Updated audio subsystem from Ken Pettit

1 files changed, 316 insertions, 60 deletions

diff --git a/nuttx/include/nuttx/audio/audio.h b/nuttx/include/nuttx/audio/audio.h
index 6234ac0db..be03cc71e 100644
--- a/nuttx/include/nuttx/audio/audio.h
+++ b/nuttx/include/nuttx/audio/audio.h
@@ -36,10 +36,10 @@
 #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 
+/* 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
@@ -57,6 +57,8 @@
 
 #include <nuttx/fs/ioctl.h>
 #include <nuttx/spi/spi.h>
+#include <queue.h>
+#include <semaphore.h>
 
 #ifdef CONFIG_AUDIO
 
@@ -69,10 +71,10 @@
  *   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 
+ * 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 lised below:
  *
@@ -81,7 +83,7 @@
  *   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 
+ *                    overall capabilities, specify the type as
  *                    AUDIO_TYPE_QUERY, otherwise specify any type that was
  *                    reported by the device during the QUERY.
  *
@@ -104,10 +106,21 @@
  */
 
 #define AUDIOIOC_GETCAPS            _AUDIOIOC(1)
-#define AUDIOIOC_CONFIGURE          _AUDIOIOC(2)
-#define AUDIOIOC_SHUTDOWN           _AUDIOIOC(3)
-#define AUDIOIOC_START              _AUDIOIOC(4)
-#define AUDIOIOC_STOP               _AUDIOIOC(5)
+#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
@@ -129,16 +142,17 @@
 /* Audio Format Types *******************************************************/
 /* The following defines the audio data format types in NuttX.  */
 
-#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_MP3               0x07
-#define AUDIO_FMT_MIDI              0x08
-#define AUDIO_FMT_OGG_VORBIS        0x09
+#define AUDIO_FMT_UNDEF             0x000
+#define AUDIO_FMT_OTHER             0x001
+#define AUDIO_FMT_MPEG              0x002
+#define AUDIO_FMT_AC3               0x004
+#define AUDIO_FMT_WMA               0x008
+#define AUDIO_FMT_DTS               0x010
+#define AUDIO_FMT_PCM               0x020
+#define AUDIO_FMT_WAV               0x020
+#define AUDIO_FMT_MP3               0x040
+#define AUDIO_FMT_MIDI              0x080
+#define AUDIO_FMT_OGG_VORBIS        0x100
 
 /* Audio Sub-Format Types ***************************************************/
 
@@ -156,21 +170,72 @@
 
 /* Supported Sampling Rates *************************************************/
 
-#define AUDIO_RATE_22K              0x01
-#define AUDIO_RATE_44K              0x02
-#define AUDIO_RATE_48K              0x03
-#define AUDIO_RATE_96K              0x04
-#define AUDIO_RATE_128K             0x05
-#define AUDIO_RATE_160K             0x06
-#define AUDIO_RATE_172K             0x07
-#define AUDIO_RATE_192K             0x08
-#define AUDIO_RATE_320K             0x09
+#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
+
+/* 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
+
+/* 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 **********************************/
 
@@ -186,6 +251,25 @@
                                              *   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   0x0001;
+#define AUDIO_APB_OUTPUT_PROCESS    0x0002;
+#define AUDIO_APB_DEQUEUED          0x0004;
+
 /****************************************************************************
  * Public Types
  ****************************************************************************/
@@ -212,6 +296,14 @@ struct audio_caps_s
                              * by this lower-half driver. */
 };
 
+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
@@ -222,21 +314,99 @@ struct audio_info_s
   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 */
-  apb_samp_t            nmaxsamples;/* The maximum number of samples */
-  apb_samp_t            nsamples;   /* The number of samples used */
+#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;
+};
+
+
+/* Strucure 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 enqueuing 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 alloced 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
@@ -249,25 +419,29 @@ 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 
+   * 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, 
+  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, 
+   * 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.
    */
 
-  CODE int (*configure)(FAR struct audio_lowerhalf_s *dev, 
-      FAR const struct audio_caps_s *pCaps,
-      audio_callback_t upper, FAR void *priv);
+#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
@@ -280,26 +454,75 @@ struct audio_ops_s
 
   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 
+  /* 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 Pipline 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 kumalloc using normal user-space
+   * memory region.
+   */
+
+  CODE int (*allocbuffer)(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 
-  j* 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 
+  /* 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.
    */
@@ -316,6 +539,37 @@ struct audio_ops_s
 
   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
@@ -325,8 +579,8 @@ struct audio_ops_s
  * 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 
+ * 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.
  */
 
@@ -348,7 +602,7 @@ struct audio_lowerhalf_s
 
   FAR void *priv;
 
-  /* The custom Audio device state structure may include additional fields 
+  /* The custom Audio device state structure may include additional fields
    * after the pointer to the Audio callback structure.
    */
 };
@@ -363,7 +617,8 @@ struct audio_lowerhalf_s
 
 #ifdef __cplusplus
 #define EXTERN extern "C"
-extern "C" {
+extern "C"
+{
 #else
 #define EXTERN extern
 #endif
@@ -387,7 +642,7 @@ extern "C" {
  *     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", 
+ *     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
@@ -398,7 +653,7 @@ extern "C" {
  *
  ****************************************************************************/
 
-EXTERN int audio_register(FAR const char *name, FAR struct audio_lowerhalf_s *dev);
+int audio_register(FAR const char *name, FAR struct audio_lowerhalf_s *dev);
 
 /****************************************************************************
  * Name: abp_alloc
@@ -410,13 +665,14 @@ EXTERN int audio_register(FAR const char *name, FAR struct audio_lowerhalf_s *de
  *   and then call apb_prepare, passing it the allocated memory.
  *
  * Input parameters:
+ *   bufdesc:   Pointer to a buffer descriptor
  *
  * Returned Value:
  *   Pointer to the allocated buffer or NULL if no memory.
  *
  ****************************************************************************/
 
-FAR struct ap_buffer_s *apb_alloc(int type, int sampleCount);
+int apb_alloc(FAR struct audio_buf_desc_s *bufdesc);
 
 /****************************************************************************
  * Name: abp_prepare
@@ -437,8 +693,8 @@ FAR struct ap_buffer_s *apb_alloc(int type, int sampleCount);
  *
  ****************************************************************************/
 
-EXTERN void apb_prepare(struct ap_buffer_s *apb, int8_t allocmode, uint8_t format,
-    uint8_t subformat, apb_samp_t maxsamples);
+void apb_prepare(struct ap_buffer_s *apb, int8_t allocmode, uint8_t format,
+                 uint8_t subformat, apb_samp_t maxsamples);
 
 /****************************************************************************
  * Name: apb_free
@@ -447,7 +703,7 @@ EXTERN void apb_prepare(struct ap_buffer_s *apb, int8_t allocmode, uint8_t forma
  *
  ****************************************************************************/
 
-EXTERN void apb_free(FAR struct ap_buffer_s *apb);
+void apb_free(FAR struct ap_buffer_s *apb);
 
 /****************************************************************************
  * Name: apb_reference
@@ -458,7 +714,7 @@ EXTERN void apb_free(FAR struct ap_buffer_s *apb);
  *
  ****************************************************************************/
 
-EXTERN void apb_reference(FAR struct ap_buffer_s *apb);
+void apb_reference(FAR struct ap_buffer_s *apb);
 
 /****************************************************************************
  * Platform-Dependent "Lower-Half" Audio Driver Interfaces