feat(fs): add support for memory-mapped files (#4462)
Co-authored-by: Zoltan Janosy <zjanosy@fishman.com> Co-authored-by: Gabor Kiss-Vamosi <kisvegabor@gmail.com>
This commit is contained in:
Zoltan Janosy
218
src/libs/fsdrv/lv_fs_memfs.c
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218
src/libs/fsdrv/lv_fs_memfs.c
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/**
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* @file lv_fs_memfs.c
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*
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* File System Interface driver for memory-mapped files
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*
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* This driver allows using a memory area as a file that can be read by normal file operations. It can
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* be used, e.g., to store font files in slow flash memory, and load them into RAM on demand.
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*
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* You can enable it in lv_conf.h:
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*
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* #define LV_USE_FS_MEMFS 1
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*
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* The actual implementation uses the built-in cache mechanism of the file system interface.
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*
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* Since this is not an actual file system, file write and directories are not supported.
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*
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* The default drive letter is 'M', but this can be changed in lv_conf.h:
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*
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* #define LV_FS_MEMFS_LETTER 'M'
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*
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* To use it seamlessly with the file system interface a new extended path object has been introduced:
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*
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* lv_fs_path_ex_t mempath;
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*
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* This structure can be initialized with the helper function:
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*
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* lv_fs_make_path_ex(&mempath, (const uint8_t *) & my_mem_buffer, sizeof(my_mem_buffer));
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*
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* Then the "file" can be opened with:
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*
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* lv_fs_file_t file;
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* lv_fs_res_t res = lv_fs_open(&file, (const char *) & mempath, LV_FS_MODE_RD);
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*
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* The path object can be used at any place where a file path is required, e.g.:
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*
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* lv_font_t* my_font = lv_font_load((const char *) & mempath);
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*
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*/
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/*********************
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* INCLUDES
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*********************/
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#include "../../../lvgl.h"
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#if LV_USE_FS_MEMFS
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/*********************
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* DEFINES
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*********************/
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/**********************
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* TYPEDEFS
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**********************/
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/**********************
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* STATIC PROTOTYPES
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**********************/
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static void * fs_open(lv_fs_drv_t * drv, const char * path, lv_fs_mode_t mode);
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static lv_fs_res_t fs_close(lv_fs_drv_t * drv, void * file_p);
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static lv_fs_res_t fs_read(lv_fs_drv_t * drv, void * file_p, void * buf, uint32_t btr, uint32_t * br);
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static lv_fs_res_t fs_seek(lv_fs_drv_t * drv, void * file_p, uint32_t pos, lv_fs_whence_t whence);
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static lv_fs_res_t fs_tell(lv_fs_drv_t * drv, void * file_p, uint32_t * pos_p);
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/**********************
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* STATIC VARIABLES
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**********************/
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static lv_fs_drv_t fs_drv; /*A driver descriptor*/
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/**********************
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* MACROS
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**********************/
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/**********************
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* GLOBAL FUNCTIONS
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**********************/
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/**
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* Register a driver for the File system interface
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*/
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void lv_fs_memfs_init(void)
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{
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/*---------------------------------------------------
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* Register the file system interface in LVGL
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*--------------------------------------------------*/
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/*Add a simple drive to open images*/
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lv_fs_drv_init(&fs_drv);
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/*Set up fields...*/
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fs_drv.letter = LV_FS_MEMFS_LETTER;
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fs_drv.cache_size = LV_FS_CACHE_FROM_BUFFER;
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fs_drv.open_cb = fs_open;
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fs_drv.close_cb = fs_close;
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fs_drv.read_cb = fs_read;
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fs_drv.write_cb = NULL;
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fs_drv.seek_cb = fs_seek;
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fs_drv.tell_cb = fs_tell;
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fs_drv.dir_close_cb = NULL;
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fs_drv.dir_open_cb = NULL;
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fs_drv.dir_read_cb = NULL;
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lv_fs_drv_register(&fs_drv);
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}
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/**********************
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* STATIC FUNCTIONS
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**********************/
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/**
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* Open a file
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* @param drv pointer to a driver where this function belongs
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* @param path pointer to an extended path object containing the memory buffer address and size
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* @param mode read: FS_MODE_RD (currently only reading from the buffer is supported)
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* @return pointer to FIL struct or NULL in case of fail
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*/
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static void * fs_open(lv_fs_drv_t * drv, const char * path, lv_fs_mode_t mode)
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{
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LV_UNUSED(drv);
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LV_UNUSED(mode);
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return (void *)path;
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}
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/**
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* Close an opened file
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* @param drv pointer to a driver where this function belongs
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* @param file_p pointer to a FILE variable. (opened with fs_open)
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* @return LV_FS_RES_OK: no error, the file is read
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* any error from lv_fs_res_t enum
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*/
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static lv_fs_res_t fs_close(lv_fs_drv_t * drv, void * file_p)
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{
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LV_UNUSED(drv);
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LV_UNUSED(file_p);
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return LV_FS_RES_OK;
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}
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/**
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* Read data from an opened file
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* @param drv pointer to a driver where this function belongs
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* @param file_p pointer to a FILE variable.
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* @param buf pointer to a memory block where to store the read data
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* @param btr number of Bytes To Read
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* @param br the real number of read bytes (Byte Read)
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* @return LV_FS_RES_OK: no error, the file is read
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* any error from lv_fs_res_t enum
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*/
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static lv_fs_res_t fs_read(lv_fs_drv_t * drv, void * file_p, void * buf, uint32_t btr, uint32_t * br)
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{
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LV_UNUSED(drv);
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LV_UNUSED(file_p);
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LV_UNUSED(buf);
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LV_UNUSED(btr);
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*br = 0;
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return LV_FS_RES_OK;
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}
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/**
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* Set the read pointer.
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* @param drv pointer to a driver where this function belongs
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* @param file_p pointer to a FILE variable. (opened with fs_open )
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* @param pos the new position of read pointer
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* @return LV_FS_RES_OK: no error, the file is read
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* any error from lv_fs_res_t enum
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*/
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static lv_fs_res_t fs_seek(lv_fs_drv_t * drv, void * file_p, uint32_t pos, lv_fs_whence_t whence)
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{
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/* NOTE: this function is only called to determine the end of the buffer when LV_FS_SEEK_END was given to lv_fs_seek() */
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LV_UNUSED(drv);
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lv_fs_file_t * fp = (lv_fs_file_t *)file_p;
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switch(whence) {
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case LV_FS_SEEK_SET: {
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fp->cache->file_position = pos;
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break;
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}
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case LV_FS_SEEK_CUR: {
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fp->cache->file_position += pos;
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break;
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}
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case LV_FS_SEEK_END: {
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fp->cache->file_position = fp->cache->end - pos;
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break;
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}
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}
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if(fp->cache->file_position < fp->cache->start)
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fp->cache->file_position = fp->cache->start;
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else if(fp->cache->file_position > fp->cache->end)
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fp->cache->file_position = fp->cache->end;
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return LV_FS_RES_OK;
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}
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/**
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* Give the position of the read write pointer
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* @param drv pointer to a driver where this function belongs
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* @param file_p pointer to a FILE variable.
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* @param pos_p pointer to to store the result
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* @return LV_FS_RES_OK: no error, the file is read
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* any error from lv_fs_res_t enum
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*/
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static lv_fs_res_t fs_tell(lv_fs_drv_t * drv, void * file_p, uint32_t * pos_p)
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{
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LV_UNUSED(drv);
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*pos_p = ((lv_fs_file_t *)file_p)->cache->file_position;
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return LV_FS_RES_OK;
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}
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#else /*LV_USE_FS_MEMFS == 0*/
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#if defined(LV_FS_MEMFS_LETTER) && LV_FS_MEMFS_LETTER != '\0'
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#warning "LV_USE_FS_MEMFS is not enabled but LV_FS_MEMFS_LETTER is set"
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#endif
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#endif /*LV_USE_FS_MEMFS*/
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