *mask)
{
        snd_mask_none((snd_mask_t *) mask);
}

/**
 * \brief set all bits in a #snd_pcm_access_mask_t
 * \param mask pointer to mask
 */
void snd_pcm_access_mask_any(snd_pcm_access_mask_t *mask)
{
        snd_mask_any((snd_mask_t *) mask);
}

/**
 * \brief test the presence of an access type in a #snd_pcm_access_mask_t
 * \param mask pointer to mask
 * \param val access type
 */
int snd_pcm_access_mask_test(const snd_pcm_access_mask_t *mask, snd_pcm_access_t val)
{
        return snd_mask_test((const snd_mask_t *) mask, (unsigned long) val);
}

/**
 * \brief test, if given a #snd_pcm_access_mask_t is empty
 * \param mask pointer to mask
 * \retval 0 not empty
 * \retval 1 empty
 */
int snd_pcm_access_mask_empty(const snd_pcm_access_mask_t *mask)
{
        return snd_mask_empty((const snd_mask_t *) mask);
}

/**
 * \brief make an access type present in a #snd_pcm_access_mask_t
 * \param mask pointer to mask
 * \param val access type
 */
void snd_pcm_access_mask_set(snd_pcm_access_mask_t *mask, snd_pcm_access_t val)
{
        snd_mask_set((snd_mask_t *) mask, (unsigned long) val);
}

/**
 * \brief make an access type missing from a #snd_pcm_access_mask_t
 * \param mask pointer to mask
 * \param val access type
 */
void snd_pcm_access_mask_reset(snd_pcm_access_mask_t *mask, snd_pcm_access_t val)
{
        snd_mask_reset((snd_mask_t *) mask, (unsigned long) val);
}

/**
 * \brief get size of #snd_pcm_format_mask_t
 * \return size in bytes
 */
size_t snd_pcm_format_mask_sizeof()
{
        return sizeof(snd_pcm_format_mask_t);
}

/**
 * \brief allocate an empty #snd_pcm_format_mask_t using standard malloc
 * \param ptr returned pointer
 * \return 0 on success otherwise negative error code
 */
int snd_pcm_format_mask_malloc(snd_pcm_format_mask_t **ptr)
{
        assert(ptr);
        *ptr = calloc(1, sizeof(snd_pcm_format_mask_t));
        if (!*ptr)
                return -ENOMEM;
        return 0;
}

/**
 * \brief frees a previously allocated #snd_pcm_format_mask_t
 * \param obj pointer to object to free
 */
void snd_pcm_format_mask_free(snd_pcm_format_mask_t *obj)
{
        free(obj);
}

/**
 * \brief copy one #snd_pcm_format_mask_t to another
 * \param dst pointer to destination
 * \param src pointer to source
 */
void snd_pcm_format_mask_copy(snd_pcm_format_mask_t *dst, const snd_pcm_format_mask_t *src)
{
        assert(dst && src);
        *dst = *src;
}

/**
 * \brief reset all bits in a #snd_pcm_format_mask_t
 * \param mask pointer to mask
 */
void snd_pcm_format_mask_none(snd_pcm_format_mask_t *mask)
{
        snd_mask_none((snd_mask_t *) mask);
}

/**
 * \brief set all bits in a #snd_pcm_format_mask_t
 * \param mask pointer to mask
 */
void snd_pcm_format_mask_any(snd_pcm_format_mask_t *mask)
{
        snd_mask_any((snd_mask_t *) mask);
}

/**
 * \brief test the presence of a format in a #snd_pcm_format_mask_t
 * \param mask pointer to mask
 * \param val format
 */
int snd_pcm_format_mask_test(const snd_pcm_format_mask_t *mask, snd_pcm_format_t val)
{
        return snd_mask_test((const snd_mask_t *) mask, (unsigned long) val);
}

/**
 * \brief test, if given a #snd_pcm_format_mask_t is empty
 * \param mask pointer to mask
 * \retval 0 not empty
 * \retval 1 empty
 */
int snd_pcm_format_mask_empty(const snd_pcm_format_mask_t *mask)
{
        return snd_mask_empty((const snd_mask_t *) mask);
}

/**
 * \brief make a format present in a #snd_pcm_format_mask_t
 * \param mask pointer to mask
 * \param val format
 */
void snd_pcm_format_mask_set(snd_pcm_format_mask_t *mask, snd_pcm_format_t val)
{
        snd_mask_set((snd_mask_t *) mask, (unsigned long) val);
}

/**
 * \brief make a format missing from a #snd_pcm_format_mask_t
 * \param mask pointer to mask
 * \param val format
 */
void snd_pcm_format_mask_reset(snd_pcm_format_mask_t *mask, snd_pcm_format_t val)
{
        snd_mask_reset((snd_mask_t *) mask, (unsigned long) val);
}


/**
 * \brief get size of #snd_pcm_subformat_mask_t
 * \return size in bytes
 */
size_t snd_pcm_subformat_mask_sizeof()
{
        return sizeof(snd_pcm_subformat_mask_t);
}

/**
 * \brief allocate an empty #snd_pcm_subformat_mask_t using standard malloc
 * \param ptr returned pointer
 * \return 0 on success otherwise negative error code
 */
int snd_pcm_subformat_mask_malloc(snd_pcm_subformat_mask_t **ptr)
{
        assert(ptr);
        *ptr = calloc(1, sizeof(snd_pcm_subformat_mask_t));
        if (!*ptr)
                return -ENOMEM;
        return 0;
}

/**
 * \brief frees a previously allocated #snd_pcm_subformat_mask_t
 * \param obj pointer to object to free
 */
void snd_pcm_subformat_mask_free(snd_pcm_subformat_mask_t *obj)
{
        free(obj);
}

/**
 * \brief copy one #snd_pcm_subformat_mask_t to another
 * \param dst pointer to destination
 * \param src pointer to source
 */
void snd_pcm_subformat_mask_copy(snd_pcm_subformat_mask_t *dst, const snd_pcm_subformat_mask_t *src)
{
        assert(dst && src);
        *dst = *src;
}

/**
 * \brief reset all bits in a #snd_pcm_subformat_mask_t
 * \param mask pointer to mask
 */
void snd_pcm_subformat_mask_none(snd_pcm_subformat_mask_t *mask)
{
        snd_mask_none((snd_mask_t *) mask);
}

/**
 * \brief set all bits in a #snd_pcm_subformat_mask_t
 * \param mask pointer to mask
 */
void snd_pcm_subformat_mask_any(snd_pcm_subformat_mask_t *mask)
{
        snd_mask_any((snd_mask_t *) mask);
}

/**
 * \brief test the presence of a subformat in a #snd_pcm_subformat_mask_t
 * \param mask pointer to mask
 * \param val subformat
 */
int snd_pcm_subformat_mask_test(const snd_pcm_subformat_mask_t *mask, snd_pcm_subformat_t val)
{
        return snd_mask_test((const snd_mask_t *) mask, (unsigned long) val);
}

/**
 * \brief test, if given a #snd_pcm_subformat_mask_t is empty
 * \param mask pointer to mask
 * \retval 0 not empty
 * \retval 1 empty
 */
int snd_pcm_subformat_mask_empty(const snd_pcm_subformat_mask_t *mask)
{
        return snd_mask_empty((const snd_mask_t *) mask);
}

/**
 * \brief make a subformat present in a #snd_pcm_subformat_mask_t
 * \param mask pointer to mask
 * \param val subformat
 */
void snd_pcm_subformat_mask_set(snd_pcm_subformat_mask_t *mask, snd_pcm_subformat_t val)
{
        snd_mask_set((snd_mask_t *) mask, (unsigned long) val);
}

/**
 * \brief make a subformat missing from a #snd_pcm_subformat_mask_t
 * \param mask pointer to mask
 * \param val subformat
 */
void snd_pcm_subformat_mask_reset(snd_pcm_subformat_mask_t *mask, snd_pcm_subformat_t val)
{
        snd_mask_reset((snd_mask_t *) mask, (unsigned long) val);
}


/**
 * \brief get size of #snd_pcm_hw_params_t
 * \return size in bytes
 */
size_t snd_pcm_hw_params_sizeof()
{
        return sizeof(snd_pcm_hw_params_t);
}

/**
 * \brief allocate an invalid #snd_pcm_hw_params_t using standard malloc
 * \param ptr returned pointer
 * \return 0 on success otherwise negative error code
 */
int snd_pcm_hw_params_malloc(snd_pcm_hw_params_t **ptr)
{
        assert(ptr);
        *ptr = calloc(1, sizeof(snd_pcm_hw_params_t));
        if (!*ptr)
                return -ENOMEM;
        return 0;
}

/**
 * \brief frees a previously allocated #snd_pcm_hw_params_t
 * \param obj pointer to object to free
 */
void snd_pcm_hw_params_free(snd_pcm_hw_params_t *obj)
{
        free(obj);
}

/**
 * \brief copy one #snd_pcm_hw_params_t to another
 * \param dst pointer to destination
 * \param src pointer to source
 */
void snd_pcm_hw_params_copy(snd_pcm_hw_params_t *dst, const snd_pcm_hw_params_t *src)
{
        assert(dst && src);
        *dst = *src;
}


/**
 * \brief Extract access type from a configuration space
 * \param params Configuration space
 * \param access Returned value
 * \return access type otherwise a negative error code if not exactly one is present
 */
#ifndef DOXYGEN
int INTERNAL(snd_pcm_hw_params_get_access)(const snd_pcm_hw_params_t *params, snd_pcm_access_t *access)
#else
int snd_pcm_hw_params_get_access(const snd_pcm_hw_params_t *params, snd_pcm_access_t *access)
#endif
{
        unsigned int _val;
        int err = snd_pcm_hw_param_get(params, SND_PCM_HW_PARAM_ACCESS, &_val, NULL);
        if (err >= 0)
                *access = _val;
        return err;
}

/**
 * \brief Verify if an access type is available inside a configuration space for a PCM
 * \param pcm PCM handle
 * \param params Configuration space
 * \param access access type
 * \return 0 if available a negative error code otherwise
 */
int snd_pcm_hw_params_test_access(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, snd_pcm_access_t access)
{
        return snd_pcm_hw_param_set(pcm, params, SND_TEST, SND_PCM_HW_PARAM_ACCESS, access, 0);
}

/**
 * \brief Restrict a configuration space to contain only one access type
 * \param pcm PCM handle
 * \param params Configuration space
 * \param access access type
 * \return 0 otherwise a negative error code if configuration space would become empty
 */
int snd_pcm_hw_params_set_access(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, snd_pcm_access_t access)
{
        return snd_pcm_hw_param_set(pcm, params, SND_TRY, SND_PCM_HW_PARAM_ACCESS, access, 0);
}

/**
 * \brief Restrict a configuration space to contain only its first access type
 * \param pcm PCM handle
 * \param params Configuration space
 * \param access Returned first access type
 * \return 0 otherwise a negative error code
 */
#ifndef DOXYGEN
int INTERNAL(snd_pcm_hw_params_set_access_first)(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, snd_pcm_access_t *access)
#else
int snd_pcm_hw_params_set_access_first(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, snd_pcm_access_t *access)
#endif
{
        return snd_pcm_hw_param_set_first(pcm, params, SND_PCM_HW_PARAM_ACCESS, access, NULL);
}

/**
 * \brief Restrict a configuration space to contain only its last access type
 * \param pcm PCM handle
 * \param params Configuration space
 * \param access Returned last access type
 * \return 0 otherwise a negative error code
 */
#ifndef DOXYGEN
int INTERNAL(snd_pcm_hw_params_set_access_last)(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, snd_pcm_access_t *access)
#else
int snd_pcm_hw_params_set_access_last(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, snd_pcm_access_t *access)
#endif
{
        return snd_pcm_hw_param_set_last(pcm, params, SND_PCM_HW_PARAM_ACCESS, access, NULL);
}

/**
 * \brief Restrict a configuration space to contain only a set of access types
 * \param pcm PCM handle
 * \param params Configuration space
 * \param mask Access mask
 * \return 0 otherwise a negative error code
 */
int snd_pcm_hw_params_set_access_mask(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, snd_pcm_access_mask_t *mask)
{
        return snd_pcm_hw_param_set_mask(pcm, params, SND_TRY, SND_PCM_HW_PARAM_ACCESS, (snd_mask_t *) mask);
}

/**
 * \brief Get access mask from a configuration space
 * \param params Configuration space
 * \param mask Returned Access mask
 */
int snd_pcm_hw_params_get_access_mask(snd_pcm_hw_params_t *params, snd_pcm_access_mask_t *mask)
{
        if (params == NULL || mask == NULL)
                return -EINVAL;
        snd_pcm_access_mask_copy(mask, snd_pcm_hw_param_get_mask(params, SND_PCM_HW_PARAM_ACCESS));
        return 0;
}


/**
 * \brief Extract format from a configuration space
 * \param params Configuration space
 * \param format returned format
 * \return format otherwise a negative error code if not exactly one is present
 */
#ifndef DOXYGEN
int INTERNAL(snd_pcm_hw_params_get_format)(const snd_pcm_hw_params_t *params, snd_pcm_format_t *format)
#else
int snd_pcm_hw_params_get_format(const snd_pcm_hw_params_t *params, snd_pcm_format_t *format)
#endif
{
        return snd_pcm_hw_param_get(params, SND_PCM_HW_PARAM_FORMAT, (unsigned int *)format, NULL);
}

/**
 * \brief Verify if a format is available inside a configuration space for a PCM
 * \param pcm PCM handle
 * \param params Configuration space
 * \param format format
 * \return 0 if available a negative error code otherwise
 */
int snd_pcm_hw_params_test_format(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, snd_pcm_format_t format)
{
        return snd_pcm_hw_param_set(pcm, params, SND_TEST, SND_PCM_HW_PARAM_FORMAT, format, 0);
}

/**
 * \brief Restrict a configuration space to contain only one format
 * \param pcm PCM handle
 * \param params Configuration space
 * \param format format
 * \return 0 otherwise a negative error code
 */
int snd_pcm_hw_params_set_format(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, snd_pcm_format_t format)
{
        return snd_pcm_hw_param_set(pcm, params, SND_TRY, SND_PCM_HW_PARAM_FORMAT, format, 0);
}

/**
 * \brief Restrict a configuration space to contain only its first format
 * \param pcm PCM handle
 * \param params Configuration space
 * \param format Returned first format
 * \return 0 otherwise a negative error code
 */
#ifndef DOXYGEN
int INTERNAL(snd_pcm_hw_params_set_format_first)(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, snd_pcm_format_t *format)
#else
int snd_pcm_hw_params_set_format_first(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, snd_pcm_format_t *format)
#endif
{
        return snd_pcm_hw_param_set_first(pcm, params, SND_PCM_HW_PARAM_FORMAT, (unsigned int *)format, NULL);
}

/**
 * \brief Restrict a configuration space to contain only its last format
 * \param pcm PCM handle
 * \param params Configuration space
 * \param format Returned last format
 * \return 0 otherwise a negative error code
 */
#ifndef DOXYGEN
int INTERNAL(snd_pcm_hw_params_set_format_last)(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, snd_pcm_format_t *format)
#else
int snd_pcm_hw_params_set_format_last(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, snd_pcm_format_t *format)
#endif
{
        return snd_pcm_hw_param_set_last(pcm, params, SND_PCM_HW_PARAM_FORMAT, (unsigned int *)format, NULL);
}

/**
 * \brief Restrict a configuration space to contain only a set of formats
 * \param pcm PCM handle
 * \param params Configuration space
 * \param mask Format mask
 * \return 0 otherwise a negative error code
 */
int snd_pcm_hw_params_set_format_mask(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, snd_pcm_format_mask_t *mask)
{
        return snd_pcm_hw_param_set_mask(pcm, params, SND_TRY, SND_PCM_HW_PARAM_FORMAT, (snd_mask_t *) mask);
}

/**
 * \brief Get format mask from a configuration space
 * \param params Configuration space
 * \param mask Returned Format mask
 */
void snd_pcm_hw_params_get_format_mask(snd_pcm_hw_params_t *params, snd_pcm_format_mask_t *mask)
{
        snd_pcm_format_mask_copy(mask, snd_pcm_hw_param_get_mask(params, SND_PCM_HW_PARAM_FORMAT));
}


/**
 * \brief Extract subformat from a configuration space
 * \param params Configuration space
 * \param subformat Returned subformat value
 * \return subformat otherwise a negative error code if not exactly one is present
 */
#ifndef DOXYGEN
int INTERNAL(snd_pcm_hw_params_get_subformat)(const snd_pcm_hw_params_t *params, snd_pcm_subformat_t *subformat)
#else
int snd_pcm_hw_params_get_subformat(const snd_pcm_hw_params_t *params, snd_pcm_subformat_t *subformat)
#endif
{
        return snd_pcm_hw_param_get(params, SND_PCM_HW_PARAM_SUBFORMAT, subformat, NULL);
}

/**
 * \brief Verify if a subformat is available inside a configuration space for a PCM
 * \param pcm PCM handle
 * \param params Configuration space
 * \param subformat subformat value
 * \return 0 if available a negative error code otherwise
 */
int snd_pcm_hw_params_test_subformat(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, snd_pcm_subformat_t subformat)
{
        return snd_pcm_hw_param_set(pcm, params, SND_TEST, SND_PCM_HW_PARAM_SUBFORMAT, subformat, 0);
}

/**
 * \brief Restrict a configuration space to contain only one subformat
 * \param pcm PCM handle
 * \param params Configuration space
 * \param subformat subformat value
 * \return 0 otherwise a negative error code if configuration space would become empty
 */
int snd_pcm_hw_params_set_subformat(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, snd_pcm_subformat_t subformat)
{
        return snd_pcm_hw_param_set(pcm, params, SND_TRY, SND_PCM_HW_PARAM_SUBFORMAT, subformat, 0);
}

/**
 * \brief Restrict a configuration space to contain only its first subformat
 * \param pcm PCM handle
 * \param params Configuration space
 * \param subformat Returned subformat
 * \return 0 otherwise a negative error code
 */
#ifndef DOXYGEN
int INTERNAL(snd_pcm_hw_params_set_subformat_first)(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, snd_pcm_subformat_t *subformat)
#else
int snd_pcm_hw_params_set_subformat_first(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, snd_pcm_subformat_t *subformat)
#endif
{
        return snd_pcm_hw_param_set_first(pcm, params, SND_PCM_HW_PARAM_SUBFORMAT, subformat, NULL);
}

/**
 * \brief Restrict a configuration space to contain only its last subformat
 * \param pcm PCM handle
 * \param params Configuration space
 * \param subformat Returned subformat
 * \return 0 otherwise a negative error code
 */
#ifndef DOXYGEN
int INTERNAL(snd_pcm_hw_params_set_subformat_last)(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, snd_pcm_subformat_t *subformat)
#else
int snd_pcm_hw_params_set_subformat_last(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, snd_pcm_subformat_t *subformat)
#endif
{
        return snd_pcm_hw_param_set_last(pcm, params, SND_PCM_HW_PARAM_SUBFORMAT, subformat, NULL);
}

/**
 * \brief Restrict a configuration space to contain only a set of subformats
 * \param pcm PCM handle
 * \param params Configuration space
 * \param mask Subformat mask
 * \return 0 otherwise a negative error code
 */
int snd_pcm_hw_params_set_subformat_mask(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, snd_pcm_subformat_mask_t *mask)
{
        return snd_pcm_hw_param_set_mask(pcm, params, SND_TRY, SND_PCM_HW_PARAM_SUBFORMAT, (snd_mask_t *) mask);
}

/**
 * \brief Get subformat mask from a configuration space
 * \param params Configuration space
 * \param mask Returned Subformat mask
 */
void snd_pcm_hw_params_get_subformat_mask(snd_pcm_hw_params_t *params, snd_pcm_subformat_mask_t *mask)
{
        snd_pcm_subformat_mask_copy(mask, snd_pcm_hw_param_get_mask(params, SND_PCM_HW_PARAM_SUBFORMAT));
}


/**
 * \brief Extract channels from a configuration space
 * \param params Configuration space
 * \param val Returned channels count
 * \return 0 otherwise a negative error code if not exactly one is present
 */
#ifndef DOXYGEN
int INTERNAL(snd_pcm_hw_params_get_channels)(const snd_pcm_hw_params_t *params, unsigned int *val)
#else
int snd_pcm_hw_params_get_channels(const snd_pcm_hw_params_t *params, unsigned int *val)
#endif
{
        return snd_pcm_hw_param_get(params, SND_PCM_HW_PARAM_CHANNELS, val, NULL);
}

/**
 * \brief Extract minimum channels count from a configuration space
 * \param params Configuration space
 * \param val minimum channels count
 * \return 0 otherwise a negative error code
 */
#ifndef DOXYGEN
int INTERNAL(snd_pcm_hw_params_get_channels_min)(const snd_pcm_hw_params_t *params, unsigned int *val)
#else
int snd_pcm_hw_params_get_channels_min(const snd_pcm_hw_params_t *params, unsigned int *val)
#endif
{
        return snd_pcm_hw_param_get_min(params, SND_PCM_HW_PARAM_CHANNELS, val, NULL);
}

/**
 * \brief Extract maximum channels count from a configuration space
 * \param params Configuration space
 * \param val maximum channels count
 * \return 0 otherwise a negative error code
 */
#ifndef DOXYGEN
int INTERNAL(snd_pcm_hw_params_get_channels_max)(const snd_pcm_hw_params_t *params, unsigned int *val)
#else
int snd_pcm_hw_params_get_channels_max(const snd_pcm_hw_params_t *params, unsigned int *val)
#endif
{
        return snd_pcm_hw_param_get_max(params, SND_PCM_HW_PARAM_CHANNELS, val, NULL);
}

/**
 * \brief Verify if a channels count is available inside a configuration space for a PCM
 * \param pcm PCM handle
 * \param params Configuration space
 * \param val channels count
 * \return 0 if available a negative error code otherwise
 */
int snd_pcm_hw_params_test_channels(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int val)
{
        return snd_pcm_hw_param_set(pcm, params, SND_TEST, SND_PCM_HW_PARAM_CHANNELS, val, 0);
}

/**
 * \brief Restrict a configuration space to contain only one channels count
 * \param pcm PCM handle
 * \param params Configuration space
 * \param val channels count
 * \return 0 otherwise a negative error code if configuration space would become empty
 */
int snd_pcm_hw_params_set_channels(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int val)
{
        return snd_pcm_hw_param_set(pcm, params, SND_TRY, SND_PCM_HW_PARAM_CHANNELS, val, 0);
}

/**
 * \brief Restrict a configuration space with a minimum channels count
 * \param pcm PCM handle
 * \param params Configuration space
 * \param val minimum channels count (on return filled with actual minimum)
 * \return 0 otherwise a negative error code if configuration space would become empty
 */
int snd_pcm_hw_params_set_channels_min(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int *val)
{
        return snd_pcm_hw_param_set_min(pcm, params, SND_TRY, SND_PCM_HW_PARAM_CHANNELS, val, NULL);
}

/**
 * \brief Restrict a configuration space with a maximum channels count
 * \param pcm PCM handle
 * \param params Configuration space
 * \param val maximum channels count (on return filled with actual maximum)
 * \return 0 otherwise a negative error code if configuration space would become empty
 */
int snd_pcm_hw_params_set_channels_max(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int *val)
{
        return snd_pcm_hw_param_set_max(pcm, params, SND_TRY, SND_PCM_HW_PARAM_CHANNELS, val, NULL);
}

/**
 * \brief Restrict a configuration space to have channels counts in a given range
 * \param pcm PCM handle
 * \param params Configuration space
 * \param min minimum channels count (on return filled with actual minimum)
 * \param max maximum channels count (on return filled with actual maximum)
 * \return 0 otherwise a negative error code if configuration space would become empty
 */
int snd_pcm_hw_params_set_channels_minmax(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int *min, unsigned int *max)
{
        return snd_pcm_hw_param_set_minmax(pcm, params, SND_TRY, SND_PCM_HW_PARAM_CHANNELS, min, NULL, max, NULL);
}

/**
 * \brief Restrict a configuration space to have channels count nearest to a target
 * \param pcm PCM handle
 * \param params Configuration space
 * \param val target channels count, returned chosen channels count
 * \return 0 otherwise a negative error code if configuration space is empty
 */
#ifndef DOXYGEN
int INTERNAL(snd_pcm_hw_params_set_channels_near)(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int *val)
#else
int snd_pcm_hw_params_set_channels_near(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int *val)
#endif
{
        return snd_pcm_hw_param_set_near(pcm, params, SND_PCM_HW_PARAM_CHANNELS, val, NULL);
}

/**
 * \brief Restrict a configuration space to contain only its minimum channels count
 * \param pcm PCM handle
 * \param params Configuration space
 * \param val minimum channels count
 * \return 0 otherwise a negative error code
 */
#ifndef DOXYGEN
int INTERNAL(snd_pcm_hw_params_set_channels_first)(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int *val)
#else
int snd_pcm_hw_params_set_channels_first(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int *val)
#endif
{
        return snd_pcm_hw_param_set_first(pcm, params, SND_PCM_HW_PARAM_CHANNELS, val, NULL);
}

/**
 * \brief Restrict a configuration space to contain only its maximum channels count
 * \param pcm PCM handle
 * \param params Configuration space
 * \param val maximum channels count
 * \return 0 otherwise a negative error code
 */
#ifndef DOXYGEN
int INTERNAL(snd_pcm_hw_params_set_channels_last)(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int *val)
#else
int snd_pcm_hw_params_set_channels_last(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int *val)
#endif
{
        return snd_pcm_hw_param_set_last(pcm, params, SND_PCM_HW_PARAM_CHANNELS, val, NULL);
}


/**
 * \brief Extract rate from a configuration space
 * \param params Configuration space
 * \param val Returned approximate rate
 * \param dir Sub unit direction
 * \return 0 otherwise a negative error code if not exactly one is present
 *
 * Actual exact value is <,=,> the approximate one following dir (-1, 0, 1)
 */
#ifndef DOXYGEN
int INTERNAL(snd_pcm_hw_params_get_rate)(const snd_pcm_hw_params_t *params, unsigned int *val, int *dir)
#else
int snd_pcm_hw_params_get_rate(const snd_pcm_hw_params_t *params, unsigned int *val, int *dir)
#endif
{
        return snd_pcm_hw_param_get(params, SND_PCM_HW_PARAM_RATE, val, dir);
}

/**
 * \brief Extract minimum rate from a configuration space
 * \param params Configuration space
 * \param val Returned approximate minimum rate
 * \param dir Sub unit direction
 * \return 0 otherwise a negative error code
 *
 * Exact value is <,=,> the returned one following dir (-1,0,1)
 */
#ifndef DOXYGEN
int INTERNAL(snd_pcm_hw_params_get_rate_min)(const snd_pcm_hw_params_t *params, unsigned int *val, int *dir)
#else
int snd_pcm_hw_params_get_rate_min(const snd_pcm_hw_params_t *params, unsigned int *val, int *dir)
#endif
{
        return snd_pcm_hw_param_get_min(params, SND_PCM_HW_PARAM_RATE, val, dir);
}

/**
 * \brief Extract maximum rate from a configuration space
 * \param params Configuration space
 * \param val Returned approximate maximum rate
 * \param dir Sub unit direction
 * \return 0 otherwise a negative error code
 *
 * Exact value is <,=,> the returned one following dir (-1,0,1)
 */
#ifndef DOXYGEN
int INTERNAL(snd_pcm_hw_params_get_rate_max)(const snd_pcm_hw_params_t *params, unsigned int *val, int *dir)
#else
int snd_pcm_hw_params_get_rate_max(const snd_pcm_hw_params_t *params, unsigned int *val, int *dir)
#endif
{
        return snd_pcm_hw_param_get_max(params, SND_PCM_HW_PARAM_RATE, val, dir);
}

/**
 * \brief Verify if a rate is available inside a configuration space for a PCM
 * \param pcm PCM handle
 * \param params Configuration space
 * \param val approximate rate
 * \param dir Sub unit direction
 * \return 0 if available a negative error code otherwise
 *
 * Wanted exact value is <,=,> val following dir (-1,0,1)
 */
int snd_pcm_hw_params_test_rate(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int val, int dir)
{
        return snd_pcm_hw_param_set(pcm, params, SND_TEST, SND_PCM_HW_PARAM_RATE, val, dir);
}

/**
 * \brief Restrict a configuration space to contain only one rate
 * \param pcm PCM handle
 * \param params Configuration space
 * \param val approximate rate
 * \param dir Sub unit direction
 * \return 0 otherwise a negative error code if configuration space would become empty
 *
 * Wanted exact value is <,=,> val following dir (-1,0,1)
 */
int snd_pcm_hw_params_set_rate(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int val, int dir)
{
        return snd_pcm_hw_param_set(pcm, params, SND_TRY, SND_PCM_HW_PARAM_RATE, val, dir);
}

/**
 * \brief Restrict a configuration space with a minimum rate
 * \param pcm PCM handle
 * \param params Configuration space
 * \param val approximate minimum rate (on return filled with actual minimum)
 * \param dir Sub unit direction (on return filled with actual direction)
 * \return 0 otherwise a negative error code if configuration space would become empty
 *
 * Wanted/actual exact minimum is <,=,> val following dir (-1,0,1)
 */
int snd_pcm_hw_params_set_rate_min(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int *val, int *dir)
{
        return snd_pcm_hw_param_set_min(pcm, params, SND_TRY, SND_PCM_HW_PARAM_RATE, val, dir);
}

/**
 * \brief Restrict a configuration space with a maximum rate
 * \param pcm PCM handle
 * \param params Configuration space
 * \param val approximate maximum rate (on return filled with actual maximum)
 * \param dir Sub unit direction (on return filled with actual direction)
 * \return 0 otherwise a negative error code if configuration space would become empty
 *
 * Wanted/actual exact maximum is <,=,> val following dir (-1,0,1)
 */
int snd_pcm_hw_params_set_rate_max(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int *val, int *dir)
{
        return snd_pcm_hw_param_set_max(pcm, params, SND_TRY, SND_PCM_HW_PARAM_RATE, val, dir);
}

/**
 * \brief Restrict a configuration space to have rates in a given range
 * \param pcm PCM handle
 * \param params Configuration space
 * \param min approximate minimum rate (on return filled with actual minimum)
 * \param mindir Sub unit direction for minimum (on return filled with actual direction)
 * \param max approximate maximum rate (on return filled with actual maximum)
 * \param maxdir Sub unit direction for maximum (on return filled with actual direction)
 * \return 0 otherwise a negative error code if configuration space would become empty
 *
 * Wanted/actual exact min/max is <,=,> val following dir (-1,0,1)
 */
int snd_pcm_hw_params_set_rate_minmax(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int *min, int *mindir, unsigned int *max, int *maxdir)
{
        return snd_pcm_hw_param_set_minmax(pcm, params, SND_TRY, SND_PCM_HW_PARAM_RATE, min, mindir, max, maxdir);
}

/**
 * \brief Restrict a configuration space to have rate nearest to a target
 * \param pcm PCM handle
 * \param params Configuration space
 * \param val approximate target rate / returned approximate set rate
 * \param dir Sub unit direction
 * \return 0 otherwise a negative error code if configuration space is empty
 *
 * target/chosen exact value is <,=,> val following dir (-1,0,1)
 */
#ifndef DOXYGEN
int INTERNAL(snd_pcm_hw_params_set_rate_near)(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int *val, int *dir)
#else
int snd_pcm_hw_params_set_rate_near(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int *val, int *dir)
#endif
{
        return snd_pcm_hw_param_set_near(pcm, params, SND_PCM_HW_PARAM_RATE, val, dir);
}

/**
 * \brief Restrict a configuration space to contain only its minimum rate
 * \param pcm PCM handle
 * \param params Configuration space
 * \param val Returned minimum approximate rate
 * \param dir Sub unit direction
 * \return 0 otherwise a negative error code
 *
 * Actual exact value is <,=,> the approximate one following dir (-1, 0, 1)
 */
#ifndef DOXYGEN
int INTERNAL(snd_pcm_hw_params_set_rate_first)(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int *val, int *dir)
#else
int snd_pcm_hw_params_set_rate_first(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int *val, int *dir)
#endif
{
        return snd_pcm_hw_param_set_first(pcm, params, SND_PCM_HW_PARAM_RATE, val, dir);
}

/**
 * \brief Restrict a configuration space to contain only its maximum rate
 * \param pcm PCM handle
 * \param params Configuration space
 * \param val Returned maximum approximate rate
 * \param dir Sub unit direction
 * \return 0 otherwise a negative error code
 *
 * Actual exact value is <,=,> the approximate one following dir (-1, 0, 1)
 */
#ifndef DOXYGEN
int INTERNAL(snd_pcm_hw_params_set_rate_last)(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int *val, int *dir)
#else
int snd_pcm_hw_params_set_rate_last(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int *val, int *dir)
#endif
{
        return snd_pcm_hw_param_set_last(pcm, params, SND_PCM_HW_PARAM_RATE, val, dir);
}

/**
 * \brief Restrict a configuration space to contain only real hardware rates
 * \param pcm PCM handle
 * \param params Configuration space
 * \param val 0 = disable, 1 = enable (default) rate resampling
 * \return 0 otherwise a negative error code
 */
int snd_pcm_hw_params_set_rate_resample(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int val)
{
        assert(pcm && params);
        if (!val)
                params->flags |= SND_PCM_HW_PARAMS_NORESAMPLE;
        else
                params->flags &= ~SND_PCM_HW_PARAMS_NORESAMPLE;
        return snd_pcm_hw_refine(pcm, params);
}

/**
 * \brief Extract resample state from a configuration space
 * \param pcm PCM handle
 * \param params Configuration space
 * \param val 0 = disable, 1 = enable rate resampling
 * \return 0 otherwise a negative error code
 */
int snd_pcm_hw_params_get_rate_resample(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int *val)
{
        assert(pcm && params && val);
        *val = params->flags & SND_PCM_HW_PARAMS_NORESAMPLE ? 0 : 1;
        return 0;
}

/**
 * \brief Restrict a configuration space to allow the buffer accessible from outside
 * \param pcm PCM handle
 * \param params Configuration space
 * \param val 0 = disable, 1 = enable (default) exporting buffer
 * \return 0 otherwise a negative error code
 */
int snd_pcm_hw_params_set_export_buffer(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int val)
{
        assert(pcm && params);
        if (val)
                params->flags |= SND_PCM_HW_PARAMS_EXPORT_BUFFER;
        else
                params->flags &= ~SND_PCM_HW_PARAMS_EXPORT_BUFFER;
        return snd_pcm_hw_refine(pcm, params);
}

/**
 * \brief Extract buffer accessibility from a configuration space
 * \param pcm PCM handle
 * \param params Configuration space
 * \param val 0 = disable, 1 = enable exporting buffer
 * \return 0 otherwise a negative error code
 */
int snd_pcm_hw_params_get_export_buffer(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int *val)
{
        assert(pcm && params && val);
        *val = params->flags & SND_PCM_HW_PARAMS_EXPORT_BUFFER ? 1 : 0;
        return 0;
}

/**
 * \brief Extract period time from a configuration space
 * \param params Configuration space
 * \param val Returned approximate period duration in us
 * \param dir Sub unit direction
 * \return 0 otherwise a negative error code if not exactly one is present
 *
 * Actual exact value is <,=,> the approximate one following dir (-1, 0, 1)
 */
#ifndef DOXYGEN
int INTERNAL(snd_pcm_hw_params_get_period_time)(const snd_pcm_hw_params_t *params, unsigned int *val, int *dir)
#else
int snd_pcm_hw_params_get_period_time(const snd_pcm_hw_params_t *params, unsigned int *val, int *dir)
#endif
{
        return snd_pcm_hw_param_get(params, SND_PCM_HW_PARAM_PERIOD_TIME, val, dir);
}

/**
 * \brief Extract minimum period time from a configuration space
 * \param params Configuration space
 * \param val approximate minimum period duration in us
 * \param dir Sub unit direction
 * \return 0 otherwise a negative error code
 *
 * Exact value is <,=,> the returned one following dir (-1,0,1)
 */
#ifndef DOXYGEN
int INTERNAL(snd_pcm_hw_params_get_period_time_min)(const snd_pcm_hw_params_t *params, unsigned int *val, int *dir)
#else
int snd_pcm_hw_params_get_period_time_min(const snd_pcm_hw_params_t *params, unsigned int *val, int *dir)
#endif
{
        return snd_pcm_hw_param_get_min(params, SND_PCM_HW_PARAM_PERIOD_TIME, val, dir);
}

/**
 * \brief Extract maximum period time from a configuration space
 * \param params Configuration space
 * \param val approximate maximum period duration in us
 * \param dir Sub unit direction
 * \return 0 otherwise a negative error code
 *
 * Exact value is <,=,> the returned one following dir (-1,0,1)
 */
#ifndef DOXYGEN
int INTERNAL(snd_pcm_hw_params_get_period_time_max)(const snd_pcm_hw_params_t *params, unsigned int *val, int *dir)
#else
int snd_pcm_hw_params_get_period_time_max(const snd_pcm_hw_params_t *params, unsigned int *val, int *dir)
#endif
{
        return snd_pcm_hw_param_get_max(params, SND_PCM_HW_PARAM_PERIOD_TIME, val, dir);
}

/**
 * \brief Verify if a period time is available inside a configuration space for a PCM
 * \param pcm PCM handle
 * \param params Configuration space
 * \param val approximate period duration in us
 * \param dir Sub unit direction
 * \return 0 if available a negative error code otherwise
 *
 * Wanted exact value is <,=,> val following dir (-1,0,1)
 */
int snd_pcm_hw_params_test_period_time(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int val, int dir)
{
        return snd_pcm_hw_param_set(pcm, params, SND_TEST, SND_PCM_HW_PARAM_PERIOD_TIME, val, dir);
}

/**
 * \brief Restrict a configuration space to contain only one period time
 * \param pcm PCM handle
 * \param params Configuration space
 * \param val approximate period duration in us
 * \param dir Sub unit direction
 * \return 0 otherwise a negative error code if configuration space would become empty
 *
 * Wanted exact value is <,=,> val following dir (-1,0,1)
 */
int snd_pcm_hw_params_set_period_time(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int val, int dir)
{
        return snd_pcm_hw_param_set(pcm, params, SND_TRY, SND_PCM_HW_PARAM_PERIOD_TIME, val, dir);
}


/**
 * \brief Restrict a configuration space with a minimum period time
 * \param pcm PCM handle
 * \param params Configuration space
 * \param val approximate minimum period duration in us (on return filled with actual minimum)
 * \param dir Sub unit direction (on return filled with actual direction)
 * \return 0 otherwise a negative error code if configuration space would become empty
 *
 * Wanted/actual exact minimum is <,=,> val following dir (-1,0,1)
 */
int snd_pcm_hw_params_set_period_time_min(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int *val, int *dir)
{
        return snd_pcm_hw_param_set_min(pcm, params, SND_TRY, SND_PCM_HW_PARAM_PERIOD_TIME, val, dir);
}

/**
 * \brief Restrict a configuration space with a maximum period time
 * \param pcm PCM handle
 * \param params Configuration space
 * \param val approximate maximum period duration in us (on return filled with actual maximum)
 * \param dir Sub unit direction (on return filled with actual direction)
 * \return 0 otherwise a negative error code if configuration space would become empty
 *
 * Wanted/actual exact maximum is <,=,> val following dir (-1,0,1)
 */
int snd_pcm_hw_params_set_period_time_max(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int *val, int *dir)
{
        return snd_pcm_hw_param_set_max(pcm, params, SND_TRY, SND_PCM_HW_PARAM_PERIOD_TIME, val, dir);
}

/**
 * \brief Restrict a configuration space to have period times in a given range
 * \param pcm PCM handle
 * \param params Configuration space
 * \param min approximate minimum period duration in us (on return filled with actual minimum)
 * \param mindir Sub unit direction for minimum (on return filled with actual direction)
 * \param max approximate maximum period duration in us (on return filled with actual maximum)
 * \param maxdir Sub unit direction for maximum (on return filled with actual direction)
 * \return 0 otherwise a negative error code if configuration space would become empty
 *
 * Wanted/actual exact min/max is <,=,> val following dir (-1,0,1)
 */
int snd_pcm_hw_params_set_period_time_minmax(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int *min, int *mindir, unsigned int *max, int *maxdir)
{
        return snd_pcm_hw_param_set_minmax(pcm, params, SND_TRY, SND_PCM_HW_PARAM_PERIOD_TIME, min, mindir, max, maxdir);
}

/**
 * \brief Restrict a configuration space to have period time nearest to a target
 * \param pcm PCM handle
 * \param params Configuration space
 * \param val approximate target period duration in us / returned chosen approximate target period duration
 * \param dir Sub unit direction
 * \return 0 otherwise a negative error code if configuration space is empty
 *
 * target/chosen exact value is <,=,> val following dir (-1,0,1)
 */
#ifndef DOXYGEN
int INTERNAL(snd_pcm_hw_params_set_period_time_near)(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int *val, int *dir)
#else
int snd_pcm_hw_params_set_period_time_near(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int *val, int *dir)
#endif
{
        return snd_pcm_hw_param_set_near(pcm, params, SND_PCM_HW_PARAM_PERIOD_TIME, val, dir);
}

/**
 * \brief Restrict a configuration space to contain only its minimum period time
 * \param pcm PCM handle
 * \param params Configuration space
 * \param val Returned approximate period duration in us
 * \param dir Sub unit direction
 * \return 0 otherwise a negative error code
 *