USBD_Audio_DrvStreamRecordRx

Description

Get a ready record buffer from codec.

Files

usbd_audio_drv_<codec-name>.h / usbd_audio_drv_<codec-name>.c

Prototype

static  void  USBD_Audio_DrvStreamRecordRx (USBD_AUDIO_DRV  *p_audio_drv,
                                            CPU_INT08U       terminal_id_link,
                                            void            *p_buf,
                                            CPU_INT16U      *p_buf_len,
                                            USBD_ERR        *p_err)

Arguments

p_audio_drv

Pointer to audio driver structure.

terminal_id_link

Terminal ID associated to this stream.

p_buf

Pointer to record buffer.

p_buf_len

Pointer to buffer length in bytes.

p_err

Pointer to variable that will receive the return error code from this function.

USBD_ERR_NONE

USBD_ERR_RX

Returned Value

None.

...Pointer to a ready record buffer, if NO error(s) occurred.

Null pointer, otherwise.

Callers

Audio Class.

Implementation guidelines

This listing shows an example usage of this function.

Listing - USBD_Audio_DrvStreamRecordRx() Example Usage

static  void  *USBD_Audio_DrvStreamRecordRx (USBD_AUDIO_DRV  *p_audio_drv,
                                             CPU_INT08U       terminal_id_link,
											 void            *p_buf,
                                             CPU_INT16U      *p_buf_len,
                                             USBD_ERR        *p_err)
{
	/* $$$$ Retrieve a ready record buffer. */						          (1)
}

(1) When an audio transfer is completed, the codec driver should signal the record task that a buffer is ready by sending calling the function USBD_Audio_RecordRxCmpl. This function will post a request to the record task. Upon reception of this request, the record task will call the function USBD_Audio_DrvStreamRecordRx() through a function pointer to get a ready buffer. If the audio peripheral uses DMA, the buffer is already ready and there is nothing special to do in this function. If the audio peripheral uses a FIFO mode, you may have to copy the received audio samples to the buffer referenced by the pointer p_buf.

The Audio Peripheral Driver should support at least double-buffering to optimize the record streaming.

(2) In case of error, you may return the error code USBD_ERR_RX.