How to determine whether master volume is enabled?

[Artem Moroz]

I'm using class CVolumeOutMaster - it sets and gets master volume. The class could be found here: http://www.codeproject.com/audio/volumeclasses.asp It determines the volume like this:

DWORD CVolumeOutMaster::GetCurrentVolume()
{
if ( !m_bAvailable )
return BAD_DWORD;
MIXERCONTROLDETAILS_UNSIGNED* aDetails = (MIXERCONTROLDETAILS_UNSIGNED*)malloc(m_nChannelCount*sizeof(MIXERCONTROLDETAILS_UNSIGNED));
if ( !aDetails )
return BAD_DWORD;
MIXERCONTROLDETAILS ControlDetails;
memset( &ControlDetails, 0, sizeof(MIXERCONTROLDETAILS) );
ControlDetails.cbStruct = sizeof(MIXERCONTROLDETAILS);
ControlDetails.dwControlID = m_dwVolumeControlID;
ControlDetails.cChannels = m_nChannelCount;
ControlDetails.cMultipleItems = 0;
ControlDetails.cbDetails = sizeof(MIXERCONTROLDETAILS_UNSIGNED);
ControlDetails.paDetails = &aDetails[0];
MMRESULT mmResult = mixerGetControlDetails( (HMIXEROBJ)m_dwMixerHandle, &ControlDetails, MIXER_GETCONTROLDETAILSF_VALUE );
DWORD dw = aDetails[0].dwValue;
free( aDetails );
if ( mmResult != MMSYSERR_NOERROR )
{
TRACE(".MasterOutputVolume: FAILURE: Could not get volume. mmResult=%d\n", mmResult );
return BAD_DWORD;
}
return dw;
}

How to determine whether master volume is enabled or disabled?