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elua/docs/the_rom_file_system.txt
2008-09-02 10:55:35 +00:00

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The ROM file system
================================================================================
This is a small, read-only file system built inside eLua. It is integrated with
Newlib, so you can use standard POSIX calls (fopen/fread/fwrite...) to access
it. It is also accessible directly from Lua. The files in the file system are
part of the eLua binary image, thus they can't be modified after the image is
built. For the seame reason, you can't add/delete files after the image is built.
To use this file system:
- copy all the files you need to the romfs/ directory.
- Build eLua (docs/building.txt). As part of the build process, "mkfs.py" will
be called, which will read the contents of the "romfs/" directory and will
output a file that contains a binary description of the file system.
- burn your image to the target
- from your code, whenever you want to access a file, prefix its name with
"/rom/". For example, if you want to open the "a.txt" file, you should call
fopen like this:
f = fopen( "/rom/a.txt", "rb" )
If you want to execute one file from the ROM file system with Lua, simply do
this from the shell:
eLua# lua /rom/bisect.lua
Or directly from Lua:
> dofile "/rom/bisect.lua"
The maximum file name of a ROMFS file is 14 characters, including the dot
between the file name and its extension. Make sure that the file names from
romfs/ follow this rule.