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lvgl/docs/libs/fs.rst
Liam 4e85b0faa5
feat(fs): file writes update the file cache (#6186)
Co-authored-by: kevinkang-Globe <139213362+kevinkang-Globe@users.noreply.github.com>
2024-05-13 19:09:22 +02:00

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.. _libs_filesystem:
======================
File System Interfaces
======================
LVGL has a :ref:`overview_file_system` module
to provide an abstraction layer for various file system drivers.
LVG has built in support for:
- `FATFS <http://elm-chan.org/fsw/ff/00index_e.html>`__
- STDIO (Linux and Windows using C standard function .e.g ``fopen``, ``fread``)
- POSIX (Linux and Windows using POSIX function .e.g ``open``, ``read``)
- WIN32 (Windows using Win32 API function .e.g ``CreateFileA``, ``ReadFile``)
- MEMFS (read a file from a memory buffer)
- LITTLEFS (a little fail-safe filesystem designed for microcontrollers)
- Arduino ESP LITTLEFS (a little fail-safe filesystem designed for Arduino ESP)
- Arduino SD (allows for reading from and writing to SD cards)
You still need to provide the drivers and libraries, this extension
provides only the bridge between FATFS, STDIO, POSIX, WIN32 and LVGL.
.. _libs_filesystem_usage:
Usage
*****
In ``lv_conf.h`` enable ``LV_USE_FS_...`` and assign an upper cased
letter to ``LV_FS_..._LETTER`` (e.g. ``'S'``). After that you can access
files using that driver letter. E.g. ``"S:path/to/file.txt"``.
The work directory can be set with ``LV_FS_..._PATH``. E.g.
``"/home/joe/projects/"`` The actual file/directory paths will be
appended to it.
:ref:`Cached reading <overview_file_system_cache>` is also supported if ``LV_FS_..._CACHE_SIZE`` is set to
not ``0`` value. :cpp:func:`lv_fs_read` caches this size of data to lower the
number of actual reads from the storage.
To use the memory-mapped file emulation an ``lv_fs_path_ex_t`` object must be
created and initialized. This object can be passed to :cpp:func:`lv_fs_open` as
the file name:
.. code:: c
lv_fs_path_ex_t mempath;
lv_fs_file_t file;
uint8_t *buffer;
uint32_t size;
/*Initialize buffer*/
...
lv_fs_make_path_from_buffer(&mempath, LV_FS_MEMFS_LETTER, (void*)buffer, size);
lv_fs_res_t res = lv_fs_open(&file, (const char *)&mempath, LV_FS_MODE_RD);
.. _libs_filesystem_api:
API
***