picture shows relation between amount of used bytes (x axis) and compression ratio in % (y axis)
modcomp can compress and decompress data algorithm works by checking how many bytes are used in sourcefile and then changing the base of the file to that amount. in a uncompressed file the base is 256 (1 byte). if for instance 90 bytes are used, the new base is 90. good things: ------------ compression ratio can be calculated in constant time and only depends on amount of used bytes. bad things: ----------- needed time per byte per byte > 0. (some say O(n^2) but i ain't sure) bad compression ratio on average files ;) VERY slow. NOT block alignable without wasting space. (although some students at university of stuttgart, germany thought so) output of this programm cannot be compressed by gzip or bzip2 (the size INCREASES by those programs ;) so what do you learn from this ? -------------------------------- it is a REAL bad idea to compress by changing bases! it is only good if new base is 2^x. and then you could do it with bitshifts and it is trivial. sincerly yours, erik. erikyyy at erikyyy dot de