FSRW 2.6 root directory

William50

What is the maximum amount of files that can be stored and/or addressed in the root directory using FSRW 2.6?

Tracy Allen

I believe the limit is 512 files. 8.3 names only, FAT16 or FAT32. Individual file size up to 4GB.

JonnyMac

While it's true that FSRW only understands 8.3 names, you can in fact use long names on your SD card -- I'm doing this now. The key is to ensure that the first six characters of the file names are unique.

I'm working on a project that uses several sounds; for example:

100_mainmenu.wav

Internally, I have a dat table like this:

dat

  AudioFiles    byte    "100_ma~1.wav", 0                        ' 100_mainmenu.wav

By prefixing the sound file name with a number I can keep the first six characters unique, and allow the program to switch to a different group of files by changing the first character of the names in my table; this is very useful in multi-lingual apps. In the example above, group 1 is English, and file 00 is the main menu audio. As you can see, the table entry uses the first six characters of the file name, with "~1" after. If you read the directory with FSRW you will see the files listed in this manner (8.3 format). Note that I only use 3-character extensions on my files.

In my case it's easy to get to the nth file name in the list because all entries use 13 bytes (8 + 1 + 3 + 1 [terminating zerol]); when my strings are variable length I use this method to find the address of the nth item in a list (as above).

pub str_pntr(idx, p_list)

'' Returns to pointer to idx'th string in list (at p_list)
'' -- string may be variable length

  repeat idx
    p_list += strsize(p_list) + 1                                ' skip current string

  return p_list

Publison

Jon,

That's pretty slick!

Tracy Allen

That's very clever Jon.

Correct me if I'm wrong, but doing that does limit the number of file entries available. Each 11 characters added to a long file name uses up one of the available file entry slots. While FSRW does support FAT32 in terms of the size of files and media, I don't think it allows any entries past the 512 that fit in the fixed size root directory.

JonnyMac

To be honest with you, FSRW is an object I use all the time without understanding the internals (I will ultimately learn and attempt my own driver -- FSRW code is very messy and that make me nuts). The project I'm working on has three groups of about 20 files, so I am not pushing any limits. My goal was to make file naming easier for the customer while working with 8.3 names inside FSRW.