LUFA/Drivers/USB/Class/Device/Audio.h

   1 /*
   2              LUFA Library
   3      Copyright (C) Dean Camera, 2009.
   4
   5   dean [at] fourwalledcubicle [dot] com
   6       www.fourwalledcubicle.com
   7 */
   8
   9 /*
  10   Copyright 2009  Dean Camera (dean [at] fourwalledcubicle [dot] com)
  11
  12   Permission to use, copy, modify, and distribute this software
  13   and its documentation for any purpose and without fee is hereby
  14   granted, provided that the above copyright notice appear in all
  15   copies and that both that the copyright notice and this
  16   permission notice and warranty disclaimer appear in supporting
  17   documentation, and that the name of the author not be used in
  18   advertising or publicity pertaining to distribution of the
  19   software without specific, written prior permission.
  20
  21   The author disclaim all warranties with regard to this
  22   software, including all implied warranties of merchantability
  23   and fitness.  In no event shall the author be liable for any
  24   special, indirect or consequential damages or any damages
  25   whatsoever resulting from loss of use, data or profits, whether
  26   in an action of contract, negligence or other tortious action,
  27   arising out of or in connection with the use or performance of
  28   this software.
  29 */
  30
  31 /** \ingroup Group_USBDeviceClassDrivers
  32  *  @defgroup Group_USBClassAudioDevice Audio Device Class Driver - LUFA/Drivers/Class/Device/Audio.h
  33  *
  34  *  \section Sec_Dependencies Module Source Dependencies
  35  *  The following files must be built with any user project that uses this module:
  36  *    - LUFA/Drivers/USB/Class/Device/Audio.c
  37  *
  38  *  \section Module Description
  39  *  Functions, macros, variables, enums and types related to the management of USB Audio Class interfaces
  40  *  within a USB device.
  41  *
  42  *  @{
  43  */
  44
  45 #ifndef _AUDIO_CLASS_H_
  46 #define _AUDIO_CLASS_H_
  47
  48         /* Includes: */
  49                 #include "../../USB.h"
  50
  51                 #include <string.h>
  52
  53         /* Enable C linkage for C++ Compilers: */
  54                 #if defined(__cplusplus)
  55                         extern "C" {
  56                 #endif
  57
  58         /* Macros: */
  59                 /** Descriptor header constant to indicate a Audio class interface descriptor. */
  60                 #define DTYPE_AudioInterface         0x24
  61
  62                 /** Descriptor header constant to indicate a Audio class endpoint descriptor. */
  63                 #define DTYPE_AudioEndpoint          0x25
  64
  65                 /** Audio class descriptor subtype value for a Audio class specific header descriptor. */
  66                 #define DSUBTYPE_Header              0x01
  67
  68                 /** Audio class descriptor subtype value for an Output Terminal Audio class specific descriptor. */
  69                 #define DSUBTYPE_InputTerminal       0x02
  70
  71                 /** Audio class descriptor subtype value for an Input Terminal Audio class specific descriptor. */
  72                 #define DSUBTYPE_OutputTerminal      0x03
  73
  74                 /** Audio class descriptor subtype value for a Feature Unit Audio class specific descriptor. */
  75                 #define DSUBTYPE_FeatureUnit         0x06
  76
  77                 /** Audio class descriptor subtype value for a general Audio class specific descriptor. */
  78                 #define DSUBTYPE_General             0x01
  79
  80                 /** Audio class descriptor subtype value for an Audio class specific descriptor indicating the format of an audio stream. */
  81                 #define DSUBTYPE_Format              0x02
  82
  83                 /** Supported channel mask for an Audio class terminal descriptor. See the Audio class specification for more details. */
  84                 #define CHANNEL_LEFT_FRONT           (1 << 0)
  85
  86                 /** Supported channel mask for an Audio class terminal descriptor. See the Audio class specification for more details. */
  87                 #define CHANNEL_RIGHT_FRONT          (1 << 1)
  88
  89                 /** Supported channel mask for an Audio class terminal descriptor. See the Audio class specification for more details. */
  90                 #define CHANNEL_CENTER_FRONT         (1 << 2)
  91
  92                 /** Supported channel mask for an Audio class terminal descriptor. See the Audio class specification for more details. */
  93                 #define CHANNEL_LOW_FREQ_ENHANCE     (1 << 3)
  94
  95                 /** Supported channel mask for an Audio class terminal descriptor. See the Audio class specification for more details. */
  96                 #define CHANNEL_LEFT_SURROUND        (1 << 4)
  97
  98                 /** Supported channel mask for an Audio class terminal descriptor. See the Audio class specification for more details. */
  99                 #define CHANNEL_RIGHT_SURROUND       (1 << 5)
 100
 101                 /** Supported channel mask for an Audio class terminal descriptor. See the Audio class specification for more details. */
 102                 #define CHANNEL_LEFT_OF_CENTER       (1 << 6)
 103
 104                 /** Supported channel mask for an Audio class terminal descriptor. See the Audio class specification for more details. */
 105                 #define CHANNEL_RIGHT_OF_CENTER      (1 << 7)
 106
 107                 /** Supported channel mask for an Audio class terminal descriptor. See the Audio class specification for more details. */
 108                 #define CHANNEL_SURROUND             (1 << 8)
 109
 110                 /** Supported channel mask for an Audio class terminal descriptor. See the Audio class specification for more details. */
 111                 #define CHANNEL_SIDE_LEFT            (1 << 9)
 112
 113                 /** Supported channel mask for an Audio class terminal descriptor. See the Audio class specification for more details. */
 114                 #define CHANNEL_SIDE_RIGHT           (1 << 10)
 115
 116                 /** Supported channel mask for an Audio class terminal descriptor. See the Audio class specification for more details. */
 117                 #define CHANNEL_TOP                  (1 << 11)
 118
 119                 /** Supported feature mask for an Audio class feature unit descriptor. See the Audio class specification for more details. */
 120                 #define FEATURE_MUTE                 (1 << 0)
 121
 122                 /** Supported feature mask for an Audio class feature unit descriptor. See the Audio class specification for more details. */
 123                 #define FEATURE_VOLUME               (1 << 1)
 124
 125                 /** Supported feature mask for an Audio class feature unit descriptor. See the Audio class specification for more details. */
 126                 #define FEATURE_BASS                 (1 << 2)
 127
 128                 /** Supported feature mask for an Audio class feature unit descriptor. See the Audio class specification for more details. */
 129                 #define FEATURE_MID                  (1 << 3)
 130
 131                 /** Supported feature mask for an Audio class feature unit descriptor. See the Audio class specification for more details. */
 132                 #define FEATURE_TREBLE               (1 << 4)
 133
 134                 /** Supported feature mask for an Audio class feature unit descriptor. See the Audio class specification for more details. */
 135                 #define FEATURE_GRAPHIC_EQUALIZER    (1 << 5)
 136
 137                 /** Supported feature mask for an Audio class feature unit descriptor. See the Audio class specification for more details. */
 138
 139                 /** Supported feature mask for an Audio class feature unit descriptor. See the Audio class specification for more details. */
 140                 #define FEATURE_AUTOMATIC_GAIN       (1 << 6)
 141
 142                 /** Supported feature mask for an Audio class feature unit descriptor. See the Audio class specification for more details. */
 143                 #define FEATURE_DELAY                (1 << 7)
 144
 145                 /** Supported feature mask for an Audio class feature unit descriptor. See the Audio class specification for more details. */
 146                 #define FEATURE_BASS_BOOST           (1 << 8)
 147
 148                 /** Supported feature mask for an Audio class feature unit descriptor. See the Audio class specification for more details. */
 149                 #define FEATURE_BASS_LOUDNESS        (1 << 9)
 150
 151                 /** Terminal type constant for an Audio class terminal descriptor. See the Audio class specification for more details. */
 152                 #define TERMINAL_UNDEFINED           0x0100
 153
 154                 /** Terminal type constant for an Audio class terminal descriptor. See the Audio class specification for more details. */
 155                 #define TERMINAL_STREAMING           0x0101
 156
 157                 /** Terminal type constant for an Audio class terminal descriptor. See the Audio class specification for more details. */
 158                 #define TERMINAL_VENDOR              0x01FF
 159
 160                 /** Terminal type constant for an Audio class terminal descriptor. See the Audio class specification for more details. */
 161                 #define TERMINAL_IN_UNDEFINED        0x0200
 162
 163                 /** Terminal type constant for an Audio class terminal descriptor. See the Audio class specification for more details. */
 164                 #define TERMINAL_IN_MIC              0x0201
 165
 166                 /** Terminal type constant for an Audio class terminal descriptor. See the Audio class specification for more details. */
 167                 #define TERMINAL_IN_DESKTOP_MIC      0x0202
 168
 169                 /** Terminal type constant for an Audio class terminal descriptor. See the Audio class specification for more details. */
 170                 #define TERMINAL_IN_PERSONAL_MIC     0x0203
 171
 172                 /** Terminal type constant for an Audio class terminal descriptor. See the Audio class specification for more details. */
 173                 #define TERMINAL_IN_OMNIDIR_MIC      0x0204
 174
 175                 /** Terminal type constant for an Audio class terminal descriptor. See the Audio class specification for more details. */
 176                 #define TERMINAL_IN_MIC_ARRAY        0x0205
 177
 178                 /** Terminal type constant for an Audio class terminal descriptor. See the Audio class specification for more details. */
 179                 #define TERMINAL_IN_PROCESSING_MIC   0x0206
 180
 181                 /** Terminal type constant for an Audio class terminal descriptor. See the Audio class specification for more details. */
 182                 #define TERMINAL_IN_OUT_UNDEFINED    0x0300
 183
 184                 /** Terminal type constant for an Audio class terminal descriptor. See the Audio class specification for more details. */
 185                 #define TERMINAL_OUT_SPEAKER         0x0301
 186
 187                 /** Terminal type constant for an Audio class terminal descriptor. See the Audio class specification for more details. */
 188                 #define TERMINAL_OUT_HEADPHONES      0x0302
 189
 190                 /** Terminal type constant for an Audio class terminal descriptor. See the Audio class specification for more details. */
 191                 #define TERMINAL_OUT_HEAD_MOUNTED    0x0303
 192
 193                 /** Terminal type constant for an Audio class terminal descriptor. See the Audio class specification for more details. */
 194                 #define TERMINAL_OUT_DESKTOP         0x0304
 195
 196                 /** Terminal type constant for an Audio class terminal descriptor. See the Audio class specification for more details. */
 197                 #define TERMINAL_OUT_ROOM            0x0305
 198
 199                 /** Terminal type constant for an Audio class terminal descriptor. See the Audio class specification for more details. */
 200                 #define TERMINAL_OUT_COMMUNICATION   0x0306
 201
 202                 /** Terminal type constant for an Audio class terminal descriptor. See the Audio class specification for more details. */
 203                 #define TERMINAL_OUT_LOWFREQ         0x0307
 204
 205                 /** Convenience macro, to fill a 24-bit AudioSampleFreq_t structure with the given sample rate as a 24-bit number.
 206                  *
 207                  *  \param freq  Required audio sampling frequency in HZ
 208                  */
 209                 #define AUDIO_SAMPLE_FREQ(freq)  {LowWord: ((uint32_t)freq & 0x00FFFF), HighByte: (((uint32_t)freq >> 16) & 0x0000FF)}
 210
 211                 /** Mask for the attributes parameter of an Audio class specific Endpoint descriptor, indicating that the endpoint
 212                  *  accepts only filled endpoint packets of audio samples.
 213                  */
 214                 #define EP_ACCEPTS_ONLY_FULL_PACKETS (1 << 7)
 215
 216                 /** Mask for the attributes parameter of an Audio class specific Endpoint descriptor, indicating that the endpoint
 217                  *  will accept partially filled endpoint packets of audio samples.
 218                  */
 219                 #define EP_ACCEPTS_SMALL_PACKETS     (0 << 7)
 220
 221         /* Type Defines: */
 222                 /** Type define for an Audio class specific interface descriptor. This follows a regular interface descriptor to
 223                  *  supply extra information about the audio device's layout to the host. See the USB Audio specification for more
 224                  *  details.
 225                  */
 226                 typedef struct
 227                 {
 228                         USB_Descriptor_Header_t   Header; /**< Regular descriptor header containing the descriptor's type and length */
 229                         uint8_t                   Subtype; /**< Sub type value used to distinguish between audio class specific descriptors */
 230
 231                         uint16_t                  ACSpecification; /**< Binary coded decimal value, indicating the supported Audio Class specification version */
 232                         uint16_t                  TotalLength; /**< Total length of the Audio class specific descriptors, including this descriptor */
 233
 234                         uint8_t                   InCollection; /**< Total number of audio class interfaces within this device */
 235                         uint8_t                   InterfaceNumbers[1]; /**< Interface numbers of each audio interface */
 236                 } USB_AudioInterface_AC_t;
 237
 238                 /** Type define for an Audio class specific Feature Unit descriptor. This indicates to the host what features
 239                  *  are present in the device's audio stream for basic control, such as per-channel volume. See the USB Audio
 240                  *  specification for more details.
 241                  */
 242                 typedef struct
 243                 {
 244                         USB_Descriptor_Header_t   Header; /**< Regular descriptor header containing the descriptor's type and length */
 245                         uint8_t                   Subtype; /**< Sub type value used to distinguish between audio class specific descriptors */
 246
 247                         uint8_t                   UnitID; /**< ID value of this feature unit - must be a unique value within the device */
 248                         uint8_t                   SourceID; /**< Source ID value of the audio source input into this feature unit */
 249
 250                         uint8_t                   ControlSize; /**< Size of each element in the ChanelControlls array */
 251                         uint8_t                   ChannelControls[3]; /**< Feature masks for the control channel, and each separate audio channel */
 252
 253                         uint8_t                   FeatureUnitStrIndex; /**< Index of a string descriptor describing this descriptor within the device */
 254                 } USB_AudioFeatureUnit_t;
 255
 256                 /** Type define for an Audio class specific input terminal descriptor. This indicates to the host that the device
 257                  *  contains an input audio source, either from a physical terminal on the device, or a logical terminal (for example,
 258                  *  a USB endpoint). See the USB Audio specification for more details.
 259                  */
 260                 typedef struct
 261                 {
 262                         USB_Descriptor_Header_t   Header; /**< Regular descriptor header containing the descriptor's type and length */
 263                         uint8_t                   Subtype; /**< Sub type value used to distinguish between audio class specific descriptors */
 264
 265                         uint8_t                   TerminalID; /**< ID value of this terminal unit - must be a unique value within the device */
 266                         uint16_t                  TerminalType; /**< Type of terminal, a TERMINAL_* mask */
 267                         uint8_t                   AssociatedOutputTerminal; /**< ID of associated output terminal, for physically grouped terminals
 268                                                                              *   such as the speaker and microphone of a phone handset
 269                                                                              */
 270                         uint8_t                   TotalChannels; /**< Total number of separate audio channels within this interface (right, left, etc.) */
 271                         uint16_t                  ChannelConfig; /**< CHANNEL_* masks indicating what channel layout is supported by this terminal */
 272
 273                         uint8_t                   ChannelStrIndex; /**< Index of a string descriptor describing this channel within the device */
 274                         uint8_t                   TerminalStrIndex; /**< Index of a string descriptor describing this descriptor within the device */
 275                 } USB_AudioInputTerminal_t;
 276
 277                 /** Type define for an Audio class specific output terminal descriptor. This indicates to the host that the device
 278                  *  contains an output audio sink, either to a physical terminal on the device, or a logical terminal (for example,
 279                  *  a USB endpoint). See the USB Audio specification for more details.
 280                  */
 281                 typedef struct
 282                 {
 283                         USB_Descriptor_Header_t   Header; /**< Regular descriptor header containing the descriptor's type and length */
 284                         uint8_t                   Subtype; /**< Sub type value used to distinguish between audio class specific descriptors */
 285
 286                         uint8_t                   TerminalID; /**< ID value of this terminal unit - must be a unique value within the device */
 287                         uint16_t                  TerminalType; /**< Type of terminal, a TERMINAL_* mask */
 288                         uint8_t                   AssociatedInputTerminal; /**< ID of associated input terminal, for physically grouped terminals
 289                                                                             *   such as the speaker and microphone of a phone handset
 290                                                                             */
 291                         uint8_t                   SourceID; /**< ID value of the unit this terminal's audio is sourced from */
 292
 293                         uint8_t                   TerminalStrIndex; /**< Index of a string descriptor describing this descriptor within the device */
 294                 } USB_AudioOutputTerminal_t;
 295
 296                 /** Type define for an Audio class specific streaming interface descriptor. This indicates to the host
 297                  *  how audio streams within the device are formatted. See the USB Audio specification for more details.
 298                  */
 299                 typedef struct
 300                 {
 301                         USB_Descriptor_Header_t   Header; /**< Regular descriptor header containing the descriptor's type and length */
 302                         uint8_t                   Subtype; /**< Sub type value used to distinguish between audio class specific descriptors */
 303
 304                         uint8_t                   TerminalLink; /**< ID value of the output terminal this descriptor is describing */
 305
 306                         uint8_t                   FrameDelay; /**< Delay in frames resulting from the complete sample processing from input to output */
 307                         uint16_t                  AudioFormat; /**< Format of the audio stream, see Audio Device Formats specification */
 308                 } USB_AudioInterface_AS_t;
 309
 310                 /** Type define for a 24bit audio sample frequency structure. GCC does not contain a built in 24bit datatype,
 311                  *  this this structure is used to build up the value instead. Fill this structure with the SAMPLE_FREQ() macro.
 312                  */
 313                 typedef struct
 314                 {
 315                         uint16_t                  LowWord; /**< Low 16 bits of the 24-bit value */
 316                         uint8_t                   HighByte; /**< Upper 8 bits of the 24-bit value */
 317                 } AudioSampleFreq_t;
 318
 319                 /** Type define for an Audio class specific audio format descriptor. This is used to give the host full details
 320                  *  about the number of channels, the sample resolution, acceptable sample frequencies and encoding method used
 321                  *  in the device's audio streams. See the USB Audio specification for more details.
 322                  */
 323                 typedef struct
 324                 {
 325                         USB_Descriptor_Header_t   Header; /**< Regular descriptor header containing the descriptor's type and length */
 326                         uint8_t                   Subtype; /**< Sub type value used to distinguish between audio class specific descriptors */
 327
 328                         uint8_t                   FormatType; /**< Format of the audio stream, see Audio Device Formats specification */
 329                         uint8_t                   Channels; /**< Total number of discrete channels in the stream */
 330
 331                         uint8_t                   SubFrameSize; /**< Size in bytes of each channel's sample data in the stream */
 332                         uint8_t                   BitResolution; /**< Bits of resolution of each channel's samples in the stream */
 333
 334                         uint8_t                   SampleFrequencyType; /**< Total number of sample frequencies supported by the device */
 335                         AudioSampleFreq_t         SampleFrequencies[1]; /**< Sample frequencies supported by the device */
 336                 } USB_AudioFormat_t;
 337
 338                 /** Type define for an Audio class specific endpoint descriptor. This contains a regular endpoint
 339                  *  descriptor with a few Audio-class specific extensions. See the USB Audio specification for more details.
 340                  */
 341                 typedef struct
 342                 {
 343                         USB_Descriptor_Endpoint_t Endpoint; /**< Standard endpoint descriptor describing the audio endpoint */
 344
 345                         uint8_t                   Refresh; /**< Always set to zero */
 346                         uint8_t                   SyncEndpointNumber; /**< Endpoint address to send synchronisation information to, if needed (zero otherwise) */
 347                 } USB_AudioStreamEndpoint_Std_t;
 348
 349                 /** Type define for an Audio class specific extended endpoint descriptor. This contains extra information
 350                  *  on the usage of endpoints used to stream audio in and out of the USB Audio device, and follows an Audio
 351                  *  class specific extended endpoint descriptor. See the USB Audio specification for more details.
 352                  */
 353                 typedef struct
 354                 {
 355                         USB_Descriptor_Header_t   Header; /**< Regular descriptor header containing the descriptor's type and length */
 356                         uint8_t                   Subtype; /**< Sub type value used to distinguish between audio class specific descriptors */
 357
 358                         uint8_t                   Attributes; /**< Audio class specific endpoint attributes, such as ACCEPTS_SMALL_PACKETS */
 359
 360                         uint8_t                   LockDelayUnits; /**< Units used for the LockDelay field, see Audio class specification */
 361                         uint16_t                  LockDelay; /**< Time required to internally lock endpoint's internal clock recovery circuitry */
 362                 } USB_AudioStreamEndpoint_Spc_t;
 363
 364                 /** Type define for an Audio Class interface configuration and state structure. This structure should be used for each Audio
 365                  *  Class unit within the device, and passed (per-interface) to the Audio Class driver functions so that each Audio interface
 366                  *  has seperate state and configuration data and can be controlled seperately.
 367                  */
 368                 typedef struct
 369                 {
 370                         uint8_t  StreamingInterfaceNumber; /**< Index of the Audio Streaming interface within the device this structure controls */
 371
 372                         uint8_t  DataINEndpointNumber; /**< Endpoint number of the incomming Audio Streaming data, if available (zero if unused) */
 373                         uint16_t DataINEndpointSize; /**< Size in bytes of the incomming Audio Streaming data endpoint, if available (zero if unused) */
 374
 375                         uint8_t  DataOUTEndpointNumber; /**< Endpoint number of the outgoing Audio Streaming data, if available (zero if unused) */
 376                         uint16_t DataOUTEndpointSize; /**< Size in bytes of the outgoing Audio Streaming data endpoint, if available (zero if unused) */
 377
 378                         bool     InterfaceEnabled; /**< Set and cleared by the class driver to indicate if the host has enabled the streaming endpoints
 379                                                     *   of the Audio Streaming interface
 380                                                     */
 381                 } USB_ClassInfo_Audio_t;
 382
 383         /* Function Prototypes: */
 384                 /** Configures the endpoints of a given Audio interface, ready for use. This should be linked to the library
 385                  *  \ref EVENT_USB_ConfigurationChanged() event so that the endpoints are configured when the configuration containing the
 386                  *  given Audio interface is selected.
 387                  *
 388                  *  \param AudioInterfaceInfo  Pointer to a structure containing an Audio Class configuration and state.
 389                  *
 390                  *  \return Boolean true if the endpoints were sucessfully configured, false otherwise
 391                  */
 392                 bool USB_Audio_ConfigureEndpoints(USB_ClassInfo_Audio_t* AudioInterfaceInfo);
 393
 394                 /** Processes incomming control requests from the host, that are directed to the given Audio class interface. This should be
 395                  *  linked to the library \ref EVENT_USB_UnhandledControlPacket() event.
 396                  *
 397                  *  \param AudioInterfaceInfo  Pointer to a structure containing an Audio Class configuration and state.
 398                  */
 399                 void USB_Audio_ProcessControlPacket(USB_ClassInfo_Audio_t* AudioInterfaceInfo);
 400
 401                 /** General management task for a given Audio class interface, required for the correct operation of the interface. This should
 402                  *  be called frequently in the main program loop, before the master USB management task \ref USB_USBTask().
 403                  *
 404                  *  \param AudioInterfaceInfo  Pointer to a structure containing an Audio Class configuration and state.
 405                  */
 406                 void USB_Audio_USBTask(USB_ClassInfo_Audio_t* AudioInterfaceInfo);
 407
 408                 /** Reads the next 8-bit audio sample from the current audio interface.
 409                  *
 410                  *  \note This should be preceeded immediately by a call to the USB_Audio_IsSampleReceived() function to ensure that
 411                  *        the correct endpoint is selected and ready for data.
 412                  *
 413                  *  \return  Signed 8-bit audio sample from the audio interface
 414                  */
 415                 int8_t USB_Audio_ReadSample8(void);
 416
 417                 /** Reads the next 16-bit audio sample from the current audio interface.
 418                  *
 419                  *  \note This should be preceeded immediately by a call to the USB_Audio_IsSampleReceived() function to ensure that
 420                  *        the correct endpoint is selected and ready for data.
 421                  *
 422                  *  \return  Signed 16-bit audio sample from the audio interface
 423                  */
 424                 int16_t USB_Audio_ReadSample16(void);
 425
 426                 /** Reads the next 24-bit audio sample from the current audio interface.
 427                  *
 428                  *  \note This should be preceeded immediately by a call to the USB_Audio_IsSampleReceived() function to ensure that
 429                  *        the correct endpoint is selected and ready for data.
 430                  *
 431                  *  \return  Signed 24-bit audio sample from the audio interface
 432                  */
 433                 int32_t USB_Audio_ReadSample24(void);
 434
 435                 /** Writes the next 8-bit audio sample to the current audio interface.
 436                  *
 437                  *  \note This should be preceeded immediately by a call to the USB_Audio_IsReadyForNextSample() function to ensure that
 438                  *        the correct endpoint is selected and ready for data.
 439                  *
 440                  *  \param Sample  Signed 8-bit audio sample
 441                  */
 442                 void USB_Audio_WriteSample8(int8_t Sample);
 443
 444                 /** Writes the next 16-bit audio sample to the current audio interface.
 445                  *
 446                  *  \note This should be preceeded immediately by a call to the USB_Audio_IsReadyForNextSample() function to ensure that
 447                  *        the correct endpoint is selected and ready for data.
 448                  *
 449                  *  \param Sample  Signed 16-bit audio sample
 450                  */
 451                 void USB_Audio_WriteSample16(int16_t Sample);
 452
 453                 /** Writes the next 24-bit audio sample to the current audio interface.
 454                  *
 455                  *  \note This should be preceeded immediately by a call to the USB_Audio_IsReadyForNextSample() function to ensure that
 456                  *        the correct endpoint is selected and ready for data.
 457                  *
 458                  *  \param Sample  Signed 24-bit audio sample
 459                  */
 460                 void USB_Audio_WriteSample24(int32_t Sample);
 461
 462                 /** Determines if the given audio interface is ready for a sample to be read from it.
 463                  *
 464                  *  \param AudioInterfaceInfo  Pointer to a structure containing an Audio Class configuration and state.
 465                  *
 466                  *  \return Boolean true if the given Audio interface has a sample to be read, false otherwise
 467                  */
 468                 bool USB_Audio_IsSampleReceived(USB_ClassInfo_Audio_t* AudioInterfaceInfo);
 469
 470                 /** Determines if the given audio interface is ready to accept the next sample to be written to it.
 471                  *
 472                  *  \param AudioInterfaceInfo  Pointer to a structure containing an Audio Class configuration and state.
 473                  *
 474                  *  \return Boolean true if the given Audio interface is ready to accept the next sample, false otherwise
 475                  */
 476                 bool USB_Audio_IsReadyForNextSample(USB_ClassInfo_Audio_t* AudioInterfaceInfo);
 477
 478         /* Disable C linkage for C++ Compilers: */
 479                 #if defined(__cplusplus)
 480                         }
 481                 #endif
 482
 483 #endif
 484
 485 /** @} */