VLSI Solution Oy Evaluation MP3 Player Source Code Documentation

aviplay.c

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#define btUNKNOWN 0
#define btLIST 1
#define btSTR 2
#define btAUDIO 3


#define GetLongWord() {instream.b.b0 = FGetChar(); \
 instream.b.b1 = FGetChar();\
 instream.b.b2 = FGetChar();\
 instream.b.b3 = FGetChar();}

void GetAVIBlock(){

  xdata addressType instream;
  xdata unsigned char blockType = 0;
  bit isPadded = 0;
  
  GetLongWord();
  if ((instream.b.b2 == 'w') && (instream.b.b3 == 'b')){
    blockType = btAUDIO;
  }
  if (instream.l==1414744396){ //LIST
    blockType = btLIST;
  }
  GetLongWord();
  //instream.l should now contain the chunk size.
  //its length must be even by spec. if it's odd, a pad byte is 
  //in the file but its NOT part of chunk data.
  if (instream.b.b0&1){
    isPadded = 1; //There is a pad byte to make chunk len even
  }else{
    isPadded = 0;
  }
  
  
  if (blockType == btAUDIO){
    //--------THIS PACKET IS SENT TO VS10xx---------
    //superbly hilarious effects could happen if the avifile has
    //more than 1 soundtrack as all of them would be sent to VS10xx
    
    while(instream.l){
      unsigned char c;
      
      while ((instream.l>16)&&(dataBufPtr < diskSect.raw.buf+496)){
        //We have at least 16 octets of continuous stream in mem.
        if (!MP3_DREQ){
          GREEN_LED = LED_ON;
          while (!MP3_DREQ){
            Mp3DeselectData();
            AvailableProcessorTime();
          }
        }
        GREEN_LED = LED_OFF;
        Mp3SelectData();
        SPIPutCharWithoutWaiting(*dataBufPtr++);
        SPIWait();
        SPIPutChar(*dataBufPtr++);
        SPIPutChar(*dataBufPtr++);
        SPIPutChar(*dataBufPtr++);
        SPIPutChar(*dataBufPtr++);
        SPIPutChar(*dataBufPtr++);
        SPIPutChar(*dataBufPtr++);
        SPIPutChar(*dataBufPtr++);
        SPIPutChar(*dataBufPtr++);
        SPIPutChar(*dataBufPtr++);
        SPIPutChar(*dataBufPtr++);
        SPIPutChar(*dataBufPtr++);
        SPIPutChar(*dataBufPtr++);
        SPIPutChar(*dataBufPtr++);
        SPIPutChar(*dataBufPtr++);
        SPIPutChar(*dataBufPtr++);
        instream.l-=16;
        fileSize-=16;
        SPIWait();      
      }
            
      MP3_XDCS=1;
      instream.l--;
      c=FGetChar(); //data comes first until end of sector and
                    //then a new sector is loaded automagically.
      MP3_XDCS=0;
      SPIPutCharWithoutWaiting(c);
      //SPIWait();      
    }    
    MP3_XDCS=1;
  }else if (blockType == btLIST){
    ConsoleWrite("\rAVI: List of ");
    GetLongWord();
    ConsolePutChar(instream.b.b0);
    ConsolePutChar(instream.b.b1);
    ConsolePutChar(instream.b.b2);
    ConsolePutChar(instream.b.b3);

  }else{
    //We don't need this chunk. Let's quickly skip over it.
    
    //Is pad byte insertion needed?
    if (isPadded){
      instream.l++; //instream.l contains chunk size
      isPadded = 0;
    }

    //Skip to the end of sector
    if (instream.l>(temp.i=diskSect.raw.buf+512-dataBufPtr)){
      //The packet continues after end of sector
      instream.l -= temp.i;
      fileSize -= temp.i;
      sectorAddress.l++; //Sector handled, go to next.
      dataBufPtr = 0; //Complete sector is handled.
    }
    
    //Skip unnecessary sectors
    if (instream.l>512){
      while (instream.l>512){
        sectorAddress.l++;
        instream.l -= 512;
        fileSize -= 512;
      }
      dataBufPtr = 0; //Initialize for next call to FGetChar();
    }

    //Read last sector into memory
    if (dataBufPtr == 0){
      ReadDiskSector(sectorAddress.l);
      dataBufPtr = diskSect.raw.buf;
    }
    while (instream.l--){
      dataBufPtr++;
    }    
  }//nothing interesting,skip block

  if (isPadded){
    FGetChar();
  }
      
}

unsigned char PlayAvi(){

  ReadDiskSector(sectorAddress.l);

  //DumpDiskSector();

  if (diskSect.raw.buf[8]!='A') return 0x11;
  if (diskSect.raw.buf[9]!='V') return 0x11;
  if (diskSect.raw.buf[10]!='I') return 0x11;
  ConsoleWrite("\rPlayAvi()\r");

  dataBufPtr=diskSect.raw.buf+12;

  while(fileSize){
    GetAVIBlock();
  }

  return 0;
}

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All software copyright 2000-2004 VLSI Solution OY. Redistribution of these software modules are limited to promotional use only and only with the VS1011 / VS1002 / VS1003 MP3-Evakit evaluation boards. Free or commercial use of these software modules in MP3 players is ok if the product includes MP3 decoder chip(s) from VLSI. You can request the complete (compilable) package from mp3@vlsi.fi