# Configuration Options

There are many options to configure the features of FatFs for various requirements of each project. The configuration options are defined in `ffconf.h`.

- Function Configurations
  - FF_FS_READONLY
  - FF_FS_MINIMIZE
  - FF_USE_FIND
  - FF_USE_MKFS
  - FF_USE_FASTSEEK
  - FF_USE_EXPAND
  - FF_USE_CHMOD
  - FF_USE_LABEL
  - FF_USE_FORWARD
  - FF_USE_STRFUNC
  - FF_PRINT_LLI
  - FF_PRINT_FLOAT
  - FF_STRF_ENCODE
- Namespace and Locale Configurations
  - FF_CODE_PAGE
  - FF_USE_LFN
  - FF_MAX_LFN
  - FF_LFN_UNICODE
  - FF_LFN_BUF, FF_SFN_BUF
  - FF_FS_RPATH
- Volume/Drive Configurations
  - FF_VOLUMES
  - FF_STR_VOLUME_ID
  - FF_VOLUME_STRS
  - FF_MULTI_PARTITION
  - FF_MIN_SS, FF_MAX_SS
  - FF_LBA64
  - FF_GPT_MIN
  - FF_USE_TRIM
- System Configurations
  - FF_FS_TINY
  - FF_FS_EXFAT
  - FF_FS_NORTC
  - FF_NORTC_MON, FF_NORTC_MDAY, FF_NORTC_YEAR
  - FF_FS_NOFSINFO
  - FF_FS_LOCK
  - FF_FS_REENTRANT
  - FF_FS_TIMEOUT
  - FF_SYNC_t

### Function Configurations

#### FF_FS_READONLY

Read/Write (0) or Read-only (1). Read-only configuration removes writing API functions, `f_write`, `f_sync`, `f_unlink`, `f_mkdir`, `f_chmod`, `f_rename`, `f_truncate`, `f_getfree` and optional writing functions as well.

#### FF_FS_MINIMIZE

This option defines minimization level to remove some basic API functions as follows:

Value | Description
--- | ---
0 | All basic API functions are available.
1 | `f_stat`, `f_getfree`, `f_unlink`, `f_mkdir`, `f_chmod`, `f_utime`, `f_truncate` and `f_rename` function are removed.
2 | `f_opendir`, `f_readdir` and `f_closedir` function are removed in addition to 1.
3 | `f_lseek` function is removed in addition to 2.

#### FF_USE_FIND

Disable (0) or Enable (1) filtered directory read functions, `f_findfirst` and `f_findnext`. Also `FF_FS_MINIMIZE` needs to be 0 or 1.

#### FF_USE_MKFS

Disable (0) or Enable (1) `f_mkfs` function.

#### FF_USE_FASTSEEK

Disable (0) or Enable (1) fast seek function to enable accelerated mode for `f_lseek`, `f_read` and `f_write` function. For more information, read here.

#### FF_USE_EXPAND

Disable (0) or Enable (1) `f_expand` function.

#### FF_USE_CHMOD

Disable (0) or Enable (1) metadata control functions, `f_chmod` and `f_utime`. Also `FF_FS_READONLY` needs to be 0.

#### FF_USE_LABEL

Disable (0) or Enable (1) API functions for volume label, `f_getlabel` and `f_setlabel`.

#### FF_USE_FORWARD

Disable (0) or Enable (1) `f_forward` function.

#### FF_USE_STRFUNC

This option switches string I/O functions, `f_gets`, `f_putc`, `f_puts` and `f_printf`. These functions are the equivalents of regular string stream I/O functions in POSIX. If `sprintf` is available and code conversion is not needed, `f_write` with `sprintf` will be efficient in code size and performance better than `f_printf`. When enable this feature, `stdarg.h` is included in `ff.c`.

Value | Description
--- | ---
0 | Disable string functions.
1 | Enable string functions without LF - CRLF conversion.
2 | Enable string functions with LF - CRLF conversion.

#### FF_PRINT_LLI

This option switches support for long long integer argument in `f_printf`.

Disable (0) or Enable (1). When enable this feature, C standard needs to be C99 or later. This option has no effect when `FF_USE_STRFUNC == 0`.

#### FF_PRINT_FLOAT

This option switches support for floating point argument in `f_printf`. When enable this feature, C standard needs to be C99 or later and `math.h` is included in `ff.c`. This option has no effect when `FF_USE_STRFUNC == 0`.

Value | Description
--- | ---
0 | Disable floating point argument.
1 | Enable floating point argument in type `'f'`, `'e'` and `'E'`.
2 | Same as 1 but with decimal separator `','` instead of `'.'` in output string.

#### FF_STRF_ENCODE

When the character encoding on the API is Unicode (`FF_LFN_UNICODE >= 1`), string I/O functions enabled by `FF_USE_STRFUNC` convert the character encoding in it. This option defines the assumption of character encoding on the file to be read/written via the string I/O functions. When LFN is not enabled or `FF_LFN_UNICODE == 0`, the string I/O functions work without any code conversion and this option has no effect.

Value | Character encoding on the file
--- | ---
0 | ANSI/OEM in current code page
1 | Unicode in UTF-16LE
2 | Unicode in UTF-16BE
3 | Unicode in UTF-8

### Namespace and Locale Configurations

#### FF_CODE_PAGE

This option specifies the OEM code page used on the target system. Incorrect setting of the code page can cause a file open failure. If any non-ASCII character is not used for the path name or `FF_LFN_UNICODE != 0`, there is no difference between any code page settings. Set it 437 anyway.

Value | Code page
--- | ---
0 | Includes all code pages below and set by `f_setcp()`
437 | U.S.
720 | Arabic
737 | Greek
771 | KBL
775 | Baltic
850 | Latin 1
852 | Latin 2
855 | Cyrillic
857 | Turkish
860 | Portuguese
861 | Icelandic
862 | Hebrew
863 | Canadian French
864 | Arabic
865 | Nordic
866 | Russian
869 | Greek 2
932 | Japanese (DBCS)
936 | Simplified Chinese (DBCS)
949 | Korean (DBCS)
950 | Traditional Chinese (DBCS)

#### FF_USE_LFN

This option switches the support for long file name (LFN). When enable the LFN, Unicode support module `ffunicode.c` need to be added to the project. When use stack for the working buffer, take care on stack overflow. When use heap memory for the working buffer, memory management functions (`ff_memalloc` and `ff_memfree`) need to be added to the project.

Value | Description
--- | ---
0 | Disable LFN. Path name in only 8.3 format can be used.
1 | Enable LFN with static working buffer on the BSS. Always NOT thread-safe.
2 | Enable LFN with dynamic working buffer on the STACK.
3 | Enable LFN with dynamic working buffer on the HEAP.

#### FF_MAX_LFN

LFN function requiers certain internal working buffer for the file name. This option defines size of the buffer and the value can be in range of 12 to 255 characters (actually in UTF-16 code units) of the LFN. The buffer occupies `(FF_MAX_LFN + 1) * 2` bytes and additional `(FF_MAX_LFN + 44) / 15 * 32` bytes when exFAT is enabled. It is recommended to be set 255 to fully support the LFN specification. This option has no effect when LFN is not enabled.

#### FF_LFN_UNICODE

This option switches character encoding for the file name on the API. FatFs supports the code point up to U+10FFFF. This option also affects behavior of string I/O functions (see `FF_STRF_ENCODE`).

Value | Character Encoding | `TCHAR`
--- | --- | ---
0 | ANSI/OEM in current CP | char
1 | Unicode in UTF-16 | WCHAR
2 | Unicode in UTF-8 | char
3 | Unicode in UTF-32 | DWORD

When Unicode is selected, `FF_CODE_PAGE` has actually no meaning except for compatibility with legacy systems, such as MS-DOS and any system without support for LFN.

When LFN is not enabled, this option has no effect and FatFs works in ANSI/OEM code on the API. For more information, read here.

#### FF_LFN_BUF, FF_SFN_BUF

This set of options defines size of file name members, `fname[]` and `altname[]`, in the `FILINFO` structure which is used to read out the directory items. These values should be suffcient for the file names to read. The maximum possible length of read file name depends on the character encoding scheme on the API as follows:

Encoding | LFN length | SFN length
--- | --- | ---
ANSI/OEM in SBCS | 255 items | 12 items
ANSI/OEM in DBCS | 510 items | 12 items
Unicode in UTF-16/32 | 255 items | 12 items
Unicode in UTF-8 | 765 items | 34 items

If the size of name member is insufficient for the LFN, the item is treated as without LFN. When LFN is not enabled, these options have no effect.

#### FF_FS_RPATH

This option configures relative path function. For more information, read here.

Value | Description
--- | ---
0 | Disable relative path and remove related functions.
1 | Enable relative path. `f_chdir` and `f_chdrive` function is available.
2 | `f_getcwd` function is available in addition to 1

### Volume/Drive Configurations

#### FF_VOLUMES

This option configures number of volumes (logical drives up to 10) to be used.

#### FF_STR_VOLUME_ID

This option switches the support for string volume ID. When arbitrary string for the volume ID is enabled for the drive prefix, also pre-defined strings by `FF_VOLUME_STRS` or user defined strings can be used as drive prefix in the path name. Numeric drive number is always valid regardless of this option, and also either format of drive prefix can be enabled by this option.

Value | Description | Example
--- | --- | ---
0 | DOS/Windows style drive prefix in numeric ID. | 1:/filename
1 | 0 + DOS/Windows style drive prefix in arbitry string ID. | flash:/filename
2 | 0 + Unix style drive prefix in arbitry string ID. | /flash/filename

#### FF_VOLUME_STRS

This option defines the volume ID strings for each logical drives. Number of items must not be less than `FF_VOLUMES`. Valid characters for the volume ID string are A-Z, a-z and 0-9, however, they are compared in case-insensitive. If `FF_STR_VOLUME_ID == 0`, this option has no effect. If `FF_STR_VOLUME_ID >= 1` and this option is not defined, a user defined volume string table needs to be defined as shown below. The table should not be modified on the fly.

    /* User defined volume ID strings for 0: to 3: */
    const char* VolumeStr[FF_VOLUMES] = {"ram","flash","sd","usb"};

#### FF_MULTI_PARTITION

This option switches multi-partition featuer. By default (0), each logical drive number is bound to the same physical drive number and only one volume found in the physical drive is mounted. When it is enabled (1), each logical drive is bound to the specific partition listed in the user defined partition resolution table `VolToPart[]`. Also `f_fdisk` funciton is available to create the arbitrary partitions on the physical drive. For more information, read here.

#### FF_MIN_SS, FF_MAX_SS

This set of options defines the extent of sector size used for the low level disk I/O interface, `disk_read` and `disk_write` function. Valid values are 512, 1024, 2048 and 4096. `FF_MIN_SS` defines minimum sector size and `FF_MAX_SS` defines the maximum sector size. Always set both 512 for memory card and harddisk. But a larger value may be required for on-board flash memory and some type of optical media. When `FF_MAX_SS > FF_MIN_SS`, support of variable sector size is enabled and `GET_SECTOR_SIZE` command needs to be implemented to the `disk_ioctl` function.

#### FF_LBA64

This option switches media access interface to 64-bit LBA and enables GUID Partition Table (GPT) for partition management, Enabled (1) or Disabled (0). exFAT filesystem needs to be enabled to enable this feature.

#### FF_MIN_GPT

This option specifies the threshold of determination of partitioning format when create patitions on the drive in `f_mkfs` and `f_fdisk` function. When number of available sectors is equal or larger than this value, the drive will be partitioned in GPT. This option has no effect when `FF_LBA64 == 0`.

#### FF_USE_TRIM

Disable (0) or Enable (1). This option switches ATA-TRIM function. To enable Trim function, also `CTRL_TRIM` command should be implemented to the `disk_ioctl` function.

### System Configurations

#### FF_FS_TINY

Normal (0) or Tiny (1). The tiny configuration reduces size of the `FIL` structure, file object, `FF_MAX_SS` bytes each. Instead of private sector buffer eliminated from the file object, common sector buffer in the `FATFS` structure, filesystem object, is used for the file data transfer.

#### FF_FS_EXFAT

This option switches support for exFAT filesystem in addition to the FAT/FAT32 filesystem, Enabled (1) or Disabled (0). To enable exFAT, also LFN must be enabled and configureing `FF_LFN_UNICODE >= 1` and `FF_MAX_LFN == 255` is recommended for full-featured exFAT function. Note that enabling exFAT discards ANSI C (C89) compatibility and wants C99 because of need for 64-bit integer type.

#### FF_FS_NORTC

Use RTC (0) or Do not use RTC (1). This option controls timestamp featuer. If the system does not have an RTC or valid timestamp is not needed, set `FF_FS_NORTC` to 1 to disable the timestamp function. Every objects modified by FatFs will have a constant timestamp defined by `FF_NORTC_MON`, `FF_NORTC_MDAY` and `FF_NORTC_YEAR`. To use the timestamp featuer, set `FF_FS_NORTC == 0` and add `get_fattime` function to the project to get current time form the RTC. This option has no effect in read-only configuration.

#### FF_NORTC_MON, FF_NORTC_MDAY, FF_NORTC_YEAR

This set of options defines the time to be used in no RTC systems. This option has no effect in read-only configuration or `FF_FS_NORTC == 0`.

#### FF_FS_NOFSINFO

0 to 3. If you need to know correct free space on the FAT32 volume, set bit 0 of this option, and `f_getfree` function at first time after the volume mounted will force a full FAT scan. Bit 1 controls the use of last allocated cluster number for new allocation.

Value | Description
--- | ---
bit0=0 | Use free cluster count in the FSINFO if available.
bit0=1 | Do not trust free cluster count in the FSINFO.
bit1=0 | Use last allocated cluster number in the FSINFO to find a free cluster if available.
bit1=1 | Do not trust last allocated cluster number in the FSINFO.

#### FF_FS_LOCK

This option switches file lock feature to control duplicated file open and illegal operations to the open objects. Note that this feature is independent of re-entrancy. This option must be 0 in read-only configuration.

Value | Description
--- | ---
0 | Disable file lock feature. To avoid to collapse files due to wrong file operations, application program needs to avoid illegal open, remove and rename to the open objects.
>0 | Enable file lock feature. The value defines how many files/sub-directories can be opened simultaneously under the file lock feature. Illigal operations to the open object will be rejected with `FR_LOCKED`.

#### FF_FS_REENTRANT

Disable (0) or Enable (1). This option switches the re-entrancy (thread safe) of the FatFs module itself. Note that file/directory access to the different volume is always re-entrant and it can work simultaneously regardless of this option, however, volume management functions, `f_mount`, `f_mkfs` and `f_fdisk`, are always not re-entrant. Only file/directory access to the same volume, in other words, exclusive use of each filesystem object, is under control in this feature. To enable this feature, also user provided synchronization handlers, `ff_mutex_take`, `ff_mutex_give`, `ff_mutex_create` and `ff_mutex_delete`, need to be added to the project. Sample code is available in `ffsystem.c`.

#### FF_FS_TIMEOUT

Number of O/S time ticks to abort the file function with `FR_TIMEOUT` when the wait time exceeds this period. This option has no effect when `FF_FS_REENTRANT == 0`.

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