---

/fat.h

Go to the documentation of this file.

/*! \file fat.h \brief FAT16/32 file system driver. */
//*****************************************************************************
//
// File Name    : 'fat.h'
// Title        : FAT16/32 file system driver
// Author       : Pascal Stang
// Date         : 11/07/2000
// Revised      : 12/12/2000
// Version      : 0.3
// Target MCU   : ATmega103 (should work for Atmel AVR Series)
// Editor Tabs  : 4
//
// NOTE: This code is currently below version 1.0, and therefore is considered
// to be lacking in some functionality or documentation, or may not be fully
// tested.  Nonetheless, you can expect most functions to work.
//
// This code is distributed under the GNU Public License
//      which can be found at http://www.gnu.org/licenses/gpl.txt
//
//*****************************************************************************

#ifndef FAT_H
#define FAT_H

#include "global.h"


// Some useful cluster numbers
#define MSDOSFSROOT     0               // cluster 0 means the root dir
#define CLUST_FREE      0               // cluster 0 also means a free cluster
#define MSDOSFSFREE     CLUST_FREE
#define CLUST_FIRST     2               // first legal cluster number
#define CLUST_RSRVD     0xfffffff6      // reserved cluster range
#define CLUST_BAD       0xfffffff7      // a cluster with a defect
#define CLUST_EOFS      0xfffffff8      // start of eof cluster range
#define CLUST_EOFE      0xffffffff      // end of eof cluster range

#define FAT12_MASK      0x00000fff      // mask for 12 bit cluster numbers
#define FAT16_MASK      0x0000ffff      // mask for 16 bit cluster numbers
#define FAT32_MASK      0x0fffffff      // mask for FAT32 cluster numbers


// Partition Type used in the partition record
#define PART_TYPE_UNKNOWN       0x00
#define PART_TYPE_FAT12         0x01
#define PART_TYPE_XENIX         0x02
#define PART_TYPE_DOSFAT16      0x04
#define PART_TYPE_EXTDOS        0x05
#define PART_TYPE_FAT16         0x06
#define PART_TYPE_NTFS          0x07
#define PART_TYPE_FAT32         0x0B
#define PART_TYPE_FAT32LBA      0x0C
#define PART_TYPE_FAT16LBA      0x0E
#define PART_TYPE_EXTDOSLBA     0x0F
#define PART_TYPE_ONTRACK       0x33
#define PART_TYPE_NOVELL        0x40
#define PART_TYPE_PCIX          0x4B
#define PART_TYPE_PHOENIXSAVE   0xA0
#define PART_TYPE_CPM           0xDB
#define PART_TYPE_DBFS          0xE0
#define PART_TYPE_BBT           0xFF

struct partrecord // length 16 bytes
{           
    BYTE    prIsActive;                 // 0x80 indicates active partition
    BYTE    prStartHead;                // starting head for partition
    WORD    prStartCylSect;             // starting cylinder and sector
    BYTE    prPartType;                 // partition type (see above)
    BYTE    prEndHead;                  // ending head for this partition
    WORD    prEndCylSect;               // ending cylinder and sector
    DWORD   prStartLBA;                 // first LBA sector for this partition
    DWORD   prSize;                     // size of this partition (bytes or sectors ?)
};

        
struct partsector
{
    CHAR    psPartCode[512-64-2];       // pad so struct is 512b
    BYTE    psPart[64];                 // four partition records (64 bytes)
    BYTE    psBootSectSig0;             // two signature bytes (2 bytes)
    BYTE    psBootSectSig1;
#define BOOTSIG0        0x55
#define BOOTSIG1        0xaa
};



// Format of a boot sector.  This is the first sector on a DOS floppy disk
// or the first sector of a partition on a hard disk.  But, it is not the
// first sector of a partitioned hard disk.
struct bootsector33 {
    BYTE    bsJump[3];                  // jump inst E9xxxx or EBxx90
    CHAR    bsOemName[8];               // OEM name and version
    CHAR    bsBPB[19];                  // BIOS parameter block
    CHAR    bsDriveNumber;              // drive number (0x80)
    CHAR    bsBootCode[479];            // pad so struct is 512b
    BYTE    bsBootSectSig0;             // boot sector signature byte 0x55
    BYTE    bsBootSectSig1;             // boot sector signature byte 0xAA
#define BOOTSIG0        0x55
#define BOOTSIG1        0xaa
};

struct extboot {
    CHAR    exDriveNumber;              // drive number (0x80)
    CHAR    exReserved1;                // reserved
    CHAR    exBootSignature;            // ext. boot signature (0x29)
#define EXBOOTSIG       0x29
    CHAR    exVolumeID[4];              // volume ID number
    CHAR    exVolumeLabel[11];          // volume label
    CHAR    exFileSysType[8];           // fs type (FAT12 or FAT16)
};

struct bootsector50 {
    BYTE    bsJump[3];                  // jump inst E9xxxx or EBxx90
    CHAR    bsOemName[8];               // OEM name and version
    CHAR    bsBPB[25];                  // BIOS parameter block
    CHAR    bsExt[26];                  // Bootsector Extension
    CHAR    bsBootCode[448];            // pad so structure is 512b
    BYTE    bsBootSectSig0;             // boot sector signature byte 0x55 
    BYTE    bsBootSectSig1;             // boot sector signature byte 0xAA
#define BOOTSIG0        0x55
#define BOOTSIG1        0xaa
};

struct bootsector710 {
    BYTE    bsJump[3];                  // jump inst E9xxxx or EBxx90
    CHAR    bsOEMName[8];               // OEM name and version
    CHAR    bsBPB[53];                  // BIOS parameter block
    CHAR    bsExt[26];                  // Bootsector Extension
    CHAR    bsBootCode[418];            // pad so structure is 512b
    BYTE    bsBootSectSig2;             // 2 & 3 are only defined for FAT32?
    BYTE    bsBootSectSig3;
    BYTE    bsBootSectSig0;             // boot sector signature byte 0x55
    BYTE    bsBootSectSig1;             // boot sector signature byte 0xAA
#define BOOTSIG0        0x55
#define BOOTSIG1        0xaa
#define BOOTSIG2        0
#define BOOTSIG3        0
};


/***************************************************************/
/***************************************************************/

// BIOS Parameter Block (BPB) for DOS 3.3
struct bpb33 {
        WORD    bpbBytesPerSec; // bytes per sector
        BYTE    bpbSecPerClust; // sectors per cluster
        WORD    bpbResSectors;  // number of reserved sectors
        BYTE    bpbFATs;        // number of FATs
        WORD    bpbRootDirEnts; // number of root directory entries
        WORD    bpbSectors;     // total number of sectors
        BYTE    bpbMedia;       // media descriptor
        WORD    bpbFATsecs;     // number of sectors per FAT
        WORD    bpbSecPerTrack; // sectors per track
        WORD    bpbHeads;       // number of heads
        WORD    bpbHiddenSecs;  // number of hidden sectors
};

// BPB for DOS 5.0
// The difference is bpbHiddenSecs is a short for DOS 3.3,
// and bpbHugeSectors is not present in the DOS 3.3 bpb.
struct bpb50 {
        WORD    bpbBytesPerSec; // bytes per sector
        BYTE    bpbSecPerClust; // sectors per cluster
        WORD    bpbResSectors;  // number of reserved sectors
        BYTE    bpbFATs;        // number of FATs
        WORD    bpbRootDirEnts; // number of root directory entries
        WORD    bpbSectors;     // total number of sectors
        BYTE    bpbMedia;       // media descriptor
        WORD    bpbFATsecs;     // number of sectors per FAT
        WORD    bpbSecPerTrack; // sectors per track
        WORD    bpbHeads;       // number of heads
        DWORD   bpbHiddenSecs;  // # of hidden sectors
// 3.3 compat ends here
        DWORD   bpbHugeSectors; // # of sectors if bpbSectors == 0
};

// BPB for DOS 7.10 (FAT32)
// This one has a few extensions to bpb50.
struct bpb710 {
        WORD    bpbBytesPerSec; // bytes per sector
        BYTE    bpbSecPerClust; // sectors per cluster
        WORD    bpbResSectors;  // number of reserved sectors
        BYTE    bpbFATs;        // number of FATs
        WORD    bpbRootDirEnts; // number of root directory entries
        WORD    bpbSectors;     // total number of sectors
        BYTE    bpbMedia;       // media descriptor
        WORD    bpbFATsecs;     // number of sectors per FAT
        WORD    bpbSecPerTrack; // sectors per track
        WORD    bpbHeads;       // number of heads
        DWORD   bpbHiddenSecs;  // # of hidden sectors
// 3.3 compat ends here
        DWORD   bpbHugeSectors; // # of sectors if bpbSectors == 0
// 5.0 compat ends here
        DWORD     bpbBigFATsecs;// like bpbFATsecs for FAT32
        WORD      bpbExtFlags;  // extended flags:
#define FATNUM    0xf           // mask for numbering active FAT
#define FATMIRROR 0x80          // FAT is mirrored (like it always was)
        WORD      bpbFSVers;    // filesystem version
#define FSVERS    0             // currently only 0 is understood
        DWORD     bpbRootClust; // start cluster for root directory
        WORD      bpbFSInfo;    // filesystem info structure sector
        WORD      bpbBackup;    // backup boot sector
        // There is a 12 byte filler here, but we ignore it
};




// ***************************************************************
// * byte versions of the above structs                          *
// ***************************************************************


// BIOS Parameter Block (BPB) for DOS 3.3
struct byte_bpb33 {
        CHAR bpbBytesPerSec[2];     // bytes per sector
        CHAR bpbSecPerClust;        // sectors per cluster
        CHAR bpbResSectors[2];      // number of reserved sectors
        CHAR bpbFATs;               // number of FATs
        CHAR bpbRootDirEnts[2];     // number of root directory entries
        CHAR bpbSectors[2];         // total number of sectors
        CHAR bpbMedia;              // media descriptor
        CHAR bpbFATsecs[2];         // number of sectors per FAT
        CHAR bpbSecPerTrack[2];     // sectors per track
        CHAR bpbHeads[2];           // number of heads
        CHAR bpbHiddenSecs[2];      // number of hidden sectors
};

// BPB for DOS 5.0
// The difference is bpbHiddenSecs is a short for DOS 3.3,
// and bpbHugeSectors is not in the 3.3 bpb.
struct byte_bpb50 {
        CHAR bpbBytesPerSec[2];     // bytes per sector
        CHAR bpbSecPerClust;        // sectors per cluster
        CHAR bpbResSectors[2];      // number of reserved sectors
        CHAR bpbFATs;               // number of FATs
        CHAR bpbRootDirEnts[2];     // number of root directory entries
        CHAR bpbSectors[2];         // total number of sectors
        CHAR bpbMedia;              // media descriptor
        CHAR bpbFATsecs[2];         // number of sectors per FAT
        CHAR bpbSecPerTrack[2];     // sectors per track
        CHAR bpbHeads[2];           // number of heads
        CHAR bpbHiddenSecs[4];      // number of hidden sectors
        CHAR bpbHugeSectors[4];     // # of sectors if bpbSectors == 0
};

// BPB for DOS 7.10 (FAT32).
// This one has a few extensions to bpb50.
struct byte_bpb710 {
        BYTE bpbBytesPerSec[2];     // bytes per sector
        BYTE bpbSecPerClust;        // sectors per cluster
        BYTE bpbResSectors[2];      // number of reserved sectors
        BYTE bpbFATs;               // number of FATs
        BYTE bpbRootDirEnts[2];     // number of root directory entries
        BYTE bpbSectors[2];         // total number of sectors
        BYTE bpbMedia;              // media descriptor
        BYTE bpbFATsecs[2];         // number of sectors per FAT
        BYTE bpbSecPerTrack[2];     // sectors per track
        BYTE bpbHeads[2];           // number of heads
        BYTE bpbHiddenSecs[4];      // # of hidden sectors
        BYTE bpbHugeSectors[4];     // # of sectors if bpbSectors == 0
        BYTE bpbBigFATsecs[4];      // like bpbFATsecs for FAT32
        BYTE bpbExtFlags[2];        // extended flags:
        BYTE bpbFSVers[2];          // filesystem version
        BYTE bpbRootClust[4];       // start cluster for root directory
        BYTE bpbFSInfo[2];          // filesystem info structure sector
        BYTE bpbBackup[2];          // backup boot sector
        // There is a 12 byte filler here, but we ignore it
};

// FAT32 FSInfo block.
struct fsinfo {
        BYTE fsisig1[4];
        BYTE fsifill1[480];
        BYTE fsisig2[4];
        BYTE fsinfree[4];
        BYTE fsinxtfree[4];
        BYTE fsifill2[12];
        BYTE fsisig3[4];
        BYTE fsifill3[508];
        BYTE fsisig4[4];
};


/***************************************************************/
/***************************************************************/


// Structure of a dos directory entry.
struct direntry {
        BYTE        deName[8];      // filename, blank filled
#define SLOT_EMPTY      0x00            // slot has never been used
#define SLOT_E5         0x05            // the real value is 0xe5
#define SLOT_DELETED    0xe5            // file in this slot deleted
        BYTE        deExtension[3]; // extension, blank filled
        BYTE        deAttributes;   // file attributes
#define ATTR_NORMAL     0x00            // normal file
#define ATTR_READONLY   0x01            // file is readonly
#define ATTR_HIDDEN     0x02            // file is hidden
#define ATTR_SYSTEM     0x04            // file is a system file
#define ATTR_VOLUME     0x08            // entry is a volume label
#define ATTR_LONG_FILENAME  0x0f        // this is a long filename entry                
#define ATTR_DIRECTORY  0x10            // entry is a directory name
#define ATTR_ARCHIVE    0x20            // file is new or modified
        BYTE        deLowerCase;    // NT VFAT lower case flags
#define LCASE_BASE      0x08            // filename base in lower case
#define LCASE_EXT       0x10            // filename extension in lower case
        BYTE        deCHundredth;   // hundredth of seconds in CTime
        BYTE        deCTime[2];     // create time
        BYTE        deCDate[2];     // create date
        BYTE        deADate[2];     // access date
        WORD        deHighClust;    // high bytes of cluster number
        BYTE        deMTime[2];     // last update time
        BYTE        deMDate[2];     // last update date
        WORD        deStartCluster; // starting cluster of file
        DWORD       deFileSize;     // size of file in bytes
};

// number of directory entries in one sector
#define DIRENTRIES_PER_SECTOR   0x10

// Structure of a Win95 long name directory entry
struct winentry {
        BYTE        weCnt;
#define WIN_LAST        0x40
#define WIN_CNT         0x3f
        BYTE        wePart1[10];
        BYTE        weAttributes;
#define ATTR_WIN95      0x0f
        BYTE        weReserved1;
        BYTE        weChksum;
        BYTE        wePart2[12];
        WORD        weReserved2;
        BYTE        wePart3[4];
};

#define WIN_CHARS   13      // Number of chars per winentry

// Maximum filename length in Win95
// Note: Must be < sizeof(dirent.d_name)
#define WIN_MAXLEN      255

// This is the format of the contents of the deTime field in the direntry
// structure.
// We don't use bitfields because we don't know how compilers for
// arbitrary machines will lay them out.
#define DT_2SECONDS_MASK        0x1F    // seconds divided by 2
#define DT_2SECONDS_SHIFT       0
#define DT_MINUTES_MASK         0x7E0   // minutes
#define DT_MINUTES_SHIFT        5
#define DT_HOURS_MASK           0xF800  // hours
#define DT_HOURS_SHIFT          11

// This is the format of the contents of the deDate field in the direntry
// structure.
#define DD_DAY_MASK             0x1F    // day of month
#define DD_DAY_SHIFT            0
#define DD_MONTH_MASK           0x1E0   // month
#define DD_MONTH_SHIFT          5
#define DD_YEAR_MASK            0xFE00  // year - 1980
#define DD_YEAR_SHIFT           9

// Prototypes
unsigned char fatInit( unsigned char device);
unsigned int fatClusterSize(void);
unsigned long fatGetDirEntry(unsigned int entry, unsigned int count);
unsigned long fatGetFilesize(void);
char* fatGetFilename(void);
char* fatGetDirname(void);
void fatLoadCluster(unsigned long cluster, unsigned char *buffer);
unsigned long fatNextCluster(unsigned long cluster);

#endif

---