All but one joystick drivers didn't use IRQs. Espsecially when the joystick driver kernel was the only .interruptor this meant quite some unnecessary overhead because it pulled in the whole IRQ infrastructure.
I was told that the one driver using IRQs (the DXS/HIT-4 Player joystick driver for the C64) can be reworked to not do it. Until this is done that driver is defunct.
So far the joy_masks array allowed several joystick drivers for a single target to each have different joy_read return values. However this meant that every call to joy_read implied an additional joy_masks lookup to post-process the return value.
Given that almost all targets only come with a single joystick driver this seems an inappropriate overhead. Therefore now the target header files contain constants matching the return value of the joy_read of the joystick driver(s) on that target.
If there indeed are several joystick drivers for a single target they must agree on a common return value for joy_read. In some cases this was alredy the case as there's a "natural" return value for joy_read. However a few joystick drivers need to be adjusted. This may cause some overhead inside the driver. But that is for sure smaller than the overhead introduced by the joy_masks lookup before.
!!! ToDo !!!
The following three joystick drivers become broken with this commit and need to be adjusted:
- atrmj8.s
- c64-numpad.s
- vic20-stdjoy.s
This change includes some cleanups, removal of mainargs.s (game console
programs never have arguments), and a workaround for a problem I'm seeing.
The problem is that sometimes (in fact, more often than not) the clrscr()
call in testcode/lib/joy-test.c writes some garbage chars on the screen (most
often a "P"). Could be my hardware (I haven't seen it on MAME), but to
me the root cause is still unknown.
Stefan Dorndorf, author of XDOS, pointed out that retrieving the
default device by looking at an undocumented memory location won't
work in future XDOS versions.
He also showed a way to get the default device in a compatible
manner.
This change implements his method and adds a version check (XDOS
versions below 2.4 don't support this -- for them the behaviour
will be the same as, for example, AtariDOS: no notion of a default
drive).
- Adds new ENOEXEC error code, also used by Apple2 targets.
- Maximum command line length is 40, incl. program name. This is
an XDOS restriction.
- testcode/lib/tinyshell.c has been extended to be able to run
programs.
When a program starts running, INIT is moved from one place to another place. Then, INIT's code is executed; and, the first place is re-used for variables. After the INIT code has finished, the second place can be re-used by the heap and the C stack. That means that initiation code and data won't waste any RAM space after they stop being needed.
Up to now static drivers were created via co65 from dynamic drivers. However there was an issue with that approach:
The dynamic drivers are "o65 simple files" which obligates that they start with the 'code' segment. However dynamic drivers need to start with the module header - which is written to. For dynamic drivers this isn't more than a conceptual issue because they are always contain a 'data' segment and may therefore only be loaded into writable memory.
However when dynamic drivers are converted to static drivers using co65 then that issue becomes a real problem as then the 'code' segment may end up in non-writable memory - and thus writing to the module header fails.
Instead of changing the way dynamic drivers work I opted to rather make static driver creation totally independent from dynamic drivers. This allows to place the module header in the 'data' segment (see 'module.mac').
