//
// Copyright (c) Microsoft Corporation.  All rights reserved.
//
//
// Use of this source code is subject to the terms of the Microsoft shared
// source or premium shared source license agreement under which you licensed
// this source code. If you did not accept the terms of the license agreement,
// you are not authorized to use this source code. For the terms of the license,
// please see the license agreement between you and Microsoft or, if applicable,
// see the SOURCE.RTF on your install media or the root of your tools installation.
// THE SOURCE CODE IS PROVIDED "AS IS", WITH NO WARRANTIES.
//
//==========================================================================;
//
//  pcm.c
//
//  Description:
//      This is the 'PCM' converter.  it is just like any other 'real'
//      audio converter.  It has a standard ConverterProc.
//
//      the ACM calls
//
//      acmDriverAdd(pcmDriverProc,
//                   ACM_DRIVERADDF_FUNCTION | ACM_DRIVERADDF_GLOBAL);
//
//      when it is loaded.
//
//==========================================================================;

#include <windows.h>
#include <windowsx.h>
#include <mmddk.h>
#include <mmreg.h>
#include <msacm.h>
#include <memory.h>
#include "muldiv32.h"
#include "msacmdrv.h"
#include "pcm.h"
#include <wavedev.h>

//
//  we use this dwId to determine when we where opened as an audio codec
//  by the ACM or from the control panel, etc. see acmdDriverOpen for more
//  information.
//
#define BOGUS_DRIVER_ID     1L


#define SIZEOF_ARRAY(ar)        (sizeof(ar)/sizeof((ar)[0]))

//
//  array of WAVE format tags supported.
//
//  NOTE! if you change anything in this structure (order, addition, removal)
//  you must also fix acmdFormatTagDetails!
//
static const UINT gauFormatTagIndexToTag[] =
{
    WAVE_FORMAT_PCM
};

#define CODEC_MAX_FORMAT_TAGS   SIZEOF_ARRAY(gauFormatTagIndexToTag)


//
//  array of _standard_ sample rates supported
//
//
static const UINT gauFormatIndexToSampleRate[] =
{
    8000,
    11025,
    22050,
    44100
};

#define CODEC_MAX_SAMPLE_RATES  SIZEOF_ARRAY(gauFormatIndexToSampleRate)

//
//
//
//
#define CODEC_MAX_CHANNELS      (MSPCM_MAX_CHANNELS)

//
//  array of bits per sample supported
//
//
static const UINT gauFormatIndexToBitsPerSample[] =
{
    8,
    16
};

#define CODEC_MAX_BITSPERSAMPLE_PCM SIZEOF_ARRAY(gauFormatIndexToBitsPerSample)




//
//  number of formats we enumerate per channels is number of sample rates
//  times number of channels times number of
//  (bits per sample) types.
//
#define CODEC_MAX_STANDARD_FORMATS_PCM  (CODEC_MAX_SAMPLE_RATES *   \
                                         CODEC_MAX_CHANNELS *       \
                                         CODEC_MAX_BITSPERSAMPLE_PCM)



//
//  array of WAVE filter tags supported.
//
//static DWORD gauFilterIndexToTag[] =
//{
//};
#define CODEC_MAX_FILTER_TAGS   0


//
//
//
//
typedef struct tCODECINST
{
    //
    //  although not required, it is suggested that the first two members
    //  of this structure remain as fccType and DriverProc _in this order_.
    //  the reason for this is that the codec will be easier to combine
    //  with other types of codecs (defined by AVI) in the future.
    //
    FOURCC          fccType;        // type of codec: 'audc'
//    DRIVERPROC      fnDriverProc;   // driver proc for the instance

    //
    //  the remaining members of this structure are entirely open to what
    //  your codec requires.
    //
    HDRVR           hdrvr;          // driver handle we were opened with
    DWORD           vdwACM;         // current version of ACM opening you
    DWORD           dwFlags;        // flags from open description

} CODECINST, *PCODECINST, FAR *LPCODECINST;



//
//
//
    EXTERN_C DWORD pcmConvert_C
    (
        LPPCMWAVEFORMAT pwfSrc,
        LPBYTE          pbSrc,
        LPPCMWAVEFORMAT pwfDst,
        LPBYTE          pbDst,
        DWORD           dwSrcSamples,
        BOOL            fPartialSampleAtTheEnd,
        LPBYTE          pbDstEnd
    );

#define pcmConvert          pcmConvert_C



typedef DWORD (*CONVERTPROC)
(
    LPPCMWAVEFORMAT,
    LPBYTE,
    LPPCMWAVEFORMAT,
    LPBYTE,
    DWORD,
    BOOL,
    LPBYTE
);


//==========================================================================;
//
//
//
//
//==========================================================================;

//--------------------------------------------------------------------------;
//
//  BOOL pcmIsValidFormat
//
//  Description:
//      This function verifies that a wave format header is a valid PCM
//      header that _this_ ACM driver can deal with.
//
//  Arguments:
//      LPWAVEFORMATEX pwfx: Pointer to format header to verify.
//
//  Return (BOOL):
//      The return value is non-zero if the format header looks valid. A
//      zero return means the header is not valid.
//
//--------------------------------------------------------------------------;

BOOL pcmIsValidFormat(
    LPWAVEFORMATEX  pwfx
    )
{
    UINT    uBlockAlign;

    FUNC("pcmIsValidFormat");

    if (NULL == pwfx)
        return (FALSE);

    if (WAVE_FORMAT_PCM != pwfx->wFormatTag)
        return (FALSE);

    //
    //  verify nChannels member is within the allowed range
    //
    if ((pwfx->nChannels < 1) || (pwfx->nChannels > MSPCM_MAX_CHANNELS))
        return (FALSE);

    //
    //  only allow the bits per sample that we can encode and decode with
    //
    if ((8 != pwfx->wBitsPerSample) && (16 != pwfx->wBitsPerSample))
        return (FALSE);

    //
    //  now verify that the block alignment is correct..
    //
    uBlockAlign = PCM_BLOCKALIGNMENT((LPPCMWAVEFORMAT)pwfx);
    if (uBlockAlign != (UINT)pwfx->nBlockAlign)
        return (FALSE);

    if ((0L == pwfx->nSamplesPerSec) || (0x3FFFFFFF < pwfx->nSamplesPerSec))
    {
        return (FALSE);
    }


    //
    //  finally, verify that avg bytes per second is correct
    //
    if ((pwfx->nSamplesPerSec * uBlockAlign) != pwfx->nAvgBytesPerSec)
        return (FALSE);

    return (TRUE);
} // pcmIsValidFormat()


//==========================================================================;
//
//
//
//
//
//==========================================================================;

//--------------------------------------------------------------------------;
//
//  LRESULT acmdDriverOpen
//
//  Description:
//      This function is used to handle the DRV_OPEN message for the ACM
//      driver. The driver is 'opened' for many reasons with the most common
//      being in preperation for conversion work. It is very important that
//      the driver be able to correctly handle multiple open driver
//      instances.
//
//      Read the comments for this function carefully!
//
//      Note that multiple _streams_ can and will be opened on a single
//      open _driver instance_. Do not store create instance data that must
//      be unique for each stream in this function. See the acmdStreamOpen
//      function for information on conversion streams.
//
//  Arguments:
//      HDRVR hdrvr: Driver handle that will be returned to caller of the
//      OpenDriver function. Normally, this will be the ACM--but this is
//      not guaranteed. For example, if an ACM driver is implemented within
//      a waveform driver, then the driver will be opened by both MMSYSTEM
//      and the ACM.
//
//      LPACMDRVOPENDESC paod: Open description defining how the ACM driver
//      is being opened. This argument may be NULL--see the comments below
//      for more information.
//
//  Return (LRESULT):
//      The return value is non-zero if the open is successful. A zero
//      return signifies that the driver cannot be opened.
//
//--------------------------------------------------------------------------;

LRESULT acmdDriverOpen(
    HDRVR               hdrvr,
    LPACMDRVOPENDESC    paod
)
{
    PCODECINST      pci;

    FUNC("acmdDriverOpen");
    //
    //  if paod is NULL, then the driver is being opened for some purpose
    //  other than converting (that is, there will be no stream open
    //  requests for this instance of being opened). the most common case
    //  of this is the Control Panel's Drivers option checking for config
    //  support (DRV_[QUERY]CONFIGURE).
    //
    //  we want to succeed this open, but be able to know that this
    //  open instance is bogus for creating streams. for this purpose we
    //  return a special non-zero value (it will be passed back as dwId
    //  to the DriverProc on following messages).
    //
    if (NULL == paod)
        return (BOGUS_DRIVER_ID);

    //
    //  the open description that is passed to this driver can be from
    //  multiple 'managers.' for example, AVI looks for installable drivers
    //  that are tagged with 'vidc' and 'vcap'. we need to verify that we
    //  are being opened as an Audio Compression Manager driver.
    //
    //  refuse to open if we are not being opened as an ACM driver. note
    //  that we do NOT modify the value of paod->dwError in this case.
    //
    if (ACMDRIVERDETAILS_FCCTYPE_AUDIOCODEC != paod->fccType)
        return (0L);


    //
    //  we are being opened as an ACM driver--we can allocate some
    //  instance data to be returned in dwId argument of the DriverProc;
    //  or simply return non-zero to succeed the open.
    //
    //  this driver allocates a small instance structure.
    //
    pci = (PCODECINST)LocalAlloc(LPTR, sizeof(*pci));

    //
    //  if we cannot allocate our instance structure, then we must fail
    //  the open request. however, we also want to give the reason why
    //  we are failing the open--so we fill in the dwError member of
    //  the ACMDRVOPENDESC structure...
    //
    if (NULL == pci)
    {
        paod->dwError = MMSYSERR_NOMEM;
        return (0L);
    }


    //
    //  fill in our instance structure... note that this instance data
    //  can be anything that the ACM driver wishes to maintain the
    //  open driver instance. this data should not contain any information
    //  that must be maintained per open stream since multiple streams
    //  can be opened on a single driver instance.
    //
    //  also note that we do _not_ check the version of the ACM opening
    //  us (paod->dwVersion) to see if it is at least new enough to work
    //  with this driver (for example, if this driver required Version 3.0
    //  of the ACM and a Version 2.0 installation tried to open us). the
    //  reason we do not fail is to allow the ACM to get the driver details
    //  which contains the version of the ACM that is _required_ by this
    //  driver. the ACM will examine that value (in padd->vdwACM) and
    //  do the right thing for this driver... like not load it and inform
    //  the user of the problem.
    //
    pci->fccType      = paod->fccType;
//    pci->fnDriverProc = (DRIVERPROC)NULL;

    pci->hdrvr        = hdrvr;              // driver handle to our driver
    pci->vdwACM       = paod->dwVersion;    // version of ACM opening us
    pci->dwFlags      = paod->dwFlags;      // flags opened with


    //
    //  finally, succeed the open... return our instance data pointer.
    //  this pointer will be passed as the dwId argument of our driver
    //  procedure on all following messages for this open instance.
    //
    paod->dwError = MMSYSERR_NOERROR;


    //
    //  non-zero return is success for DRV_OPEN
    //
    return ((LRESULT)(UINT)pci);
} // acmdDriverOpen()


//--------------------------------------------------------------------------;
//
//  LRESULT acmdDriverClose
//
//  Description:
//      This function handles the DRV_CLOSE message for the ACM driver. The
//      driver receives a DRV_CLOSE message for each succeeded DRV_OPEN
//      message (see acmdDriverOpen). The driver will only receive a close
//      message for _successful_ opens.
//
//  Arguments:
//      PCODECINST pci: Pointer to private ACM driver instance structure.
//      This structure is [optionally] allocated during the DRV_OPEN message
//      which is handled by the acmdDriverOpen function.
//
//  Return (LRESULT):
//      The return value is non-zero if the open instance can be closed.
//      A zero return signifies that the ACM driver instance could not be
//      closed.
//
//      NOTE! It is _strongly_ recommended that the driver never fail to
//      close. Note that the ACM will never allow a driver instance to
//      be closed if there are open streams. An ACM driver does not need
//      to check for this case.
//
//--------------------------------------------------------------------------;

LRESULT acmdDriverClose
(
    PCODECINST              pci
)
{
    //
    //  check to see if we allocated instance data. if we did not, then
    //  immediately succeed.
    //
    if (NULL != pci)
    {
        //
        //  close down the driver instance. this driver simply needs
        //  to free the instance data structure... note that if this
        //  'free' fails, then this ACM driver probably trashed its
        //  heap; assume we didn't do that.
        //
        LocalFree((HLOCAL)pci);
    }


    //
    //  non-zero return is success for DRV_CLOSE
    //
    return (1L);
} // acmdDriverClose()


//--------------------------------------------------------------------------;
//
//  LRESULT acmdDriverConfigure
//
//  Description:
//      This function is called to handle the DRV_[QUERY]CONFIGURE messages.
//      These messages are for 'configuration' support of the driver.
//      Normally this will be for 'hardware'--that is, a dialog should be
//      displayed to configure ports, IRQ's, memory mappings, etc if it
//      needs to. However, a software only ACM driver may also require
//      configuration for 'what is real time' or other quality vs time
//      issues.
//
//      The most common way that these messages are generated under Win 3.1
//      and NT Product 1 is from the Control Panel's Drivers option. Other
//      sources may generate these messages in future versions of Windows.
//
//  Arguments:
//      PCODECINST pci: Pointer to private ACM driver instance structure.
//      This structure is [optionally] allocated during the DRV_OPEN message
//      which is handled by the acmdDriverOpen function.
//
//      HWND hwnd: Handle to parent window to use when displaying the
//      configuration dialog box. An ACM driver is _required_ to display a
//      modal dialog box using this hwnd argument as the parent. This
//      argument may be (HWND)-1 which tells the driver that it is only
//      being queried for configuration support.
//
//      LPDRVCONFIGINFO pdci: Pointer to optional DRVCONFIGINFO structure.
//      If this argument is NULL, then the ACM driver should invent its own
//      storage location.
//
//  Return (LRESULT):
//      If the driver is being 'queried' for configuration support (that is,
//      hwnd == (HWND)-1), then non-zero should be returned specifying
//      the driver does support a configuration dialog--or zero should be
//      returned specifying that no configuration dialog is supported.
//
//      If the driver is being called to display the configuration dialog
//      (that is, hwnd != (HWND)-1), then one of the following values
//      should be returned:
//
//      DRVCNF_CANCEL (0x0000): specifies that the dialog was displayed
//      and canceled by the user. this value should also be returned if
//      no configuration information was modified.
//
//      DRVCNF_OK (0x0001): specifies that the dialog was displayed and
//      some configuration information was changed. however, the driver
//      does not require Windows to be restarted--the changes have already
//      been applied.
//
//      DRVCNF_RESTART (0x0002): specifies that the dialog was displayed
//      and some configuration information was changed that requires
//      Windows to be restarted before the changes take affect. the driver
//      should remain configured with current values until the driver
//      has been 'rebooted'.
//
//--------------------------------------------------------------------------;

LRESULT acmdDriverConfigure
(
    PCODECINST              pci,
    HWND                    hwnd
//    LPDRVCONFIGINFO         pdci
)
{
    //
    //  first check to see if we are only being queried for configuration
    //  support. if hwnd == (HWND)-1 then we are being queried and should
    //  return zero for 'not supported' and non-zero for 'supported'.
    //
    if ((HWND)-1 == hwnd)
    {
        //
        //  this ACM driver does NOT support a configuration dialog box, so
        //  return zero...
        //
        return (0L);
    }


    //
    //  we are being asked to bring up our configuration dialog. if this
    //  driver supports a configuration dialog box, then after the dialog
    //  is dismissed we must return one of the following values:
    //
    //  DRVCNF_CANCEL (0x0000): specifies that the dialog was displayed
    //  and canceled by the user. this value should also be returned if
    //  no configuration information was modified.
    //
    //  DRVCNF_OK (0x0001): specifies that the dialog was displayed and
    //  some configuration information was changed. however, the driver
    //  does not require Windows to be restarted--the changes have already
    //  been applied.
    //
    //  DRVCNF_RESTART (0x0002): specifies that the dialog was displayed
    //  and some configuration information was changed that requires
    //  Windows to be restarted before the changes take affect. the driver
    //  should remain configured with current values until the driver
    //  has been 'rebooted'.
    //
    //
    //  return DRVCNF_CANCEL--this ACM driver does not support configuration
    //
//    return (DRVCNF_CANCEL);
    return (0);
} // acmdDriverConfigure()


//--------------------------------------------------------------------------;
//
//  LRESULT acmdDriverDetails
//
//  Description:
//      This function handles the ACMDM_DRIVER_DETAILS message. The ACM
//      driver is responsible for filling in the ACMDRIVERDETAILS structure
//      with various information.
//
//      NOTE! It is *VERY* important that you fill in your ACMDRIVERDETAILS
//      structure correctly. The ACM and applications must be able to
//      rely on this information.
//
//      WARNING! The _reserved_ bits of any fields of the ACMDRIVERDETAILS
//      structure are _exactly that_: RESERVED. Do NOT use any extra
//      flag bits, etc. for custom information. The proper way to add
//      custom capabilities to your ACM driver is this:
//
//      o   define a new message in the ACMDM_USER range.
//
//      o   an application that wishes to use one of these extra features
//          should then:
//
//          o   open the driver with acmDriverOpen.
//
//          o   check for the proper wMid and wPid using acmDriverDetails.
//
//          o   send the 'user defined' message with acmDriverMessage
//              to retrieve additional information, etc.
//
//          o   close the driver with acmDriverClose.
//
//  Arguments:
//      PCODECINST pci: Pointer to private ACM driver instance structure.
//      This structure is [optionally] allocated during the DRV_OPEN message
//      which is handled by the acmdDriverOpen function.
//
//      LPACMDRIVERDETAILS padd: Pointer to ACMDRIVERDETAILS structure to
//      fill in for the caller. This structure may be larger or smaller than
//      the current definition of ACMDRIVERDETAILS--cbStruct specifies the
//      valid size.
//
//  Return (LRESULT):
//      The return value is zero (MMSYSERR_NOERROR) for success. Non-zero
//      signifies that the driver details could not be retrieved.
//
//      NOTE THAT THIS FUNCTION SHOULD NEVER FAIL! There are two possible
//      error conditions:
//
//      o   if padd is NULL or an invalid pointer.
//
//      o   if cbStruct is less than four; in this case, there is not enough
//          room to return the number of bytes filled in.
//
//      Because these two error conditions are easily defined, the ACM
//      will catch these errors. The driver does NOT need to check for these
//      conditions.
//
//--------------------------------------------------------------------------;

LRESULT acmdDriverDetails
(
    PCODECINST              pci,
    LPACMDRIVERDETAILS      padd
)
{
    ACMDRIVERDETAILS    add;
    DWORD               cbStruct;

    FUNC_ACM("+acmdDriverDetails");
    //
    //  it is easiest to fill in a temporary structure with valid info
    //  and then copy the requested number of bytes to the destination
    //  buffer.
    //
    cbStruct            = min(padd->cbStruct, sizeof(ACMDRIVERDETAILS));
    add.cbStruct        = cbStruct;


    //
    //  for the current implementation of an ACM driver, the fccType and
    //  fccComp members *MUST* always be ACMDRIVERDETAILS_FCCTYPE_AUDIOCODEC
    //  ('audc') and ACMDRIVERDETAILS_FCCCOMP_UNDEFINED (0) respectively.
    //
    add.fccType         = ACMDRIVERDETAILS_FCCTYPE_AUDIOCODEC;
    add.fccComp         = ACMDRIVERDETAILS_FCCCOMP_UNDEFINED;


    //
    //  the manufacturer id (wMid) and product id (wPid) must be filled
    //  in with your company's _registered_ identifier's.
    //  note that during the development phase or your ACM driver, you may
    //  use the reserved value of '0' for both wMid and wPid. however it
    //  is not acceptable to ship a driver with these values.
    //
    add.wMid            = MM_MICROSOFT;
    add.wPid            = MM_MSFT_ACM_PCM;


    //
    //  the vdwACM and vdwDriver members contain version information for
    //  the driver.
    //
    //  vdwACM: must contain the version of the *ACM* that the driver was
    //  _designed_ for. this is the _minimum_ version number of the ACM
    //  that the driver will work with. this value must be >= V2.00.000.
    //
    //  vdwDriver: the version of this ACM driver.
    //
    //  ACM driver versions are 32 bit numbers broken into three parts as
    //  follows (note these parts are displayed as decimal values):
    //
    //      bits 24 - 31:   8 bit _major_ version number
    //      bits 16 - 23:   8 bit _minor_ version number
    //      bits  0 - 15:   16 bit build number
    //
    add.vdwACM          = 0x04001997; // which version?
    add.vdwDriver       = VERSION_CODEC;


    //
    //  the following flags are used to specify the type of conversion(s)
    //  that the ACM driver supports. note that a driver may support one or
    //  more of these flags in any combination.
    //
    //  ACMDRIVERDETAILS_SUPPORTF_CODEC: this flag is set if the driver
    //  supports conversions from one format tag to another format tag. for
    //  example, if a converter compresses or decompresses WAVE_FORMAT_PCM
    //  and WAVE_FORMAT_IMA_ADPCM, then this bit should be set. this is
    //  true even if the data is not actually changed in size--for example
    //  a conversion from u-Law to A-Law will still set this bit because
    //  the format tags differ.
    //
    //  ACMDRIVERDETAILS_SUPPORTF_CONVERTER: this flags is set if the
    //  driver supports conversions on the same format tag. as an example,
    //  the PCM converter that is built into the ACM sets this bit (and only
    //  this bit) because it converts only between PCM formats (bits, sample
    //  rate).
    //
    //  ACMDRIVERDETAILS_SUPPORTF_FILTER: this flag is set if the driver
    //  supports transformations on a single format tag but does change
    //  the base characteristics of the format (bit depth, sample rate, etc
    //  will remain the same). for example, a driver that changed the
    //  'volume' of PCM data or applied a low pass filter would set this bit.
    //
    add.fdwSupport      = ACMDRIVERDETAILS_SUPPORTF_CONVERTER;


    //
    //  the number of individual format tags this ACM driver supports. for
    //  example, if a driver uses the WAVE_FORMAT_IMA_ADPCM and
    //  WAVE_FORMAT_PCM format tags, then this value would be two. if the
    //  driver only supports filtering on WAVE_FORMAT_PCM, then this value
    //  would be one. if this driver supported WAVE_FORMAT_ALAW,
    //  WAVE_FORMAT_MULAW and WAVE_FORMAT_PCM, then this value would be
    //  three. etc, etc.
    //
    add.cFormatTags     = CODEC_MAX_FORMAT_TAGS;

    //
    //  the number of individual filter tags this ACM driver supports. if
    //  a driver supports no filters (ACMDRIVERDETAILS_SUPPORTF_FILTER is
    //  NOT set in the fdwSupport member), then this value must be zero.
    //
    add.cFilterTags     = CODEC_MAX_FILTER_TAGS;


    //
    //  the remaining members in the ACMDRIVERDETAILS structure are sometimes
    //  not needed. because of this we make a quick check to see if we
    //  should go through the effort of filling in these members.
    //
//    if (FIELD_OFFSET(ACMDRIVERDETAILS, hicon) < cbStruct)
//    {
//        PACMGARB pag;
//
//        //
//        //  fill in the hicon member will a handle to a custom icon for
//        //  the ACM driver. this allows the driver to be represented by
//        //  an application graphically (usually this will be a company
//        //  logo or something). if a driver does not wish to have a custom
//        //  icon displayed, then simply set this member to NULL and a
//        //  generic icon will be displayed instead.
//        //
//        add.hicon = NULL;
//
//        pag = pagFind();
//        if (NULL == pag)
//        {
//            //DPF(1, "acmdDriverDetails: NULL pag!!!");
//        }
//        else
//        {
//            //
//            //  the short name and long name are used to represent the driver
//            //  in a unique description. the short name is intended for small
//            //  display areas (for example, in a menu or combo box). the long
//            //  name is intended for more descriptive displays (for example,
//            //  in an 'about box').
//            //
//            //  NOTE! an ACM driver should never place formatting characters
//            //  of any sort in these strings (for example CR/LF's, etc). it
//            //  is up to the application to format the text.
//            //
//            LoadStringW(pag->hinst, IDS_CODEC_SHORTNAME, add.szShortName, SIZEOFW(add.szShortName));
//            LoadStringW(pag->hinst, IDS_CODEC_LONGNAME,  add.szLongName,  SIZEOFW(add.szLongName));
//
//            //
//            //  the last three members are intended for 'about box' information.
//            //  these members are optional and may be zero length strings if
//            //  the driver wishes.
//            //
//            //  NOTE! an ACM driver should never place formatting characters
//            //  of any sort in these strings (for example CR/LF's, etc). it
//            //  is up to the application to format the text.
//            //
//            if (FIELD_OFFSET(ACMDRIVERDETAILS, szCopyright) < cbStruct)
//            {
//                LoadStringW(pag->hinst, IDS_CODEC_COPYRIGHT, add.szCopyright, SIZEOFW(add.szCopyright));
//                LoadStringW(pag->hinst, IDS_CODEC_LICENSING, add.szLicensing, SIZEOFW(add.szLicensing));
//                LoadStringW(pag->hinst, IDS_CODEC_FEATURES,  add.szFeatures,  SIZEOFW(add.szFeatures));
//            }
//        }
//    }

    wsprintf(add.szShortName, TEXT("MS-PCM"));
    wsprintf(add.szLongName, TEXT("Microsoft PCM Converter"));
    wsprintf(add.szCopyright, TEXT("Copyright (c) 1992-1995 Microsoft Corporation"));
    wsprintf(add.szLicensing, TEXT(""));
    wsprintf(add.szFeatures, TEXT("Converts frequency and bits per sample of PCM audio data."));

    //
    //  now copy the correct number of bytes to the caller's buffer
    //
    _fmemcpy(padd, &add, (UINT)add.cbStruct);


    //
    //  success!
    //
    FUNC_ACM("+acmdDriverDetails");
    return (MMSYSERR_NOERROR);
} // acmdDriverDetails()


//--------------------------------------------------------------------------;
//
//  LRESULT acmdDriverAbout
//
//  Description:
//      This function is called to handle the ACMDM_DRIVER_ABOUT message.
//      An ACM driver has the option of displaying its own 'about box' or
//      letting the ACM (or calling application) display one for it. This
//      message is normally sent by the Control Panel's Sound Mapper
//      option.
//
//      It is recommended that an ACM driver allow a default about box
//      be displayed for it--there should be no reason to bloat the size
//      of a driver to simply display copyright, etc information when that
//      information is contained in the ACMDRIVERDETAILS structure.
//
//  Arguments:
//      PCODECINST pci: Pointer to private ACM driver instance structure.
//      This structure is [optionally] allocated during the DRV_OPEN message
//      which is handled by the acmdDriverOpen function.
//
//      HWND hwnd: Handle to parent window to use when displaying the
//      configuration dialog box. An ACM driver is _required_ to display a
//      modal dialog box using this hwnd argument as the parent. This
//      argument may be (HWND)-1 which tells the driver that it is only
//      being queried for about box support.
//
//  Return (LRESULT):
//      The return value is MMSYSERR_NOTSUPPORTED if the ACM driver does
//      not support a custom dialog box. In this case, the ACM or calling
//      application will display a generic about box using the information
//      contained in the ACMDRIVERDETAILS structure returned by the
//      ACMDM_DRIVER_DETAILS message.
//
//      If the driver chooses to display its own dialog box, then after
//      the dialog is dismissed by the user, MMSYSERR_NOERROR should be
//      returned.
//
//      If the hwnd argument is equal to (HWND)-1, then no dialog should
//      be displayed (the driver is only being queried for support). The
//      driver must still return MMSYSERR_NOERROR (supported) or
//      MMSYSERR_NOTSUPPORTED (no custom about box supported).
//
//--------------------------------------------------------------------------;

LRESULT acmdDriverAbout
(
    PCODECINST              pci,
    HWND                    hwnd
)
{
    //
    //  first check to see if we are only being queried for custom about
    //  box support. if hwnd == (HWND)-1 then we are being queried and
    //  should return MMSYSERR_NOTSUPPORTED for 'not supported' and
    //  MMSYSERR_NOERROR for 'supported'.
    //
    if ((HWND)-1 == hwnd)
    {
        //
        //  this ACM driver does NOT support a custom about box, so
        //  return MMSYSERR_NOTSUPPORTED...
        //
        return (MMSYSERR_NOTSUPPORTED);
    }


    //
    //  this driver does not support a custom dialog, so tell the ACM or
    //  calling application to display one for us. note that this is the
    //  _recommended_ method for consistency and simplicity of ACM drivers.
    //  why write code when you don't have to?
    //
    return (MMSYSERR_NOTSUPPORTED);
} // acmdDriverAbout()


//==========================================================================;
//
//
//
//
//==========================================================================;


//--------------------------------------------------------------------------;
//
//  LRESULT acmdFormatSuggest
//
//  Description:
//      This function handles the ACMDM_FORMAT_SUGGEST message. The purpose
//      of this function is to provide a way for the ACM, a wave mapper or
//      an application to quickly get a destination format that this driver
//      can convert the source format to. The 'suggested' format should
//      be as close to a common format as possible. This message is normally
//      sent in response to an acmFormatSuggest function call.
//
//      Another way to think about this message is: what format would this
//      driver like to convert the source format to?
//
//      The caller may place restrictions on the destination format that
//      should be suggested. The padfs->fdwSuggest member contains the
//      restriction bits passed by the caller--see the description for
//      the return value for more information.
//
//  Arguments:
//      PCODECINST pci: Pointer to private ACM driver instance structure.
//      This structure is [optionally] allocated during the DRV_OPEN message
//      which is handled by the acmdDriverOpen function.
//
//      LPACMDRVFORMATSUGGEST padfs: Pointer to an ACMDRVFORMATSUGGEST
//      structure that describes the source and destination (possibly with
//      restrictions) for a conversion.
//
//  Return (LRESULT):
//      The return value is zero (MMSYSERR_NOERROR) if this function
//      succeeds with no errors. The return value is a non-zero error code
//      if the function fails.
//
//      The driver should return MMSYSERR_NOTSUPPORTED if one or more of
//      the destination restriction bits is not supported. It is strongly
//      recommended that the driver support at least the following suggestion
//      restriction bits:
//
//      ACM_FORMATSUGGESTF_WFORMATTAG: The destination format tag must be
//      the same as the wFormatTag member in the destination format header.
//
//      ACM_FORMATSUGGESTF_NCHANNELS: The destination channel count must be
//      the same as the nChannels member in the destination format header.
//
//      ACM_FORMATSUGGESTF_NSAMPLESPERSEC: The destination samples per
//      second must be the same as the nSamplesPerSec member in the
//      destination format header.
//
//      ACM_FORMATSUGGESTF_WBITSPERSAMPLE: The destination bits per sample
//      must be the same as the wBitsPerSample member in the destination
//      format header.
//
//      If no destintation format can be suggested, then the driver should
//      return ACMERR_NOTPOSSIBLE.
//
//--------------------------------------------------------------------------;

LRESULT acmdFormatSuggest
(
    PCODECINST              pci,
    LPACMDRVFORMATSUGGEST   padfs
)
{
    #define ACMD_FORMAT_SUGGEST_SUPPORT (ACM_FORMATSUGGESTF_WFORMATTAG |    \
                                         ACM_FORMATSUGGESTF_NCHANNELS |     \
                                         ACM_FORMATSUGGESTF_NSAMPLESPERSEC |\
                                         ACM_FORMATSUGGESTF_WBITSPERSAMPLE)

    LPWAVEFORMATEX          pwfxSrc;
    LPWAVEFORMATEX          pwfxDst;
    DWORD                   fdwSuggest;


    //
    //  grab the suggestion restriction bits and verify that we support
    //  the ones that are specified... an ACM driver must return the
    //  MMSYSERR_NOTSUPPORTED if the suggestion restriction bits specified
    //  are not supported.
    //
    fdwSuggest = (ACM_FORMATSUGGESTF_TYPEMASK & padfs->fdwSuggest);

    if (~ACMD_FORMAT_SUGGEST_SUPPORT & fdwSuggest)
        return (MMSYSERR_NOTSUPPORTED);


    //
    //  get the source and destination formats in more convenient variables
    //
    pwfxSrc = padfs->pwfxSrc;
    pwfxDst = padfs->pwfxDst;


    //
    //
    //
    //
    switch (pwfxSrc->wFormatTag)
    {
        case WAVE_FORMAT_PCM:
            //
            //  strictly verify that the source format is acceptable for
            //  this driver
            //
            if (!pcmIsValidFormat(pwfxSrc))
                break;


            //
            //  if the destination format tag is restricted, verify that
            //  it is within our capabilities...
            //
            //  this driver is only able to convert PCM
            //
            if (ACM_FORMATSUGGESTF_WFORMATTAG & fdwSuggest)
            {
                if (WAVE_FORMAT_PCM != pwfxDst->wFormatTag)
                    return (ACMERR_NOTPOSSIBLE);
            }
            else
            {
                pwfxDst->wFormatTag = WAVE_FORMAT_PCM;
            }


            //
            //  if the destination channel count is restricted, verify that
            //  it is within our capabilities...
            //
            //  this driver is only able to deal with 1 and 2 channels.
            //
            if (ACM_FORMATSUGGESTF_NCHANNELS & fdwSuggest)
            {
                if ((pwfxDst->nChannels < 1) ||
                    (pwfxDst->nChannels > MSPCM_MAX_CHANNELS))
                    return (ACMERR_NOTPOSSIBLE);
            }
            else
            {
                pwfxDst->nChannels = pwfxSrc->nChannels;
            }


            //
            //  if the destination samples per second is restricted, verify
            //  that it is within our capabilities...
            //
            //  this driver does any sample rate conversions...
            //
            if (0 == (ACM_FORMATSUGGESTF_NSAMPLESPERSEC & fdwSuggest))
            {
                pwfxDst->nSamplesPerSec = pwfxSrc->nSamplesPerSec;
            }


            //
            //  if the destination bits per sample is restricted, verify
            //  that it is within our capabilities...
            //
            //  this driver is only able to convert to 16 or 8 bit
            //
            if (ACM_FORMATSUGGESTF_WBITSPERSAMPLE & fdwSuggest)
            {
                if ((16 != pwfxDst->wBitsPerSample) &&
                    (8  != pwfxDst->wBitsPerSample))
                    return (ACMERR_NOTPOSSIBLE);
            }
            else
            {
                pwfxDst->wBitsPerSample = pwfxSrc->wBitsPerSample;
            }


            //
            //  at this point, we have filled in all fields except the
            //  following for our 'suggested' destination format:
            //
            //      nAvgBytesPerSec
            //      nBlockAlign
            //      cbSize              !!! not used for PCM !!!
            //
            pwfxDst->nBlockAlign     = PCM_BLOCKALIGNMENT((LPPCMWAVEFORMAT)pwfxDst);
            pwfxDst->nAvgBytesPerSec = pwfxDst->nSamplesPerSec *
                                       pwfxDst->nBlockAlign;

            // pwfxDst->cbSize       = not used;

            return (MMSYSERR_NOERROR);
    }


    //
    //  can't suggest anything because either the source format is foreign
    //  or the destination format has restrictions that this ACM driver
    //  cannot deal with.
    //
    return (ACMERR_NOTPOSSIBLE);
} // acmdFormatSuggest()


//==========================================================================;
//
//
//
//
//==========================================================================;

//--------------------------------------------------------------------------;
//
//  LRESULT acmdFormatTagDetails
//
//  Description:
//      This function handles the ACMDM_FORMATTAG_DETAILS message. This
//      message is normally sent in response to an acmFormatTagDetails or
//      acmFormatTagEnum function call. The purpose of this function is
//      to get details about a specific format tag supported by this ACM
//      driver.
//
//  Arguments:
//      PCODECINST pci: Pointer to private ACM driver instance structure.
//      This structure is [optionally] allocated during the DRV_OPEN message
//      which is handled by the acmdDriverOpen function.
//
//      LPACMFORMATTAGDETAILS padft: Pointer to an ACMFORMATTAGDETAILS
//      structure that describes what format tag to retrieve details for.
//
//      DWORD fdwDetails: Flags defining what format tag to retrieve the
//      details for.
//
//  Return (LRESULT):
//      The return value is zero (MMSYSERR_NOERROR) if this function
//      succeeds with no errors. The return value is a non-zero error code
//      if the function fails.
//
//      The driver should return MMSYSERR_NOTSUPPORTED if the query type
//      specified in fdwDetails is not supported. An ACM driver must
//      support at least the following query types:
//
//      ACM_FORMATTAGDETAILSF_INDEX: Indicates that a format tag index
//      was given in the dwFormatTagIndex member of the ACMFORMATTAGDETAILS
//      structure. The format tag and details must be returned in the
//      structure specified by padft. The index ranges from zero to one less
//      than the cFormatTags member returned in the ACMDRIVERDETAILS
//      structure for this driver.
//
//      ACM_FORMATTAGDETAILSF_FORMATTAG: Indicates that a format tag
//      was given in the dwFormatTag member of the ACMFORMATTAGDETAILS
//      structure. The format tag details must be returned in the structure
//      specified by padft.
//
//      ACM_FORMATTAGDETAILSF_LARGESTSIZE: Indicates that the details
//      on the format tag with the largest format size in bytes must be
//      returned. The dwFormatTag member will either be WAVE_FORMAT_UNKNOWN
//      or the format tag to find the largest size for.
//
//      If the details for the specified format tag cannot be retrieved
//      from this driver, then ACMERR_NOTPOSSIBLE should be returned.
//
//--------------------------------------------------------------------------;

LRESULT acmdFormatTagDetails
(
    PCODECINST              pci,
    LPACMFORMATTAGDETAILS   padft,
    DWORD                   fdwDetails
)
{
    UINT                uFormatTag;

    //
    //
    //
    //
    //
    switch (ACM_FORMATTAGDETAILSF_QUERYMASK & fdwDetails)
    {
        case ACM_FORMATTAGDETAILSF_INDEX:
            //
            //  if the index is too large, then they are asking for a
            //  non-existant format.  return error.
            //
            if (CODEC_MAX_FORMAT_TAGS <= padft->dwFormatTagIndex)
                return (ACMERR_NOTPOSSIBLE);

            uFormatTag = gauFormatTagIndexToTag[(UINT)padft->dwFormatTagIndex];
            break;


        case ACM_FORMATTAGDETAILSF_LARGESTSIZE:
            switch (padft->dwFormatTag)
            {
                case WAVE_FORMAT_UNKNOWN:
                case WAVE_FORMAT_PCM:
                    uFormatTag = WAVE_FORMAT_PCM;
                    break;

                default:
                    return (ACMERR_NOTPOSSIBLE);
            }
            break;


        case ACM_FORMATTAGDETAILSF_FORMATTAG:
            if (WAVE_FORMAT_PCM != padft->dwFormatTag)
                return (ACMERR_NOTPOSSIBLE);

            uFormatTag = WAVE_FORMAT_PCM;
            break;


        //
        //  if this ACM driver does not understand a query type, then
        //  return 'not supported'
        //
        default:
            return (MMSYSERR_NOTSUPPORTED);
    }



    //
    //
    //
    //
    switch (uFormatTag)
    {
        case WAVE_FORMAT_PCM:
            padft->dwFormatTagIndex = 0;
            padft->dwFormatTag      = WAVE_FORMAT_PCM;
            padft->cbFormatSize     = sizeof(PCMWAVEFORMAT);
            padft->fdwSupport       = ACMDRIVERDETAILS_SUPPORTF_CONVERTER;
            padft->cStandardFormats = CODEC_MAX_STANDARD_FORMATS_PCM;

            //
            //  the ACM is responsible for the PCM format tag name
            //
            padft->szFormatTag[0]   =  '\0';
            break;

        default:
            return (ACMERR_NOTPOSSIBLE);
    }


    //
    //  return only the requested info
    //
    //  the ACM will guarantee that the ACMFORMATTAGDETAILS structure
    //  passed is at least large enough to hold the base information of
    //  the details structure
    //
    padft->cbStruct = min(padft->cbStruct, sizeof(*padft));


    //
    //
    //
    return (MMSYSERR_NOERROR);
} // acmdFormatTagDetails()


//--------------------------------------------------------------------------;
//
//  LRESULT acmdFormatDetails
//
//  Description:
//      This function handles the ACMDM_FORMAT_DETAILS message. This
//      message is normally sent in response to an acmFormatDetails or
//      acmFormatEnum function call. The purpose of this function is
//      to get details about a specific format for a specified format tag
//      supported by this ACM driver.
//
//      Note that an ACM driver can return a zero length string for the
//      format name if it wishes to have the ACM create a format string
//      for it. This is strongly recommended to simplify internationalizing
//      the driver--the ACM will automatically take care of that. The
//      following formula is used to format a string by the ACM:
//
//      <nSamplesPerSec> kHz, <bit depth> bit, [Mono | Stereo | nChannels]
//
//      <bit depth> = <nAvgBytesPerSec> * 8 / nSamplesPerSec / nChannels;
//
//  Arguments:
//      PCODECINST pci: Pointer to private ACM driver instance structure.
//      This structure is [optionally] allocated during the DRV_OPEN message
//      which is handled by the acmdDriverOpen function.
//
//      LPACMFORMATDETAILS padf: Pointer to an ACMFORMATDETAILS structure
//      that describes what format (for a specified format tag) to retrieve
//      details for.
//
//      DWORD fdwDetails: Flags defining what format for a specified format
//      tag to retrieve the details for.
//
//  Return (LRESULT):
//      The return value is zero (MMSYSERR_NOERROR) if this function
//      succeeds with no errors. The return value is a non-zero error code
//      if the function fails.
//
//      The driver should return MMSYSERR_NOTSUPPORTED if the query type
//      specified in fdwDetails is not supported. An ACM driver must
//      support at least the following query types:
//
//      ACM_FORMATDETAILSF_INDEX: Indicates that a format index for the
//      format tag was given in the dwFormatIndex member of the
//      ACMFORMATDETAILS structure. The format details must be returned in
//      the structure specified by padf. The index ranges from zero to one
//      less than the cStandardFormats member returned in the
//      ACMFORMATTAGDETAILS structure for a format tag.
//
//      ACM_FORMATDETAILSF_FORMAT: Indicates that a WAVEFORMATEX structure
//      pointed to by pwfx of the ACMFORMATDETAILS structure was given and
//      the remaining details should be returned. The dwFormatTag member
//      of the ACMFORMATDETAILS will be initialized to the same format
//      tag as the pwfx member specifies. This query type may be used to
//      get a string description of an arbitrary format structure.
//
//      If the details for the specified format cannot be retrieved
//      from this driver, then ACMERR_NOTPOSSIBLE should be returned.
//
//--------------------------------------------------------------------------;

LRESULT acmdFormatDetails
(
    PCODECINST              pci,
    LPACMFORMATDETAILS      padf,
    DWORD                   fdwDetails
)
{
    LPWAVEFORMATEX      pwfx;
    UINT                uFormatIndex;
    UINT                u;

    FUNC("acmdFormatDetails");
    //
    //
    //
    //
    //
    switch (ACM_FORMATDETAILSF_QUERYMASK & fdwDetails)
    {
        //
        //  enumerate by index
        //
        //  verify that the format tag is something we know about and
        //  return the details on the 'standard format' supported by
        //  this driver at the specified index...
        //
        case ACM_FORMATDETAILSF_INDEX:
            //
            //  verify that the format tag is something we know about
            //
            if (WAVE_FORMAT_PCM != padf->dwFormatTag)
                return (ACMERR_NOTPOSSIBLE);

            if (CODEC_MAX_STANDARD_FORMATS_PCM <= padf->dwFormatIndex)
                return (ACMERR_NOTPOSSIBLE);

            //
            //  put some stuff in more accessible variables--note that we
            //  bring variable sizes down to a reasonable size for 16 bit
            //  code...
            //
            pwfx = padf->pwfx;
            uFormatIndex = (UINT)padf->dwFormatIndex;

            //
            //  now fill in the format structure
            //
            pwfx->wFormatTag      = WAVE_FORMAT_PCM;

            u = uFormatIndex / (CODEC_MAX_BITSPERSAMPLE_PCM * CODEC_MAX_CHANNELS);
            pwfx->nSamplesPerSec  = gauFormatIndexToSampleRate[u];

            u = uFormatIndex % CODEC_MAX_CHANNELS;
            pwfx->nChannels       = u + 1;

            u = (uFormatIndex / CODEC_MAX_CHANNELS) % CODEC_MAX_CHANNELS;
            pwfx->wBitsPerSample  = gauFormatIndexToBitsPerSample[u];

            pwfx->nBlockAlign     = PCM_BLOCKALIGNMENT((LPPCMWAVEFORMAT)pwfx);
            pwfx->nAvgBytesPerSec = pwfx->nSamplesPerSec * pwfx->nBlockAlign;

            //
            //  note that the cbSize field is NOT valid for PCM formats
            //
            //  pwfx->cbSize      = 0;
            break;


        //
        //  return details on specified format
        //
        //  the caller normally uses this to verify that the format is
        //  supported and to retrieve a string description...
        //
        case ACM_FORMATDETAILSF_FORMAT:
            if (!pcmIsValidFormat(padf->pwfx))
                return (ACMERR_NOTPOSSIBLE);

            break;


        default:
            //
            //  don't know how to do the query type passed--return 'not
            //  supported'.
            //
            return (MMSYSERR_NOTSUPPORTED);
    }


    //
    //  return the size of the valid information we are returning
    //
    //  the ACM will guarantee that the ACMFORMATDETAILS structure
    //  passed is at least large enough to hold the base structure
    //
    //  note that we let the ACM create the format string for us since
    //  we require no special formatting (and don't want to deal with
    //  internationalization issues, etc). simply set the string to
    //  a zero length.
    //
    padf->cbStruct    = min(padf->cbStruct, sizeof(*padf));
    padf->fdwSupport  = ACMDRIVERDETAILS_SUPPORTF_CONVERTER;
    padf->szFormat[0] = TEXT('\0');


    //
    //
    //
    FUNC("-acmdFormatDetails");
    return (MMSYSERR_NOERROR);
} // acmdFormatDetails()


//==========================================================================;
//
//
//
//
//==========================================================================;

//--------------------------------------------------------------------------;
//
//  LRESULT acmdStreamOpen
//
//  Description:
//      This function handles the ACMDM_STREAM_OPEN message. This message
//      is sent to initiate a new conversion stream. This is usually caused
//      by an application calling acmStreamOpen. If this function is
//      successful, then one or more ACMDM_STREAM_CONVERT messages will be
//      sent to convert individual buffers (user calls acmStreamConvert).
//
//      Note that an ACM driver will not receive open requests for ASYNC
//      or FILTER operations unless the ACMDRIVERDETAILS_SUPPORTF_ASYNC
//      or ACMDRIVERDETAILS_SUPPORTF_FILTER flags are set in the
//      ACMDRIVERDETAILS structure. There is no need for the driver to
//      check for these requests unless it sets those support bits.
//
//      If the ACM_STREAMOPENF_QUERY flag is set in the padsi->fdwOpen
//      member, then no resources should be allocated. Just verify that
//      the conversion request is possible by this driver and return the
//      appropriate error (either ACMERR_NOTPOSSIBLE or MMSYSERR_NOERROR).
//      The driver will NOT receive an ACMDM_STREAM_CLOSE for queries.
//
//      If the ACM_STREAMOPENF_NONREALTIME bit is NOT set, then conversion
//      must be done in 'real-time'. This is a tough one to describe
//      exactly. If the driver may have trouble doing the conversion without
//      breaking up the audio, then a configuration dialog might be used
//      to allow the user to specify whether the real-time conversion
//      request should be succeeded. DO NOT SUCCEED THE CALL UNLESS YOU
//      ACTUALLY CAN DO REAL-TIME CONVERSIONS! There may be another driver
//      installed that can--so if you succeed the call you are hindering
//      the performance of the user's system!
//
//  Arguments:
//      PCODECINST pci: Pointer to private ACM driver instance structure.
//      This structure is [optionally] allocated during the DRV_OPEN message
//      which is handled by the acmdDriverOpen function.
//
//      LPACMDRVSTREAMINSTANCE padsi: Pointer to instance data for the
//      conversion stream. This structure was allocated by the ACM and
//      filled with the most common instance data needed for conversions.
//      This structure will be passed back to all future stream messages
//      if the open succeeds. The information in this structure will never
//      change during the lifetime of the stream--so it is not necessary
//      to re-verify the information referenced by this structure.
//
//  Return (LRESULT):
//      The return value is zero (MMSYSERR_NOERROR) if this function
//      succeeds with no errors. The return value is a non-zero error code
//      if the function fails.
//
//      A driver should return ACMERR_NOTPOSSIBLE if the conversion cannot
//      be performed due to incompatible source and destination formats.
//
//      A driver should return MMSYSERR_NOTSUPPORTED if the conversion
//      cannot be performed in real-time and the request does not specify
//      the ACM_STREAMOPENF_NONREALTIME flag.
//
//--------------------------------------------------------------------------;

LRESULT acmdStreamOpen
(
    PCODECINST              pci,
    LPACMDRVSTREAMINSTANCE  padsi
)
{
    LPWAVEFORMATEX      pwfxSrc;
    LPWAVEFORMATEX      pwfxDst;
    BOOL                fRealTime;


    //
    //
    //
    pwfxSrc = padsi->pwfxSrc;
    pwfxDst = padsi->pwfxDst;

    fRealTime = (0 == (padsi->fdwOpen & ACM_STREAMOPENF_NONREALTIME));


    //
    //  the most important condition to check before doing anything else
    //  is that this ACM driver can actually perform the conversion we are
    //  being opened for. this check should fail as quickly as possible
    //  if the conversion is not possible by this driver.
    //
    //  it is VERY important to fail quickly so the ACM can attempt to
    //  find a driver that is suitable for the conversion. also note that
    //  the ACM may call this driver several times with slightly different
    //  format specifications before giving up.
    //
    //  this driver first verifies that the source and destination formats
    //  are acceptable...
    //
    if (!pcmIsValidFormat(pwfxSrc) || !pcmIsValidFormat(pwfxDst))
    {
        //
        //  either the source or destination format is illegal for this
        //  codec--or the conversion between the formats can not be
        //  performed by this codec.
        //
        return (ACMERR_NOTPOSSIBLE);
    }


    //
    //  we have determined that the conversion requested is possible by
    //  this driver. now check if we are just being queried for support.
    //  if this is just a query, then do NOT allocate any instance data
    //  or create tables, etc. just succeed the call.
    //
    if (ACM_STREAMOPENF_QUERY & padsi->fdwOpen)
    {
        return (MMSYSERR_NOERROR);
    }


    //
    //  we have decided that this driver can handle the conversion stream.
    //  so we want to do _AS MUCH WORK AS POSSIBLE_ right now to prepare
    //  for converting data. any resource allocation, table building, etc
    //  that can be dealt with at this time should be done.
    //
    //  THIS IS VERY IMPORTANT! all ACMDM_STREAM_CONVERT messages need to
    //  be handled as quickly as possible.
    //
    //



    //
    //  fill in our instance data--this will be passed back to all stream
    //  messages in the ACMDRVSTREAMINSTANCE structure.
    //
    padsi->dwDriver = (DWORD)pcmConvert;

    return (MMSYSERR_NOERROR);
} // acmdStreamOpen()


//--------------------------------------------------------------------------;
//
//  LRESULT acmdStreamClose
//
//  Description:
//      This function is called to handle the ACMDM_STREAM_CLOSE message.
//      This message is sent when a conversion stream is no longer being
//      used (the stream is being closed; usually by an application
//      calling acmStreamClose). The ACM driver should clean up any resources
//      that were allocated for the stream.
//
//  Arguments:
//      PCODECINST pci: Pointer to private ACM driver instance structure.
//      This structure is [optionally] allocated during the DRV_OPEN message
//      which is handled by the acmdDriverOpen function.
//
//      LPACMDRVSTREAMINSTANCE padsi: Pointer to instance data for the
//      conversion stream. This structure was allocated by the ACM and
//      filled with the most common instance data needed for conversions.
//      The information in this structure is exactly the same as it was
//      during the ACMDM_STREAM_OPEN message--so it is not necessary
//      to re-verify the information referenced by this structure.
//
//  Return (LRESULT):
//      The return value is zero (MMSYSERR_NOERROR) if this function
//      succeeds with no errors. The return value is a non-zero error code
//      if the function fails.
//
//      NOTE! It is _strongly_ recommended that a driver not fail to close
//      a conversion stream.
//
//      An asyncronous conversion stream may fail with ACMERR_BUSY if there
//      are pending buffers. An application may call acmStreamReset to
//      force all pending buffers to be posted.
//
//--------------------------------------------------------------------------;

LRESULT acmdStreamClose
(
    PCODECINST              pci,
    LPACMDRVSTREAMINSTANCE  padsi
)
{
    //
    //  the driver should clean up all privately allocated resources that
    //  were created for maintaining the stream instance. if no resources
    //  were allocated, then simply succeed.
    //
    return (MMSYSERR_NOERROR);
} // acmdStreamClose()


//--------------------------------------------------------------------------;
//
//  LRESULT acmdStreamSize
//
//  Description:
//      This function handles the ACMDM_STREAM_SIZE message. The purpose
//      of this function is to provide the _largest size in bytes_ that
//      the source or destination buffer needs to be given the input and
//      output formats and the size in bytes of the source or destination
//      data buffer.
//
//      In other words: how big does my destination buffer need to be to
//      hold the converted data? (ACM_STREAMSIZEF_SOURCE)
//
//      Or: how big can my source buffer be given the destination buffer?
//      (ACM_STREAMSIZEF_DESTINATION)
//
//  Arguments:
//      PCODECINST pci: Pointer to private ACM driver instance structure.
//      This structure is [optionally] allocated during the DRV_OPEN message
//      which is handled by the acmdDriverOpen function.
//
//      LPACMDRVSTREAMINSTANCE padsi: Pointer to instance data for the
//      conversion stream. This structure was allocated by the ACM and
//      filled with the most common instance data needed for conversions.
//      The information in this structure is exactly the same as it was
//      during the ACMDM_STREAM_OPEN message--so it is not necessary
//      to re-verify the information referenced by this structure.
//
//      LPACMDRVSTREAMSIZE padss: Specifies a pointer to the ACMDRVSTREAMSIZE
//      structure that defines the conversion stream size query attributes.
//
//  Return (LRESULT):
//      The return value is zero (MMSYSERR_NOERROR) if this function
//      succeeds with no errors. The return value is a non-zero error code
//      if the function fails.
//
//      An ACM driver should return MMSYSERR_NOTSUPPORTED if a query type
//      is requested that the driver does not understand. Note that a driver
//      must support both the ACM_STREAMSIZEF_DESTINATION and
//      ACM_STREAMSIZEF_SOURCE queries.
//
//      If the conversion would be 'out of range' given the input arguments,
//      then ACMERR_NOTPOSSIBLE should be returned.
//
//--------------------------------------------------------------------------;

LRESULT acmdStreamSize
(
    PCODECINST              pci,
    LPACMDRVSTREAMINSTANCE  padsi,
    LPACMDRVSTREAMSIZE      padss
)
{
    LPWAVEFORMATEX      pwfxSrc;
    LPWAVEFORMATEX      pwfxDst;
    DWORD               cbSrc;
    DWORD               cbDst;

    FUNC("+acmdStreamSize");
    //
    //
    //
    //
    pwfxSrc = padsi->pwfxSrc;
    pwfxDst = padsi->pwfxDst;


    //
    //
    //
    switch (ACM_STREAMSIZEF_QUERYMASK & padss->fdwSize)
    {
        case ACM_STREAMSIZEF_SOURCE:
            cbSrc = PCM_BYTESTOSAMPLES((LPPCMWAVEFORMAT)pwfxSrc, padss->cbSrcLength);

            if (0L == cbSrc)
            {
                return (ACMERR_NOTPOSSIBLE);
            }

            //
            //  Check for overflow condition.
            //
            if (pwfxDst->nAvgBytesPerSec >= pwfxSrc->nAvgBytesPerSec)
            {
                cbDst = (0xFFFFFFFFL / pwfxDst->nAvgBytesPerSec) - pwfxDst->nBlockAlign;

                if ((padss->cbSrcLength / pwfxSrc->nAvgBytesPerSec) > cbDst)
                {
                    return (ACMERR_NOTPOSSIBLE);
                }
            }

            cbDst = MulDivRU(cbSrc,
                             pwfxDst->nSamplesPerSec,
                             pwfxSrc->nSamplesPerSec);

            cbDst = PCM_SAMPLESTOBYTES((LPPCMWAVEFORMAT)pwfxDst, cbDst);

            if (0L == cbDst)
            {
                return (ACMERR_NOTPOSSIBLE);
            }

            padss->cbDstLength = cbDst;
            return (MMSYSERR_NOERROR);


        case ACM_STREAMSIZEF_DESTINATION:
            cbDst = PCM_BYTESTOSAMPLES((LPPCMWAVEFORMAT)pwfxDst, padss->cbDstLength);

            if (0L == cbDst)
            {
                return (ACMERR_NOTPOSSIBLE);
            }

            //
            //  Check for overflow condition.
            //
            if (pwfxSrc->nAvgBytesPerSec >= pwfxDst->nAvgBytesPerSec)
            {
                cbSrc = (0xFFFFFFFFL / pwfxSrc->nAvgBytesPerSec) - pwfxSrc->nBlockAlign;

                if ((padss->cbDstLength / pwfxDst->nAvgBytesPerSec) > cbSrc)
                {
                    return (ACMERR_NOTPOSSIBLE);
                }
            }

            //
            //  Usually, we round down when calculating the size of the
            //  source buffer.  Unfortunately, this leads to a difficult
            //  problem with PCM conversion.  Normally, the calling app
            //  should be able to allocate a block-aligned dest buffer,
            //  call acmStreamSize to find out the required source buffer
            //  size, use that size, and always receive a full dest buffer.
            //  However, suppose that the app wants to record 22kHz data
            //  from a 11kHz card and provides a dest buffer with an odd
            //  number of samples.  If we round down in figuring out the
            //  source size, then the output will be one sample less than
            //  the size of the dest buffer.  BAD NEWS!  So here we round
            //  up, and then check for this case in the acmdStreamConvert
            //  function.
            //
            cbSrc = MulDivRU(cbDst,
                             pwfxSrc->nSamplesPerSec,
                             pwfxDst->nSamplesPerSec);

            cbSrc = PCM_SAMPLESTOBYTES((LPPCMWAVEFORMAT)pwfxSrc, cbSrc);

            if (0L == cbSrc)
            {
                return (ACMERR_NOTPOSSIBLE);
            }

            padss->cbSrcLength = cbSrc;
            return (MMSYSERR_NOERROR);
    }

    //
    //
    //
    return (MMSYSERR_NOTSUPPORTED);
} // acmdStreamSize()


//--------------------------------------------------------------------------;
//
//  LRESULT acmdStreamConvert
//
//  Description:
//      This function handles the ACMDM_STREAM_CONVERT message. This is the
//      whole purpose of writing an ACM driver--to convert data. This message
//      is sent after a stream has been opened (the driver receives and
//      succeeds the ACMDM_STREAM_OPEN message).
//
//  Arguments:
//      PCODECINST pci: Pointer to private ACM driver instance structure.
//      This structure is [optionally] allocated during the DRV_OPEN message
//      which is handled by the acmdDriverOpen function.
//
//      LPACMDRVSTREAMINSTANCE padsi: Pointer to instance data for the
//      conversion stream. This structure was allocated by the ACM and
//      filled with the most common instance data needed for conversions.
//      The information in this structure is exactly the same as it was
//      during the ACMDM_STREAM_OPEN message--so it is not necessary
//      to re-verify the information referenced by this structure.
//
//      LPACMDRVSTREAMHEADER padsh: Pointer to stream header structure
//      that defines the source data and destination buffer to convert.
//
//  Return (LRESULT):
//      The return value is zero (MMSYSERR_NOERROR) if this function
//      succeeds with no errors. The return value is a non-zero error code
//      if the function fails.
//
//--------------------------------------------------------------------------;

LRESULT acmdStreamConvert
(
    PCODECINST              pci,
    LPACMDRVSTREAMINSTANCE  padsi,
    LPACMDRVSTREAMHEADER    padsh
)
{
    LPPCMWAVEFORMAT     pwfSrc;
    LPPCMWAVEFORMAT     pwfDst;
    CONVERTPROC         fnConvert;
    DWORD               cb;
    DWORD               cbDst;
    DWORD               dwSrcSamples;

    BOOL                fPartialSampleAtTheEnd;
    BOOL                fDstIsBlockAligned;
    DWORD               dwDstSamples;


    //
    //  our instance data is a pointer to the conversion procedure
    //  needed to convert the pwfxSrc data to pwfxDst. the correct
    //  procedure to use was decided in acmdStreamOpen..
    //
    fnConvert = (CONVERTPROC)padsi->dwDriver;

    pwfSrc    = (LPPCMWAVEFORMAT)padsi->pwfxSrc;
    pwfDst    = (LPPCMWAVEFORMAT)padsi->pwfxDst;


    //
    //  Check if we have to hack the destination buffer to make it full -
    //  see the big comment near the end of acmdStreamSize() for more
    //  details.
    //
    dwSrcSamples    = PCM_BYTESTOSAMPLES( pwfSrc, padsh->cbSrcLength );
    dwDstSamples    = PCM_BYTESTOSAMPLES( pwfDst, padsh->cbDstLength );
    fDstIsBlockAligned = ( padsh->cbDstLength ==
                            PCM_SAMPLESTOBYTES( pwfDst, dwDstSamples )  );

    if( fDstIsBlockAligned  &&
        (dwSrcSamples == MulDivRU( dwDstSamples, pwfSrc->wf.nSamplesPerSec,
                                            pwfDst->wf.nSamplesPerSec ) )  &&
        (dwSrcSamples >  MulDivRD( dwDstSamples, pwfSrc->wf.nSamplesPerSec,
                                            pwfDst->wf.nSamplesPerSec ) )  )
    {
        fPartialSampleAtTheEnd = TRUE;
    }
    else
    {
        fPartialSampleAtTheEnd = FALSE;

        //
        //  we will only use complete samples, so drop unused partial samples
        //  if the caller is being silly...
        //
        dwSrcSamples = PCM_BYTESTOSAMPLES(pwfSrc, padsh->cbSrcLength);

        //DPF(4, "adjust source samples: BEGIN %lu", dwSrcSamples);
        for (;;)
        {
            cbDst = MulDivRU(dwSrcSamples,
                            pwfDst->wf.nSamplesPerSec,
                            pwfSrc->wf.nSamplesPerSec);

            cbDst = PCM_SAMPLESTOBYTES(pwfDst, cbDst);

            if (padsh->cbDstLength >= cbDst)
            {
                break;
            }

            //DPF(4, "adjusting source samples");
            dwSrcSamples--;
        }
        //DPF(4, "adjust source samples: END %lu", dwSrcSamples);
    }

    cb = PCM_SAMPLESTOBYTES(pwfSrc, dwSrcSamples);

    padsh->cbSrcLengthUsed = cb;

    cb = (* fnConvert)( pwfSrc,
                        padsh->pbSrc,
                        pwfDst,
                        padsh->pbDst,
                        dwSrcSamples,
                        fPartialSampleAtTheEnd,
                        padsh->pbDst + padsh->cbDstLength );


    //
    //  If we used the fPartialSampleAtTheEnd flag, then we should have
    //  completely filled the destination block.
    //
    ASSERT( (!fPartialSampleAtTheEnd) || (cb==padsh->cbDstLength) );


    //
    //  because the actual length of the converted data may not be the
    //  exact same amount as the estimate we gave in acmdStreamSize,
    //  we need to fill in the actual length we used for the destination
    //  buffer.
    //
    padsh->cbDstLengthUsed = cb;

    return (MMSYSERR_NOERROR);
} // acmdStreamConvert()


//==========================================================================;
//
//
//
//
//==========================================================================;

//--------------------------------------------------------------------------;
//
//  LRESULT pcmDriverProc
//
//  Description:
//
//
//  Arguments:
//      DWORD dwId: For most messages, dwId is the DWORD value that
//      the driver returns in response to a DRV_OPEN message. Each time
//      the driver is opened, through the OpenDriver API, the driver
//      receives a DRV_OPEN message and can return an arbitrary, non-zero
//      value. The installable driver interface saves this value and returns
//      a unique driver handle to the application. Whenever the application
//      sends a message to the driver using the driver handle, the interface
//      routes the message to this entry point and passes the corresponding
//      dwId. This mechanism allows the driver to use the same or different
//      identifiers for multiple opens but ensures that driver handles are
//      unique at the application interface layer.
//
//      The following messages are not related to a particular open instance
//      of the driver. For these messages, the dwId will always be zero.
//
//          DRV_LOAD, DRV_FREE, DRV_ENABLE, DRV_DISABLE, DRV_OPEN
//
//      HDRVR hdrvr: This is the handle returned to the application
//      by the driver interface.
//
//      UINT uMsg: The requested action to be performed. Message
//      values below DRV_RESERVED are used for globally defined messages.
//      Message values from DRV_RESERVED to DRV_USER are used for defined
//      driver protocols. Messages above DRV_USER are used for driver
//      specific messages.
//
//      LPARAM lParam1: Data for this message. Defined separately for
//      each message.
//
//      LPARAM lParam2: Data for this message. Defined separately for
//      each message.
//
//  Return (LRESULT):
//      Defined separately for each message.
//
//--------------------------------------------------------------------------;

LRESULT DriverProc(
    DWORD                   dwId,
    HACMDRIVERID            hadid,
    UINT                    uMsg,
    LPARAM                  lParam1,
    LPARAM                  lParam2
    )
{
    LRESULT             lr;
    PCODECINST          pci;

    FUNC_ACM("+DriverProc");
    HEXPARAM(dwId);
    HEXPARAM(hadid);
    HEXPARAM(uMsg);
    HEXPARAM(lParam1);
    HEXPARAM(lParam2);

    //
    //  make pci either NULL or a valid instance pointer. note that dwId
    //  is 0 for several of the DRV_* messages (ie DRV_LOAD, DRV_OPEN...)
    //  see acmdDriverOpen for information on BOGUS_DRIVER_ID.
    //
    pci = (dwId == BOGUS_DRIVER_ID) ? NULL : (PCODECINST)(UINT)dwId;

    switch (uMsg)
    {
        //
        //  lParam1: Unused.
        //
        //  lParam2: Unused.
        //
        case DRV_LOAD:
        case DRV_FREE:
            lr = 0;
            break;


        //
        //  lParam1: Not used. Ignore this argument.
        //
        //  lParam2: Pointer to ACMDRVOPENDESC (or NULL).
        //
        case DRV_OPEN:
            lr = acmdDriverOpen(NULL, (LPACMDRVOPENDESC)lParam2);
            break;

        //
        //  lParam1: Unused.
        //
        //  lParam2: Unused.
        //
        case DRV_CLOSE:
            lr = acmdDriverClose(pci);
            break;

        //
        //  lParam1: Unused.
        //
        //  lParam2: Unused.
        //
//        case DRV_INSTALL:
//            lr = (LRESULT)DRVCNF_RESTART;
//            break;
//
//        //
//        //  lParam1: Unused.
//        //
//        //  lParam2: Unused.
//        //
//        case DRV_REMOVE:
//            lr = (LRESULT)DRVCNF_RESTART;
//            break;
//
//
//
//        //
//        //  lParam1: Not used.
//        //
//        //  lParam2: Not used.
//        //
//        case DRV_QUERYCONFIGURE:
//            //
//            //  set up lParam1 and lParam2 to values that can be used by
//            //  acmdDriverConfigure to know that it is being 'queried'
//            //  for configuration support.
//            //
//            lParam1 = -1L;
//            lParam2 = 0L;
//
//            //--fall through--//
//
//        //
//        //  lParam1: Handle to parent window for the configuration dialog
//        //           box.
//        //
//        //  lParam2: Optional pointer to DRVCONFIGINFO structure.
//        //
//        case DRV_CONFIGURE:
//            lr = acmdDriverConfigure(pci, (HWND)lParam1, (LPDRVCONFIGINFO)lParam2);
//            break;


        //
        //  lParam1: Pointer to ACMDRIVERDETAILS structure.
        //
        //  lParam2: Size in bytes of ACMDRIVERDETAILS stucture passed.
        //
        case ACMDM_DRIVER_DETAILS:
            lr = acmdDriverDetails(pci, (LPACMDRIVERDETAILS)lParam1);
            break;

        //
        //  lParam1: Handle to parent window to use if displaying your own
        //           about box.
        //
        //  lParam2: Not used.
        //
        case ACMDM_DRIVER_ABOUT:
            lr = acmdDriverAbout(pci, (HWND)lParam1);
            break;

//--------------------------------------------------------------------------;
//--------------------------------------------------------------------------;

        //
        //  lParam1: Pointer to ACMDRVFORMATSUGGEST structure.
        //
        //  lParam2: Not used.
        //
       case ACMDM_FORMAT_SUGGEST:
            lr = acmdFormatSuggest(pci, (LPACMDRVFORMATSUGGEST)lParam1);
            break;


        //
        //  lParam1: Pointer to FORMATTAGDETAILS structure.
        //
        //  lParam2: fdwDetails
        //
        case ACMDM_FORMATTAG_DETAILS:
            lr = acmdFormatTagDetails(pci, (LPACMFORMATTAGDETAILS)lParam1, lParam2);
            break;


        //
        //  lParam1: Pointer to FORMATDETAILS structure.
        //
        //  lParam2: fdwDetails
        //
        case ACMDM_FORMAT_DETAILS:
            lr = acmdFormatDetails(pci, (LPACMFORMATDETAILS)lParam1, lParam2);
            break;

//--------------------------------------------------------------------------;
//--------------------------------------------------------------------------;

        //
        //  lParam1: Pointer to ACMDRVSTREAMINSTANCE structure.
        //
        //  lParam2: Not used.
        //
        case ACMDM_STREAM_OPEN:
            lr = acmdStreamOpen(pci, (LPACMDRVSTREAMINSTANCE)lParam1);
            break;

        //
        //  lParam1: Pointer to ACMDRVSTREAMINSTANCE structure.
        //
        //  lParam2: Not Used.
        //
        case ACMDM_STREAM_CLOSE:
            lr = acmdStreamClose(pci, (LPACMDRVSTREAMINSTANCE)lParam1);
            break;

        //
        //  lParam1: Pointer to ACMDRVSTREAMINSTANCE structure.
        //
        //  lParam2: Pointer to ACMDRVSTREAMSIZE structure.
        //
        case ACMDM_STREAM_SIZE:
            lr = acmdStreamSize(pci, (LPACMDRVSTREAMINSTANCE)lParam1, (LPACMDRVSTREAMSIZE)lParam2);
            break;

        //
        //  lParam1: Pointer to ACMDRVSTREAMINSTANCE structure.
        //
        //  lParam2: Pointer to ACMDRVSTREAMHEADER structure.
        //
        case ACMDM_STREAM_CONVERT:
            lr = acmdStreamConvert(pci, (LPACMDRVSTREAMINSTANCE)lParam1, (LPACMDRVSTREAMHEADER)lParam2);
            break;

        default:
            //
            //  if we are executing the following code, then this ACM driver does not
            //  handle the message that was sent. there are two ranges of messages
            //  we need to deal with:
            //
            //  o   ACM specific driver messages: if an ACM driver does not answer a
            //      message sent in the ACM driver message range, then it must
            //      return MMSYSERR_NOTSUPPORTED. this applies to the 'user'
            //      range as well (for consistency).
            //
            //  o   other installable driver messages: if an ACM driver does not
            //      answer a message that is NOT in the ACM driver message range,
            //      then it must call DefDriverProc and return that result.
            //      the exception to this is ACM driver procedures installed as
            //      ACM_DRIVERADDF_FUNCTION through acmDriverAdd. in this case,
            //      the driver procedure should conform to the ACMDRIVERPROC
            //      prototype and also return zero instead of calling DefDriverProc.
            //
            if (uMsg >= ACMDM_USER)
                lr = MMSYSERR_NOTSUPPORTED;
            else
                //
                //  if installed as a _function_ instead of as an installable driver,
                //  just return 0L for non-ACM messages we don't handle
                //
                lr = 0L;
    }


    FUNC_ACM("-DriverProc");
    HEXPARAM(lr);
    return (lr);
} // pcmDriverProc()



int CALLBACK LibMain
(
    HINSTANCE   hinst,
    WORD        wDataSeg,
    WORD        cbHeapSize,
    LPSTR       pszCmdLine
)
{
    return (TRUE);
} // LibMain()

#ifdef DEBUG
// debug zone support structure
DBGPARAM dpCurSettings =
{
    TEXT("pcmconv"),
    {
	    TEXT("ZONE_0"),		// 0
	    TEXT("ZONE_1"),  		// 1
	    TEXT("ZONE_2"),		// 2
	    TEXT("ZONE_3"),             // 3

	    TEXT("ZONE_4"), 		// 4
	    TEXT("ZONE_5"),			// 5
	    TEXT("ZONE_6"),			// 6
	    TEXT("ZONE_7"),			// 7

	    TEXT("ZONE_8"),			// 8
	    TEXT("ZONE_9"),			// 9
	    TEXT("ZONE_10"),		// 10
	    TEXT("ZONE_11"),		// 11

	    TEXT("ZONE_12"),		// 12
	    TEXT("ZONE_13"),		// 13
	    TEXT("ZONE_14"),		// 14
	    TEXT("ZONE_INT3"),		// 15
    },
    0x0000 // errors and warnings
};
#endif
