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<h2>FATFS</h2>
<p>The <tt>FATFS</tt> structure (filesystem object) holds dynamic work area of individual logical drives. It is given by application program and registerd/unregisterd to the FatFs module with <tt>f_mount</tt> function. Initialization of the structure is done by volume mount process whenever necessary. Application program must not modify any member in this structure, or the FAT volume can be collapsed.</p>
<pre>
<span class="k">typedef</span> <span class="k">struct</span> {
BYTE fs_type; <span class="c">/* FAT type (0, FS_FAT12, FS_FAT16, FS_FAT32 or FS_EXFAT) */</span>
BYTE pdrv; <span class="c">/* Hosting physical drive of this volume */</span>
BYTE n_fats; <span class="c">/* Number of FAT copies (1,2) */</span>
BYTE wflag; <span class="c">/* win[] flag (b0:win[] is dirty) */</span>
BYTE fsi_flag; <span class="c">/* FSINFO flags (b7:Disabled, b0:Dirty) */</span>
WORD id; <span class="c">/* Volume mount ID */</span>
WORD n_rootdir; <span class="c">/* Number of root directory entries (FAT12/16) */</span>
WORD csize; <span class="c">/* Sectors per cluster */</span>
<span class="k">#if</span> FF_MAX_SS != FF_MIN_SS
WORD ssize; <span class="c">/* Sector size (512,1024,2048 or 4096) */</span>
<span class="k">#endif</span>
<span class="k">#if FF_FS_EXFAT</span>
BYTE* dirbuf; <span class="c">/* Directory entry block scratchpad buffer */</span>
<span class="k">#endif</span>
<span class="k">#if</span> FF_FS_REENTRANT
FF_SYNC_t sobj; <span class="c">/* Identifier of sync object */</span>
<span class="k">#endif</span>
<span class="k">#if</span> !FF_FS_READONLY
DWORD last_clust; <span class="c">/* FSINFO: Last allocated cluster (0xFFFFFFFF if invalid) */</span>
DWORD free_clust; <span class="c">/* FSINFO: Number of free clusters (0xFFFFFFFF if invalid) */</span>
<span class="k">#endif</span>
<span class="k">#if</span> FF_FS_RPATH
DWORD cdir; <span class="c">/* Cluster number of current directory (0:root) */</span>
<span class="k">#if FF_FS_EXFAT</span>
DWORD cdc_scl; <span class="c">/* Containing directory start cluster (invalid when cdir is 0) */</span>
DWORD cdc_size; <span class="c">/* b31-b8:Size of containing directory, b7-b0: Chain status */</span>
DWORD cdc_ofs; <span class="c">/* Offset in the containing directory (invalid when cdir is 0) */</span>
<span class="k">#endif</span>
<span class="k">#endif</span>
DWORD n_fatent; <span class="c">/* Number of FAT entries (Number of clusters + 2) */</span>
DWORD fsize; <span class="c">/* Sectors per FAT */</span>
DWORD volbase; <span class="c">/* Volume base LBA */</span>
DWORD fatbase; <span class="c">/* FAT base LBA */</span>
DWORD dirbase; <span class="c">/* Root directory base (LBA|Cluster) */</span>
DWORD database; <span class="c">/* Data base LBA */</span>
DWORD winsect; <span class="c">/* Sector LBA appearing in the win[] */</span>
BYTE win[FF_MAX_SS]; <span class="c">/* Disk access window for directory, FAT (and file data at tiny cfg) */</span>
} FATFS;
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