MICSetDataConsumed

Syntax

#include <cafe/mic.h>

int MICSetDataConsumed(mic_handle_t h_mic, unsigned int c_samples);

Parameters

h_mic Handle returned from MICInit.
c_samples The number of audio samples of type mic_pcm_sample_t that was consumed (i.e., taken from the ring buffer) by the caller.

Return Values

A value of MIC_ERROR_NONE (0) indicates success and any other value indicates the type of error that was encountered.

MIC_ERROR_INV_ARG is returned if an invalid handle is passed in. MIC_ERROR_NOT_INIT is returned when the function is called before MICInit or after MICClose. -81 is returned if the ring buffer underflows as a result of updating its state.

Description

This function is used to keep the shared ring buffer state coherent between the microphone driver and the sink, i.e., the consumer of the audio samples. The AX system in Cafe is capable of playing back the DRC microphone's PCM data stream directly out of the shared ring buffer without any further data copies. This function is used to keep the finite state machine in the microphone driver up to date with the actual data consumption.

It is permissible to consume more data than are available in the ring buffer. All arithmetic is performed 'modulo ring buffer size'. That means that after consuming more data than available, MICGetStatus will indicate that samples are available although the ring buffer had underflowed. An underflow is indicated by an unnamed return value of -81.

The ring buffer state update is performed even when an underflow occurred. The PCM data can be played back with a free running finite state machine and there can be corner cases under which a buffer underflow might happen.

The processing performed in MICSetDataConumed is lightweight and calling this function from a timing sensitive thread, such as the AX callback, can be performed.

Do Not Call From

Background Do not call this function from the background.
Interrupt handler Do not call this function from any interrupt handler.
Exception handler Do not call this function from any exception handler.

See Also

mic_handle_t
mic_pcm_sample_t
MICInit
MICGetStatus
Error Codes

Revision History

2013/05/08 Automated cleanup pass.
2012/08/03 Cleanup Pass.
2012/06/08 Update to match SDK 2.06.
2011/10/27 Initial version.


CONFIDENTIAL