LoCode 1/5

 BBS: Inland Empire Archive
Date: 01-04-56 (01:04)             Number: 1466
From: BRENT ASHLEY                 Refer#: NONE
  To: ALLAN ZACHARY                 Recvd: NO  
Subj: LoCode 1/5                     Conf: (2) Quik_Bas
Hi Allan;

     When you wondered aloud recently how UUENCODE did its thing
with only a ~3/2 expansion ratio, it set me to thinking.  Four
hours later, I had these two programs finished - LoCode and UnLoc.
The text files produced by LoCode consist of only low-ascii codes,
specifically only upper and lower alpha, numbers, round brackets
and CR/LF pairs.  No @ signs for fido to choke on.  In the
interests of keeping overhead low, there is very little
error-checking, but I think enough to flag problems.

     The programs are based on the idea that using 6 bits of each
byte, it will take four such bytes to accumulate 24 bits, which
can in turn be re-split to represent 3 8-bit bytes.  This should
thoeretically give a 4/3 expansion ratio, but overhead bytes
(CR/LF, flags, identifiers) push that closer to 3/2.

Below are the 4 coded bytes, with the Xs as unused bits (0s) and
the bit positions for the three original bytes marked by number.

      byte 1          byte 2          byte 3         byte 4

 |X X 3 3 3 3 3 3|X X 3 3 2 2 2 2|X X 2 2 2 2 1 1|X X 1 1 1 1 1 1|

     The six bits represent 64 codes, and I use a character set
made up of 64 of the most innocuous characters to represent those
64 choices.

     The code follows in the next few messages.

 X DeLuxe2 1.12 #10383 X

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