From: Marko Mäkelä (marko.makela_at_hut.fi)
Date: 2003-06-26 01:16:59
Let's get back on topic: On Fri, Jun 20, 2003 at 11:48:57PM +0200, Andre Fachat wrote: > For my GeckOS/A65 I wrote a small ROM filesystem that is linked by > storing the size of the next segment (file) at the start, so the file > handler could jump from one to the next segment. Using an $FFFF as > end marker gave me the possibility to expand the (EP)ROM by overburning > just the next part from the empty EPROM $FF value to the data values :-) How does your system keep track of available bytes? With a bitmap or by traversing a pointer structure? Currently, my directory entries have two 3-byte pointers to next and previous entry, and a file name followed by the file contents. For subdirectories, the contents is a 3-byte pointer into the first directory entry. In this way, there can be multiple "hard links" into the same directory, e.g., ".." for the parent directory. It looks like I will have to add one more piece of data into file entries: the length of the compressed data in bytes. Otherwise, finding the first unused byte will require that the last file found is decompressed. Even with this addition, allocating space for a new file requires traversal of all "next" and "subdirectory" links, but it shouldn't be a problem, as there will be at most a few thousand files. Marko Message was sent through the cbm-hackers mailing list
Archive generated by hypermail pre-2.1.8.