Path: utzoo!mnetor!tmsoft!torsqnt!news-server.csri.toronto.edu!bonnie.concordia.ca!uunet!viusys!uxui!unislc!dave From: dave@unislc.uucp (Dave Martin) Newsgroups: comp.sys.amiga.misc Subject: Re: A compression filesystem Message-ID: <1991Feb18.201014.16812@unislc.uucp> Date: 18 Feb 91 20:10:14 GMT References: <1213@macuni.mqcc.mq.oz> Organization: unisys Lines: 42 From article <1213@macuni.mqcc.mq.oz>, by ifarqhar@sunb.mqcc.mq.oz.au (Ian Farquhar): > In article cpc@czaeap.UUCP (Chris Cebelenski) writes: >> Advantages: No special "data decoder" or headers required to >> de-compress files when they are loaded, the device takes care ^^^^^^^^^^^^^^^^^ >> of it itself. Reduced storage needed for seldom-changed files. ^^^^^^^^^^^^ >> Pseudo file can be backed up just like any other file. > > No headers? Depends on what compression system you use. A standard > huffman encoder becomes quite a reasonable encryption system if you > forgot the decoding tree. You also probably need an index (see later.) > > No data decoder? I presume that you mean hardware, because you are sure > going to need something (hardware or software) to turn your file back into > raw data. Of course there are headers and "data decoders" but they are handled in the handler. The application programs would never see them, need to deal with them, or even know they exist. The idea is that applications/utilities would have no idea that the files are compressed, or care. Personally, I would like to see a bit in the protection mask that tells the handler that this file is compressed. Changing the bit with the protect command (without a NOACTION keyword) would cause the file to be converted to compressed/uncompressed state. If there were insufficient disk space then an error would be given and the action would not occur. If protect were used with some sort of NOACTION type of keyword, then the bit state will be changed without anything being done otherwise; this would assume that the user knew what s/he were doing. You could even disable random access on (C)ompressed files, or (preferred) document that there will be a performance penalty for seeks. Files that get seeked in a lot could just have their C bit cleared first by the user. Well, just some wishful thinking on my part, perhaps I'll experiment with this when I have some time. -- VAX Headroom Speaking for myself only... blah blah blahblah blah... Internet: DMARTIN@CC.WEBER.EDU dave@saltlcy-unisys.army.mil uucp: dave@unislc.uucp or use the Path: line. Now was that civilized? No, clearly not. Fun, but in no sense civilized.