decoders writing control-1 chars?
Ilya N. Golubev
Tue Oct 31 01:07:02 EST 2006
On 2005/11/28 02:10:19 +0 Vin Shelton committed in "stable"
`release-21-4' branch this change.
2005-04-05 Aidan Kehoe <kehoea at parhasard.net>
* mule-ccl.c (ccl_driver): Calculate the charset and position code
for control-1 characters properly, both when reading multibyte
characters and writing them.
This changes what `write-multibyte-character' CCL instruction writes
when passed a representation of `control-1' charset character. So the
change is obviously visible to lisp programmer. Still it is not noted
in `NEWS' file.
`control-1' emchars are just like any others, and coding systems
decoding data to these emchars certainly make sense. How do we
implement such a coding systems in CCL? Assume that CCL program have
prepared generic emchar representation for `write-multibyte-character'
in its registers, and this emchar may be or not be in `control-1'
charset. How do we have it write `control-1' emchar out after that
Another issue is that emchar value being written out for `(control-1
CODE)' chars, 0 <= CODE < 32, is negative, which makes little sense.
Please resolve the issue. Perhaps you decide to revert the change.
Or perhaps you devise and recommend the workaround. Then please note
the change in <Lisp and internal changes> section of `NEWS' with
stating how to work around that, how to write `control-1' emchars out.
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