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# 3.3.4.48 USB_HOST_AUDIO_V1_ENTITY_REQUEST_CALLBACK Type

## C

    typedef void (* USB_HOST_AUDIO_V1_ENTITY_REQUEST_CALLBACK)(USB_HOST_AUDIO_V1_OBJ audioObj, USB_HOST_AUDIO_V1_REQUEST_HANDLE requestHandle, USB_HOST_AUDIO_V1_RESULT result, size_t size, uintptr_t context);

## Summary

USB Host Audio v1.0 Class driver Control Transfer Complete Callback Function Pointer type

This data type defines the required function signature of the USB Host Audio v1.0 class driver control transfer complete callback function. The client must provide a pointer to a control transfer complete callback function whose function signature (parameter and return value types) must match the types specified by this function pointer to receive notification when a control transfer has completed. The application should use the USB_HOST_AUDIO_V1_EntityRequestCallbackSet function to register an entity control request callback. The Audio v1.0 client driver will call this function with the relevant event parameters. The descriptions of the event handler function parameters are as follows:

- audioObj - Audio v1.0 client driver object associated with this event.
- requestHandle - Request handle of the control transfer request that caused this event.
- result - Completion result of the control transfer. This will be USB_HOST_AUDIO_V1_RESULT_SUCCESS if the control transfer completed successfully, USB_HOST_AUDIO_V1_RESULT_FAILURE if an unknown failure occurred, or USB_HOST_AUDIO_V1_RESULT_REQUEST_STALLED if the request was stalled.
- size - Size of the data stage that was transferred.
- context - Value identifying the context of the application that was provided when the USB_HOST_AUDIO_V1_ControlRequest function was called.

## Remarks

None.