aboutsummaryrefslogtreecommitdiffstats
path: root/distrib/sdl-1.2.15/src/cdrom/macosx/AudioFileReaderThread.c
diff options
context:
space:
mode:
authorJesse Hall <jessehall@google.com>2012-07-23 10:12:30 -0700
committerandroid code review <noreply-gerritcodereview@google.com>2012-07-23 10:12:30 -0700
commit2b3a42e7d0b441f71fc2e2b07269dd1f8151c977 (patch)
treeded6ee18c4e1f33df235e53615a6d65e2d64f4ef /distrib/sdl-1.2.15/src/cdrom/macosx/AudioFileReaderThread.c
parent3dcbebfd43e409c3bbff7fc79288e40666a947fd (diff)
parent9682c8870b8ff5e4ac2e4c70b759f791c6f38c1f (diff)
downloadexternal_qemu-2b3a42e7d0b441f71fc2e2b07269dd1f8151c977.zip
external_qemu-2b3a42e7d0b441f71fc2e2b07269dd1f8151c977.tar.gz
external_qemu-2b3a42e7d0b441f71fc2e2b07269dd1f8151c977.tar.bz2
Merge changes I505c4aea,I2ae0529c
* changes: Import SDL release-1.2.15 Handle SDL windows with BGRA color
Diffstat (limited to 'distrib/sdl-1.2.15/src/cdrom/macosx/AudioFileReaderThread.c')
-rw-r--r--distrib/sdl-1.2.15/src/cdrom/macosx/AudioFileReaderThread.c610
1 files changed, 610 insertions, 0 deletions
diff --git a/distrib/sdl-1.2.15/src/cdrom/macosx/AudioFileReaderThread.c b/distrib/sdl-1.2.15/src/cdrom/macosx/AudioFileReaderThread.c
new file mode 100644
index 0000000..0007c07
--- /dev/null
+++ b/distrib/sdl-1.2.15/src/cdrom/macosx/AudioFileReaderThread.c
@@ -0,0 +1,610 @@
+/*
+ SDL - Simple DirectMedia Layer
+ Copyright (C) 1997-2012 Sam Lantinga
+
+ This library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Library General Public
+ License as published by the Free Software Foundation; either
+ version 2 of the License, or (at your option) any later version.
+
+ This library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Library General Public License for more details.
+
+ You should have received a copy of the GNU Library General Public
+ License along with this library; if not, write to the Free
+ Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+
+ Sam Lantinga
+ slouken@libsdl.org
+
+ This file based on Apple sample code. We haven't changed the file name,
+ so if you want to see the original search for it on apple.com/developer
+*/
+#include "SDL_config.h"
+
+/*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ AudioFileManager.cpp
+*/
+#include "AudioFilePlayer.h"
+#include <mach/mach.h> /* used for setting policy of thread */
+#include "SDLOSXCAGuard.h"
+#include <pthread.h>
+
+/*#include <list>*/
+
+/*typedef void *FileData;*/
+typedef struct S_FileData
+{
+ AudioFileManager *obj;
+ struct S_FileData *next;
+} FileData;
+
+
+typedef struct S_FileReaderThread {
+/*public:*/
+ SDLOSXCAGuard* (*GetGuard)(struct S_FileReaderThread *frt);
+ void (*AddReader)(struct S_FileReaderThread *frt);
+ void (*RemoveReader)(struct S_FileReaderThread *frt, AudioFileManager* inItem);
+ int (*TryNextRead)(struct S_FileReaderThread *frt, AudioFileManager* inItem);
+
+ int mThreadShouldDie;
+
+/*private:*/
+ /*typedef std::list<AudioFileManager*> FileData;*/
+
+ SDLOSXCAGuard *mGuard;
+ UInt32 mThreadPriority;
+
+ int mNumReaders;
+ FileData *mFileData;
+
+
+ void (*ReadNextChunk)(struct S_FileReaderThread *frt);
+ int (*StartFixedPriorityThread)(struct S_FileReaderThread *frt);
+ /*static*/
+ UInt32 (*GetThreadBasePriority)(pthread_t inThread);
+ /*static*/
+ void* (*DiskReaderEntry)(void *inRefCon);
+} FileReaderThread;
+
+
+static SDLOSXCAGuard* FileReaderThread_GetGuard(FileReaderThread *frt)
+{
+ return frt->mGuard;
+}
+
+/* returns 1 if succeeded */
+static int FileReaderThread_TryNextRead (FileReaderThread *frt, AudioFileManager* inItem)
+{
+ int didLock = 0;
+ int succeeded = 0;
+ if (frt->mGuard->Try(frt->mGuard, &didLock))
+ {
+ /*frt->mFileData.push_back (inItem);*/
+ /* !!! FIXME: this could be faster with a "tail" member. --ryan. */
+ FileData *i = frt->mFileData;
+ FileData *prev = NULL;
+
+ FileData *newfd = (FileData *) SDL_malloc(sizeof (FileData));
+ newfd->obj = inItem;
+ newfd->next = NULL;
+
+ while (i != NULL) { prev = i; i = i->next; }
+ if (prev == NULL)
+ frt->mFileData = newfd;
+ else
+ prev->next = newfd;
+
+ frt->mGuard->Notify(frt->mGuard);
+ succeeded = 1;
+
+ if (didLock)
+ frt->mGuard->Unlock(frt->mGuard);
+ }
+
+ return succeeded;
+}
+
+static void FileReaderThread_AddReader(FileReaderThread *frt)
+{
+ if (frt->mNumReaders == 0)
+ {
+ frt->mThreadShouldDie = 0;
+ frt->StartFixedPriorityThread (frt);
+ }
+ frt->mNumReaders++;
+}
+
+static void FileReaderThread_RemoveReader (FileReaderThread *frt, AudioFileManager* inItem)
+{
+ if (frt->mNumReaders > 0)
+ {
+ int bNeedsRelease = frt->mGuard->Lock(frt->mGuard);
+
+ /*frt->mFileData.remove (inItem);*/
+ FileData *i = frt->mFileData;
+ FileData *prev = NULL;
+ while (i != NULL)
+ {
+ FileData *next = i->next;
+ if (i->obj != inItem)
+ prev = i;
+ else
+ {
+ if (prev == NULL)
+ frt->mFileData = next;
+ else
+ prev->next = next;
+ SDL_free(i);
+ }
+ i = next;
+ }
+
+ if (--frt->mNumReaders == 0) {
+ frt->mThreadShouldDie = 1;
+ frt->mGuard->Notify(frt->mGuard); /* wake up thread so it will quit */
+ frt->mGuard->Wait(frt->mGuard); /* wait for thread to die */
+ }
+
+ if (bNeedsRelease) frt->mGuard->Unlock(frt->mGuard);
+ }
+}
+
+static int FileReaderThread_StartFixedPriorityThread (FileReaderThread *frt)
+{
+ pthread_attr_t theThreadAttrs;
+ pthread_t pThread;
+
+ OSStatus result = pthread_attr_init(&theThreadAttrs);
+ if (result) return 0; /*THROW_RESULT("pthread_attr_init - Thread attributes could not be created.")*/
+
+ result = pthread_attr_setdetachstate(&theThreadAttrs, PTHREAD_CREATE_DETACHED);
+ if (result) return 0; /*THROW_RESULT("pthread_attr_setdetachstate - Thread attributes could not be detached.")*/
+
+ result = pthread_create (&pThread, &theThreadAttrs, frt->DiskReaderEntry, frt);
+ if (result) return 0; /*THROW_RESULT("pthread_create - Create and start the thread.")*/
+
+ pthread_attr_destroy(&theThreadAttrs);
+
+ /* we've now created the thread and started it
+ we'll now set the priority of the thread to the nominated priority
+ and we'll also make the thread fixed */
+ thread_extended_policy_data_t theFixedPolicy;
+ thread_precedence_policy_data_t thePrecedencePolicy;
+ SInt32 relativePriority;
+
+ /* make thread fixed */
+ theFixedPolicy.timeshare = 0; /* set to 1 for a non-fixed thread */
+ result = thread_policy_set (pthread_mach_thread_np(pThread), THREAD_EXTENDED_POLICY, (thread_policy_t)&theFixedPolicy, THREAD_EXTENDED_POLICY_COUNT);
+ if (result) return 0; /*THROW_RESULT("thread_policy - Couldn't set thread as fixed priority.")*/
+ /* set priority */
+ /* precedency policy's "importance" value is relative to spawning thread's priority */
+ relativePriority = frt->mThreadPriority - frt->GetThreadBasePriority(pthread_self());
+
+ thePrecedencePolicy.importance = relativePriority;
+ result = thread_policy_set (pthread_mach_thread_np(pThread), THREAD_PRECEDENCE_POLICY, (thread_policy_t)&thePrecedencePolicy, THREAD_PRECEDENCE_POLICY_COUNT);
+ if (result) return 0; /*THROW_RESULT("thread_policy - Couldn't set thread priority.")*/
+
+ return 1;
+}
+
+static UInt32 FileReaderThread_GetThreadBasePriority (pthread_t inThread)
+{
+ thread_basic_info_data_t threadInfo;
+ policy_info_data_t thePolicyInfo;
+ unsigned int count;
+
+ /* get basic info */
+ count = THREAD_BASIC_INFO_COUNT;
+ thread_info (pthread_mach_thread_np (inThread), THREAD_BASIC_INFO, (integer_t*)&threadInfo, &count);
+
+ switch (threadInfo.policy) {
+ case POLICY_TIMESHARE:
+ count = POLICY_TIMESHARE_INFO_COUNT;
+ thread_info(pthread_mach_thread_np (inThread), THREAD_SCHED_TIMESHARE_INFO, (integer_t*)&(thePolicyInfo.ts), &count);
+ return thePolicyInfo.ts.base_priority;
+ break;
+
+ case POLICY_FIFO:
+ count = POLICY_FIFO_INFO_COUNT;
+ thread_info(pthread_mach_thread_np (inThread), THREAD_SCHED_FIFO_INFO, (integer_t*)&(thePolicyInfo.fifo), &count);
+ if (thePolicyInfo.fifo.depressed) {
+ return thePolicyInfo.fifo.depress_priority;
+ } else {
+ return thePolicyInfo.fifo.base_priority;
+ }
+ break;
+
+ case POLICY_RR:
+ count = POLICY_RR_INFO_COUNT;
+ thread_info(pthread_mach_thread_np (inThread), THREAD_SCHED_RR_INFO, (integer_t*)&(thePolicyInfo.rr), &count);
+ if (thePolicyInfo.rr.depressed) {
+ return thePolicyInfo.rr.depress_priority;
+ } else {
+ return thePolicyInfo.rr.base_priority;
+ }
+ break;
+ }
+
+ return 0;
+}
+
+static void *FileReaderThread_DiskReaderEntry (void *inRefCon)
+{
+ FileReaderThread *frt = (FileReaderThread *)inRefCon;
+ frt->ReadNextChunk(frt);
+ #if DEBUG
+ printf ("finished with reading file\n");
+ #endif
+
+ return 0;
+}
+
+static void FileReaderThread_ReadNextChunk (FileReaderThread *frt)
+{
+ OSStatus result;
+ ByteCount dataChunkSize;
+ AudioFileManager* theItem = 0;
+
+ for (;;)
+ {
+ { /* this is a scoped based lock */
+ int bNeedsRelease = frt->mGuard->Lock(frt->mGuard);
+
+ if (frt->mThreadShouldDie) {
+ frt->mGuard->Notify(frt->mGuard);
+ if (bNeedsRelease) frt->mGuard->Unlock(frt->mGuard);
+ return;
+ }
+
+ /*if (frt->mFileData.empty())*/
+ if (frt->mFileData == NULL)
+ {
+ frt->mGuard->Wait(frt->mGuard);
+ }
+
+ /* kill thread */
+ if (frt->mThreadShouldDie) {
+
+ frt->mGuard->Notify(frt->mGuard);
+ if (bNeedsRelease) frt->mGuard->Unlock(frt->mGuard);
+ return;
+ }
+
+ /*theItem = frt->mFileData.front();*/
+ /*frt->mFileData.pop_front();*/
+ theItem = NULL;
+ if (frt->mFileData != NULL)
+ {
+ FileData *next = frt->mFileData->next;
+ theItem = frt->mFileData->obj;
+ SDL_free(frt->mFileData);
+ frt->mFileData = next;
+ }
+
+ if (bNeedsRelease) frt->mGuard->Unlock(frt->mGuard);
+ }
+
+ if ((theItem->mFileLength - theItem->mReadFilePosition) < theItem->mChunkSize)
+ dataChunkSize = theItem->mFileLength - theItem->mReadFilePosition;
+ else
+ dataChunkSize = theItem->mChunkSize;
+
+ /* this is the exit condition for the thread */
+ if (dataChunkSize <= 0) {
+ theItem->mFinishedReadingData = 1;
+ continue;
+ }
+ /* construct pointer */
+ char* writePtr = (char *) (theItem->GetFileBuffer(theItem) +
+ (theItem->mWriteToFirstBuffer ? 0 : theItem->mChunkSize));
+
+ /* read data */
+ result = theItem->Read(theItem, writePtr, &dataChunkSize);
+ if (result != noErr && result != eofErr) {
+ AudioFilePlayer *afp = (AudioFilePlayer *) theItem->GetParent(theItem);
+ afp->DoNotification(afp, result);
+ continue;
+ }
+
+ if (dataChunkSize != theItem->mChunkSize)
+ {
+ writePtr += dataChunkSize;
+
+ /* can't exit yet.. we still have to pass the partial buffer back */
+ SDL_memset(writePtr, 0, (theItem->mChunkSize - dataChunkSize));
+ }
+
+ theItem->mWriteToFirstBuffer = !theItem->mWriteToFirstBuffer; /* switch buffers */
+
+ if (result == eofErr)
+ theItem->mReadFilePosition = theItem->mFileLength;
+ else
+ theItem->mReadFilePosition += dataChunkSize; /* increment count */
+ }
+}
+
+void delete_FileReaderThread(FileReaderThread *frt)
+{
+ if (frt != NULL)
+ {
+ delete_SDLOSXCAGuard(frt->mGuard);
+ SDL_free(frt);
+ }
+}
+
+FileReaderThread *new_FileReaderThread ()
+{
+ FileReaderThread *frt = (FileReaderThread *) SDL_malloc(sizeof (FileReaderThread));
+ if (frt == NULL)
+ return NULL;
+ SDL_memset(frt, '\0', sizeof (*frt));
+
+ frt->mGuard = new_SDLOSXCAGuard();
+ if (frt->mGuard == NULL)
+ {
+ SDL_free(frt);
+ return NULL;
+ }
+
+ #define SET_FILEREADERTHREAD_METHOD(m) frt->m = FileReaderThread_##m
+ SET_FILEREADERTHREAD_METHOD(GetGuard);
+ SET_FILEREADERTHREAD_METHOD(AddReader);
+ SET_FILEREADERTHREAD_METHOD(RemoveReader);
+ SET_FILEREADERTHREAD_METHOD(TryNextRead);
+ SET_FILEREADERTHREAD_METHOD(ReadNextChunk);
+ SET_FILEREADERTHREAD_METHOD(StartFixedPriorityThread);
+ SET_FILEREADERTHREAD_METHOD(GetThreadBasePriority);
+ SET_FILEREADERTHREAD_METHOD(DiskReaderEntry);
+ #undef SET_FILEREADERTHREAD_METHOD
+
+ frt->mThreadPriority = 62;
+ return frt;
+}
+
+
+static FileReaderThread *sReaderThread;
+
+
+static int AudioFileManager_DoConnect (AudioFileManager *afm)
+{
+ if (!afm->mIsEngaged)
+ {
+ OSStatus result;
+
+ /*afm->mReadFilePosition = 0;*/
+ afm->mFinishedReadingData = 0;
+
+ afm->mNumTimesAskedSinceFinished = 0;
+ afm->mLockUnsuccessful = 0;
+
+ ByteCount dataChunkSize;
+
+ if ((afm->mFileLength - afm->mReadFilePosition) < afm->mChunkSize)
+ dataChunkSize = afm->mFileLength - afm->mReadFilePosition;
+ else
+ dataChunkSize = afm->mChunkSize;
+
+ result = afm->Read(afm, afm->mFileBuffer, &dataChunkSize);
+ if (result) return 0; /*THROW_RESULT("AudioFileManager::DoConnect(): Read")*/
+
+ afm->mReadFilePosition += dataChunkSize;
+
+ afm->mWriteToFirstBuffer = 0;
+ afm->mReadFromFirstBuffer = 1;
+
+ sReaderThread->AddReader(sReaderThread);
+
+ afm->mIsEngaged = 1;
+ }
+ /*
+ else
+ throw static_cast<OSStatus>(-1); */ /* thread has already been started */
+
+ return 1;
+}
+
+static void AudioFileManager_Disconnect (AudioFileManager *afm)
+{
+ if (afm->mIsEngaged)
+ {
+ sReaderThread->RemoveReader (sReaderThread, afm);
+ afm->mIsEngaged = 0;
+ }
+}
+
+static OSStatus AudioFileManager_Read(AudioFileManager *afm, char *buffer, ByteCount *len)
+{
+ return FSReadFork (afm->mForkRefNum,
+ fsFromStart,
+ afm->mReadFilePosition + afm->mAudioDataOffset,
+ *len,
+ buffer,
+ len);
+}
+
+static OSStatus AudioFileManager_GetFileData (AudioFileManager *afm, void** inOutData, UInt32 *inOutDataSize)
+{
+ if (afm->mFinishedReadingData)
+ {
+ ++afm->mNumTimesAskedSinceFinished;
+ *inOutDataSize = 0;
+ *inOutData = 0;
+ return noErr;
+ }
+
+ if (afm->mReadFromFirstBuffer == afm->mWriteToFirstBuffer) {
+ #if DEBUG
+ printf ("* * * * * * * Can't keep up with reading file\n");
+ #endif
+
+ afm->mParent->DoNotification (afm->mParent, kAudioFilePlayErr_FilePlayUnderrun);
+ *inOutDataSize = 0;
+ *inOutData = 0;
+ } else {
+ *inOutDataSize = afm->mChunkSize;
+ *inOutData = afm->mReadFromFirstBuffer ? afm->mFileBuffer : (afm->mFileBuffer + afm->mChunkSize);
+ }
+
+ afm->mLockUnsuccessful = !sReaderThread->TryNextRead (sReaderThread, afm);
+
+ afm->mReadFromFirstBuffer = !afm->mReadFromFirstBuffer;
+
+ return noErr;
+}
+
+static void AudioFileManager_AfterRender (AudioFileManager *afm)
+{
+ if (afm->mNumTimesAskedSinceFinished > 0)
+ {
+ int didLock = 0;
+ SDLOSXCAGuard *guard = sReaderThread->GetGuard(sReaderThread);
+ if (guard->Try(guard, &didLock)) {
+ afm->mParent->DoNotification (afm->mParent, kAudioFilePlay_FileIsFinished);
+ if (didLock)
+ guard->Unlock(guard);
+ }
+ }
+
+ if (afm->mLockUnsuccessful)
+ afm->mLockUnsuccessful = !sReaderThread->TryNextRead (sReaderThread, afm);
+}
+
+static void AudioFileManager_SetPosition (AudioFileManager *afm, SInt64 pos)
+{
+ if (pos < 0 || pos >= afm->mFileLength) {
+ SDL_SetError ("AudioFileManager::SetPosition - position invalid: %d filelen=%d\n",
+ (unsigned int)pos, (unsigned int)afm->mFileLength);
+ pos = 0;
+ }
+
+ afm->mReadFilePosition = pos;
+}
+
+static void AudioFileManager_SetEndOfFile (AudioFileManager *afm, SInt64 pos)
+{
+ if (pos <= 0 || pos > afm->mFileLength) {
+ SDL_SetError ("AudioFileManager::SetEndOfFile - position beyond actual eof\n");
+ pos = afm->mFileLength;
+ }
+
+ afm->mFileLength = pos;
+}
+
+static const char *AudioFileManager_GetFileBuffer(AudioFileManager *afm)
+{
+ return afm->mFileBuffer;
+}
+
+const AudioFilePlayer *AudioFileManager_GetParent(AudioFileManager *afm)
+{
+ return afm->mParent;
+}
+
+static int AudioFileManager_GetByteCounter(AudioFileManager *afm)
+{
+ return afm->mByteCounter;
+}
+
+static OSStatus AudioFileManager_FileInputProc (void *inRefCon,
+ AudioUnitRenderActionFlags *ioActionFlags,
+ const AudioTimeStamp *inTimeStamp,
+ UInt32 inBusNumber,
+ UInt32 inNumberFrames,
+ AudioBufferList *ioData)
+{
+ AudioFileManager* afm = (AudioFileManager*)inRefCon;
+ return afm->Render(afm, ioData);
+}
+
+static OSStatus AudioFileManager_Render (AudioFileManager *afm, AudioBufferList *ioData)
+{
+ OSStatus result = noErr;
+ AudioBuffer *abuf;
+ UInt32 i;
+
+ for (i = 0; i < ioData->mNumberBuffers; i++) {
+ abuf = &ioData->mBuffers[i];
+ if (afm->mBufferOffset >= afm->mBufferSize) {
+ result = afm->GetFileData(afm, &afm->mTmpBuffer, &afm->mBufferSize);
+ if (result) {
+ SDL_SetError ("AudioConverterFillBuffer:%ld\n", result);
+ afm->mParent->DoNotification(afm->mParent, result);
+ return result;
+ }
+
+ afm->mBufferOffset = 0;
+ }
+
+ if (abuf->mDataByteSize > afm->mBufferSize - afm->mBufferOffset)
+ abuf->mDataByteSize = afm->mBufferSize - afm->mBufferOffset;
+ abuf->mData = (char *)afm->mTmpBuffer + afm->mBufferOffset;
+ afm->mBufferOffset += abuf->mDataByteSize;
+
+ afm->mByteCounter += abuf->mDataByteSize;
+ afm->AfterRender(afm);
+ }
+ return result;
+}
+
+
+void delete_AudioFileManager (AudioFileManager *afm)
+{
+ if (afm != NULL) {
+ if (afm->mFileBuffer) {
+ free(afm->mFileBuffer);
+ }
+
+ SDL_free(afm);
+ }
+}
+
+
+AudioFileManager *new_AudioFileManager(AudioFilePlayer *inParent,
+ SInt16 inForkRefNum,
+ SInt64 inFileLength,
+ UInt32 inChunkSize)
+{
+ AudioFileManager *afm;
+
+ if (sReaderThread == NULL)
+ {
+ sReaderThread = new_FileReaderThread();
+ if (sReaderThread == NULL)
+ return NULL;
+ }
+
+ afm = (AudioFileManager *) SDL_malloc(sizeof (AudioFileManager));
+ if (afm == NULL)
+ return NULL;
+ SDL_memset(afm, '\0', sizeof (*afm));
+
+ #define SET_AUDIOFILEMANAGER_METHOD(m) afm->m = AudioFileManager_##m
+ SET_AUDIOFILEMANAGER_METHOD(Disconnect);
+ SET_AUDIOFILEMANAGER_METHOD(DoConnect);
+ SET_AUDIOFILEMANAGER_METHOD(Read);
+ SET_AUDIOFILEMANAGER_METHOD(GetFileBuffer);
+ SET_AUDIOFILEMANAGER_METHOD(GetParent);
+ SET_AUDIOFILEMANAGER_METHOD(SetPosition);
+ SET_AUDIOFILEMANAGER_METHOD(GetByteCounter);
+ SET_AUDIOFILEMANAGER_METHOD(SetEndOfFile);
+ SET_AUDIOFILEMANAGER_METHOD(Render);
+ SET_AUDIOFILEMANAGER_METHOD(GetFileData);
+ SET_AUDIOFILEMANAGER_METHOD(AfterRender);
+ SET_AUDIOFILEMANAGER_METHOD(FileInputProc);
+ #undef SET_AUDIOFILEMANAGER_METHOD
+
+ afm->mParent = inParent;
+ afm->mForkRefNum = inForkRefNum;
+ afm->mBufferSize = inChunkSize;
+ afm->mBufferOffset = inChunkSize;
+ afm->mChunkSize = inChunkSize;
+ afm->mFileLength = inFileLength;
+ afm->mFileBuffer = (char*) SDL_malloc(afm->mChunkSize * 2);
+ FSGetForkPosition(afm->mForkRefNum, &afm->mAudioDataOffset);
+ assert (afm->mFileBuffer != NULL);
+ return afm;
+}
+