This PR is the second of two PRs that replaces earlier PRs #2589 and #2590. Due to a git branching mishap it was decided to re-partition the new functionality in two sequential PRs that offer self-contained, new functionality to sim65.
The functionality in this second and last PR provides the following things in relation to the new "peripheral" support:
* C support: there is now an include/sim65.h that can be included from C. It provides access to the memory-mapped peripheral addresses.
* Asm support: there is now an asminc/sim65.inc that can be included from assembly. It provides symbolic labels for the memory-mapped peripheral addresses.
Note: the two items above are implemented by adding a "_peripherals" symbol to cfg/sim6502.cfg and cfg/sim65c02.cfg, with the fixed base address of the peripherals memory aperture (0xffc0).
* Updated the sim65 documentation to describe the peripherals in some detail, with examples that show to use the new features from within C.
* Some examples in the new samples/sim5/ directory. These are currently not integrated in the build system (in other words, there's no Makefile there), because I don't know how to do that. I will happily implement that after #2582 is taken care of.
If that is not acceptable, the next best thing will be for somebody else (who understands how the Makefiles are set up) to take care of this.
If that's not going to happen, and we don't want examples that are not properly integrated with the build system, there's always the option of removing these samples from the PR.
are legal in C. With the changes from #2495, such calls will usually crash the
machine. But recursive calls to main() are rare and on the 6502 every byte
saved is precious. So this change limits the effect of #2495 to cc65 mode and
at the same time disallows recursive calls to main() in this mode. If
recursive calls to main() are actually required, the code must be compiled in
c89 or c99 mode.
