This PR is mostly a complete rewrite of the emulator for 6502/65c02 opcodes.
It provides an easier to maintain implementation of the instructions, by using few macros rather than having hand-written code for each function.
All undocumented, previously missing opcodes for 6502 are also implemented.
The patch also includes a detailed documentation of those opcodes, for reference to developers.
This PR should fix one of the milestones listed here for the next version of CC65:
https://github.com/cc65/wiki/wiki/Before-the-next-release
MaxCycleCount is accounted by countdown, eliminating the 1-instruction-overhead issue, and removing the need to compare against a growing TotalCycles.
Makes main.c responsible for counting total cycles, instead of 6502.c, so the size of MaxCycleCount etc. is fully determined in one location.
Makes error.c responsible for PrintCycles instead of paravirt.c, so that it can be treated globally instead of
Return value of main() should be SIM65_ERROR because it is unreachable by design.
test/val/constexpr.c relies on close(-1) to return -1 for some reason (comment says "abuse"), but on MSVC close(-1) is treated as a security issue and terminates the program instead of returning -1
simulating this desire for sim65, though constexpr.c may also warrant a review
long is 64-bit on some platforms, making this inconsistent, added range check to catch overflow.
reduced tests requesting 5 billion cycles to 2^32-1 so they can fun on 32-bit long sim65.
The Pop() function was not handling stack pointer wrap around correctly.
Also, change the simulated RTS implementation in ParaVirtHooks() to
explicitly sequence the two Pop() calls in the correct order.
load and run address now configured from header
fix error codes not to conflict with test
fix test/misc/endless.c which is supposed to fail if an endless loop does not occur
The Linux build was failing with:
sim65/paravirt.c: In function ‘PVOpen’:
sim65/paravirt.c:217:18: error: ‘S_IREAD’ undeclared (first use in this function)
OMode |= S_IREAD;
^
sim65/paravirt.c:217:18: note: each undeclared identifier is reported only once for each function it appears in
sim65/paravirt.c:220:18: error: ‘S_IWRITE’ undeclared (first use in this function)
OMode |= S_IWRITE;
^
make[1]: *** [../wrk/sim65/paravirt.o] Error 1
Files created by my programs running under sim65 had really weird permissions:
--w-r--r-x 1 ppelleti staff 19 Aug 16 23:22 json.test.print.tmp
So, for example, my program running under sim65 was not able to read
the file it had just written.
This is because the third argument to open (mode) was not being
specified in paravirt.c, so it was just picking up random crud off the
stack to use as the mode.
I added a mode of 0666, and now my program runs correctly.
* The pointer wraps around the stack page.
* The break flag exists on only the stack, and only after an interrupt.
* 65C02 interrupts clear the decimal-mode flag.
