Simple FS for flash
// First, we need import flash and flashFS modules // Use require("Flash").getFree() for choose free space for file system
let flash = require("Flash"); let fs = new FlashFS(flash, 1048576, 2097152); // 2 МБ
// Lets start with formating (erase flash space) or call prepare for create only FS header
fs.format() or fs.prepare()
// Open file for writing or reading, if file already created var f = fs.openFile("somefile.txt", "w") f.write("Bla bla bla"); f.write(0x10); f.write(0x13); f.write(0x10); f.write([20, 21, 22, 23]); f.close();
// function list show all file descriptors when created in file system fs.list()
[ { bof: 1048579, path: "somefile.txt", length: 15, addr: 1052672, eof: 1048604 } ]
Structure
Example data Size Offset Description
56 46 53 3 0 FS Header, ASCII 'VFS' FA 1 3 Start of each file (BOF) 48 65 6C 6C 6F 57 6F 72 6C 64 2E 70 6E 67 00 00 16 4 FilePath has 16 bytes 'HelloWorld.png' 00 00 00 0A 4 20 Filesize for content 'HelloWorld 12345', 16 bytes 00 77 88 99 4 24 FileAddr from flash FB 1 28 End of each file (EOF)
FS header and indexes used first flash page and used 4096 bytes. FS contains maximum 163 files. Content is being writed with second page and more. Content of file writing in start of page. Note: file 4000 bytes has reserving 4096 bytes of page. File 4100 bytes has reserving 8192 bytes.