fat.c

嵌入式FAT文件系统源码免费下载

    CORE.ClusterNum = CORE.ClusterOfDirectoryEntry;
    CORE.SectorNum = FirstSectorofCluster(CORE.ClusterNum);
  } 
  CORE.offset = 0;
  read_flash_sector(buf,CORE.SectorNum);
  while(1)
  { 
    SectorNum_LOCAL = CORE.SectorNum; // 保存当前ENTRY的首位置
    ClusterNum_LOCAL = CORE.ClusterNum;
    Offset_LOCAL = CORE.offset;
	found_flag = 0;
	Empty_Entry_Space_Count = 0;
    do{
       if(buf[CORE.offset] == 0xe5 || buf[CORE.offset] == 0)//空ENTRY
	   {
	    Empty_Entry_Space_Count++;
		//直到找到指定数量的空ENTRY
	    if(Empty_Entry_Space_Count >= Entry_Resuested_QTY)
		{
	     found_flag = 1;
	     break;
		}
	   }
	   else
	     break;
	   if(CORE_offset_add_32_With_EMPTY_CLUSTER_ALLOCATION(buf) == FAIL)
			return(FAIL);
	}while(1);
    if(found_flag)//找到指定数量的空ENTRY
	{ 
	 CORE.SectorNum = SectorNum_LOCAL; //置空ENTRY的首位置
     CORE.ClusterNum = ClusterNum_LOCAL;
     CORE.offset = Offset_LOCAL;
     break;
	}
	else if(CORE_offset_add_32_With_EMPTY_CLUSTER_ALLOCATION(buf) == FAIL)
	   return(FAIL);
  }   
 return(SUCC); 

}
/*===============================================================================
函数 
填写一个LFN directory entry
入口：u8 * Directory_Entry_buf,u8 * Entry_Name,u8 LFN_record_FLAG
      u8 Entry_Name,u8 checksum
出口：SUCC,FAIL
===============================================================================*/
static u8 Fill_LFN_Directory_Entry(u8 * Directory_Entry_buf,u8 * Entry_Name,u8 LFN_record_FLAG,u8 checksum)
{
  u8 i; 
  i = LengthofString(Entry_Name); 
  if(i < 12) 
  {
	  do{          //填写空白空间
		i++;
		if(i >= 13)
			break;
        Entry_Name[i] = 0xff;
	  }while(1);
  }
  Directory_Entry_buf[0] = LFN_record_FLAG;;
  //填写前5个字节
  for(i = 0;i < 5;i++)
  {
	Directory_Entry_buf[1 + i * 2] = Entry_Name[i];
	if(Entry_Name[i] != 0xff)
	  Directory_Entry_buf[2 + i * 2] = 0;
	else 
      Directory_Entry_buf[2 + i * 2] = 0xff;
  }
  Directory_Entry_buf[11] = ATTR_LONG_NAME; //0x0F, impossible file attribute used as signature
  Directory_Entry_buf[12] = 0;    //Reserved (?). Set to 0x00
  Directory_Entry_buf[13] = checksum;//填写校验和
  //填写中间6个字节
  for(i = 0;i < 6;i++)
  {
	Directory_Entry_buf[14 + i * 2] = Entry_Name[5 + i];
	if(Entry_Name[5 + i] != 0xff)
	  Directory_Entry_buf[15 + i * 2] = 0;
	else
      Directory_Entry_buf[15 + i * 2] = 0xff;
  }
  Directory_Entry_buf[26] = 0;  //First cluster number (always 0x0000 for long filename records)
  Directory_Entry_buf[27] = 0;
  //填写2个字节
  for(i = 0;i < 2;i++)
  {
	Directory_Entry_buf[28 + i * 2] = Entry_Name[11 + i];
	if(Entry_Name[11 + i] != 0xff)
	  Directory_Entry_buf[29 + i * 2] = 0;
	else
      Directory_Entry_buf[29 + i * 2] = 0xff;
  }
  return(SUCC);
}
/*===============================================================================
函数 
填写短文件directory entry
入口：u8 * Directory_Entry_buf,u8 * Entry_Name,u32 first_cluster,
      u32 FileSize,u8 attr
出口：SUCC,FAIL
===============================================================================*/
static u8 Fill_SFN_Directory_Entry(u8 * Directory_Entry_buf,u8 * Entry_Name,u32 first_cluster,u32 FileSize,u8 attr)
{
 u8 i,flag,j;
 for(i = 0;i < 11;i++)
   Directory_Entry_buf[i] = 0x20; 
  i = 0; 
  j = 0;
  flag = FILE_NAME;
  do{ //Directory_Entry分离取得Shortfile Entry name and file extension           
     if( ( * Entry_Name) != 0) 
       { 
        if( flag == FILE_NAME)
         {            
          if(*Entry_Name == '.')//遇到'.',转入填写File extension
             {
              flag  = FILE_EXTENSION;
			  Entry_Name++;
             }  
          else
            {
             Directory_Entry_buf[i] =  *Entry_Name;//填写Entry Name
             i++; 
             Entry_Name++;
			 if( i > 8 )
               break;
		  }
          }
        else if( flag  == FILE_EXTENSION)
         {
          if( j >= 3 )
            break;
           Directory_Entry_buf[8+j] =  *Entry_Name;//填写File extension
          j++;
          Entry_Name++;
         } 
      }
	  else
		 break;
 }while(1);
 Directory_Entry_buf[11] = attr;
 Directory_Entry_buf[12] = 0;
 Directory_Entry_buf[26] = (u8)(first_cluster & 0xff);  //填写首簇号
 Directory_Entry_buf[27] = (u8)((first_cluster >> 8) & 0xff);
 Directory_Entry_buf[28] = (u8)(FileSize & 0xff);////填写文件长度
 Directory_Entry_buf[29] = (u8)((FileSize >> 8) & 0xff);
 Directory_Entry_buf[30] = (u8)((FileSize >> 16) & 0xff);
 Directory_Entry_buf[31] = (u8)((FileSize >> 24) & 0xff);
 return(SUCC);
}
/*===============================================================================
函数 
把Longfilename Directory Entry转换为short filename
入口：Directory_Entry:Directory_Entry name,attr:attr of Directory_Entry
出口：SUCC,FAIL
===============================================================================*/
static u8 LFN_convert_to_SFN(u8 * Directory_Entry,u8 * SFN_Directory_Entry_buf)
{
 u8 i,flag,j;
 for(i = 0;i < 11;i++)
   SFN_Directory_Entry_buf[i] = 0x20; //初始化DIRECTORY ENTRY
  i = 0; 
  j = 0;
  flag = FILE_NAME;
  do{           
     if( ( * Directory_Entry) != 0) 
       { 
        if( flag == FILE_NAME)
         {            
          if(*Directory_Entry == '.')//遇到'.',转入填写File extension
             {
              flag  = FILE_EXTENSION;
			  Directory_Entry++;
             }  
          else
            {
             SFN_Directory_Entry_buf[i] =  *Directory_Entry;//填写Entry Name
             i++; 
			 if(i >= 6)
			 {
			  SFN_Directory_Entry_buf[i] = '~';
              SFN_Directory_Entry_buf[i+1] = '1';
              do{ 
			      if(*Directory_Entry == '.' || ( * Directory_Entry) == 0 )	  
				  {
				    flag  = FILE_EXTENSION;
				    break;
				  }
				  else
                    Directory_Entry++;
			  }while(1);
			 }
             Directory_Entry++;
            }
          }
        else if( flag  == FILE_EXTENSION)
         {
          if( j >= 3 )
            return(FAIL);//填写File extension
          SFN_Directory_Entry_buf[8+j] =  *Directory_Entry;
          j++;
          Directory_Entry++;
         } 
      }
	  else
		  return(SUCC);
 }while(1);
}

/*===============================================================================
函数 
将写Longfilename Directory Entry入磁盘
入口：Directory_Entry:Directory_Entry name,attr:attr of Directory_Entry
出口：SUCC,FAIL
===============================================================================*/
static u8 Write_LongFileName_Entry(u8 * Directory_Entry,u8 attr,u32 first_cluster,u8 * buf,u32 FileSize)
{
  u16 len;
  u8 i,checksum;
  u8 Directory_Entry_buf[32];
  u8 SN,LFN_record_FLAG;
  //计算需要的Directory_Entry空间，每个Directory_Entry空间为32个字节,计算结果放在len中
  len = LengthofString(Directory_Entry) / 13;
  if(LengthofString(Directory_Entry) % 13)
	len++;
  SN = len; 
  //从long-filename directory entry处理得其对应的short-filename directory entry
  LFN_convert_to_SFN(Directory_Entry,Directory_Entry_buf);
  //计算short-filename directory entry校验和
  checksum = calculate_checksum_longfilenameentry(Directory_Entry_buf);
  //处理last long-filename directory entry for file
  read_flash_sector(buf,CORE.SectorNum);    
  LFN_record_FLAG = SN | (u8)Last_LFN_Record;
  Fill_LFN_Directory_Entry(buf + CORE.offset,Directory_Entry + (len - 1) * 13,LFN_record_FLAG,checksum);
  len--;
  write_flash_sector(buf,CORE.SectorNum);
  CORE_offset_add_32(buf);
  LFN_record_FLAG = SN;
  //处理其它LFN directory entry
  //do{
  while(len){
   SN--;
   Directory_Entry[len * 13] = 0;
   Fill_LFN_Directory_Entry(buf + CORE.offset,Directory_Entry + (len - 1) * 13,SN,checksum);
   len--;
   write_flash_sector(buf,CORE.SectorNum);
   CORE_offset_add_32(buf);
  }

  
  //处理LFN 相应的short-filename directory entry
  Directory_Entry_buf[11] = attr;
  Directory_Entry_buf[12] = 0;
  Directory_Entry_buf[26] = (u8)(first_cluster & 0xff);  //填写首簇号
  Directory_Entry_buf[27] = (u8)((first_cluster >> 8) & 0xff);
  Directory_Entry_buf[28] = (u8)(FileSize & 0xff);////填写文件长度
  Directory_Entry_buf[29] = (u8)((FileSize >> 8) & 0xff);
  Directory_Entry_buf[30] = (u8)((FileSize >> 16) & 0xff);
  Directory_Entry_buf[31] = (u8)((FileSize >> 24) & 0xff); 
  for(i = 0;i < 32;i++)
	{
	  buf[CORE.offset + i] = Directory_Entry_buf[i];
	}
  write_flash_sector(buf,CORE.SectorNum);
  return(SUCC);
}
/*===============================================================================
函数 
添加Directory_Entry至目录
入口：Directory_Entry-
出口：SUCC,FAIL
===============================================================================*/
static u8 Add_A_Directory_Entry_(u8 * Directory_Entry,u8 attr,u32 first_cluster,u32 FileSize)
{
	u16 len;
	u8 buf[512];
	u8 Directory_Entry_buf[32];
	u8 temp,i;//,j;
    
	if(attr & ATTR_DIRECTORY)
	{//给新建的directory分配簇号再写入默认两个目录，“.”和“..”
	  u32 sector_local;
	  if( Allocate_An_Empty_cluster(&first_cluster,buf)== FAIL)
	  	  return(FAIL);
	  //初始化默认两个目录，目录名分别取名为“.”和“..”
	  sector_local =  FirstSectorofCluster(first_cluster);
      for(i = 0;i < 11;i++)
		 buf[i] = 0x20; 
	  buf[0] = '.';//填写目录名“.”
	  buf[11] = attr;
	  buf[12] = 0;
	  buf[26] = (u8)(first_cluster & 0xff);  //填写当前目录簇号
	  buf[27] = (u8)((first_cluster >> 8) & 0xff);
	  buf[28] = 0;////填写文件长度
	  buf[29] = 0;
	  buf[30] = 0;
	  buf[31] = 0;
      for(i = 0;i < 11;i++)
		 buf[i + 32] = 0x20; 
	  buf[32] = '.';   //填写目录名“..”
	  buf[33] = '.';
	  buf[32+11] = attr;
	  buf[32+12] = 0;
	  buf[32+26] = (u8)(CORE.ClusterNum & 0xff);  //填写当前目录父目录的首簇号
	  buf[32+27] = (u8)((CORE.ClusterNum >> 8) & 0xff);
	  buf[32+28] = 0;////填写文件长度
	  buf[32+29] = 0;
	  buf[32+30] = 0;
	  buf[32+31] = 0;
	  buf[64] = 0;
	  write_flash_sector(buf,sector_local);
	}
	//计算Directory_Entry需要多少个空间，Directory_Entry每个空间为32个字节,计算结果放在len中	
	len = LengthofString(Directory_Entry) / 13;
	if(LengthofString(Directory_Entry) % 13)
		len++;
	if(len > 1)
		len++;
	if(len == 1)
	{  
	   u8 count;
	   count = 0;
	   do{
		   if(Directory_Entry[count] == 0 || Directory_Entry[count] == '.')
			   break;
		   count++;
	   }while(1);
	   if(count > 8)
		   len = 2;
	
	}
	//寻找指定数量的空间
	if(Seek_Space_to_Write_Directory_Entry(len,buf) == SUCC)
	{ 
	  if(len == 1)  //写短文件名
	  {
		UPCASE(Directory_Entry);
		Fill_SFN_Directory_Entry(Directory_Entry_buf,Directory_Entry, first_cluster,FileSize,attr);
		read_flash_sector(buf,CORE.SectorNum);
		for(temp = 0;temp < 32;temp++)
		{ 
		  buf[CORE.offset + temp] = Directory_Entry_buf[temp];
		}
		write_flash_sector(buf,CORE.SectorNum);
		return(SUCC);
	  } 
	  else//写长文件名
	  { 
	 	  return(Write_LongFileName_Entry(Directory_Entry,attr,first_cluster,buf,FileSize));
	  }
	}
	else
	 return(FAIL);
}

/*===============================================================================
函数 
建立文件
入口：无
出口：无
===============================================================================*/  
#if complie_create_file
u8 create_file(u8 * filename)
{ 
 u16 len;
 u16 temp;
 u8 buf[260],status;
 stringcpy(filename,buf);
 CORE.FullPathType = FilePath;
 if(FullPathToSectorCluster(filename) != SUCC)  //检查文件是否已经存在
 {   //文件不存在,才可以建文件
     len = LengthofString(buf);
	 //从文件名中分离路径
     temp = len - 1;
     do{ 
         if(buf[temp] =='\\')
		  {
	        buf[temp] = 0;
			temp++;
	        break;
		  }	
	      if(!temp)
  	         break;
	      temp--;
	 }while(1);
     CORE.FullPathType = DirectoryPath; 
	 if(!temp)
	 {  //相