audible.c

基于EP7312的MP3播放器源代码,包括MCU和PC端代码.

    //
    return(0);
}

//****************************************************************************
//
// AudibleGetNumSections returns the number of sections in the current Audible
// program.
//
//****************************************************************************
unsigned long
AudibleGetNumSections(void)
{
    //
    // Return the number of sections in the current program if the current file
    // contains an Audible program.
    //
    if(sAudible.ulMetaDataOffset)
    {
        return(sAudible.ulNumSections);
    }

    //
    // The current file does not contain an Audible program, so return 0.
    //
    return(0);
}

//****************************************************************************
//
// AudibleGetPreviousSection returns the time of the section that occurs
// before the specified time in the Audible program.  If the specified time
// is within the first 3 seconds of a section, then the time of the previous
// section will be returned.
//
//****************************************************************************
unsigned long
AudibleGetPreviousSection(unsigned long ulTime)
{
    tFile sFile;
    unsigned long *pulSections, ulIdx, ulAvailable, ulSection;
    unsigned char *pucBuffer;

    //
    // Get a pointer to the file system's scratch buffer.
    //
    pucBuffer = FSGetScratch();

    //
    // If the current file does not contain an Audible program, then return 0
    // to indicate that the previous "section" is at the start of the file.
    //
    if(!sAudible.ulMetaDataOffset)
    {
        return(0);
    }

    //
    // Open the Audible meta-data file.
    //
    if(FSOpen(&sFile, sAudible.ulMetaDataOffset & 255, pusAudibleFile,
              FS_OPEN_READ) == 0)
    {
        return(0);
    }

    //
    // Seek to the block containing the meta-data.
    //
    if(FSSeek(&sFile, sAudible.ulMetaDataOffset & ~511) == 0)
    {
        FSClose(&sFile);
        return(0);
    }

    //
    // Read the block containing the meta-data.
    //
    if(FSRead(&sFile, pucBuffer, 512) != 512)
    {
        FSClose(&sFile);
        return(0);
    }

    //
    // Get a pointer to the table of section offsets.
    //
    pulSections = ((tAudibleMetaData *)(pucBuffer + 4))->pulSectionStart;

    //
    // There is enough space in the first block of meta-data for 17 section
    // offsets.
    //
    ulAvailable = 17;

    //
    // The current previous section offset is zero.
    //
    ulSection = 0;

    //
    // Loop through all of the sections in this program.
    //
    for(ulIdx = 0; ulIdx < sAudible.ulNumSections; ulIdx++)
    {
        //
        // See if there are any more section offsets available in this block of
        // meta-data.
        //
        if(ulAvailable == 0)
        {
            //
            // Get the offset of the next block of meta-data.
            //
            ulAvailable = *(unsigned long *)pucBuffer;
            if(ulAvailable & 511)
            {
                FSClose(&sFile);
                return(ulSection);
            }

            //
            // Seek to the next block of meta-data.
            //
            if(FSSeek(&sFile, ulAvailable) == 0)
            {
                FSClose(&sFile);
                return(ulSection);
            }

            //
            // Read the next block of meta-data.
            //
            if(FSRead(&sFile, pucBuffer, 512) != 512)
            {
                FSClose(&sFile);
                return(ulSection);
            }

            //
            // Get a pointer to the table of section offsets.
            //
            pulSections = (unsigned long *)(pucBuffer + 4);

            //
            // There is enough space in the subsequent blocks of meta-data for
            // 127 section offsets.
            //
            ulAvailable = 127;
        }

        //
        // If this section offset is after the current time, or is less than
        // three seconds before the current time, then the previous section
        // offset is the one we should return.
        //
        if((*pulSections + 3000) > ulTime)
        {
            //
            // Close the meta-data file.
            //
            FSClose(&sFile);

            //
            // Return the time of the previous section.
            //
            return(ulSection);
        }

        //
        // Remember the current section offset as the new previous section
        // offset, and skip to the next section offset in the table.
        //
        ulSection = *pulSections++;

        //
        // Decrement the number of section offsets available.
        //
        ulAvailable--;
    }

    //
    // Close the meta-data file.
    //
    FSClose(&sFile);

    //
    // Since we fell out of the above loop, the last section offset from the
    // table is the previous section in the program.
    //
    return(ulSection);
}

//****************************************************************************
//
// AudibleGetNextSection returns the time of the section that occurs after the
// specified time in the Audible program.  If there is no section after the
// specified time, then a time of -1 will be returned.
//
//****************************************************************************
unsigned long
AudibleGetNextSection(unsigned long ulTime)
{
    tFile sFile;
    unsigned long *pulSections, ulIdx, ulAvailable;
    unsigned char *pucBuffer;

    //
    // Get a pointer to the file system's scratch buffer.
    //
    pucBuffer = FSGetScratch();

    //
    // If the current file does not contain an Audible program, then return 0
    // to indicate that the previous "section" is at the start of the file.
    //
    if(!sAudible.ulMetaDataOffset)
    {
        return(0);
    }

    //
    // Open the Audible meta-data file.
    //
    if(FSOpen(&sFile, sAudible.ulMetaDataOffset & 255, pusAudibleFile,
              FS_OPEN_READ) == 0)
    {
        return(0);
    }

    //
    // Seek to the block containing the meta-data.
    //
    if(FSSeek(&sFile, sAudible.ulMetaDataOffset & ~511) == 0)
    {
        FSClose(&sFile);
        return(0);
    }

    //
    // Read the block containing the meta-data.
    //
    if(FSRead(&sFile, pucBuffer, 512) != 512)
    {
        FSClose(&sFile);
        return(0);
    }

    //
    // Get a pointer to the table of section offsets.
    //
    pulSections = ((tAudibleMetaData *)(pucBuffer + 4))->pulSectionStart;

    //
    // There is enough space in the first block of meta-data for 17 section
    // offsets.
    //
    ulAvailable = 17;

    //
    // Loop through all of the sections in this program.
    //
    for(ulIdx = 0; ulIdx < sAudible.ulNumSections; ulIdx++)
    {
        //
        // See if there are any more section offsets available in this block of
        // meta-data.
        //
        if(ulAvailable == 0)
        {
            //
            // Get the offset of the next block of meta-data.
            //
            ulAvailable = *(unsigned long *)pucBuffer;
            if(ulAvailable & 511)
            {
                FSClose(&sFile);
                return(-1);
            }

            //
            // Seek to the next block of meta-data.
            //
            if(FSSeek(&sFile, ulAvailable) == 0)
            {
                FSClose(&sFile);
                return(-1);
            }

            //
            // Read the next block of meta-data.
            //
            if(FSRead(&sFile, pucBuffer, 512) != 512)
            {
                FSClose(&sFile);
                return(-1);
            }

            //
            // Get a pointer to the table of section offsets.
            //
            pulSections = (unsigned long *)(pucBuffer + 4);

            //
            // There is enough space in the subsequent blocks of meta-data for
            // 127 section offsets.
            //
            ulAvailable = 127;
        }

        //
        // If this section offset is after the current time then it is the
        // section we should return.
        //
        if(*pulSections > (ulTime + 500))
        {
            //
            // Close the meta-data file.
            //
            FSClose(&sFile);

            //
            // Return the time of this section.
            //
            return(*pulSections);
        }

        //
        // Skip to the next section offset in the table.
        //
        pulSections++;

        //
        // Decrement the number of section offsets available.
        //
        ulAvailable--;
    }

    //
    // Close the meta-data file.
    //
    FSClose(&sFile);

    //
    // Since we fell out of the above loop, we are already in the last section
    // of the program.
    //
    return(-1);
}

//****************************************************************************
//
// AudibleSetPlayedThrough is used to indicate that we've played through the
// entire Audible program.
//
//****************************************************************************
void
AudibleSetPlayedThrough(void)
{
    //
    // Set the played through indicator if the current file contains an Audible
    // program.
    //
    if(sAudible.ulMetaDataOffset)
    {
        sAudible.ulMetaDataOffset |= 0x100;
    }
}
#endif