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incubator-nuttx/include/nuttx/audio/audio.h

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/****************************************************************************
* include/nuttx/audio/audio.h
*
* Copyright (C) 2013 Ken Pettit. All rights reserved.
* Author: Ken Pettit <pettitkd@gmail.com>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name NuttX nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
****************************************************************************/
#ifndef __INCLUDE_NUTTX_AUDIO_AUDIO_H
#define __INCLUDE_NUTTX_AUDIO_AUDIO_H
/* For the purposes of this driver, an Audio device is any device that
* generates, records, mixes, or otherwise modifies audio data in any format,
* such as PCM, MP3, AAC, etc.
*
* The Audio driver is split into two parts:
*
* 1) An "upper half", generic driver that provides the comman Audio interface
* to application level code, and
* 2) A "lower half", platform-specific driver that implements the low-level
* controls to configure and communicate with the audio device(s).
*/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <nuttx/compiler.h>
#include <nuttx/fs/ioctl.h>
#include <nuttx/spi/spi.h>
#include <queue.h>
#include <semaphore.h>
#ifdef CONFIG_AUDIO
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/* Configuration ************************************************************/
/* CONFIG_AUDIO - Enables Audio driver support
* CONFIG_DEBUG_AUDIO - If enabled (with CONFIG_DEBUG and, optionally,
* CONFIG_DEBUG_VERBOSE), this will generate output that can be used to
* debug Audio drivers.
*/
/* IOCTL Commands ***********************************************************/
/* The Audio module uses a standard character driver framework. However, a
* lot of the Audio driver functionality is configured via a device control
* interface, such as sampling rate, volume, data format, etc.
* The Audio ioctl commands are listed below:
*
* AUDIOIOC_GETCAPS - Get the Audio Device Capabilities
*
* ioctl argument: Pointer to the audio_caps_s structure to receive the
* capabilities info. The "len" and "type" fields should
* be filled in prior to calling this ioctl. To get
* overall capabilities, specify the type as
* AUDIO_TYPE_QUERY, otherwise specify any type that was
* reported by the device during the QUERY.
*
* AUDIOIOC_CONFIGURE - Configure device for the specified mode
*
* ioctl argument: Pointer to the audio_caps_s structure which identifies
* the capabilities to configure for.
*
* AUDIOIOC_SHUTDOWN - Shutdown the device.
*
* ioctl argument: None
*
* AUDIOIOC_START - Start Audio streaming
*
* ioctl argument: None
*
* AUDIOIOC_STOP - Stop Audio streaming
*
* ioctl argument: None
*/
#define AUDIOIOC_GETCAPS _AUDIOIOC(1)
#define AUDIOIOC_RESERVE _AUDIOIOC(2)
#define AUDIOIOC_RELEASE _AUDIOIOC(3)
#define AUDIOIOC_CONFIGURE _AUDIOIOC(4)
#define AUDIOIOC_SHUTDOWN _AUDIOIOC(5)
#define AUDIOIOC_START _AUDIOIOC(6)
#define AUDIOIOC_STOP _AUDIOIOC(7)
#define AUDIOIOC_PAUSE _AUDIOIOC(8)
#define AUDIOIOC_RESUME _AUDIOIOC(9)
#define AUDIOIOC_GETBUFFERINFO _AUDIOIOC(10)
#define AUDIOIOC_ALLOCBUFFER _AUDIOIOC(11)
#define AUDIOIOC_FREEBUFFER _AUDIOIOC(12)
#define AUDIOIOC_ENQUEUEBUFFER _AUDIOIOC(13)
#define AUDIOIOC_REGISTERMQ _AUDIOIOC(14)
#define AUDIOIOC_UNREGISTERMQ _AUDIOIOC(15)
#define AUDIOIOC_HWRESET _AUDIOIOC(16)
/* Audio Device Types *******************************************************/
/* The NuttX audio interface support different types of audio devices for
* input, output, synthesis, and manipulation of audio data. A given driver/
* device could support a combination of these device type. The following
* is a list of bit-field definitions for defining the device type.
*/
#define AUDIO_TYPE_QUERY 0x00
#define AUDIO_TYPE_INPUT 0x02
#define AUDIO_TYPE_OUTPUT 0x02
#define AUDIO_TYPE_MIXER 0x04
#define AUDIO_TYPE_SELECTOR 0x08
#define AUDIO_TYPE_FEATURE 0x10
#define AUDIO_TYPE_EFFECT 0x20
#define AUDIO_TYPE_PROCESSING 0x40
#define AUDIO_TYPE_EXTENSION 0x80
/* Audio Format Types *******************************************************/
/* The following defines the audio data format types in NuttX. During a
* format query, these will be converted to bit positions within the
* ac_format field, meaning we currently only support up to 16 formats. To
* support more than that, we will use the FMT_OTHER entry, and the
* interfacing software can perform a second query to get the other formats.
*/
#define AUDIO_FMT_UNDEF 0x00
#define AUDIO_FMT_OTHER 0x01
#define AUDIO_FMT_MPEG 0x02
#define AUDIO_FMT_AC3 0x03
#define AUDIO_FMT_WMA 0x04
#define AUDIO_FMT_DTS 0x05
#define AUDIO_FMT_PCM 0x06
#define AUDIO_FMT_WAV 0x07
#define AUDIO_FMT_MP3 0x08
#define AUDIO_FMT_MIDI 0x09
#define AUDIO_FMT_OGG_VORBIS 0x0a
#define AUDIO_FMT_FLAC 0x0b
/* Audio Sub-Format Types ***************************************************/
#define AUDIO_SUBFMT_END 0x00
#define AUDIO_SUBFMT_PCM_MP1 0x01
#define AUDIO_SUBFMT_PCM_MP2 0x02
#define AUDIO_SUBFMT_PCM_MP3 0x03
#define AUDIO_SUBFMT_PCM_MU_LAW 0x04
#define AUDIO_SUBFMT_PCM_A_LAW 0x05
#define AUDIO_SUBFMT_PCM_U8 0x06
#define AUDIO_SUBFMT_PCM_S8 0x07
#define AUDIO_SUBFMT_PCM_U16_LE 0x08
#define AUDIO_SUBFMT_PCM_S16_BE 0x09
#define AUDIO_SUBFMT_PCM_S16_LE 0x0a
#define AUDIO_SUBFMT_PCM_U16_BE 0x0b
#define AUDIO_SUBFMT_MIDI_0 0x0c
#define AUDIO_SUBFMT_MIDI_1 0x0d
#define AUDIO_SUBFMT_MIDI_2 0x0e
/* Supported Sampling Rates *************************************************/
#define AUDIO_SAMP_RATE_8K 0x0001
#define AUDIO_SAMP_RATE_11K 0x0002
#define AUDIO_SAMP_RATE_16K 0x0004
#define AUDIO_SAMP_RATE_22K 0x0008
#define AUDIO_SAMP_RATE_32K 0x0010
#define AUDIO_SAMP_RATE_44K 0x0020
#define AUDIO_SAMP_RATE_48K 0x0040
#define AUDIO_SAMP_RATE_96K 0x0080
#define AUDIO_SAMP_RATE_128K 0x0100
#define AUDIO_SAMP_RATE_160K 0x0200
#define AUDIO_SAMP_RATE_172K 0x0400
#define AUDIO_SAMP_RATE_192K 0x0800
/* Audio Sub-sampling Ratios ***********************************************/
#define AUDIO_SUBSAMPLE_NONE 0
#define AUDIO_SUBSAMPLE_2X 2
#define AUDIO_SUBSAMPLE_4X 4
#define AUDIO_SUBSAMPLE_8X 8
#define AUDIO_SUBSAMPLE_16X 16
#define AUDIO_SUBSAMPLE_MIN AUDIO_SUBSAMPLE_2X
#define AUDIO_SUBSAMPLE_MAX AUDIO_SUBSAMPLE_16X
/* Supported Bit Rates *************************************************/
#define AUDIO_BIT_RATE_22K 0x01
#define AUDIO_BIT_RATE_44K 0x02
#define AUDIO_BIT_RATE_48K 0x04
#define AUDIO_BIT_RATE_96K 0x08
#define AUDIO_BIT_RATE_128K 0x10
#define AUDIO_BIT_RATE_160K 0x20
#define AUDIO_BIT_RATE_172K 0x40
#define AUDIO_BIT_RATE_192K 0x80
/* Supported Feature Units controls *****************************************/
#define AUDIO_FU_UNDEF 0x0000
#define AUDIO_FU_MUTE 0x0001
#define AUDIO_FU_VOLUME 0x0002
#define AUDIO_FU_BASS 0x0004
#define AUDIO_FU_MID 0x0008
#define AUDIO_FU_TREBLE 0x0010
#define AUDIO_FU_EQUALIZER 0x0020
#define AUDIO_FU_AGC 0x0040
#define AUDIO_FU_DELAY 0x0080
#define AUDIO_FU_BASS_BOOST 0x0100
#define AUDIO_FU_LOUDNESS 0x0200
#define AUDIO_FU_INP_GAIN 0x0400
#define AUDIO_FU_BALANCE 0x0800
#define AUDIO_FU_PHASE_INVERT 0x1000
#define AUDIO_FU_UNDERFLOW 0x2000
#define AUDIO_FU_OVERFLOW 0x4000
#define AUDIO_FU_LATENCY 0x8000
/* Processing Unit controls *************************************************/
#define AUDIO_PU_UNDEF 0x00
#define AUDIO_PU_UPDOWNMIX 0x01
#define AUDIO_PU_DOLBY_PROLOGIC 0x02
#define AUDIO_PU_STEREO_EXTENDER 0x03
#define AUDIO_PU_SUBSAMPLE_FORWARD 0x04
#define AUDIO_PU_SUBSAMPLE_REWIND 0x05
/* Stereo Extender PU Controls **********************************************/
#define AUDIO_STEXT_UNDEF 0x00
#define AUDIO_STEXT_ENABLE 0x01
#define AUDIO_STEXT_WIDTH 0x02
#define AUDIO_STEXT_UNDERFLOW 0x03
#define AUDIO_STEXT_OVERFLOW 0x04
#define AUDIO_STEXT_LATENCY 0x05
/* Audio Callback Reasons ***************************************************/
#define AUDIO_CALLBACK_UNDEF 0x00
#define AUDIO_CALLBACK_DEQUEUE 0x01
#define AUDIO_CALLBACK_IOERR 0x02
#define AUDIO_CALLBACK_COMPLETE 0x03
/* Audio Pipeline Buffer (AP Buffer) flags **********************************/
#define AUDIO_ABP_ALIGNMENT 0x000f /* Mask to define buffer alignment */
#define AUDIO_ABP_CANDMA 0x0010 /* Set if the data is DMA'able */
#define AUDIO_ABP_STATIC 0x0020 /* Set if statically allocated */
#define AUDIO_ABP_ACTIVE 0x0040 /* Set if this buffer is still active.
* A buffer could become inactive
* if it is processed by an output
* device or a processing device
* that replaces it with an alternate
* buffer as a result of some DSP
* operation, etc.
*/
/* Standard Audio Message Queue message IDs */
#define AUDIO_MSG_NONE 0
#define AUDIO_MSG_DEQUEUE 1
#define AUDIO_MSG_START 2
#define AUDIO_MSG_STOP 3
#define AUDIO_MSG_PAUSE 4
#define AUDIO_MSG_RESUME 5
#define AUDIO_MSG_DATA_REQUEST 6
#define AUDIO_MSG_ENQUEUE 7
#define AUDIO_MSG_COMPLETE 8
#define AUDIO_MSG_USER 64
/* Audio Pipeline Buffer flags */
#define AUDIO_APB_OUTPUT_ENQUEUED (1 << 0)
#define AUDIO_APB_OUTPUT_PROCESS (1 << 1)
#define AUDIO_APB_DEQUEUED (1 << 2)
#define AUDIO_APB_FINAL (1 << 3) /* Last buffer in the stream */
/****************************************************************************
* Public Types
****************************************************************************/
/* Define the size of AP Buffer sample count base on CONFIG */
#ifdef CONFIG_AUDIO_LARGE_BUFFERS
typedef uint32_t apb_samp_t;
#else
typedef uint16_t apb_samp_t;
#endif
/* This structure is used to describe the audio device capabilities */
struct audio_caps_s
{
uint8_t ac_len; /* Length of the structure */
uint8_t ac_type; /* Capabilities (device) type */
uint8_t ac_subtype; /* Capabilities sub-type, if needed */
uint8_t ac_channels; /* Number of channels (1, 2, 5, 7) */
union /* Audio data format(s) for this device */
{
uint8_t b[2];
uint16_t hw;
} ac_format;
union /* Device specific controls. For AUDIO_DEVICE_QUERY, */
{ /* this field reports the device type supported */
uint8_t b[4]; /* by this lower-half driver. */
uint16_t hw[2];
uint32_t w;
} ac_controls;
};
struct audio_caps_desc_s
{
#ifdef CONFIG_AUDIO_MULTI_SESSION
FAR void *session; /* Associated session */
#endif
struct audio_caps_s caps; /* The capabilities struct */
};
/* This structure describes the characteristics of the Audio samples */
struct audio_info_s
{
uint8_t samplerate; /* Sample Rate of the audio data */
uint8_t channels; /* Number of channels (1, 2, 5, 7) */
uint8_t format; /* Audio data format */
uint8_t subformat; /* Audio subformat (maybe should be combined with format? */
};
/* This structure describes the preferred number and size of
* audio pipeline buffers for the audio device. Each device
* may have unique needs regarding size and qty of buffers,
* so this info is queried from the lower-half driver.
*/
#ifdef CONFIG_AUDIO_DRIVER_SPECIFIC_BUFFERS
struct ap_buffer_info_s
{
apb_samp_t nbuffers; /* Preferred qty of buffers */
apb_samp_t buffer_size; /* Preferred size of the buffers */
};
#endif
/* This structure describes an Audio Pipeline Buffer */
struct ap_buffer_s
{
struct dq_entry_s dq_entry; /* Double linked queue entry */
struct audio_info_s i; /* The info for samples in this buffer */
#ifdef CONFIG_AUDIO_MULTI_SESSION
FAR void *session; /* Associated session */
#endif
apb_samp_t nmaxbytes; /* The maximum number of bytes */
apb_samp_t nbytes; /* The number of bytes used */
apb_samp_t curbyte; /* Next byte to be processed */
sem_t sem; /* Reference locking semaphore */
uint16_t flags; /* Buffer flags */
uint16_t crefs; /* Number of reference counts */
uint8_t samp[0]; /* Offset of the first sample */
} packed_struct;
/* Structure defining the messages passed to a listening audio thread
* for dequeuing buffers and other operations. Also used to allocate
* and enqueue buffers via the AUDIOIOC_ALLOCBUFFER, AUDIOIOC_FREEBUFFER,
* and AUDIOIOC_ENQUEUEBUFFER ioctls.
*/
struct audio_msg_s
{
#ifdef CONFIG_AUDIO_MULTI_SESSION
FAR void *session; /* Associated channel */
#endif
uint16_t msgId; /* Message ID */
union
{
FAR void * pPtr; /* Buffer being dequeued */
uint32_t data; /* Message data */
} u;
};
/* Structure defining the built-in sounds */
#ifdef CONFIG_AUDIO_BUILTIN_SOUNDS
struct audio_sound_s
{
const char *name; /* Name of the sound */
uint32_t id; /* ID of the sound */
uint32_t type; /* Type of sound */
uint32_t size; /* Number of bytes in the sound */
const uint8_t *data; /* Pointer to the data */
};
#endif
/* Structure for allocating, freeing and enqueueing audio pipeline
* buffers via the AUDIOIOC_ALLOCBUFFER, AUDIOIOC_FREEBUFFER,
* and AUDIOIOC_ENQUEUEBUFFER ioctls.
*/
struct audio_buf_desc_s
{
#ifdef CONFIG_AUDIO_MULTI_SESSION
FAR void *session; /* Associated channel */
#endif
uint16_t numbytes; /* Number of bytes to allocate */
union
{
FAR struct ap_buffer_s *pBuffer; /* Buffer to free / enqueue */
FAR struct ap_buffer_s **ppBuffer; /* Pointer to receive allocated buffer */
} u;
};
/* Typedef for lower-level to upper-level callback for buffer dequeuing */
#ifdef CONFIG_AUDIO_MULTI_SESSION
typedef CODE void (*audio_callback_t)(FAR void *priv, uint16_t reason,
FAR struct ap_buffer_s *apb, uint16_t status, FAR void *session);
#else
typedef CODE void (*audio_callback_t)(FAR void *priv, uint16_t reason,
FAR struct ap_buffer_s *apb, uint16_t status);
#endif
/* This structure is a set a callback functions used to call from the upper-
* half, generic Audo driver into lower-half, platform-specific logic that
* supports the low-level functionality.
*/
struct audio_lowerhalf_s;
struct audio_ops_s
{
/* This method is called to retrieve the lower-half device capabilities.
* It will be called with device type AUDIO_TYPE_QUERY to request the
* overall capabilities, such as to determine the types of devices supported
* audio formats supported, etc. Then it may be called once or more with
* reported supported device types to determine the specific capabilities
* of that device type (such as MP3 encoder, WMA encoder, PCM output, etc.).
*/
CODE int (*getcaps)(FAR struct audio_lowerhalf_s *dev, int type,
FAR struct audio_caps_s *pCaps);
/* This method is called to bind the lower-level driver to the upper-level
* driver and to configure the driver for a specific mode of
* operation defined by the parameters selected in supplied device caps
* structure. The lower-level device should perform any initialization
* needed to prepare for operations in the specified mode. It should not,
* however, process any audio data until the start method is called.
*/
#ifdef CONFIG_AUDIO_MULTI_SESSION
CODE int (*configure)(FAR struct audio_lowerhalf_s *dev,
FAR void *session, FAR const struct audio_caps_s *pCaps);
#else
CODE int (*configure)(FAR struct audio_lowerhalf_s *dev,
FAR const struct audio_caps_s *pCaps);
#endif
/* This method is called when the driver is closed. The lower half driver
* should stop processing audio data, including terminating any active
* output generation. It should also disable the audio hardware and put
* it into the lowest possible power usage state.
*
* Any enqueued Audio Pipeline Buffers that have not been processed / dequeued
* should be dequeued by this function.
*/
CODE int (*shutdown)(FAR struct audio_lowerhalf_s *dev);
/* Start audio streaming in the configured mode. For input and synthesis
* devices, this means it should begin sending streaming audio data. For output
* or processing type device, it means it should begin processing of any enqueued
* Audio Pipeline Buffers.
*/
#ifdef CONFIG_AUDIO_MULTI_SESSION
CODE int (*start)(FAR struct audio_lowerhalf_s *dev, FAR void *session);
#else
CODE int (*start)(FAR struct audio_lowerhalf_s *dev);
#endif
/* Stop audio streaming and/or processing of enqueued Audio Pipeline Buffers */
#ifndef CONFIG_AUDIO_EXCLUDE_STOP
#ifdef CONFIG_AUDIO_MULTI_SESSION
CODE int (*stop)(FAR struct audio_lowerhalf_s *dev, FAR void *session);
#else
CODE int (*stop)(FAR struct audio_lowerhalf_s *dev);
#endif
#endif
/* Pause the audio stream. Should keep current playback context active
* in case a resume is issued. Could be called and then followed by a stop.
*/
#ifndef CONFIG_AUDIO_EXCLUDE_PAUSE_RESUME
#ifdef CONFIG_AUDIO_MULTI_SESSION
CODE int (*pause)(FAR struct audio_lowerhalf_s *dev, FAR void *session);
#else
CODE int (*pause)(FAR struct audio_lowerhalf_s *dev);
#endif
/* Resumes audio streaming after a pause */
#ifdef CONFIG_AUDIO_MULTI_SESSION
CODE int (*resume)(FAR struct audio_lowerhalf_s *dev, FAR void *session);
#else
CODE int (*resume)(FAR struct audio_lowerhalf_s *dev);
#endif
#endif /* CONFIG_AUDIO_EXCLUDE_PAUSE_RESUME */
/* Allocate an audio pipeline buffer. This routine provides the
* lower-half driver with the opportunity to perform special buffer
* allocation if needed, such as allocating from a specific memory
* region (DMA-able, etc.). If not supplied, then the top-half
* driver will perform a standard kumm_malloc using normal user-space
* memory region.
*/
CODE int (*allocbuffer)(FAR struct audio_lowerhalf_s *dev,
FAR struct audio_buf_desc_s *apb);
/* Free an audio pipeline buffer. If the lower-level driver
* provides an allocbuffer routine, it should also provide the
* freebuffer routine to perform the free operation.
*/
CODE int (*freebuffer)(FAR struct audio_lowerhalf_s *dev,
FAR struct audio_buf_desc_s *apb);
/* Enqueue a buffer for processing. This is a non-blocking enqueue operation.
* If the lower-half driver's buffer queue is full, then it should return an
* error code of -ENOMEM, and the upper-half driver can decide to either block
* the calling thread or deal with it in a non-blocking manner.
* For each call to enqueuebuffer, the lower-half driver must call
* audio_dequeuebuffer when it is finished processing the bufferr, passing the
* previously enqueued apb and a dequeue status so that the upper-half driver
* can decide if a waiting thread needs to be release, if the dequeued buffer
* should be passed to the next block in the Audio Pipeline, etc.
*/
CODE int (*enqueuebuffer)(FAR struct audio_lowerhalf_s *dev,
FAR struct ap_buffer_s *apb);
/* Cancel a previously enqueued buffer. */
CODE int (*cancelbuffer)(FAR struct audio_lowerhalf_s *dev,
FAR struct ap_buffer_s *apb);
/* Lower-half logic may support platform-specific ioctl commands */
CODE int (*ioctl)(FAR struct audio_lowerhalf_s *dev,
int cmd, unsigned long arg);
/* Lower-half logic may support platform-specific read commands */
CODE int (*read)(FAR struct audio_lowerhalf_s *dev,
FAR char *buffer, size_t buflen);
/* Lower-half logic may support platform-specific write commands */
CODE int (*write)(FAR struct audio_lowerhalf_s *dev,
FAR const char *buffer, size_t buflen);
/* Reserve a session (may only be one per device or may be multiple) for
* use by a client. Client software can open audio devices and issue
* AUDIOIOC_GETCAPS calls freely, but other operations require a
* reservation. A session reservation will assign a context that must
* be passed with
*/
#ifdef CONFIG_AUDIO_MULTI_SESSION
CODE int (*reserve)(FAR struct audio_lowerhalf_s *dev, FAR void **psession);
#else
CODE int (*reserve)(FAR struct audio_lowerhalf_s *dev);
#endif
/* Release a session. */
#ifdef CONFIG_AUDIO_MULTI_SESSION
CODE int (*release)(FAR struct audio_lowerhalf_s *dev, FAR void *session);
#else
CODE int (*release)(FAR struct audio_lowerhalf_s *dev);
#endif
};
/* This structure is the generic form of state structure used by lower half
* Audio driver. This state structure is passed to the Audio driver when the
* driver is initialized. Then, on subsequent callbacks into the lower half
* Audio logic, this structure is provided so that the Audio logic can
* maintain state information.
*
* Normally that Audio logic will have its own, custom state structure
* that is simply cast to struct audio_lowerhalf_s. In order to perform such
* casts, the initial fields of the custom state structure match the initial
* fields of the following generic Audio state structure.
*/
struct audio_lowerhalf_s
{
/* The first field of this state structure must be a pointer to the Audio
* callback structure:
*/
FAR const struct audio_ops_s *ops;
/* The bind data to the upper-half driver used for callbacks of dequeuing
* buffer, reporting asynchronous event, reporting errors, etc.
*/
FAR audio_callback_t upper;
/* The private opaque pointer to be passed to upper-layer during callbacks */
FAR void *priv;
/* The custom Audio device state structure may include additional fields
* after the pointer to the Audio callback structure.
*/
};
/****************************************************************************
* Public Data
****************************************************************************/
/****************************************************************************
* Public Function Prototypes
****************************************************************************/
#ifdef __cplusplus
#define EXTERN extern "C"
extern "C"
{
#else
#define EXTERN extern
#endif
/****************************************************************************
* "Upper-Half" Audio Driver Interfaces
****************************************************************************/
/****************************************************************************
* Name: audio_register
*
* Description:
* This function binds an instance of a "lower half" Audio driver with the
* "upper half" Audio device and registers that device so that can be used
* by application code.
*
* When this function is called, the "lower half" driver should be in the
* reset state (as if the shutdown() method had already been called).
*
* Input parameters:
* name - The name of the audio device. This name will be used to generate
* a full path to the driver in the format "/dev/audio/[name]" in the NuttX
* filesystem (i.e. the path "/dev/audio" will be prepended to the supplied
* device name. The recommended convention is to name Audio drivers
* based on the type of functionality they provide, such as "/dev/audio/pcm0",
* "/dev/audio/midi0", "/dev/audio/mp30, etc.
* dev - A pointer to an instance of lower half audio driver. This instance
* is bound to the Audio driver and must persists as long as the driver
* persists.
*
* Returned Value:
* Zero on success; a negated errno value on failure.
*
****************************************************************************/
int audio_register(FAR const char *name, FAR struct audio_lowerhalf_s *dev);
/****************************************************************************
* Name: abp_alloc
*
* Description:
* Allocated an AP Buffer and prepares it for use. This allocates a dynamically
* allocated buffer that has no special DMA capabilities.
*
* Input parameters:
* bufdesc: Pointer to a buffer descriptor
*
* Returned Value:
* Pointer to the allocated buffer or NULL if no memory.
*
****************************************************************************/
int apb_alloc(FAR struct audio_buf_desc_s *bufdesc);
/****************************************************************************
* Name: apb_free
*
* Free's a previously allocated or referenced Audio Pipeline Buffer
*
****************************************************************************/
void apb_free(FAR struct ap_buffer_s *apb);
/****************************************************************************
* Name: apb_reference
*
* Claim a reference to an Audio Pipeline Buffer. Each call to apb_reference
* will increment the reference count and must have a matching apb_free
* call. When the refcount decrements to zero, the buffer will be freed.
*
****************************************************************************/
void apb_reference(FAR struct ap_buffer_s *apb);
/****************************************************************************
* Platform-Dependent "Lower-Half" Audio Driver Interfaces
****************************************************************************/
#undef EXTERN
#ifdef __cplusplus
}
#endif
#endif /* CONFIG_AUDIO */
#endif /* __INCLUDE_NUTTX_AUDIO_AUDIO_H */
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