FIL

The FIL structure (file object) holds state of a file. It is created by f_open function and discarded by f_close function. There is no member that can be changed by the application program.

FatFs

typedef struct _FIL {
    WORD    id;             /* Owner file system mount ID (inverted) */
    BYTE    flag;           /* File status flags */
    BYTE    sect_clust;     /* Left sectors in cluster */
    FATFS*  fs;             /* Pointer to the owner file system object */
    DWORD   fptr;           /* File R/W pointer */
    DWORD   fsize;          /* File size */
    DWORD   org_clust;      /* File start cluster */
    DWORD   curr_clust;     /* Current cluster */
    DWORD   curr_sect;      /* Current sector */
    DWORD   dir_sect;       /* Sector containing the directory entry */
    BYTE*   dir_ptr;        /* Ponter to the directory entry in the window */
    BYTE    buffer[512];    /* File R/W buffer */
} FIL;

Tiny-FatFs

typedef struct _FIL {
    WORD    id;             /* Owner file system mount ID (inverted) */
    BYTE    flag;           /* File status flags */
    BYTE    sect_clust;     /* Left sectors in cluster */
    FATFS*  fs;             /* Pointer to owner file system */
    DWORD   fptr;           /* File R/W pointer */
    DWORD   fsize;          /* File size */
    CLUST   org_clust;      /* File start cluster */
    CLUST   curr_clust;     /* Current cluster */
    DWORD   curr_sect;      /* Current sector */
    DWORD   dir_sect;       /* Sector containing the directory entry */
    BYTE*   dir_ptr;        /* Ponter to the directory entry in the window */
} FIL;