Support for MCCS and other font character codes, medley-font format

[rmkaplan]

This is the first draft of changes aimed at the font problems discussed in #2120 and #2135 and elsewhere.

It introduces and integrates a new, medley-specific font-file format that let's us write out and read in font information apart from the legacy font formats (strike, ac, ip...), and introduces support for font character-set manipulation (including clarifying and defining the MCCS encoding and its relationship to Unicode and XCCS.

The code for the medleyfont format is described in the doc/internal/ tedit file. I'm also writing up description of the changes/extensions to FONT.

The point of this PR/draft is that things should work as they used to, that the integration of new stuff hasn't broken anything even though it may not yet have improved anything.

[rmkaplan]

Other initial commentS: You will see that there is a new file MCCS early in the loadup, as a replacement for the previous XCCS file, which I am deprecating. This file defines the future -oriented MCCS external format but also still includes the legacy XCCS external format and translation functions that map between MCCS and XCCS (and actually a new encoding XCCS$ (like XCCS but the $ and currency are swapped) that corresponds to the encoding of our NS fonts).

The new Unicode tables and translation functions map between MCCS and Unicode (the XCCS translation functions are still there). These changes also have to be documented.

[pamoroso]

I built this branch on Linux Mint 22.1 Cinnamon and so far I'm noticing the following error in the main Exec of a session freshly started with medley -a -e -n -s 1920x1005 -v +:

Undefined car of form
EXEC#INTERLISP

where # is a black box. I haven't changed anything in my setup.

[rmkaplan]

What is (FILEDATE 'LLKEY) (or the filecreated date if you look at the file)? Should be May 5.

[nbriggs]

It's May 5 in the branch you pushed.

 git diff ad5216cf 032f719b
diff --git a/ad5216cf b/032f719b
index ad5216cf..032f719b 100644
--- a/ad5216cf
+++ b/032f719b
@@ -1,13 +1,12 @@
 (DEFINE-FILE-INFO ^^PACKAGE "INTERLISP" ^^READTABLE "INTERLISP" ^^BASE 10)
 
-(FILECREATED " 4-Apr-2025 17:10:10" ^F^D{WMEDLEY}<sources>LLKEY.;11 199518 
+(FILECREATED " 5-May-2025 20:57:08" ^F^D{WMEDLEY}<sources>LLKEY.;15 199508 
 

[rmkaplan]

What character are you trying to get into that string? If an underscore and if the LLKEY version is correct, try typing it with Function 10? You should still see a left arrow, since the fonts are not yet translated here.

If you (CHCON "string") typed with either shift-hyphen or F10, you should see 95 for F10 and 172 for shift-hyphen, even though the glyphs are mixed up.

[pamoroso]

The date of LLKEY is May 5 according to FILEDATE:

6> (IL:FILEDATE 'LLKEY)
" 5-May-2025 20:57:08"

I'm not sure about your question on the character to get into a string as I'm not typing any particular character. Anyway, with this PR I can get the underscore/left arrow as usual by typing _ and (CHCON "#") (where # is a black box typed by F10) yields 95:

7> (IL:CHCON "_")
(172)
8> (IL:CHCON "¬")
(95)

[rmkaplan]

I added an MCCS.TEDIT documentation file.

I have seen some crashes in Tedit that seem unrelated to MCCS but might interact in some way, so perhaps defer testing this until I get a little more information.