dlls/dmusic/instrument.c - wine - Git at Google

 /* IDirectMusicInstrument Implementation
  *
  * Copyright (C) 2003-2004 Rok Mandeljc
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either
  * version 2.1 of the License, or (at your option) any later version.
  *
  * This program 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
  * Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public
  * License along with this program; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
  */

 #include "dmusic_private.h"

 WINE_DEFAULT_DEBUG_CHANNEL(dmusic);

 static const GUID IID_IDirectMusicInstrumentPRIVATE = {0xbcb20080,0xa40c,0x11d1,{0x86,0xbc,0x00,0xc0,0x4f,0xbf,0x8f,0xef}};

 static ULONG WINAPI IDirectMusicInstrumentImpl_IUnknown_AddRef (LPUNKNOWN iface);
 static ULONG WINAPI IDirectMusicInstrumentImpl_IDirectMusicInstrument_AddRef (LPDIRECTMUSICINSTRUMENT iface);

 /* IDirectMusicInstrument IUnknown part: */
 static HRESULT WINAPI IDirectMusicInstrumentImpl_IUnknown_QueryInterface (LPUNKNOWN iface, REFIID riid, LPVOID *ppobj) {
 	ICOM_THIS_MULTI(IDirectMusicInstrumentImpl, UnknownVtbl, iface);
 	TRACE("(%p, %s, %p)\n", This, debugstr_dmguid(riid), ppobj);

 	if (IsEqualIID (riid, &IID_IUnknown)) {
 		*ppobj = &This->UnknownVtbl;
 		IDirectMusicInstrumentImpl_IUnknown_AddRef ((LPUNKNOWN)&This->UnknownVtbl);
 		return S_OK;
 	} else if (IsEqualIID (riid, &IID_IDirectMusicInstrument)) {
 		*ppobj = &This->InstrumentVtbl;
 		IDirectMusicInstrumentImpl_IDirectMusicInstrument_AddRef ((LPDIRECTMUSICINSTRUMENT)&This->InstrumentVtbl);
 		return S_OK;
 	} else if (IsEqualIID (riid, &IID_IDirectMusicInstrumentPRIVATE)) {
 		/* it seems to me that this interface is only basic IUnknown, without any
 			other inherited functions... *sigh* this is the worst scenario, since it means
 			that whoever calls it knows the layout of original implementation table and therefore
 			tries to get data by direct access... expect crashes */
 		FIXME("*sigh*... requested private/unspecified interface\n");
 		*ppobj = &This->UnknownVtbl;
 		IDirectMusicInstrumentImpl_IUnknown_AddRef ((LPUNKNOWN)&This->UnknownVtbl);
 		return S_OK;
 	}

 	WARN("(%p, %s, %p): not found\n", This, debugstr_dmguid(riid), ppobj);
 	return E_NOINTERFACE;
 }

 static ULONG WINAPI IDirectMusicInstrumentImpl_IUnknown_AddRef (LPUNKNOWN iface) {
 	ICOM_THIS_MULTI(IDirectMusicInstrumentImpl, UnknownVtbl, iface);
 	ULONG refCount = InterlockedIncrement(&This->ref);

 	TRACE("(%p)->(ref before=%u)\n", This, refCount - 1);

 	DMUSIC_LockModule();

 	return refCount;
 }

 static ULONG WINAPI IDirectMusicInstrumentImpl_IUnknown_Release (LPUNKNOWN iface) {
 	ICOM_THIS_MULTI(IDirectMusicInstrumentImpl, UnknownVtbl, iface);
 	ULONG refCount = InterlockedDecrement(&This->ref);

 	TRACE("(%p)->(ref before=%u)\n", This, refCount + 1);

 	if (!refCount) {
 		HeapFree(GetProcessHeap(), 0, This);
 	}

 	DMUSIC_UnlockModule();

 	return refCount;
 }

 static const IUnknownVtbl DirectMusicInstrument_Unknown_Vtbl = {
 	IDirectMusicInstrumentImpl_IUnknown_QueryInterface,
 	IDirectMusicInstrumentImpl_IUnknown_AddRef,
 	IDirectMusicInstrumentImpl_IUnknown_Release
 };

 /* IDirectMusicInstrumentImpl IDirectMusicInstrument part: */
 static HRESULT WINAPI IDirectMusicInstrumentImpl_IDirectMusicInstrument_QueryInterface (LPDIRECTMUSICINSTRUMENT iface, REFIID riid, LPVOID *ppobj) {
 	ICOM_THIS_MULTI(IDirectMusicInstrumentImpl, InstrumentVtbl, iface);
 	return IDirectMusicInstrumentImpl_IUnknown_QueryInterface ((LPUNKNOWN)&This->UnknownVtbl, riid, ppobj);
 }

 static ULONG WINAPI IDirectMusicInstrumentImpl_IDirectMusicInstrument_AddRef (LPDIRECTMUSICINSTRUMENT iface) {
 	ICOM_THIS_MULTI(IDirectMusicInstrumentImpl, InstrumentVtbl, iface);
 	return IDirectMusicInstrumentImpl_IUnknown_AddRef ((LPUNKNOWN)&This->UnknownVtbl);
 }

 static ULONG WINAPI IDirectMusicInstrumentImpl_IDirectMusicInstrument_Release (LPDIRECTMUSICINSTRUMENT iface) {
 	ICOM_THIS_MULTI(IDirectMusicInstrumentImpl, InstrumentVtbl, iface);
 	return IDirectMusicInstrumentImpl_IUnknown_Release ((LPUNKNOWN)&This->UnknownVtbl);
 }

 static HRESULT WINAPI IDirectMusicInstrumentImpl_IDirectMusicInstrument_GetPatch (LPDIRECTMUSICINSTRUMENT iface, DWORD* pdwPatch) {
 	ICOM_THIS_MULTI(IDirectMusicInstrumentImpl, InstrumentVtbl, iface);
 	TRACE("(%p, %p)\n", This, pdwPatch);
 	*pdwPatch = MIDILOCALE2Patch(&This->pHeader->Locale);
 	return S_OK;
 }

 static HRESULT WINAPI IDirectMusicInstrumentImpl_IDirectMusicInstrument_SetPatch (LPDIRECTMUSICINSTRUMENT iface, DWORD dwPatch) {
 	ICOM_THIS_MULTI(IDirectMusicInstrumentImpl, InstrumentVtbl, iface);
 	TRACE("(%p, %d): stub\n", This, dwPatch);
 	Patch2MIDILOCALE(dwPatch, &This->pHeader->Locale);
 	return S_OK;
 }

 static const IDirectMusicInstrumentVtbl DirectMusicInstrument_Instrument_Vtbl = {
 	IDirectMusicInstrumentImpl_IDirectMusicInstrument_QueryInterface,
 	IDirectMusicInstrumentImpl_IDirectMusicInstrument_AddRef,
 	IDirectMusicInstrumentImpl_IDirectMusicInstrument_Release,
 	IDirectMusicInstrumentImpl_IDirectMusicInstrument_GetPatch,
 	IDirectMusicInstrumentImpl_IDirectMusicInstrument_SetPatch
 };

 /* for ClassFactory */
 HRESULT DMUSIC_CreateDirectMusicInstrumentImpl (LPCGUID lpcGUID, LPVOID* ppobj, LPUNKNOWN pUnkOuter) {
 	IDirectMusicInstrumentImpl* dminst;

 	dminst = HeapAlloc(GetProcessHeap(), HEAP_ZERO_MEMORY, sizeof(IDirectMusicInstrumentImpl));
 	if (NULL == dminst) {
 		*ppobj = NULL;
 		return E_OUTOFMEMORY;
 	}
 	dminst->UnknownVtbl = &DirectMusicInstrument_Unknown_Vtbl;
 	dminst->InstrumentVtbl = &DirectMusicInstrument_Instrument_Vtbl;
 	dminst->ref = 0; /* will be inited by QueryInterface */

 	return IDirectMusicInstrumentImpl_IUnknown_QueryInterface ((LPUNKNOWN)&dminst->UnknownVtbl, lpcGUID, ppobj);
 }

 static HRESULT read_from_stream(IStream *stream, void *data, ULONG size)
 {
     ULONG readed;
     HRESULT hr;

     hr = IStream_Read(stream, data, size, &readed);
     if(FAILED(hr)){
         TRACE("IStream_Read failed: %08x\n", hr);
         return hr;
     }
     if(readed < size){
         TRACE("Didn't read full chunk: %u < %u\n", readed, size);
         return E_FAIL;
     }

     return S_OK;
 }

 static inline DWORD subtract_bytes(DWORD len, DWORD bytes)
 {
     if(bytes > len){
         TRACE("Apparent mismatch in chunk lengths? %u bytes remaining, %u bytes read\n", len, bytes);
         return 0;
     }
     return len - bytes;
 }

 static HRESULT load_instrument(IDirectMusicInstrumentImpl *This, IStream *stream, DWORD length)
 {
     HRESULT hr;
     FOURCC fourcc;
     DWORD bytes;
     LARGE_INTEGER move;

     while(length){
         hr = read_from_stream(stream, &fourcc, sizeof(fourcc));
         if(FAILED(hr))
             return hr;

         hr = read_from_stream(stream, &bytes, sizeof(bytes));
         if(FAILED(hr))
             return hr;

         length = subtract_bytes(length, sizeof(fourcc) + sizeof(bytes));

         switch(fourcc){
         case FOURCC_INSH:
             TRACE("INSH chunk: %u bytes\n", bytes);
             hr = read_from_stream(stream, This->pHeader, sizeof(*This->pHeader));
             if(FAILED(hr))
                 return hr;

             move.QuadPart = bytes - sizeof(*This->pHeader);
             hr = IStream_Seek(stream, move, STREAM_SEEK_CUR, NULL);
             if(FAILED(hr)){
                 WARN("IStream_Seek failed: %08x\n", hr);
                 return hr;
             }

             length = subtract_bytes(length, bytes);
             break;

         case FOURCC_DLID:
             TRACE("DLID chunk: %u bytes\n", bytes);
             hr = read_from_stream(stream, This->pInstrumentID, sizeof(*This->pInstrumentID));
             if(FAILED(hr))
                 return hr;

             move.QuadPart = bytes - sizeof(*This->pInstrumentID);
             hr = IStream_Seek(stream, move, STREAM_SEEK_CUR, NULL);
             if(FAILED(hr)){
                 WARN("IStream_Seek failed: %08x\n", hr);
                 return hr;
             }

             length = subtract_bytes(length, bytes);
             break;

         default:
             TRACE("Unknown chunk %s: %u bytes\n", debugstr_fourcc(fourcc), bytes);

             move.QuadPart = bytes;
             hr = IStream_Seek(stream, move, STREAM_SEEK_CUR, NULL);
             if(FAILED(hr)){
                 WARN("IStream_Seek failed: %08x\n", hr);
                 return hr;
             }

             length = subtract_bytes(length, bytes);
             break;
         }
     }

     return S_OK;
 }

 /* aux. function that completely loads instrument; my tests indicate that it's
    called somewhere around IDirectMusicCollection_GetInstrument */
 HRESULT IDirectMusicInstrumentImpl_Custom_Load (LPDIRECTMUSICINSTRUMENT iface, LPSTREAM stream)
 {
     ICOM_THIS_MULTI(IDirectMusicInstrumentImpl, InstrumentVtbl, iface);
     LARGE_INTEGER move;
     FOURCC fourcc;
     DWORD bytes;
     HRESULT hr;

     TRACE("(%p, %p, offset = %s)\n", This, stream, wine_dbgstr_longlong(This->liInstrumentPosition.QuadPart));

     hr = IStream_Seek(stream, This->liInstrumentPosition, STREAM_SEEK_SET, NULL);
     if(FAILED(hr)){
         WARN("IStream_Seek failed: %08x\n", hr);
         goto load_failure;
     }

     hr = read_from_stream(stream, &fourcc, sizeof(fourcc));
     if(FAILED(hr))
         goto load_failure;

     if(fourcc != FOURCC_LIST){
         WARN("Loading failed: Expected LIST chunk, got: %s\n", debugstr_fourcc(fourcc));
         goto load_failure;
     }

     hr = read_from_stream(stream, &bytes, sizeof(bytes));
     if(FAILED(hr))
         goto load_failure;

     TRACE("LIST chunk: %u bytes\n", bytes);
     while(1){
         hr = read_from_stream(stream, &fourcc, sizeof(fourcc));
         if(FAILED(hr))
             goto load_failure;

         switch(fourcc){
         case FOURCC_INS:
             TRACE("INS  chunk: (no byte count)\n");
             hr = load_instrument(This, stream, bytes - sizeof(FOURCC));
             if(FAILED(hr))
                 goto load_failure;
             break;

         default:
             hr = read_from_stream(stream, &bytes, sizeof(bytes));
             if(FAILED(hr))
                 goto load_failure;

             TRACE("Unknown chunk %s: %u bytes\n", debugstr_fourcc(fourcc), bytes);

             move.QuadPart = bytes;
             hr = IStream_Seek(stream, move, STREAM_SEEK_CUR, NULL);
             if(FAILED(hr)){
                 WARN("IStream_Seek failed: %08x\n", hr);
                 return hr;
             }

             break;
         }
     }

     return S_OK;

 load_failure:
     return DMUS_E_UNSUPPORTED_STREAM;
 }
	/* IDirectMusicInstrument Implementation
	*
	* Copyright (C) 2003-2004 Rok Mandeljc
	*
	* This program is free software; you can redistribute it and/or
	* modify it under the terms of the GNU Lesser General Public
	* License as published by the Free Software Foundation; either
	* version 2.1 of the License, or (at your option) any later version.
	*
	* This program 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
	* Lesser General Public License for more details.
	*
	* You should have received a copy of the GNU Lesser General Public
	* License along with this program; if not, write to the Free Software
	* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
	*/

	#include "dmusic_private.h"

	WINE_DEFAULT_DEBUG_CHANNEL(dmusic);

	static const GUID IID_IDirectMusicInstrumentPRIVATE = {0xbcb20080,0xa40c,0x11d1,{0x86,0xbc,0x00,0xc0,0x4f,0xbf,0x8f,0xef}};

	static ULONG WINAPI IDirectMusicInstrumentImpl_IUnknown_AddRef (LPUNKNOWN iface);
	static ULONG WINAPI IDirectMusicInstrumentImpl_IDirectMusicInstrument_AddRef (LPDIRECTMUSICINSTRUMENT iface);

	/* IDirectMusicInstrument IUnknown part: */
	static HRESULT WINAPI IDirectMusicInstrumentImpl_IUnknown_QueryInterface (LPUNKNOWN iface, REFIID riid, LPVOID *ppobj) {
	ICOM_THIS_MULTI(IDirectMusicInstrumentImpl, UnknownVtbl, iface);
	TRACE("(%p, %s, %p)\n", This, debugstr_dmguid(riid), ppobj);

	if (IsEqualIID (riid, &IID_IUnknown)) {
	*ppobj = &This->UnknownVtbl;
	IDirectMusicInstrumentImpl_IUnknown_AddRef ((LPUNKNOWN)&This->UnknownVtbl);
	return S_OK;
	} else if (IsEqualIID (riid, &IID_IDirectMusicInstrument)) {
	*ppobj = &This->InstrumentVtbl;
	IDirectMusicInstrumentImpl_IDirectMusicInstrument_AddRef ((LPDIRECTMUSICINSTRUMENT)&This->InstrumentVtbl);
	return S_OK;
	} else if (IsEqualIID (riid, &IID_IDirectMusicInstrumentPRIVATE)) {
	/* it seems to me that this interface is only basic IUnknown, without any
	other inherited functions... sigh this is the worst scenario, since it means
	that whoever calls it knows the layout of original implementation table and therefore
	tries to get data by direct access... expect crashes */
	FIXME("sigh... requested private/unspecified interface\n");
	*ppobj = &This->UnknownVtbl;
	IDirectMusicInstrumentImpl_IUnknown_AddRef ((LPUNKNOWN)&This->UnknownVtbl);
	return S_OK;
	}

	WARN("(%p, %s, %p): not found\n", This, debugstr_dmguid(riid), ppobj);
	return E_NOINTERFACE;
	}

	static ULONG WINAPI IDirectMusicInstrumentImpl_IUnknown_AddRef (LPUNKNOWN iface) {
	ICOM_THIS_MULTI(IDirectMusicInstrumentImpl, UnknownVtbl, iface);
	ULONG refCount = InterlockedIncrement(&This->ref);

	TRACE("(%p)->(ref before=%u)\n", This, refCount - 1);

	DMUSIC_LockModule();

	return refCount;
	}

	static ULONG WINAPI IDirectMusicInstrumentImpl_IUnknown_Release (LPUNKNOWN iface) {
	ICOM_THIS_MULTI(IDirectMusicInstrumentImpl, UnknownVtbl, iface);
	ULONG refCount = InterlockedDecrement(&This->ref);

	TRACE("(%p)->(ref before=%u)\n", This, refCount + 1);

	if (!refCount) {
	HeapFree(GetProcessHeap(), 0, This);
	}

	DMUSIC_UnlockModule();

	return refCount;
	}

	static const IUnknownVtbl DirectMusicInstrument_Unknown_Vtbl = {
	IDirectMusicInstrumentImpl_IUnknown_QueryInterface,
	IDirectMusicInstrumentImpl_IUnknown_AddRef,
	IDirectMusicInstrumentImpl_IUnknown_Release
	};

	/* IDirectMusicInstrumentImpl IDirectMusicInstrument part: */
	static HRESULT WINAPI IDirectMusicInstrumentImpl_IDirectMusicInstrument_QueryInterface (LPDIRECTMUSICINSTRUMENT iface, REFIID riid, LPVOID *ppobj) {
	ICOM_THIS_MULTI(IDirectMusicInstrumentImpl, InstrumentVtbl, iface);
	return IDirectMusicInstrumentImpl_IUnknown_QueryInterface ((LPUNKNOWN)&This->UnknownVtbl, riid, ppobj);
	}

	static ULONG WINAPI IDirectMusicInstrumentImpl_IDirectMusicInstrument_AddRef (LPDIRECTMUSICINSTRUMENT iface) {
	ICOM_THIS_MULTI(IDirectMusicInstrumentImpl, InstrumentVtbl, iface);
	return IDirectMusicInstrumentImpl_IUnknown_AddRef ((LPUNKNOWN)&This->UnknownVtbl);
	}

	static ULONG WINAPI IDirectMusicInstrumentImpl_IDirectMusicInstrument_Release (LPDIRECTMUSICINSTRUMENT iface) {
	ICOM_THIS_MULTI(IDirectMusicInstrumentImpl, InstrumentVtbl, iface);
	return IDirectMusicInstrumentImpl_IUnknown_Release ((LPUNKNOWN)&This->UnknownVtbl);
	}

	static HRESULT WINAPI IDirectMusicInstrumentImpl_IDirectMusicInstrument_GetPatch (LPDIRECTMUSICINSTRUMENT iface, DWORD* pdwPatch) {
	ICOM_THIS_MULTI(IDirectMusicInstrumentImpl, InstrumentVtbl, iface);
	TRACE("(%p, %p)\n", This, pdwPatch);
	*pdwPatch = MIDILOCALE2Patch(&This->pHeader->Locale);
	return S_OK;
	}

	static HRESULT WINAPI IDirectMusicInstrumentImpl_IDirectMusicInstrument_SetPatch (LPDIRECTMUSICINSTRUMENT iface, DWORD dwPatch) {
	ICOM_THIS_MULTI(IDirectMusicInstrumentImpl, InstrumentVtbl, iface);
	TRACE("(%p, %d): stub\n", This, dwPatch);
	Patch2MIDILOCALE(dwPatch, &This->pHeader->Locale);
	return S_OK;
	}

	static const IDirectMusicInstrumentVtbl DirectMusicInstrument_Instrument_Vtbl = {
	IDirectMusicInstrumentImpl_IDirectMusicInstrument_QueryInterface,
	IDirectMusicInstrumentImpl_IDirectMusicInstrument_AddRef,
	IDirectMusicInstrumentImpl_IDirectMusicInstrument_Release,
	IDirectMusicInstrumentImpl_IDirectMusicInstrument_GetPatch,
	IDirectMusicInstrumentImpl_IDirectMusicInstrument_SetPatch
	};

	/* for ClassFactory */
	HRESULT DMUSIC_CreateDirectMusicInstrumentImpl (LPCGUID lpcGUID, LPVOID* ppobj, LPUNKNOWN pUnkOuter) {
	IDirectMusicInstrumentImpl* dminst;

	dminst = HeapAlloc(GetProcessHeap(), HEAP_ZERO_MEMORY, sizeof(IDirectMusicInstrumentImpl));
	if (NULL == dminst) {
	*ppobj = NULL;
	return E_OUTOFMEMORY;
	}
	dminst->UnknownVtbl = &DirectMusicInstrument_Unknown_Vtbl;
	dminst->InstrumentVtbl = &DirectMusicInstrument_Instrument_Vtbl;
	dminst->ref = 0; /* will be inited by QueryInterface */

	return IDirectMusicInstrumentImpl_IUnknown_QueryInterface ((LPUNKNOWN)&dminst->UnknownVtbl, lpcGUID, ppobj);
	}

	static HRESULT read_from_stream(IStream stream, void data, ULONG size)
	{
	ULONG readed;
	HRESULT hr;

	hr = IStream_Read(stream, data, size, &readed);
	if(FAILED(hr)){
	TRACE("IStream_Read failed: %08x\n", hr);
	return hr;
	}
	if(readed < size){
	TRACE("Didn't read full chunk: %u < %u\n", readed, size);
	return E_FAIL;
	}

	return S_OK;
	}

	static inline DWORD subtract_bytes(DWORD len, DWORD bytes)
	{
	if(bytes > len){
	TRACE("Apparent mismatch in chunk lengths? %u bytes remaining, %u bytes read\n", len, bytes);
	return 0;
	}
	return len - bytes;
	}

	static HRESULT load_instrument(IDirectMusicInstrumentImpl This, IStream stream, DWORD length)
	{
	HRESULT hr;
	FOURCC fourcc;
	DWORD bytes;
	LARGE_INTEGER move;

	while(length){
	hr = read_from_stream(stream, &fourcc, sizeof(fourcc));
	if(FAILED(hr))
	return hr;

	hr = read_from_stream(stream, &bytes, sizeof(bytes));
	if(FAILED(hr))
	return hr;

	length = subtract_bytes(length, sizeof(fourcc) + sizeof(bytes));

	switch(fourcc){
	case FOURCC_INSH:
	TRACE("INSH chunk: %u bytes\n", bytes);
	hr = read_from_stream(stream, This->pHeader, sizeof(*This->pHeader));
	if(FAILED(hr))
	return hr;

	move.QuadPart = bytes - sizeof(*This->pHeader);
	hr = IStream_Seek(stream, move, STREAM_SEEK_CUR, NULL);
	if(FAILED(hr)){
	WARN("IStream_Seek failed: %08x\n", hr);
	return hr;
	}

	length = subtract_bytes(length, bytes);
	break;

	case FOURCC_DLID:
	TRACE("DLID chunk: %u bytes\n", bytes);
	hr = read_from_stream(stream, This->pInstrumentID, sizeof(*This->pInstrumentID));
	if(FAILED(hr))
	return hr;

	move.QuadPart = bytes - sizeof(*This->pInstrumentID);
	hr = IStream_Seek(stream, move, STREAM_SEEK_CUR, NULL);
	if(FAILED(hr)){
	WARN("IStream_Seek failed: %08x\n", hr);
	return hr;
	}

	length = subtract_bytes(length, bytes);
	break;

	default:
	TRACE("Unknown chunk %s: %u bytes\n", debugstr_fourcc(fourcc), bytes);

	move.QuadPart = bytes;
	hr = IStream_Seek(stream, move, STREAM_SEEK_CUR, NULL);
	if(FAILED(hr)){
	WARN("IStream_Seek failed: %08x\n", hr);
	return hr;
	}

	length = subtract_bytes(length, bytes);
	break;
	}
	}

	return S_OK;
	}

	/* aux. function that completely loads instrument; my tests indicate that it's
	called somewhere around IDirectMusicCollection_GetInstrument */
	HRESULT IDirectMusicInstrumentImpl_Custom_Load (LPDIRECTMUSICINSTRUMENT iface, LPSTREAM stream)
	{
	ICOM_THIS_MULTI(IDirectMusicInstrumentImpl, InstrumentVtbl, iface);
	LARGE_INTEGER move;
	FOURCC fourcc;
	DWORD bytes;
	HRESULT hr;

	TRACE("(%p, %p, offset = %s)\n", This, stream, wine_dbgstr_longlong(This->liInstrumentPosition.QuadPart));

	hr = IStream_Seek(stream, This->liInstrumentPosition, STREAM_SEEK_SET, NULL);
	if(FAILED(hr)){
	WARN("IStream_Seek failed: %08x\n", hr);
	goto load_failure;
	}

	hr = read_from_stream(stream, &fourcc, sizeof(fourcc));
	if(FAILED(hr))
	goto load_failure;

	if(fourcc != FOURCC_LIST){
	WARN("Loading failed: Expected LIST chunk, got: %s\n", debugstr_fourcc(fourcc));
	goto load_failure;
	}

	hr = read_from_stream(stream, &bytes, sizeof(bytes));
	if(FAILED(hr))
	goto load_failure;

	TRACE("LIST chunk: %u bytes\n", bytes);
	while(1){
	hr = read_from_stream(stream, &fourcc, sizeof(fourcc));
	if(FAILED(hr))
	goto load_failure;

	switch(fourcc){
	case FOURCC_INS:
	TRACE("INS chunk: (no byte count)\n");
	hr = load_instrument(This, stream, bytes - sizeof(FOURCC));
	if(FAILED(hr))
	goto load_failure;
	break;

	default:
	hr = read_from_stream(stream, &bytes, sizeof(bytes));
	if(FAILED(hr))
	goto load_failure;

	TRACE("Unknown chunk %s: %u bytes\n", debugstr_fourcc(fourcc), bytes);

	move.QuadPart = bytes;
	hr = IStream_Seek(stream, move, STREAM_SEEK_CUR, NULL);
	if(FAILED(hr)){
	WARN("IStream_Seek failed: %08x\n", hr);
	return hr;
	}

	break;
	}
	}

	return S_OK;

	load_failure:
	return DMUS_E_UNSUPPORTED_STREAM;
	}