xxencoding
xxencode is a
The encoding process
xxencoded data starts with a line of the form:
begin <mode> <file>
Where <mode> is the file's read/write/execute permissions as three octal digits, and <file> is the name to be used when recreating the binary data.
xxencode repeatedly takes in groups of three bytes, adding trailing zeroes if there are fewer than three bytes left. These 24 bits are split into four 6-bit numbers, each of which is then translated to the th character in the following table:
1 2 3 4 5 6 0123456789012345678901234567890123456789012345678901234567890123 | | | | | | | +-0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz
Each group of sixty output characters (corresponding to 45 input bytes) is output as a separate line preceded by an encoded character giving the number of encoded bytes on that line. For all lines except the last, this will be the character 'h' (the character mapping to the value 45). If the input is not evenly divisible by 45, the last line will contain the remaining N output characters, preceded by the number of remaining input bytes encoded as above. Finally, a line containing just a single space (or plus character) is output, followed by one line containing the string "end".
xxencoded data is generally distinguishable from
Example
The following is an example of xxencoding a one-line text file. In this example, %0D is the byte representation for
- file
File Name = wikipedia-url.txt File Contents = http://www.wikipedia.org%0D%0A
- xxencoding
begin 644 wikipedia-url.txt OO5FoQ1cj9rRrRmtrOKhdQ4JYOK2iPr7b1Ec+ end
See also
- Binary-to-text encoding for a comparison of various encoding algorithms
External links
- XXENCODE-XXDECODE - Free on-line XXEncoder and XXDecoder
References
- ^ Tony Catone (February 1995). "Keys to the kingdom: Unlocking Internet file formats". University of Pennsylvania.