Add or fix options to control static and dynamic configuration. Keep
the default of scteken, but default to statically configuring all available
emulators (now 3 instead of 1).
The dumb emulator is almost usable. libedit and libreadline handle
dumb terminals perfectly for at least shell history. less(1) works
as well as possible except on exit. But curses programs make messes.
The dumb emulator has strange color support, with 2 dumb colors for
normal output but fancy colorization for the cursor, mouse pointer and
(with a non-dumb initial emulator) for low-level console output.
Using the sc emulator instead of the default of scteken fixes at least
the following bugs:
- NUL is a printing character in cons25 but not in teken
- teken doesn't support fixed colors for "reverse" video.
- The best versions of sc are about 10 times faster than scteken (for
printing to the frame buffer). This version is only about 5 times
faster.
Fix configuration features:
- make SC_DFLT_TERM (for setting the initial emulator) a normal option.
Add configuration features:
- negative options SC_NO_TERM_* for omitting emulators in the static config.
Modules for emulators might work, but I don't know of any
- vidcontrol -e shows the available emulators
- vidcontrol -E <emulator> sets the active emulator.
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