audiofilereaderthread.c

SDL库 在进行视频显示程序spcaview安装时必须的库文件

/*
    SDL - Simple DirectMedia Layer
    Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002  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
    [e-mail]

    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;
    UInt32  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));