oxygine-sound/dependencies/openal/Alc/backends/winmm.c

/**
 * OpenAL cross platform audio library
 * Copyright (C) 1999-2007 by authors.
 * This library is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU Library General Public
 *  License as published by the Free Software Foundation; either
 *  version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *  Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public
 *  License along with this library; if not, write to the
 *  Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 *  Boston, MA  02111-1307, USA.
 * Or go to http://www.gnu.org/copyleft/lgpl.html
 */

#include "config.h"

#include <stdlib.h>
#include <stdio.h>
#include <memory.h>

#include <windows.h>
#include <mmsystem.h>

#include "alMain.h"
#include "AL/al.h"
#include "AL/alc.h"

#ifndef WAVE_FORMAT_IEEE_FLOAT
#define WAVE_FORMAT_IEEE_FLOAT  0x0003
#endif


typedef struct {
    // MMSYSTEM Device
    volatile ALboolean bWaveShutdown;
    HANDLE  hWaveThreadEvent;
    HANDLE  hWaveThread;
    DWORD   ulWaveThreadID;
    volatile LONG lWaveBuffersCommitted;
    WAVEHDR WaveBuffer[4];

    union {
        HWAVEIN  In;
        HWAVEOUT Out;
    } hWaveHandle;

    WAVEFORMATEX wfexFormat;

    RingBuffer *pRing;
} WinMMData;


static ALCchar **PlaybackDeviceList;
static ALuint  NumPlaybackDevices;
static ALCchar **CaptureDeviceList;
static ALuint  NumCaptureDevices;


static void ProbePlaybackDevices(void)
{
    ALuint i;

    for(i = 0;i < NumPlaybackDevices;i++)
        free(PlaybackDeviceList[i]);

    NumPlaybackDevices = waveOutGetNumDevs();
    PlaybackDeviceList = realloc(PlaybackDeviceList, sizeof(ALCchar*) * NumPlaybackDevices);
    for(i = 0;i < NumPlaybackDevices;i++)
    {
        WAVEOUTCAPS WaveCaps;

        PlaybackDeviceList[i] = NULL;
        if(waveOutGetDevCaps(i, &WaveCaps, sizeof(WaveCaps)) == MMSYSERR_NOERROR)
        {
            char name[1024];
            ALuint count, j;

            count = 0;
            do {
                if(count == 0)
                    snprintf(name, sizeof(name), "%s", WaveCaps.szPname);
                else
                    snprintf(name, sizeof(name), "%s #%d", WaveCaps.szPname, count+1);
                count++;

                for(j = 0;j < i;j++)
                {
                    if(strcmp(name, PlaybackDeviceList[j]) == 0)
                        break;
                }
            } while(j != i);

            PlaybackDeviceList[i] = strdup(name);
        }
    }
}

static void ProbeCaptureDevices(void)
{
    ALuint i;

    for(i = 0;i < NumCaptureDevices;i++)
        free(CaptureDeviceList[i]);

    NumCaptureDevices = waveInGetNumDevs();
    CaptureDeviceList = realloc(CaptureDeviceList, sizeof(ALCchar*) * NumCaptureDevices);
    for(i = 0;i < NumCaptureDevices;i++)
    {
        WAVEINCAPS WaveInCaps;

        CaptureDeviceList[i] = NULL;
        if(waveInGetDevCaps(i, &WaveInCaps, sizeof(WAVEINCAPS)) == MMSYSERR_NOERROR)
        {
            char name[1024];
            ALuint count, j;

            count = 0;
            do {
                if(count == 0)
                    snprintf(name, sizeof(name), "%s", WaveInCaps.szPname);
                else
                    snprintf(name, sizeof(name), "%s #%d", WaveInCaps.szPname, count+1);
                count++;

                for(j = 0;j < i;j++)
                {
                    if(strcmp(name, CaptureDeviceList[j]) == 0)
                        break;
                }
            } while(j != i);

            CaptureDeviceList[i] = strdup(name);
        }
    }
}


/*
    WaveOutProc

    Posts a message to 'PlaybackThreadProc' everytime a WaveOut Buffer is completed and
    returns to the application (for more data)
*/
static void CALLBACK WaveOutProc(HWAVEOUT hDevice,UINT uMsg,DWORD_PTR dwInstance,DWORD_PTR dwParam1,DWORD_PTR dwParam2)
{
    ALCdevice *pDevice = (ALCdevice*)dwInstance;
    WinMMData *pData = pDevice->ExtraData;

    (void)hDevice;
    (void)dwParam2;

    if(uMsg != WOM_DONE)
        return;

    InterlockedDecrement(&pData->lWaveBuffersCommitted);
    PostThreadMessage(pData->ulWaveThreadID, uMsg, 0, dwParam1);
}

/*
    PlaybackThreadProc

    Used by "MMSYSTEM" Device.  Called when a WaveOut buffer has used up its
    audio data.
*/
static DWORD WINAPI PlaybackThreadProc(LPVOID lpParameter)
{
    ALCdevice *pDevice = (ALCdevice*)lpParameter;
    WinMMData *pData = pDevice->ExtraData;
    LPWAVEHDR pWaveHdr;
    ALuint FrameSize;
    MSG msg;

    FrameSize = FrameSizeFromDevFmt(pDevice->FmtChans, pDevice->FmtType);

    SetRTPriority();

    while(GetMessage(&msg, NULL, 0, 0))
    {
        if(msg.message != WOM_DONE)
            continue;

        if(pData->bWaveShutdown)
        {
            if(pData->lWaveBuffersCommitted == 0)
                break;
            continue;
        }

        pWaveHdr = ((LPWAVEHDR)msg.lParam);

        aluMixData(pDevice, pWaveHdr->lpData, pWaveHdr->dwBufferLength/FrameSize);

        // Send buffer back to play more data
        waveOutWrite(pData->hWaveHandle.Out, pWaveHdr, sizeof(WAVEHDR));
        InterlockedIncrement(&pData->lWaveBuffersCommitted);
    }

    // Signal Wave Thread completed event
    if(pData->hWaveThreadEvent)
        SetEvent(pData->hWaveThreadEvent);

    ExitThread(0);

    return 0;
}

/*
    WaveInProc

    Posts a message to 'CaptureThreadProc' everytime a WaveIn Buffer is completed and
    returns to the application (with more data)
*/
static void CALLBACK WaveInProc(HWAVEIN hDevice,UINT uMsg,DWORD_PTR dwInstance,DWORD_PTR dwParam1,DWORD_PTR dwParam2)
{
    ALCdevice *pDevice = (ALCdevice*)dwInstance;
    WinMMData *pData = pDevice->ExtraData;

    (void)hDevice;
    (void)dwParam2;

    if(uMsg != WIM_DATA)
        return;

    InterlockedDecrement(&pData->lWaveBuffersCommitted);
    PostThreadMessage(pData->ulWaveThreadID,uMsg,0,dwParam1);
}

/*
    CaptureThreadProc

    Used by "MMSYSTEM" Device.  Called when a WaveIn buffer had been filled with new
    audio data.
*/
static DWORD WINAPI CaptureThreadProc(LPVOID lpParameter)
{
    ALCdevice *pDevice = (ALCdevice*)lpParameter;
    WinMMData *pData = pDevice->ExtraData;
    LPWAVEHDR pWaveHdr;
    ALuint FrameSize;
    MSG msg;

    FrameSize = FrameSizeFromDevFmt(pDevice->FmtChans, pDevice->FmtType);

    while(GetMessage(&msg, NULL, 0, 0))
    {
        if(msg.message != WIM_DATA)
            continue;
        /* Don't wait for other buffers to finish before quitting. We're
         * closing so we don't need them. */
        if(pData->bWaveShutdown)
            break;

        pWaveHdr = ((LPWAVEHDR)msg.lParam);

        WriteRingBuffer(pData->pRing, (ALubyte*)pWaveHdr->lpData,
                        pWaveHdr->dwBytesRecorded/FrameSize);

        // Send buffer back to capture more data
        waveInAddBuffer(pData->hWaveHandle.In,pWaveHdr,sizeof(WAVEHDR));
        InterlockedIncrement(&pData->lWaveBuffersCommitted);
    }

    // Signal Wave Thread completed event
    if(pData->hWaveThreadEvent)
        SetEvent(pData->hWaveThreadEvent);

    ExitThread(0);

    return 0;
}


static ALCenum WinMMOpenPlayback(ALCdevice *pDevice, const ALCchar *deviceName)
{
    WinMMData *pData = NULL;
    UINT lDeviceID = 0;
    MMRESULT res;
    ALuint i = 0;

    if(!PlaybackDeviceList)
        ProbePlaybackDevices();

    // Find the Device ID matching the deviceName if valid
    for(i = 0;i < NumPlaybackDevices;i++)
    {
        if(PlaybackDeviceList[i] &&
           (!deviceName || strcmp(deviceName, PlaybackDeviceList[i]) == 0))
        {
            lDeviceID = i;
            break;
        }
    }
    if(i == NumPlaybackDevices)
        return ALC_INVALID_VALUE;

    pData = calloc(1, sizeof(*pData));
    if(!pData)
        return ALC_OUT_OF_MEMORY;
    pDevice->ExtraData = pData;

retry_open:
    memset(&pData->wfexFormat, 0, sizeof(WAVEFORMATEX));
    if(pDevice->FmtType == DevFmtFloat)
    {
        pData->wfexFormat.wFormatTag = WAVE_FORMAT_IEEE_FLOAT;
        pData->wfexFormat.wBitsPerSample = 32;
    }
    else
    {
        pData->wfexFormat.wFormatTag = WAVE_FORMAT_PCM;
        if(pDevice->FmtType == DevFmtUByte || pDevice->FmtType == DevFmtByte)
            pData->wfexFormat.wBitsPerSample = 8;
        else
            pData->wfexFormat.wBitsPerSample = 16;
    }
    pData->wfexFormat.nChannels = ((pDevice->FmtChans == DevFmtMono) ? 1 : 2);
    pData->wfexFormat.nBlockAlign = pData->wfexFormat.wBitsPerSample *
                                    pData->wfexFormat.nChannels / 8;
    pData->wfexFormat.nSamplesPerSec = pDevice->Frequency;
    pData->wfexFormat.nAvgBytesPerSec = pData->wfexFormat.nSamplesPerSec *
                                        pData->wfexFormat.nBlockAlign;
    pData->wfexFormat.cbSize = 0;

    if((res=waveOutOpen(&pData->hWaveHandle.Out, lDeviceID, &pData->wfexFormat, (DWORD_PTR)&WaveOutProc, (DWORD_PTR)pDevice, CALLBACK_FUNCTION)) != MMSYSERR_NOERROR)
    {
        if(pDevice->FmtType == DevFmtFloat)
        {
            pDevice->FmtType = DevFmtShort;
            goto retry_open;
        }
        ERR("waveOutOpen failed: %u\n", res);
        goto failure;
    }

    pData->hWaveThreadEvent = CreateEvent(NULL, FALSE, FALSE, NULL);
    if(pData->hWaveThreadEvent == NULL)
    {
        ERR("CreateEvent failed: %lu\n", GetLastError());
        goto failure;
    }

    pDevice->szDeviceName = strdup(PlaybackDeviceList[lDeviceID]);
    return ALC_NO_ERROR;

failure:
    if(pData->hWaveThreadEvent)
        CloseHandle(pData->hWaveThreadEvent);

    if(pData->hWaveHandle.Out)
        waveOutClose(pData->hWaveHandle.Out);

    free(pData);
    pDevice->ExtraData = NULL;
    return ALC_INVALID_VALUE;
}

static void WinMMClosePlayback(ALCdevice *device)
{
    WinMMData *pData = (WinMMData*)device->ExtraData;

    // Close the Wave device
    CloseHandle(pData->hWaveThreadEvent);
    pData->hWaveThreadEvent = 0;

    waveOutClose(pData->hWaveHandle.Out);
    pData->hWaveHandle.Out = 0;

    free(pData);
    device->ExtraData = NULL;
}

static ALCboolean WinMMResetPlayback(ALCdevice *device)
{
    WinMMData *data = (WinMMData*)device->ExtraData;

    device->UpdateSize = (ALuint)((ALuint64)device->UpdateSize *
                                  data->wfexFormat.nSamplesPerSec /
                                  device->Frequency);
    device->UpdateSize = (device->UpdateSize*device->NumUpdates + 3) / 4;
    device->NumUpdates = 4;
    device->Frequency = data->wfexFormat.nSamplesPerSec;

    if(data->wfexFormat.wFormatTag == WAVE_FORMAT_IEEE_FLOAT)
    {
        if(data->wfexFormat.wBitsPerSample == 32)
            device->FmtType = DevFmtFloat;
        else
        {
            ERR("Unhandled IEEE float sample depth: %d\n", data->wfexFormat.wBitsPerSample);
            return ALC_FALSE;
        }
    }
    else if(data->wfexFormat.wFormatTag == WAVE_FORMAT_PCM)
    {
        if(data->wfexFormat.wBitsPerSample == 16)
            device->FmtType = DevFmtShort;
        else if(data->wfexFormat.wBitsPerSample == 8)
            device->FmtType = DevFmtUByte;
        else
        {
            ERR("Unhandled PCM sample depth: %d\n", data->wfexFormat.wBitsPerSample);
            return ALC_FALSE;
        }
    }
    else
    {
        ERR("Unhandled format tag: 0x%04x\n", data->wfexFormat.wFormatTag);
        return ALC_FALSE;
    }

    if(data->wfexFormat.nChannels == 2)
        device->FmtChans = DevFmtStereo;
    else if(data->wfexFormat.nChannels == 1)
        device->FmtChans = DevFmtMono;
    else
    {
        ERR("Unhandled channel count: %d\n", data->wfexFormat.nChannels);
        return ALC_FALSE;
    }
    SetDefaultWFXChannelOrder(device);

    return ALC_TRUE;
}

static ALCboolean WinMMStartPlayback(ALCdevice *device)
{
    WinMMData *pData = (WinMMData*)device->ExtraData;
    ALbyte *BufferData;
    ALint lBufferSize;
    ALuint i;

    pData->hWaveThread = CreateThread(NULL, 0, (LPTHREAD_START_ROUTINE)PlaybackThreadProc, (LPVOID)device, 0, &pData->ulWaveThreadID);
    if(pData->hWaveThread == NULL)
        return ALC_FALSE;

    pData->lWaveBuffersCommitted = 0;

    // Create 4 Buffers
    lBufferSize  = device->UpdateSize*device->NumUpdates / 4;
    lBufferSize *= FrameSizeFromDevFmt(device->FmtChans, device->FmtType);

    BufferData = calloc(4, lBufferSize);
    for(i = 0;i < 4;i++)
    {
        memset(&pData->WaveBuffer[i], 0, sizeof(WAVEHDR));
        pData->WaveBuffer[i].dwBufferLength = lBufferSize;
        pData->WaveBuffer[i].lpData = ((i==0) ? (LPSTR)BufferData :
                                       (pData->WaveBuffer[i-1].lpData +
                                        pData->WaveBuffer[i-1].dwBufferLength));
        waveOutPrepareHeader(pData->hWaveHandle.Out, &pData->WaveBuffer[i], sizeof(WAVEHDR));
        waveOutWrite(pData->hWaveHandle.Out, &pData->WaveBuffer[i], sizeof(WAVEHDR));
        InterlockedIncrement(&pData->lWaveBuffersCommitted);
    }

    return ALC_TRUE;
}

static void WinMMStopPlayback(ALCdevice *device)
{
    WinMMData *pData = (WinMMData*)device->ExtraData;
    void *buffer = NULL;
    int i;

    if(pData->hWaveThread == NULL)
        return;

    // Set flag to stop processing headers
    pData->bWaveShutdown = AL_TRUE;

    // Wait for signal that Wave Thread has been destroyed
    WaitForSingleObjectEx(pData->hWaveThreadEvent, 5000, FALSE);

    CloseHandle(pData->hWaveThread);
    pData->hWaveThread = 0;

    pData->bWaveShutdown = AL_FALSE;

    // Release the wave buffers
    for(i = 0;i < 4;i++)
    {
        waveOutUnprepareHeader(pData->hWaveHandle.Out, &pData->WaveBuffer[i], sizeof(WAVEHDR));
        if(i == 0) buffer = pData->WaveBuffer[i].lpData;
        pData->WaveBuffer[i].lpData = NULL;
    }
    free(buffer);
}


static ALCenum WinMMOpenCapture(ALCdevice *pDevice, const ALCchar *deviceName)
{
    ALbyte *BufferData = NULL;
    DWORD ulCapturedDataSize;
    WinMMData *pData = NULL;
    UINT lDeviceID = 0;
    ALint lBufferSize;
    MMRESULT res;
    ALuint i;

    if(!CaptureDeviceList)
        ProbeCaptureDevices();

    // Find the Device ID matching the deviceName if valid
    for(i = 0;i < NumCaptureDevices;i++)
    {
        if(CaptureDeviceList[i] &&
           (!deviceName || strcmp(deviceName, CaptureDeviceList[i]) == 0))
        {
            lDeviceID = i;
            break;
        }
    }
    if(i == NumCaptureDevices)
        return ALC_INVALID_VALUE;

    switch(pDevice->FmtChans)
    {
        case DevFmtMono:
        case DevFmtStereo:
            break;

        case DevFmtQuad:
        case DevFmtX51:
        case DevFmtX51Side:
        case DevFmtX61:
        case DevFmtX71:
            return ALC_INVALID_ENUM;
    }

    switch(pDevice->FmtType)
    {
        case DevFmtUByte:
        case DevFmtShort:
        case DevFmtInt:
        case DevFmtFloat:
            break;

        case DevFmtByte:
        case DevFmtUShort:
        case DevFmtUInt:
            return ALC_INVALID_ENUM;
    }

    pData = calloc(1, sizeof(*pData));
    if(!pData)
        return ALC_OUT_OF_MEMORY;
    pDevice->ExtraData = pData;

    memset(&pData->wfexFormat, 0, sizeof(WAVEFORMATEX));
    pData->wfexFormat.wFormatTag = ((pDevice->FmtType == DevFmtFloat) ?
                                    WAVE_FORMAT_IEEE_FLOAT : WAVE_FORMAT_PCM);
    pData->wfexFormat.nChannels = ChannelsFromDevFmt(pDevice->FmtChans);
    pData->wfexFormat.wBitsPerSample = BytesFromDevFmt(pDevice->FmtType) * 8;
    pData->wfexFormat.nBlockAlign = pData->wfexFormat.wBitsPerSample *
                                    pData->wfexFormat.nChannels / 8;
    pData->wfexFormat.nSamplesPerSec = pDevice->Frequency;
    pData->wfexFormat.nAvgBytesPerSec = pData->wfexFormat.nSamplesPerSec *
                                        pData->wfexFormat.nBlockAlign;
    pData->wfexFormat.cbSize = 0;

    if((res=waveInOpen(&pData->hWaveHandle.In, lDeviceID, &pData->wfexFormat, (DWORD_PTR)&WaveInProc, (DWORD_PTR)pDevice, CALLBACK_FUNCTION)) != MMSYSERR_NOERROR)
    {
        ERR("waveInOpen failed: %u\n", res);
        goto failure;
    }

    pData->hWaveThreadEvent = CreateEvent(NULL, FALSE, FALSE, NULL);
    if(pData->hWaveThreadEvent == NULL)
    {
        ERR("CreateEvent failed: %lu\n", GetLastError());
        goto failure;
    }

    // Allocate circular memory buffer for the captured audio
    ulCapturedDataSize = pDevice->UpdateSize*pDevice->NumUpdates;

    // Make sure circular buffer is at least 100ms in size
    if(ulCapturedDataSize < (pData->wfexFormat.nSamplesPerSec / 10))
        ulCapturedDataSize = pData->wfexFormat.nSamplesPerSec / 10;

    pData->pRing = CreateRingBuffer(pData->wfexFormat.nBlockAlign, ulCapturedDataSize);
    if(!pData->pRing)
        goto failure;

    pData->lWaveBuffersCommitted = 0;

    // Create 4 Buffers of 50ms each
    lBufferSize = pData->wfexFormat.nAvgBytesPerSec / 20;
    lBufferSize -= (lBufferSize % pData->wfexFormat.nBlockAlign);

    BufferData = calloc(4, lBufferSize);
    if(!BufferData)
        goto failure;

    for(i = 0;i < 4;i++)
    {
        memset(&pData->WaveBuffer[i], 0, sizeof(WAVEHDR));
        pData->WaveBuffer[i].dwBufferLength = lBufferSize;
        pData->WaveBuffer[i].lpData = ((i==0) ? (LPSTR)BufferData :
                                       (pData->WaveBuffer[i-1].lpData +
                                        pData->WaveBuffer[i-1].dwBufferLength));
        pData->WaveBuffer[i].dwFlags = 0;
        pData->WaveBuffer[i].dwLoops = 0;
        waveInPrepareHeader(pData->hWaveHandle.In, &pData->WaveBuffer[i], sizeof(WAVEHDR));
        waveInAddBuffer(pData->hWaveHandle.In, &pData->WaveBuffer[i], sizeof(WAVEHDR));
        InterlockedIncrement(&pData->lWaveBuffersCommitted);
    }

    pData->hWaveThread = CreateThread(NULL, 0, (LPTHREAD_START_ROUTINE)CaptureThreadProc, (LPVOID)pDevice, 0, &pData->ulWaveThreadID);
    if (pData->hWaveThread == NULL)
        goto failure;

    pDevice->szDeviceName = strdup(CaptureDeviceList[lDeviceID]);
    return ALC_NO_ERROR;

failure:
    if(pData->hWaveThread)
        CloseHandle(pData->hWaveThread);

    if(BufferData)
    {
        for(i = 0;i < 4;i++)
            waveInUnprepareHeader(pData->hWaveHandle.In, &pData->WaveBuffer[i], sizeof(WAVEHDR));
        free(BufferData);
    }

    if(pData->pRing)
        DestroyRingBuffer(pData->pRing);

    if(pData->hWaveThreadEvent)
        CloseHandle(pData->hWaveThreadEvent);

    if(pData->hWaveHandle.In)
        waveInClose(pData->hWaveHandle.In);

    free(pData);
    pDevice->ExtraData = NULL;
    return ALC_INVALID_VALUE;
}

static void WinMMCloseCapture(ALCdevice *pDevice)
{
    WinMMData *pData = (WinMMData*)pDevice->ExtraData;
    void *buffer = NULL;
    int i;

    /* Tell the processing thread to quit and wait for it to do so. */
    pData->bWaveShutdown = AL_TRUE;
    PostThreadMessage(pData->ulWaveThreadID, WM_QUIT, 0, 0);

    WaitForSingleObjectEx(pData->hWaveThreadEvent, 5000, FALSE);

    /* Make sure capture is stopped and all pending buffers are flushed. */
    waveInReset(pData->hWaveHandle.In);

    CloseHandle(pData->hWaveThread);
    pData->hWaveThread = 0;

    // Release the wave buffers
    for(i = 0;i < 4;i++)
    {
        waveInUnprepareHeader(pData->hWaveHandle.In, &pData->WaveBuffer[i], sizeof(WAVEHDR));
        if(i == 0) buffer = pData->WaveBuffer[i].lpData;
        pData->WaveBuffer[i].lpData = NULL;
    }
    free(buffer);

    DestroyRingBuffer(pData->pRing);
    pData->pRing = NULL;

    // Close the Wave device
    CloseHandle(pData->hWaveThreadEvent);
    pData->hWaveThreadEvent = 0;

    waveInClose(pData->hWaveHandle.In);
    pData->hWaveHandle.In = 0;

    free(pData);
    pDevice->ExtraData = NULL;
}

static void WinMMStartCapture(ALCdevice *pDevice)
{
    WinMMData *pData = (WinMMData*)pDevice->ExtraData;
    waveInStart(pData->hWaveHandle.In);
}

static void WinMMStopCapture(ALCdevice *pDevice)
{
    WinMMData *pData = (WinMMData*)pDevice->ExtraData;
    waveInStop(pData->hWaveHandle.In);
}

static ALCenum WinMMCaptureSamples(ALCdevice *pDevice, ALCvoid *pBuffer, ALCuint lSamples)
{
    WinMMData *pData = (WinMMData*)pDevice->ExtraData;
    ReadRingBuffer(pData->pRing, pBuffer, lSamples);
    return ALC_NO_ERROR;
}

static ALCuint WinMMAvailableSamples(ALCdevice *pDevice)
{
    WinMMData *pData = (WinMMData*)pDevice->ExtraData;
    return RingBufferSize(pData->pRing);
}


static const BackendFuncs WinMMFuncs = {
    WinMMOpenPlayback,
    WinMMClosePlayback,
    WinMMResetPlayback,
    WinMMStartPlayback,
    WinMMStopPlayback,
    WinMMOpenCapture,
    WinMMCloseCapture,
    WinMMStartCapture,
    WinMMStopCapture,
    WinMMCaptureSamples,
    WinMMAvailableSamples
};

ALCboolean alcWinMMInit(BackendFuncs *FuncList)
{
    *FuncList = WinMMFuncs;
    return ALC_TRUE;
}

void alcWinMMDeinit()
{
    ALuint lLoop;

    for(lLoop = 0;lLoop < NumPlaybackDevices;lLoop++)
        free(PlaybackDeviceList[lLoop]);
    free(PlaybackDeviceList);
    PlaybackDeviceList = NULL;

    NumPlaybackDevices = 0;


    for(lLoop = 0; lLoop < NumCaptureDevices; lLoop++)
        free(CaptureDeviceList[lLoop]);
    free(CaptureDeviceList);
    CaptureDeviceList = NULL;

    NumCaptureDevices = 0;
}

void alcWinMMProbe(enum DevProbe type)
{
    ALuint i;

    switch(type)
    {
        case ALL_DEVICE_PROBE:
            ProbePlaybackDevices();
            for(i = 0;i < NumPlaybackDevices;i++)
            {
                if(PlaybackDeviceList[i])
                    AppendAllDeviceList(PlaybackDeviceList[i]);
            }
            break;

        case CAPTURE_DEVICE_PROBE:
            ProbeCaptureDevices();
            for(i = 0;i < NumCaptureDevices;i++)
            {
                if(CaptureDeviceList[i])
                    AppendCaptureDeviceList(CaptureDeviceList[i]);
            }
            break;
    }
}