Subject: RE: [stella] AtariVox EEPROM file format From: <stella@xxxxxxxxxxxxxxx> Date: Tue, 30 Nov 2004 08:29:48 -0600 |
37 character set = 6 bits per character 8.3 format = 11 characters * 6 bits = 66 bits < 9 bytes OR Since only 37 out of 64 possible values are represented in those 6 bits, you can use the 2 most significant bits to signal the end of a filename or the beginning of the file extension (assuming ext is always 3 characters). Character set: 0 = _ 1-26 = A-Z 27=37 = 0-9 010100 000101 010011 010100 100101 11 000101 011000 000101 ------ ------ ------ ------ ------ -- ------ ------ ------ T E S T 9 . E X E # bits = (# characters) * 6 + 2 = (8) * 6 + 2 = 50 bits < 7 bytes Or if an agreed-upon lookup table for common characters can be created, a flavor of Huffman compression can potentially shrink the filenames even more. Especially since there's elbow room to play with in those 6 bits. The downside, naturally, is more code to de/compress filenames, but someone... perhaps say... Mr. Jentzsch might be able to drum up an uber-tight de/compressor just for this purpose. :) Sorry if I rehashed anything or if this is all just kinda "well, duh". I very quickly scanned through this thread. -Lee
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