fat.c

D12 的源代码

/*_____ V A R I A B L E __________________________________________________*/
bdata  bit     dir_is_root;     /* TRUE: point the root directory  */
//bdata  bit     fat_open_mode;        // READ or WRITE 

data   Byte    fat_cluster_size; /* cluster size (sector count) */
data   Byte    fat_cluster_mask; /* mask for end of cluster test */

//xdata  char    ext[3];           /* file extension (limited to 3 characters) */
xdata  Uint32  fat_nb_sector;
xdata  Uint32  fat_hidden_sector;
xdata  Byte    fat_sector_per_track;
xdata  Byte    fat_end_head;
xdata  Uint16  fat_end_cylinder;
xdata  Uint32  fat_ptr_fats;    /* address of the first byte of FAT */
xdata  Uint32  fat_ptr_rdir;    /* address of the first byte of root dir */
xdata  Uint32  fat_ptr_data;    /* address of the first byte of data */

xdata  Uint16  nb_reserved_sector;
/*F**************************************************************************
* NAME: fat_format
 PURPOSE:
*   Create single FAT12 or FAT16 partition and format the selected memory 
*/
void fat_format ()
{
  #define WAV_CLUST_SIZE  (Uint16)((WAV_SECTOR_SIZE) / fat_cluster_size)
  #define FORMAT_NB_CYLINDER            (*tab).nb_cylinder
  #define FORMAT_NB_HEAD                (*tab).nb_head
  #define FORMAT_NB_SECTOR              (*tab).nb_sector
  #define FORMAT_NB_HIDDEN_SECTOR       (*tab).nb_hidden_sector
  #define FORMAT_NB_SECTOR_PER_CLUSTER  (*tab).nb_sector_per_cluster

Byte i, j;
Uint32 nb_total_sectors;
Uint32 temp;
Uint16 nb_sector_fat;
s_format  code  *tab;

	tab = Hard_format();
	fat_cluster_size = FORMAT_NB_SECTOR_PER_CLUSTER;
	nb_total_sectors = (Uint32)FORMAT_NB_CYLINDER * ((Uint16)FORMAT_NB_HEAD * FORMAT_NB_SECTOR);
 
  // FAT type caculation 
	fat_is_fat16 = ((nb_total_sectors  / fat_cluster_size) > MAX_CLUSTERS12);

  // -- MASTER BOOT RECORD -- 
	Hard_write_open(0x00);

	for (i = 446/2; i != 0; i--)              // Boot Code 
	{
		Hard_write_byte(0x00);
		Hard_write_byte(0x00);
	}


  // First Partition entry 
i=0;
	gl_buffer[i++]=0x80;                    // Default Boot Partition 
  	gl_buffer[i++]=(Byte)(FORMAT_NB_HIDDEN_SECTOR / FORMAT_NB_SECTOR);       // Start head 
  	gl_buffer[i++]=(Byte)((FORMAT_NB_HIDDEN_SECTOR % FORMAT_NB_SECTOR) + 1); // Start Sector 
  	gl_buffer[i++]=0x00;                    // Start Cylinder 
	if (fat_is_fat16)
	{
//    if (nb_total_sectors > 0xFFFF)          // Total Sectors 
		if((((Byte *)&nb_total_sectors)[0]!=0)||(((Byte *)&nb_total_sectors)[1]!=0))
		{
      	gl_buffer[i++]=FAT16_SUP32M;        // FAT16 > 32 Mbytes 
		}
		else
		{
      	gl_buffer[i++]=FAT16_INF32M;        // FAT16 < 32 Mbytes 
		}
	}
	else
	{
		gl_buffer[i++]=FAT12;                 // FAT12 
	}
  	gl_buffer[i++]=(Byte)(FORMAT_NB_HEAD - 1); // Endhead-Zero-based(0)head number 
  	gl_buffer[i++]=(Byte)((((FORMAT_NB_CYLINDER - 1) / 0x04) & 0xC0) +  FORMAT_NB_SECTOR);  
                                                            // EndSector-Zero-based(1) sector number 
  	gl_buffer[i++]=(Byte)((FORMAT_NB_CYLINDER - 1) & 0xFF); // EndCylinder 
  	gl_buffer[i++]=(Byte)(FORMAT_NB_HIDDEN_SECTOR );        // Start sector
  	gl_buffer[i++]=0x00;
  	gl_buffer[i++]=0x00;
  	gl_buffer[i++]=0x00;
  
	temp = nb_total_sectors - FORMAT_NB_HIDDEN_SECTOR;
	gl_buffer[i++] = ((Byte *)&temp)[3];
	gl_buffer[i++] = ((Byte *)&temp)[2];
	gl_buffer[i++] = ((Byte *)&temp)[1];
	gl_buffer[i++] = ((Byte *)&temp)[0];


	for(j=0;j<48;j++)	gl_buffer[i++]=0x00;

	gl_buffer[i++]=0x55;                    // Signature Word 
	gl_buffer[i++]=0xAA;


	j=0;
	for (; i != 0; i--)              // Boot Code 
	{
		Hard_write_byte(gl_buffer[j++]);
	}

  // -- HIDDEN SECTORS -- 
  for (j = FORMAT_NB_HIDDEN_SECTOR - 1; j != 0; j--)
  {
    for (i = (SECTOR_SIZE / 4); i != 0; i--)
    {
      Hard_write_byte(0x00);
      Hard_write_byte(0x00);
      Hard_write_byte(0x00);
      Hard_write_byte(0x00);
    }
  }
 

  // -- PARTITION BOOT RECORD -- 
i=0;

	gl_buffer[i++]=0xEB;                    // JMP inst to PBR boot code 
  	gl_buffer[i++]=0x3C;
  	gl_buffer[i++]=0x90;
  	gl_buffer[i++]='O';                     // OEM name 
  	gl_buffer[i++]='E';
  	gl_buffer[i++]='M';
  	gl_buffer[i++]=' ';
  	gl_buffer[i++]='N';
  	gl_buffer[i++]='A';
  	gl_buffer[i++]='M';
  	gl_buffer[i++]='E';
  	gl_buffer[i++]=(Byte)SECTOR_SIZE;             // number of bytes per sector 
  	gl_buffer[i++]=(Byte)(SECTOR_SIZE >> 8);
  	gl_buffer[i++]=fat_cluster_size;        // Number of sector per cluster 
  	gl_buffer[i++]=(Byte)nb_reserved_sector;             // number of reserved sector 
  	gl_buffer[i++]=(Byte)(nb_reserved_sector >> 8);
  	gl_buffer[i++]=NB_FATS;                 // Number of FAT 
  	gl_buffer[i++]=(Byte)NB_ROOT_ENTRY;           // number of root directory entries 
  	gl_buffer[i++]=(Byte)(NB_ROOT_ENTRY >> 8);
                                                            
//  if (nb_total_sectors > 0xFFFF)            // Total Sectors 
	if((((Byte *)&nb_total_sectors)[0]!=0)||(((Byte *)&nb_total_sectors)[1]!=0))
  {
    	gl_buffer[i++]=0x00;
    	gl_buffer[i++]=0x00;
  }
  else
  {
		gl_buffer[i++] = ((Byte *)&temp)[3];
		gl_buffer[i++] = ((Byte *)&temp)[2];

  }

  	gl_buffer[i++]=HARD_DISK;               // Media Byte 
  // Number of sector in each FAT 

	if (fat_is_fat16) 
	{
		nb_sector_fat = ((temp / fat_cluster_size) * 2 / 512) + 1;
	}
	else
	{
		nb_sector_fat = ((temp / fat_cluster_size) * 3 / 1024) + 1;
	}

  	gl_buffer[i++]=(Byte)(nb_sector_fat);
  	gl_buffer[i++]=(Byte)(nb_sector_fat >> 8);
  	gl_buffer[i++]=(Byte)(FORMAT_NB_SECTOR);              // Number of sectors on a track 
  	gl_buffer[i++]=(Byte)(FORMAT_NB_SECTOR >> 8);
  	gl_buffer[i++]=(Byte)(FORMAT_NB_HEAD);                // Number of heads 
  	gl_buffer[i++]=(Byte)(FORMAT_NB_HEAD >> 8);

	gl_buffer[i++]=(Byte)(FORMAT_NB_HIDDEN_SECTOR);       // Number of hidden sectors 
  	gl_buffer[i++]=(Byte)(FORMAT_NB_HIDDEN_SECTOR >> 8);
  	gl_buffer[i++]=(Byte)(FORMAT_NB_HIDDEN_SECTOR >> 16);
  	gl_buffer[i++]=(Byte)(FORMAT_NB_HIDDEN_SECTOR >> 24);

//  if (nb_total_sectors > 0xFFFF)
	if((((Byte *)&nb_total_sectors)[0]!=0)||(((Byte *)&nb_total_sectors)[1]!=0))
  { // number of sectors > 65535 
		gl_buffer[i++] = ((Byte *)&temp)[3];
		gl_buffer[i++] = ((Byte *)&temp)[2];
		gl_buffer[i++] = ((Byte *)&temp)[1];
		gl_buffer[i++] = ((Byte *)&temp)[0];

  }
  else
  { // number of sectors < 65535 
    	gl_buffer[i++]=0x00;
    	gl_buffer[i++]=0x00;
    	gl_buffer[i++]=0x00;
    	gl_buffer[i++]=0x00;
  }
  	gl_buffer[i++]=FAT_DRIVE_NUMBER;        // Driver number  
  	gl_buffer[i++]=0x00;                    // not used 
  	gl_buffer[i++]=FAT_EXT_SIGN;            // extended boot signature 
  	gl_buffer[i++]=0x00;                    // volume ID 
  	gl_buffer[i++]=0x00;
  	gl_buffer[i++]=0x00;
  	gl_buffer[i++]=0x00;
  	gl_buffer[i++]='N';                     // Volume Label 
  	gl_buffer[i++]='O';
  	gl_buffer[i++]=' ';
  	gl_buffer[i++]='N';
  	gl_buffer[i++]='A';
  	gl_buffer[i++]='M';
  	gl_buffer[i++]='E';
  	gl_buffer[i++]=' ';
  	gl_buffer[i++]=' ';
  	gl_buffer[i++]=' ';
  	gl_buffer[i++]=' ';
  	gl_buffer[i++]='F';                     // File System Type in ASCII 
  	gl_buffer[i++]='A';
  	gl_buffer[i++]='T';
  	gl_buffer[i++]='1';
  if (fat_is_fat16)
  {
    	gl_buffer[i++]='6';
  }
  else
  {
    	gl_buffer[i++]='2';
  }
  	gl_buffer[i++]=' ';
  	gl_buffer[i++]=' ';
  	gl_buffer[i++]=' ';

	j=0;
	for (; i != 0; i--)              // Boot Code 
	{
		Hard_write_byte(gl_buffer[j++]);
	}

	for (i = 448/2; i != 0; i--)              // Boot Code 
	{
		Hard_write_byte(0x00);
   	Hard_write_byte(0x00);
	}
	Hard_write_byte(0x55);                    // Signature word 
	Hard_write_byte(0xAA);

  for (j = (nb_reserved_sector-1); j != 0 ; j--)
  {
    for (i = 128; i != 0; i--)
    {
      Hard_write_byte(0x00);
      Hard_write_byte(0x00);
      Hard_write_byte(0x00);
      Hard_write_byte(0x00);
    }
  }

  //------------------
  // -- FATS -- 
  // -- FAT 1 -- 
  Hard_write_byte(0xF8);                    // reserved clusters 0 & 1 
  Hard_write_byte(0xFF);
  Hard_write_byte(0xFF);
  if (fat_is_fat16)
  { // FAT16 
    Hard_write_byte(0xFF);
  }
  else
  { // FAT12 
    Hard_write_byte(0x00);
  }
  // free clusters in first FAT sector 
  for (i = (SECTOR_SIZE - 4) / 2; i != 0; i--)
  {
    Hard_write_byte(0x00);
    Hard_write_byte(0x00);
  }
  // free clusters in other FAT sectors 
  for (j = nb_sector_fat - 1; j != 0; j--)
  {
    for (i = SECTOR_SIZE / 4; i != 0; i--)
    {
      Hard_write_byte(0x00);
      Hard_write_byte(0x00);
      Hard_write_byte(0x00);
      Hard_write_byte(0x00);
    }
  }

  // -- FAT 2 -- 
  Hard_write_byte(0xF8);                    // reserved clusters 0 & 1 
  Hard_write_byte(0xFF);
  Hard_write_byte(0xFF);
  if (fat_is_fat16)
  { // FAT16 
    Hard_write_byte(0xFF);
  }
  else
  { // FAT12 
    Hard_write_byte(0x00);
  }
  // free clusters in first FAT sector 
  for (i = (SECTOR_SIZE - 4) / 2; i != 0; i--)
  {
    Hard_write_byte(0x00);
    Hard_write_byte(0x00);
  }
  // free clusters in other FAT sectors 
  for (j = nb_sector_fat - 1; j != 0; j--)
  {
    for (i = SECTOR_SIZE / 4; i != 0; i--)
    {
      Hard_write_byte(0x00);
      Hard_write_byte(0x00);
      Hard_write_byte(0x00);
      Hard_write_byte(0x00);
    }
  }


  // -- ROOT DIRECTORY ENTRIES -- 
  for (j = NB_ROOT_ENTRY / 4; j != 0 ; j--)
  {
    for (i = DIR_SIZE; i != 0; i--)
    {
      Hard_write_byte(0x00);
      Hard_write_byte(0x00);
      Hard_write_byte(0x00);
      Hard_write_byte(0x00);
    }
  }
  Hard_write_close();
}