file.c

实现了fat16文件系统的读写控制

*函数名称:read_BPB()
*功能描述:读取BPB，并将数据从小端模式转换为大端模式
*形式参数:void  
*返 回 值:void
*---------------------------------------------------------------*/ 
void read_BPB()
{
	unsigned char i;
	unsigned char xdata *p;

	mmc_readblock(BootStartSector,buffer);

	p=(unsigned char xdata *)BPB.BS_jmpBoot;

	for(i=0;i<54;i++)
		*(p++)=buffer[i];
	//喂狗
WDTCN=0xa5;			
//FAT文件系统为little endian,要将数据转换为大端模式
	//转换BPB_BytsPerSec,unsigned int
	p=(unsigned char xdata *)(&BPB.BPB_BytsPerSec);
	{
		unsigned char temp;
		temp=*p;
		*p=*(p+1);
		*(p+1)=temp;
	}
	//转换BPB_RsvdSecCnt,unsigned int
	p=(unsigned char xdata *)(&BPB.BPB_RsvdSecCnt);
	{
		unsigned char temp;
		temp=*p;
		*p=*(p+1);
		*(p+1)=temp;
	}
	//转换BPB_RootEntCnt,unsigned int
	p=(unsigned char xdata *)(&BPB.BPB_RootEntCnt);
	{
		unsigned char temp;
		temp=*p;
		*p=*(p+1);
		*(p+1)=temp;
	}
	//转换BPB_TotSec16,unsigned int
	//喂狗
WDTCN=0xa5;	
	p=(unsigned char xdata *)(&BPB.BPB_TotSec16);
	{
		unsigned char temp;
		temp=*p;
		*p=*(p+1);
		*(p+1)=temp;
	}
	//转换BPB_FATSz16,unsigned int
	p=(unsigned char xdata *)(&BPB.BPB_FATSz16);
	{
		unsigned char temp;
		temp=*p;
		*p=*(p+1);
		*(p+1)=temp;
	}
	//转换BPB_FATSz16,unsigned int
	p=(unsigned char xdata *)(&BPB.BPB_SecPerTrk);
	{
		unsigned char temp;
		temp=*p;
		*p=*(p+1);
		*(p+1)=temp;
	}
	//转换BPB_NumHeads,unsigned int
	p=(unsigned char xdata *)(&BPB.BPB_NumHeads);
	{
		unsigned char temp;
		temp=*p;
		*p=*(p+1);
		*(p+1)=temp;
	}
	//转换BPB_HiddSec,unsigned long
	p=(unsigned char xdata *)(&BPB.BPB_HiddSec);
	for(i=0;i<2;i++)
	{
		unsigned char temp;

		temp=*(p+(3-i));
		*(p+(3-i))=*(p+i);
		*(p+i)=temp;
	}
	//转换BPB_TotSec32,unsigned long
	p=(unsigned char xdata *)(&BPB.BPB_TotSec32);
	for(i=0;i<2;i++)
	{
		unsigned char temp;

		temp=*(p+(3-i));
		*(p+(3-i))=*(p+i);
		*(p+i)=temp;
	}		
}
/*------------------------------------------------------------
*函数名称:compute_BPB()
*功能描述:
*形式参数:void  
*返 回 值:void
*---------------------------------------------------------------*/
void compute_BPB()
{
	unsigned long TotSec;		//磁盘总的扇区数

	//计算2个FAT区的起始地址
	FAT1_FirstSector = BootStartSector+BPB.BPB_RsvdSecCnt;
	FAT2_FirstSector =FAT1_FirstSector+ BPB.BPB_FATSz16;
	
	//文件根目录开始的扇区号
	FDT_FirstSector = FAT2_FirstSector+BPB.BPB_FATSz16;

	//文件根目录所占的扇区数
	RootDirSectors = ((BPB.BPB_RootEntCnt*32)+(BPB.BPB_BytsPerSec-1))/BPB.BPB_BytsPerSec;

	//数据区开始的扇区号
	FirstDataSector = FDT_FirstSector+RootDirSectors;
	

	if(BPB.BPB_TotSec16 != 0)
		TotSec = BPB.BPB_TotSec16;
	else
		TotSec = BPB.BPB_TotSec32;
	
	DataSec = TotSec - FirstDataSector;
	CountofClusters = DataSec / BPB.BPB_SecPerClus; 		
}
/*------------------------------------------------------------
*函数名称:read_partition()
*功能描述:读取分区表中的信息和每个分区的入口地址和基本信息
//将信息存放到partitionTable1中
*形式参数:void  
*返 回 值:void
*---------------------------------------------------------------*/
void  read_partition()
{
	unsigned int xdata i;
	unsigned char xdata *p;
	
	mmc_readblock(0,buffer);	//读取Partition Table 中的数据
	
	p=(unsigned char xdata *)(&partitionTable1.PartionState);	//指向分区信息结构体的首地址
	
	//读取第一个分区的信息
	for(i=0;i<16;i++)
		*(p+i) = buffer[PARTITON1_START_OFFSET+i];
	
	//将短整型和长整型的数据转换为大端模式	
	
	//转换StartSector,unsigned int
	p=(unsigned char xdata *)(&partitionTable1.StartSector);
	{
		unsigned char temp;
		temp=*p;
		*p=*(p+1);
		*(p+1)=temp;
	}

	//EndSector,unsigned int
	p=(unsigned char xdata *)(&partitionTable1.EndSector);
	{
		unsigned char temp;
		temp=*p;
		*p=*(p+1);
		*(p+1)=temp;
	}

		//SectorsPrecedingPartition,unsigned long
	p=(unsigned char xdata *)(&partitionTable1.SectorsPrecedingPartition);
	for(i=0;i<2;i++)
	{
		unsigned char temp;

		temp=*(p+(3-i));
		*(p+(3-i))=*(p+i);
		*(p+i)=temp;
	}
		//SectorsInPartion,unsigned long
	p=(unsigned char xdata *)(&partitionTable1.SectorsInPartion);
	for(i=0;i<2;i++)
	{
		unsigned char temp;

		temp=*(p+(3-i));
		*(p+(3-i))=*(p+i);
		*(p+i)=temp;
	}
}

/*------------------------------------------------------------
*函数名称:file_name()
*功能描述:由系统时间，创建文件的文件名和扩展名，扩展名默认为TXT
*形式参数:void  
*返 回 值:void
*---------------------------------------------------------------*/
void file_name()
{
	unsigned char xdata month;
	unsigned char xdata day;
	unsigned char xdata hour;
	unsigned char xdata minute;
	unsigned char xdata second;

	unsigned char xdata i;
	unsigned char xdata temp;
	//先将从DS1302中获得的BCD码格式的数据转化为16进制的数据
	read_time();		//获取当前的时间

	//将BCD码表示的时间转化为十进制的数
	for(i=0;i<7;i++)
	{
		temp=time[i] &0xf0;		//取高半字节
		temp>>=4;				//放到低位参与运算
		time[i] &=0x0f;
		time[i] = temp *10 + time[i];
	}
	month = time[2];	//月
	day = time[3];		//日
	hour = time[4];
	minute =time[5];
	second = time[6];
	
	//填充文件名,都为ASCII码值
	//填充月
	if(month<10)
	{
		fileName.NAME[0]= 0x30;			//ASCII 0	
		fileName.NAME[1]= 0x30+month;
	}
	else
	{
		fileName.NAME[0]= 0x30+month/10;			
		fileName.NAME[1]= 0x30+month%10;

	}

	//填充日
	if(day<10)
	{
		fileName.NAME[2]=0x30;			//ASCII 0
		fileName.NAME[3]=0x30 +day;
	}
	else
	{
		fileName.NAME[2]=0x30 + day/10;
		fileName.NAME[3]=0x30 +day%10;
	}
		//填充时
	if(hour<10)
	{
		fileName.NAME[4]=0x30;			//ASCII 0
		fileName.NAME[5]=0x30 +hour;
	}
	else
	{
		fileName.NAME[4]=0x30 + hour/10;
		fileName.NAME[5]=0x30 +hour%10;
	}
	//填充分
	if(minute<10)
	{
		fileName.NAME[6]=0x30;			//ASCII 0
		fileName.NAME[7]=0x30 +minute;
	}
	else
	{
		fileName.NAME[6]=0x30 + minute/10;
		fileName.NAME[7]=0x30 +minute%10;
	}

	//文件类型
	fileName.TYPE[0]='T';
	fileName.TYPE[1]='X';
	fileName.TYPE[2]='T';
}

/*------------------------------------------------------------
*函数名称:file_time(unsigned char type)
*功能描述:有形式参数，确定是填充文件创建时间还是文件更新时间
*形式参数:  0：文件创建时间
			1：文件更新时间
*返 回 值:void
*---------------------------------------------------------------*/
void file_time(unsigned char type)
{
	unsigned char i;
	unsigned char temp;
	unsigned int updata=0x0000;

//创建时间的填充
	if(type ==0)
	{
			//先将从DS1302中获得的BCD码格式的数据转化为16进制的数据
		read_time();		//获取当前的时间

		//将BCD码表示的时间转化为十进制的数
		for(i=0;i<7;i++)
		{
			temp=time[i] &0xf0;		//取高半字节
			temp>>=4;				//放到低位参与运算
			time[i] &=0x0f;
			time[i] = temp *10 + time[i];
		}
		//计算年
		temp=time[0]+20;		//时间基准为1980年1月1号
		updata =temp;
		updata<<=4;				//年占高7位

		//计算月
		temp=time[2];
		updata |=temp;				//月为高四位
		updata <<=5;
		//计算data
		temp = time[3];
		updata |=temp;		//date 占低五位
		FileIndex.FileCreateDate[1]=(unsigned char)((updata &0xff00)>>8);
		FileIndex.FileCreateDate[0]=(unsigned char)(updata &0x00ff);

		FileIndex.FileCreateDate2[1]=(unsigned char)((updata &0xff00)>>8);
		FileIndex.FileCreateDate2[0]=(unsigned char)(updata &0x00ff);

		//更新的时间
		FileIndex.FileUpdateDate[1]=(unsigned char)((updata &0xff00)>>8);
		FileIndex.FileUpdateDate[0]=(unsigned char)(updata &0x00ff);

		//计算hour
		temp=time[4];
		updata = temp;
		updata <<=6; 
		//计算minute
		temp=time[5];
		updata |=temp;
		updata<<=5;
		//计算second
		temp=time[6]/2;
		updata |=temp;

		FileIndex.FileCreateTime[1]=(unsigned char)((updata &0xff00)>>8);
		FileIndex.FileCreateTime[0]=(unsigned char)(updata &0x00ff);
		
		//更新的时间
		FileIndex.FileUpdateTime[1]=(unsigned char)((updata &0xff00)>>8);
		FileIndex.FileUpdateTime[0]=(unsigned char)(updata &0x00ff);

		FileIndex.reserved = 0x10;	//填充保留值
		FileIndex.cr_time=0x06;

		FileIndex.UnUsed[0]=0;
		FileIndex.UnUsed[1]=0;

	}//endof if()
	else if(type ==1)
	{
		read_time();		//获取当前的时间
		//将BCD码表示的时间转化为十进制的数
		for(i=0;i<7;i++)
		{
			temp=time[i] &0xf0;		//取高半字节
			temp>>=4;				//放到低位参与运算
			time[i] &=0x0f;
			time[i] = temp *10 + time[i];
		}
		//计算年
		temp=time[0]+20;		//时间基准为1980年1月1号
		updata =temp;
		updata<<=4;				//年占高7位

		//计算月
		temp=time[2];
		updata |=temp;				//月为高四位
		updata <<=5;
		//计算data
		temp = time[3];
		updata |=temp;		//date 占低五位
		FileIndex.FileUpdateDate[1]=(unsigned char)((updata &0xff00)>>8);
		FileIndex.FileUpdateDate[0]=(unsigned char)(updata &0x00ff);


		//计算hour
		temp=time[4];
		updata = temp;
		updata <<=6; 
		//计算minute
		temp=time[5];
		updata |=temp;
		updata<<=5;
		//计算second
		temp=time[6]/2;
		updata |=temp;

		FileIndex.FileUpdateTime[1]=(unsigned char)((updata &0xff00)>>8);
		FileIndex.FileUpdateTime[0]=(unsigned char)(updata &0x00ff);
	}
}