audformattypeonedescriptor.h

at91sam9260-ek library file

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//------------------------------------------------------------------------------
/// \unit
/// !Purpose
/// 
/// Definitions for using USB audio format type I descriptors.
///
/// !Usage
/// 
/// -# Declare an instance of AUDFormatTypeOneDescriptor as part of the
///    configuration descriptors of an Audio device.
//------------------------------------------------------------------------------

#ifndef AUDFORMATTYPEONEDESCRIPTOR_H
#define AUDFORMATTYPEONEDESCRIPTOR_H

//------------------------------------------------------------------------------
//         Definitions
//------------------------------------------------------------------------------

/// Format type for a format type I descriptor.
#define AUDFormatTypeOneDescriptor_FORMATTYPEONE        0x01

/// AUDFormatTypeOneDescriptor_PCM - PCM format.
#define AUDFormatTypeOneDescriptor_PCM                  0x0001

/// Indicates the sampling frequency can have any value in the provided range.
#define AUDFormatTypeOneDescriptor_CONTINUOUS           0

//------------------------------------------------------------------------------
//         Types
//------------------------------------------------------------------------------

#ifdef __ICCARM__          // IAR
#pragma pack(1)            // IAR
#define __attribute__(...) // IAR
#endif                     // IAR

//------------------------------------------------------------------------------
/// Describes an audio data stream that is constructed on a sample-by-sample
/// basis. This type must be augmented with either the continuous sampling
/// frequency range (if bSamFreqType = <AUDFormatTypeOneDescriptor_CONTINUOUS>)
/// or with an array containing the possible discrete frequencies.
//------------------------------------------------------------------------------
typedef struct {

    /// Size of descriptor in bytes.
    unsigned char bLength;
    /// Descriptor type (AUDGenericDescriptor_INTERFACE).
    unsigned char bDescriptorType;
    /// Descriptor subtype (AUDStreamingInterfaceDescriptor_FORMATTYPE).
    unsigned char bDescriptorSubType;
    /// Format type (AUDFormatTypeOneDescriptor_FORMATTYPEONE).
    unsigned char bFormatType;
    /// Number of physical channels in the audio stream.
    unsigned char bNrChannels;
    /// Number of bytes occupied by one audio subframe.
    unsigned char bSubFrameSize;
    /// Number of bits effectively used in an audio subframe.
    unsigned char bBitResolution;
    /// Number of supported discrete sampling frequencies, or
    /// AUDFormatTypeOneDescriptor_CONTINUOUS.
    unsigned char bSamFreqType;

} __attribute__ ((packed)) AUDFormatTypeOneDescriptor; // GCC

#ifdef __ICCARM__          // IAR
#pragma pack()             // IAR
#endif                     // IAR

#endif //#ifndef AUDFORMATTYPEONEDESCRIPTOR_H