file_drv.c

mp4的源码,主要包括loader,usb driver,mp3 decoder,jpeg decoder,mpeg decoder部分.引导部分是基于arm9的s3c2410,部分代码未经过完善.

#include "file_drv.h"
#include "fat32.h"

extern BYTE  xdata DBUF[512];
extern BYTE  data  BPB_SecPerClus;
extern DWORD xdata ClusterSum;

DIRECTORY_INFO   data DIR;
FILE_INFO		 data FILE;

DWORD pdata EntryClusterNum; 
DWORD pdata EntrySectorNum;
WORD  pdata EntryOffSet;

WORD xdata Mp3_File_Sum=0;					//number of entries in current directory

void Init_Dir()
{
	Init_Fat32();
	DIR.StartCluster=0x03;
}


bit Get_Mp3_Sum(void)
{

	BYTE sector;	
	Mp3_File_Sum=0;
	EntryClusterNum=DIR.StartCluster;
	while(TRUE)
	{
		for(sector=0;sector<BPB_SecPerClus;sector++)
		{
			EntrySectorNum=FirstSectorofCluster_32(EntryClusterNum)+sector;
			if(!Mmc_Read_Sector(EntrySectorNum,DBUF))
				return FALSE;
			for(EntryOffSet=0;EntryOffSet<512;EntryOffSet+=32)
			{
				if(DBUF[EntryOffSet]==0x00)
					return TRUE;
				else if(DBUF[EntryOffSet]==0xE5)	//delelled entry
					continue;
				else if(DBUF[EntryOffSet+15]==0xA5)	//directory entry
					continue;
				else if(!(DBUF[EntryOffSet+8]=='M')&&(DBUF[EntryOffSet+9]=='P')&&(DBUF[EntryOffSet+10]=='3'))
					continue;
				Mp3_File_Sum++;
			}
        }
		EntryClusterNum=GetNextClusterNum_32(EntryClusterNum);
		if ((EntryClusterNum&0x0FFFFFFF)==0x0FFFFFFF)
		{
			return TRUE;
		}
		else if ((EntryClusterNum&0x0FFFFFFF)>(ClusterSum-1))	
			return FALSE;
	}
	return TRUE;
}


/*get position of the entry by index(for fat32)*/
bit	Seek_Mp3_File(WORD index)
{
	BYTE sector;
	EntryClusterNum=DIR.StartCluster;
	
	while(TRUE)
	{
		for(sector=0;sector<BPB_SecPerClus;sector++)
		{
			EntrySectorNum=FirstSectorofCluster_32(EntryClusterNum)+sector;
			if(!Mmc_Read_Sector(EntrySectorNum,DBUF))
				return FALSE;
			for(EntryOffSet=0;EntryOffSet<512;EntryOffSet+=32)
			{
				if(DBUF[EntryOffSet]==0x00)
					return TRUE;
				else if(DBUF[EntryOffSet]==0xE5)	//delelled entry
					continue;
				else if(DBUF[EntryOffSet+15]==0xA5)	//directory entry
					continue;
				else if(!(DBUF[EntryOffSet+8]=='M')&&(DBUF[EntryOffSet+9]=='P')&&(DBUF[EntryOffSet+10]=='3'))
					continue;
				TempMp3Num++;
				
				if(TempMp3Num==index)
					return TRUE;
			}
        }
		EntryClusterNum=GetNextClusterNum_32(EntryClusterNum);
		if ((EntryClusterNum&0x0FFFFFFF)==0x0FFFFFFF)
		{
			return FALSE;
		}
		else if ((EntryClusterNum&0x0FFFFFFF)>(ClusterSum-1))	
			return FALSE;
	}
	return FALSE;
}


/* init file parameter according to file entry*/
void Open_MP3_File(void)
{
	PDIR_INFO pDirInfo;
	pDirInfo=(PDIR_INFO)(DBUF+EntryOffSet);

	FILE.StartCluster=SwapINT16(pDirInfo->FirstClusHi);
	FILE.StartCluster<<=16;
	FILE.StartCluster|=SwapINT16(pDirInfo->FirstClusLow);
	FILE.LengthInByte=SwapINT32(pDirInfo->Length);
	FILE.ClusterPointer=FILE.StartCluster;
	FILE.SectorPointer=FirstSectorofCluster_32(FILE.StartCluster);
	FILE.OffsetofSector=0;
	FILE.SectorofCluster=0;
	FILE.Pointer=0;
	FILE.EndOfFile=FALSE;

	return;
}

/*max readLength is 512 byte*/
bit Read_File(WORD readLength,BYTE xdata *pBuffer)
{
	WORD xdata i;
	BYTE  xdata TempBuf[512];
	
	if(readLength>512) 	return FALSE;
	if(readLength+FILE.Pointer>FILE.LengthInByte)
	{
		End_Of_File=TRUE;
		readLength=FILE.LengthInByte-FILE.Pointer;
		if(!Mmc_Read_Sector(FILE.SectorPointer,TempBuf))	return FALSE;
		if(readLength+FILE.OffsetofSector<512)
		{
			for(i=0;i<readLength;i++)
				*(pBuffer++)=TempBuf[FILE.OffsetofSector++];
			
		}
		else
		{
			for(i=0;i<(512-FILE.OffsetofSector);i++)
				*(pBuffer++)=TempBuf[FILE.OffsetofSector+i];
			readLength-=(512-FILE.OffsetofSector);
			FILE.OffsetofSector=0;
			if(++FILE.SectorofCluster>=BPB_SecPerClus)
			{
				FILE.SectorofCluster=0;				
				FILE.ClusterPointer=GetNextClusterNum(FILE.ClusterPointer);				
				FILE.SectorPointer=FirstSectorofCluster(FILE.ClusterPointer);
			}
			if(!Mmc_Read_Sector(FILE.SectorPointer,TempBuf))	return FALSE;
			for(i=0,i<readLength,i++)
				*(pBuffer++)=TempBuf[FILE.OffsetofSector+i];
		}
		FILE.Pointer=FILE.LengthInByte-1;		
		return TRUE;
	}

	if(FILE.OffsetofSector>0)
	{
		if(!Mmc_Read_Sector(FILE.SectorPointer,TempBuf))	return FALSE;
		if(readLength+FILE.OffsetofSector<512)
		{
			for(i=0;i<readLength;i++)
				*(pBuffer++)=TempBuf[FILE.OffsetofSector++];
			
		}
		else
		{
			for(i=0;i<(512-FILE.OffsetofSector);i++)
				*(pBuffer++)=TempBuf[FILE.OffsetofSector+i];
			readLength-=(512-FILE.OffsetofSector);
			FILE.OffsetofSector=0;
			if(++FILE.SectorofCluster>=BPB_SecPerClus)
			{
				FILE.SectorofCluster=0;				
				FILE.ClusterPointer=GetNextClusterNum(FILE.ClusterPointer);				
				FILE.SectorPointer=FirstSectorofCluster(FILE.ClusterPointer);
			}
			if(!Mmc_Read_Sector(FILE.SectorPointer,TempBuf))	return FALSE;
			for(i=0,i<readLength,i++)
				*(pBuffer++)=TempBuf[FILE.OffsetofSector+i];
		}
	}
	else 
	{
		if(!Mmc_Read_Sector(FILE.SectorPointer,pBuffer))	return FALSE;
		if(++FILE.SectorofCluster>=BPB_SecPerClus)
		{
			FILE.SectorofCluster=0;				
			FILE.ClusterPointer=GetNextClusterNum(FILE.ClusterPointer);				
			FILE.SectorPointer=FirstSectorofCluster(FILE.ClusterPointer);
		}
	}		
	FILE.Pointer+=readLength;
	return TRUE;
}