🚀 go-pugleaf

In article <1ihfj7EINNhmj@uni-erlangen.de>, unrza3@cd4680fs.rrze.uni-erlangen.de (Markus Kuhn) writes:
|> terry@cs.weber.edu (A Wizard of Earth C) writes:
|> 
|> >Consider that Runic encoding is antithetical in terms of single character
|> >changes for fixed record length files by virtue of it's ability to either
|> >change record size (destroying the seek-offset record addressing) or by
|> >changing the amount of data representable in a field (destroying the
|> >ability to use fixed-length fields for input in the front end client).
|> 
|> The C type Rune has been defined in the Tompson paper about Plan 9 Unicode
|> encoding as "unsigned short" = 16bit per character. The 1+ byte encoding is
|> called by all people UTF (there are different versions, Plan 9 uses UTF-2).
|> I believe you mixed up the meanings of UTF encoded and Runic encoding.
|> 
|> It seems to be absolutely obvious that there are many applications,
|> where a fixed length runic encoding with 16 bit/character is useful.
|> That's also the reason, why UTF <-> Rune translation routines (which
|> are very easy to implement) have been included in Plan 9 libraries.
|> 
|> There are also very good reasons to use UTF, especially, where 
|> compatibility with ASCII is of benefit.
|> 
|> Sorry, I don't understand your problem at all.
|> 
|> Markus
|> 
|> -- 
|> Markus Kuhn, Computer Science student -=-=- University of Erlangen, Germany
|> Internet: mskuhn@immd4.informatik.uni-erlangen.de  |  X.500 entry available
|> --- Wer, wie, was? Wieso, weshalb, warum? Wer nichts fragt bleibt dumm. ---

Ken Thompson, in the comments utf-fss.c (anonymous FTP to metis.com), the Plan
9 UTF mechanism:

 * Proposed FSS-UTF
 * ----------------
 *
 * The proposed UCS transformation format encodes UCS values in the range
 * [0,0x7fffffff] using multibyte characters of lengths 1, 2, 3, 4, 5,
 * and 6 bytes.  For all encodings of more than one byte, the initial
 * byte determines the number of bytes used and the high-order bit in
 * each byte is set.  Every byte that does not start 10xxxxxx is the
 * start of a UCS character sequence.
 *
 * An easy way to remember this transformation format is to note that the
 * number of high-order 1's in the first byte signifies the number of
 * bytes in the multibyte character:
 *
 * Bits  Hex Min  Hex Max  Byte Sequence in Binary
 *   7  00000000 0000007f 0vvvvvvv
 *  11  00000080 000007FF 110vvvvv 10vvvvvv
 *  16  00000800 0000FFFF 1110vvvv 10vvvvvv 10vvvvvv
 *  21  00010000 001FFFFF 11110vvv 10vvvvvv 10vvvvvv 10vvvvvv
 *  26  00200000 03FFFFFF 111110vv 10vvvvvv 10vvvvvv 10vvvvvv 10vvvvvv
 *  31  04000000 7FFFFFFF 1111110v 10vvvvvv 10vvvvvv 10vvvvvv 10vvvvvv 10vvvvvv
 *
 * The UCS value is just the concatenation of the v bits in the multibyte
 * encoding.  When there are multiple ways to encode a value, for example
 * UCS 0, only the shortest encoding is legal.

My problem is not with ANSI-style fixed length Runes, but with this style of
Runic encoding, where the length is *not* fixed for the purposes of
compatability with existing 7-bit US ASCII files (this makes 7-bit ASCII
automatically "encoded" at the expense of all other characters).


					Terry Lambert
					terry@icarus.weber.edu
					terry_lambert@novell.com
---
Any opinions in this posting are my own and not those of my present
or previous employers.
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