Commit Graph

739 Commits

Author SHA1 Message Date
Tim Allen c2c957a9da Update to v101r22 release.
byuu says:

Changelog:
- Z80: all 25 remaining instructions implemented

Now onto the debugging ... :/
2016-11-01 22:42:25 +11:00
Tim Allen 8cf20dabbf Update to v101r21 release.
byuu says:

Changelog:

- Z80: emulated 83 new instructions
- Z80: timing improvements

DAA is a skeleton implementation to complete the normal opcode set. Also
worth noting that I don't know exactly what the hell RETI is doing,
so for now it acts like RET. RETN probably needs some special handling
besides just setting IFF1=IFF2 as well.

I'm now missing 24 ED-prefix instructions, plus DAA, for a total of 25
opcodes remaining. And then, of course, several weeks worth of debugging
all of the inevitable bugs in the core.
2016-11-01 08:10:33 +11:00
Tim Allen 2707c5316d Update to v101r20 release.
byuu says:

Changelog:
- Z80: emulated 272 new instructions
- hiro/GTK: fixed v101r19 Linux regression [thanks, SuperMikeMan!]
2016-10-29 11:33:30 +11:00
Tim Allen f3e67da937 Update to v101r19 release.
byuu says:

Changelog:

-   added \~130 new PAL games to icarus (courtesy of Smarthuman
    and aquaman)
-   added all three Korean-localized games to icarus
-   sfc: removed SuperDisc emulation (it was going nowhere)
-   sfc: fixed MSU1 regression where the play/repeat flags were not
    being cleared on track select
-   nall: cryptography support added; will be used to sign future
    databases (validation will always be optional)
-   minor shims to fix compilation issues due to nall changes

The real magic is that we now have 25-30% of the PAL SNES library in
icarus!

Signing will be tricky. Obviously if I put the public key inside the
higan archive, then all anyone has to do is change that public key for
their own releases. And if you download from my site (which is now over
HTTPS), then you don't need the signing to verify integrity. I may just
put the public key on my site on my site and leave it at that, we'll
see.
2016-10-28 08:16:58 +11:00
Tim Allen c6fc15f8d2 Update to v101r18 release.
byuu says:

Changelog:

  - added 30 new PAL games to icarus (courtesy of Mikerochip)
  - new version of libco no longer requires mprotect nor W|X permissions
  - nall: default C compiler to -std=c11 instead of -std=c99
  - nall: use `-fno-strict-aliasing` during compilation
  - updated nall/certificates (hopefully for the last time)
  - updated nall/http to newer coding conventions
  - nall: improve handling of range() function

I didn't really work on higan at all, this is mostly just a release
because lots of other things have changed.

The most interesting is `-fno-strict-aliasing` ... basically, it joins
`-fwrapv` as being "stop the GCC developers from doing *really* evil
shit that could lead to security vulnerabilities or instabilities."

For the most part, it's a ~2% speed penalty for higan. Except for the
Sega Genesis, where it's a ~10% speedup. I have no idea how that's
possible, but clearly something's going very wrong with strict aliasing
on the Genesis core.

So ... it is what it is. If you need the performance for the non-Genesis
cores, you can turn it off in your builds. But I'm getting quite sick of
C++'s "surprises" and clever compiler developers, so I'm keeping it on
in all of my software going forward.
2016-09-14 21:55:53 +10:00
Tim Allen d6e9d94ec3 Update to v101r17 release.
byuu says:

Changelog:

  - Z80: added most opcodes between 0x00 and 0x3f (two or three hard
    ones missing still)
  - Z80: redid register declaration *again* to handle AF', BC', DE',
    HL' (ugggggh, the fuck? Alternate registers??)
      - basically, using `#define <register name>` values to get around
        horrendously awful naming syntax
  - Z80: improved handling of displace() so that it won't ever trigger
    on (BC) or (DE)
2016-09-06 23:53:14 +10:00
Tim Allen 2fbbccf985 Update to v101r16 release.
byuu says:

Changelog:

  - Z80: implemented 113 new instructions (all the easy
    LD/ADC/ADD/AND/OR/SBC/SUB/XOR ones)
  - Z80: used alternative to castable<To, With> type (manual cast inside
    instruction() register macros)
  - Z80: debugger: used register macros to reduce typing and increase
    readability
  - Z80: debugger: smarter way of handling multiple DD/FD prefixes
    (using gotos, yay!)
  - ruby: fixed crash with Windows input driver on exit (from SuperMikeMan)

I have no idea how the P/V flag is supposed to work on AND/OR/XOR, so
that's probably wrong for now. HALT is also mostly a dummy function for
now. But I typically implement those inside instruction(), so it
probably won't need to be changed? We'll see.
2016-09-06 10:09:33 +10:00
Tim Allen 4c3f58150c Update to v101r15 release.
byuu says:

Changelog:

  - added (poorly-named) castable<To, With> template
  - Z80 debugger rewritten to make declaring instructions much simpler
  - Z80 has more instructions implemented; supports displacement on
    (IX), (IY) now
  - added `Processor::M68K::Bus` to mirror `Processor::Z80::Bus`
      - it does add a pointer indirection; so I'm not sure if I want to
        do this for all of my emulator cores ...
2016-09-04 23:51:27 +10:00
Tim Allen d91f3999cc Update to v101r14 release.
byuu says:
Changelog:

  - rewrote the Z80 core to properly handle 0xDD (IX0 and 0xFD (IY)
    prefixes
  - added Processor::Z80::Bus as a new type of abstraction
  - all of the instructions implemented have their proper T-cycle counts
    now
  - added nall/certificates for my public keys

The goal of `Processor::Z80::Bus` is to simulate the opcode fetches being
2-read + 2-wait states; operand+regular reads/writes being 3-read. For
now, this puts the cycle counts inside the CPU core. At the moment, I
can't think of any CPU core where this wouldn't be appropriate. But it's
certainly possible that such a case exists. So this may not be the
perfect solution.

The reason for having it be a subclass of Processor::Z80 instead of
virtual functions for the MasterSystem::CPU core to define is due to
naming conflicts. I wanted the core to say `in(addr)` and have it take
the four clocks. But I also wanted a version of the function that didn't
consume time when called. One way to do that would be for the core to
call `Z80::in(addr)`, which then calls the regular `in(addr)` that goes to
`MasterSystem::CPU::in(addr)`. But I don't want to put the `Z80::`
prefix on all of the opcodes. Very easy to forget it, and then end up not
consuming any time. Another is to use uglier names in the
`MasterSystem::CPU` core, like `read_`, `write_`, `in_`, `out_`, etc. But,
yuck.

So ... yeah, this is an experiment. We'll see how it goes.
2016-09-03 21:26:04 +10:00
Tim Allen 7c96826eb0 Update to v101r13 release.
byuu says:

Changelog:

  - MS: added ms/bus
  - Z80: implemented JP/JR/CP/DI/IM/IN instructions
  - MD/VDP: added window layer emulation
  - MD/controller/gamepad: fixed d2,d3 bits (Altered Beast requires
    this)

The Z80 is definitely a lot nastier than the LR35902. There's a lot of
table duplication with HL→IX→IY; and two of them nest two levels deep
(eg FD CB xx xx), so the design may change as I implement more.
2016-08-27 14:48:21 +10:00
Tim Allen 5df717ff2a Update to v101r12 release.
byuu says:

Changelog:

  - new md/bus/ module for bus reads/writes
      - abstracts byte/word accesses wherever possible (everything but
        RAM; forces all but I/O to word, I/O to byte)
      - holds the system RAM since that's technically not part of the
        CPU anyway
  - added md/controller and md/system/peripherals
  - added emulation of gamepads
  - added stub PSG audio output (silent) to cap the framerate at 60fps
    with audio sync enabled
  - fixed VSRAM reads for plane vertical scrolling (two bugs here: add
    instead of sub; interlave plane A/B)
  - mask nametable read offsets (can't exceed 8192-byte nametables
    apparently)
  - emulated VRAM/VSRAM/CRAM reads from VDP data port
  - fixed sprite width/height size calculations
  - added partial emulation of 40-tile per scanline limitation (enough
    to fix Sonic's title screen)
  - fixed off-by-one sprite range testing
  - fixed sprite tile indexing
  - Vblank happens at Y=224 with overscan disabled
      - unsure what happens when you toggle it between Y=224 and Y=240
        ... probably bad things
  - fixed reading of address register for ADDA, CMPA, SUBA
  - fixed sign extension for MOVEA effect address reads
  - updated MOVEM to increment the read addresses (but not writeback)
    for (aN) mode

With all of that out of the way, we finally have Sonic the Hedgehog
(fully?) playable. I played to stage 1-2 and through the special stage,
at least. EDIT: yeah, we probably need HIRQs for Labyrinth Zone.

Not much else works, of course. Most games hang waiting on the Z80, and
those that don't (like Altered Beast) are still royally screwed. Tons of
features still missing; including all of the Z80/PSG/YM2612.

A note on the perihperals this time around: the Mega Drive EXT port is
basically identical to the regular controller ports. So unlike with the
Famicom and Super Famicom, I'm inheriting the exension port from the
controller class.
2016-08-22 08:11:24 +10:00
Tim Allen f7ddbfc462 Update to v101r11 release.
byuu says:

Changelog:

  - 68K: fixed NEG/NEGX operand order
  - 68K: fixed bug in disassembler that was breaking trace logging
  - VDP: improved sprite rendering (still 100% broken)
  - VDP: added horizontal/vertical scrolling (90% broken)

Forgot:

  - 68K: fix extension word sign bit on indexed modes for disassembler
    as well
  - 68K: emulate STOP properly (use r.stop flag; clear on IRQs firing)

I'm really wearing out fast here. The Genesis documentation is somehow
even worse than Game Boy documentation, but this is a far more complex
system.

It's a massive time sink to sit here banging away at every possible
combination of how things could work, only to see no positive
improvements. Nothing I do seems to get sprites to do a goddamn thing.

squee says the sprite Y field is 10-bits, X field is 9-bits. genvdp says
they're both 10-bits. BlastEm treats them like they're both 10-bits,
then masks off the upper bit so it's effectively 9-bits anyway.

Nothing ever bothers to tell you whether the horizontal scroll values
are supposed to add or subtract from the current X position. Probably
the most basic detail you could imagine for explaining horizontal
scrolling and yet ... nope. Nothing.

I can't even begin to understand how the VDP FIFO functionality works,
or what the fuck is meant by "slots".

I'm completely at a loss as how how in the holy hell the 68K works with
8-bit accesses. I don't know whether I need byte/word handlers for every
device, or if I can just hook it right into the 68K core itself. This
one's probably the most major design detail. I need to know this before
I go and implement the PSG/YM2612/IO ports-\>gamepads/Z80/etc.

Trying to debug the 68K is murder because basically every game likes to
start with a 20,000,000-instruction reset phase of checksumming entire
games, and clearing out the memory as agonizingly slowly as humanly
possible. And like the ARM, there's too many registers so I'd need three
widescreen monitors to comfortably view the entire debugger output lines
onscreen.

I can't get any test ROMs to debug functionality outside of full games
because every **goddamned** test ROM coder thinks it's acceptable to tell
people to go fetch some toolchain from a link that died in the late '90s
and only works on MS-DOS 6.22 to build their fucking shit, because god
forbid you include a 32KiB assembled ROM image in your fucking archives.

... I may have to take a break for a while. We'll see.
2016-08-21 12:50:05 +10:00
Tim Allen 0b70a01b47 Update to v101r10 release.
byuu says:
Changelog:

  - 68K: MOVEQ is 8-bit signed
  - 68K: disassembler was print EOR for OR instructions
  - 68K: address/program-counter indexed mode had the signed-word/long
    bit backward
  - 68K: ADDQ/SUBQ #n,aN always works in long mode; regardless of size
  - 68K→VDP DMA needs to use `mode.bit(0)<<22|dmaSource`; increment by
    one instead of two
  - Z80: added registers and initial two instructions
  - MS: hooked up enough to load and start running games
      - Sonic the Hedgehog can execute exactly one instruction... whoo.
2016-08-20 00:11:26 +10:00
Tim Allen 4d2e17f9c0 Update to v101r09 release.
byuu says:

Sorry, two WIPs in one day. Got excited and couldn't wait.

Changelog:

  - ADDQ, SUBQ shouldn't update flags when targeting an address register
  - ADDA should sign extend effective address reads
  - JSR was pushing the PC too early
  - some improvements to 8-bit register reads on the VDP (still needs
    work)
  - added H/V counter reads to the VDP IO port region
  - icarus: added support for importing Master System and Game Gear ROMs
  - tomoko: added library sub-menus for each manufacturer
      - still need to sort Game Gear after Mega Drive somehow ...

The sub-menu system actually isn't all that bad. It is indeed a bit more
annoying, but not as annoying as I thought it was going to be. However,
it looks a hell of a lot nicer now.
2016-08-18 08:05:50 +10:00
Tim Allen 043f6a8b33 Update to v101r08 release.
byuu says:

Changelog:

  - 68K: fixed read-modify-write instructions
  - 68K: fixed ADDX bug (using wrong target)
  - 68K: fixed major bug with SUB using wrong argument ordering
  - 68K: fixed sign extension when reading address registers from
    effective addressing
  - 68K: fixed sign extension on CMPA, SUBA instructions
  - VDP: improved OAM sprite attribute table caching behavior
  - VDP: improved DMA fill operation behavior
  - added Master System / Game Gear stubs (needed for developing the Z80
    core)
2016-08-17 22:31:22 +10:00
Tim Allen ffd150735b Update to v101r07 release.
byuu says:

Added VDP sprite rendering. Can't get any games far enough in to see if
it actually works. So in other words, it doesn't work at all and is 100%
completely broken.

Also added 68K exceptions and interrupts. So far only the VDP interrupt
is present. It definitely seems to be firing in commercial games, so
that's promising. But the implementation is almost certainly completely
wrong. There is fuck all of nothing for documentation on how interrupts
actually work. I had to find out the interrupt vector numbers from
reading the comments from the Sonic the Hedgehog disassembly. I have
literally no fucking clue what I0-I2 (3-bit integer priority value in
the status register) is supposed to do. I know that Vblank=6, Hblank=4,
Ext(gamepad)=2. I know that at reset, SR.I=7. I don't know if I'm
supposed to block interrupts when I is >, >=, <, <= to the interrupt
level. I don't know what level CPU exceptions are supposed to be.

Also implemented VDP regular DMA. No idea if it works correctly since
none of the commercial games run far enough to use it. So again, it's
horribly broken for usre.

Also improved VDP fill mode. But I don't understand how it takes
byte-lengths when the bus is 16-bit. The transfer times indicate it's
actually transferring at the same speed as the 68K->VDP copy, strongly
suggesting it's actually doing 16-bit transfers at a time. In which case,
what happens when you set an odd transfer length?

Also, both DMA modes can now target VRAM, VSRAM, CRAM. Supposedly there's
all kinds of weird shit going on when you target VSRAM, CRAM with VDP
fill/copy modes, but whatever. Get to that later.

Also implemented a very lazy preliminary wait mechanism to to stall out
a processor while another processor exerts control over the bus. This
one's going to be a major work in progress. For one, it totally breaks
the model I use to do save states with libco. For another, I don't
know if a 68K->VDP DMA instantly locks the CPU, or if it the CPU could
actually keep running if it was executing out of RAM when it started
the DMA transfer from ROM (eg it's a bus busy stall, not a hard chip
stall.) That'll greatly change how I handle the waiting.

Also, the OSS driver now supports Audio::Latency. Sound should be
even lower latency now. On FreeBSD when set to 0ms, it's absolutely
incredible. Cannot detect latency whatsoever. The Mario jump sound seems
to happen at the very instant I hear my cherry blue keyswitch activate.
2016-08-15 14:56:38 +10:00
Tim Allen 427bac3011 Update to v101r06 release.
byuu says:

I reworked the video sizing code. Ended up wasting five fucking hours
fighting GTK. When you call `gtk_widget_set_size_request`, it doesn't
actually happen then. This is kind of a big deal because when I then go
to draw onto the viewport, the actual viewport child window is still the
old size, so the image gets distorted. It recovers in a frame or so with
emulation, but if we were to put a still image on there, it would stay
distorted.

The first thought is, `while(gtk_events_pending())
gtk_main_iteration_do(false);` right after the `set_size_request`. But
nope, it tells you there's no events pending. So then you think, go
deeper, use `XPending()` instead. Same thing, GTK hasn't actually issued
the command to Xlib yet. So then you think, if the widget is realized,
just call a blocking `gtk_main_iteration`. One call does nothing, two
calls results in a deadlock on the second one ... do it before program
startup, and the main window will never appear. Great.

Oh, and it's not just the viewport. It's also the widget container area
of the windows, as well as the window itself, as well as the fullscreen
mode toggle effect. They all do this.

For the latter three, I couldn't find anything that worked, so I just
added 20ms loops of constantly calling `gtk_main_iteration_do(false)`
after each one of those things. The downside here is toggling the status
bar takes 40ms, so you'll see it and it'll feel a tiny bit sluggish.

But I can't have a 20ms wait on each widget resize, that would be
catastrophic to performance on windows with lots of widgets.

I tried hooking configure-event and size-allocate, but they were very
unreliable. So instead I ended up with a loop that waits up to a maximm
of 20ms that inspects the `widget->allocation.(width,height)` values
directly and waits for them to be what we asked for with
`set_size_request`.

There was some extreme ugliness in GTK with calling
`gtk_main_iteration_do` recursively (`hiro::Widget::setGeometry` is
called recursively), so I had to lock it to only happen on the top level
widgets (the child ones should get resized while waiting on the
top-level ones, so it should be fine in practice), and also only run it
on realized widgets.

Even still, I'm getting ~3 timeouts when opening the settings dialog in
higan, but no other windows. But, this is the best I can do for now.

And the reason for all of this pain? Yeah, updated the video code.

So the Emulator::Interface now has this:

    struct VideoSize { uint width, height; };  //or requiem for a tuple
    auto videoSize() -> VideoSize;
    auto videoSize(uint width, uint height, bool arc) -> VideoSize;

The first function, for now, is just returning the literal surface size.
I may remove this ... one thing I want to allow for is cores that send
different texture sizes based on interlace/hires/overscan/etc settings.

The second function is more interesting. Instead of having the UI trying
to figure out sizing, I figure the emulation cores can do a better job
and we can customize it per-core now. So it gets the window's width and
height, and whether the user asked for aspect correction, and then
computes the best width/height ratio possible. For now they're all just
doing multiples of a 1x scale to the UI 2x,3x,4x modes.

We still need a third function, which will probably be what I repurpose
videoSize() for: to return the 'effective' size for pixel shaders, to
then feed into ruby, to then feed into quark, to then feed into our
shaders. Since shaders use normalized coordinates for pixel fetching,
this should work out just fine. The real texture size will be exposed to
quark shaders as well, of course.

Now for the main window ... it's just hard-coded to be 640x480, 960x720,
1280x960 for now. It works nicely for some cores on some modes, not so
much for others. Work in progress I guess.

I also took the opportunity to draw the about dialog box logo on the
main window. Got a bit fancy and used the old spherical gradient and
impose functionality of nall/image on it. Very minor highlight, nothing
garish. Just something nicer than a solid black window.

If you guys want to mess around with sizes, placements, and gradient
styles/colors/shapes ... feel free. If you come up with something nicer,
do share.

That's what led to all the GTK hell ... the logo wasn't drawing right as
you resized the window. But now it is, though I am not at all happy with
the hacking I had to do.

I also had to improve the video update code as a result of this:

  - when you unload a game, it blacks out the screen
      - if you are not quitting the emulator, it'll draw the logo; if
        you are, it won't
  - when you load a game, it black out the logo

These options prevent any unsightliness from resizing the viewport with
image data on it already

I need to redraw the logo when toggling fullscreen with no game loaded
as well for Windows, it seems.
2016-08-15 14:52:05 +10:00
Tim Allen ac2d0ba1cf Update to v101r05 release.
byuu says:

Changelog:

  - 68K: fixed bug that affected BSR return address
  - VDP: added very preliminary emulation of planes A, B, W (W is
    entirely broken though)
  - VDP: added command/address stuff so you can write to VRAM, CRAM,
    VSRAM
  - VDP: added VRAM fill DMA

I would be really surprised if any commercial games showed anything at
all, so I'd probably recommend against wasting your time trying, unless
you're really bored :P

Also, I wanted to add: I am accepting patches\! So if anyone wants to
look over the 68K core for bugs, that would save me untold amounts of
time in the near future :D
2016-08-13 09:47:30 +10:00
Tim Allen 1df2549d18 Update to v101r04 release.
byuu says:

Changelog:

  - pulled the (u)intN type aliases into higan instead of leaving them
    in nall
  - added 68K LINEA, LINEF hooks for illegal instructions
  - filled the rest of the 68K lambda table with generic instance of
    ILLEGAL
  - completed the 68K disassembler effective addressing modes
      - still unsure whether I should use An to decode absolute
        addresses or not
      - pro: way easier to read where accesses are taking place
      - con: requires An to be valid; so as a disassembler it does a
        poor job
      - making it optional: too much work; ick
  - added I/O decoding for the VDP command-port registers
  - added skeleton timing to all five processor cores
  - output at 1280x480 (needed for mixed 256/320 widths; and to handle
    interlace modes)

The VDP, PSG, Z80, YM2612 are all stepping one clock at a time and
syncing; which is the pathological worst case for libco. But they also
have no logic inside of them. With all the above, I'm averaging around
250fps with just the 68K core actually functional, and the VDP doing a
dumb "draw white pixels" loop. Still way too early to tell how this
emulator is going to perform.

Also, the 320x240 mode of the Genesis means that we don't need an aspect
correction ratio. But we do need to ensure the output window is a
multiple 320x240 so that the scale values work correctly. I was
hard-coding aspect correction to stretch the window an additional \*8/7.
But that won't work anymore so ... the main higan window is now 640x480,
960x720, or 1280x960. Toggling aspect correction only changes the video
width inside the window.

It's a bit jarring ... the window is a lot wider, more black space now
for most modes. But for now, it is what it is.
2016-08-12 11:07:04 +10:00
Tim Allen 9b8c3ff8c0 Update to v101r03 release.
byuu says:

The 68K core now implements all 88 instructions. It ended up being 111
instructions in my core due to splitting up opcodes with the same name
but different addressing modes or directions (removes conditions at the
expense of more code.)

Technically, I don't have exceptions actually implemented yet, and
RESET/STOP don't do anything but set flags. So there's still more to
go. But ... close enough for statistics time!

The M68K core source code is 124,712 bytes in size. The next largest
core is the ARM7 core at 70,203 bytes in size.

The M68K object size is 942KiB; with the next largest being the V30MZ
core at 173KiB.

There are a total of 19,656 invalid opcodes in the 68000 revision (unless
of course I've made mistakes in my mappings, which is very probably.)

Now the fun part ... figuring out how to fix bugs in this core without
VDP emulation :/
2016-08-11 08:02:02 +10:00
Tim Allen 0a57cac70c Update to v101r02 release.
byuu says:

Changelog:

  - Emulator: use `(uintmax)-1 >> 1` for the units of time
  - MD: implemented 13 new 68K instructions (basically all of the
    remaining easy ones); 21 remain
  - nall: replaced `(u)intmax_t` (64-bit) with *actual* `(u)intmax` type
    (128-bit where available)
      - this extends to everything: atoi, string, etc. You can even
        print 128-bit variables if you like

22,552 opcodes still don't exist in the 68K map. Looking like quite a
few entries will be blank once I finish.
2016-08-09 21:07:18 +10:00
Tim Allen 8bdf8f2a55 Update to v101r01 release.
byuu says:

Changelog:

  - added eight more 68K instructions
  - split ADD(direction) into two separate ADD functions

I now have 54 out of 88 instructions implemented (thus, 34 remaining.)
The map is missing 25,182 entries out of 65,536. Down from 32,680 for
v101.00

Aside: this version number feels really silly. r10 and r11 surely will
as well ...
2016-08-08 20:12:03 +10:00
Tim Allen e39987a3e3 Update to v101 release.
byuu says (in the public announcement):

Not a large changelog this time, sorry. This release is mostly to fix
the SA-1 issue, and to get some real-world testing of the new scheduler
model. Most of the work in the past month has gone into writing a 68000
CPU core; yet it's still only about half-way finished.

Changelog (since the previous release):

  - fixed SNES SA-1 IRQ regression (fixes Super Mario RPG level-up
    screen)
  - new scheduler for all emulator cores (precision of 2^-127)
  - icarus database adds nine new SNES games
  - added Input/Frequency to settings file (allows simulation of
    latency)

byuu says (in the WIP forum):

Changelog:

  - in 32-bit mode, Thread uses uint64\_t with 2^-63 time units (10^-7
    precision in the worst case)
      - nearly ten times the precision of an attosecond
  - in 64-bit mode, Thread uses uint128\_t with 2^-127 time units
    (10^-26 precision in the worst case)
      - far more accurate than yoctoseconds; almost closing in on planck
        time

Note: a quartz crystal is accurate to 10^-4 or 10^-5. A cesium fountain
atomic clock is accurate to 10^-15. So ... yeah. 2^-63 was perfectly
fine; but there was no speed penalty whatsoever for using uint128\_t in
64-bit mode, so why not?
2016-08-08 20:04:15 +10:00
Tim Allen f5e5bf1772 Update to v100r16 release.
byuu says:

(Windows users may need to include <sys/time.h> at the top of
nall/chrono.hpp, not sure.)

Unchangelog:
- forgot to add the Scheduler clock=0 fix because I have the memory of
  a goldfish

Changelog:
- new icarus database with nine additional games
- hiro(GTK,Qt) won't constantly write its settings.bml file to disk
  anymore
- added latency simulator for fun (settings.bml => Input/Latency in
  milliseconds)

So the last one ... I wanted to test out nall::chrono, and I was also
thinking that by polling every emulated frame, it's pretty wasteful when
you are using Fast Forward and hitting 200+fps. As I've said before,
calls to ruby::input::poll are not cheap.

So to get around this, I added a limiter so that if you called the
hardware poll function within N milliseconds, it'll return without
doing any actual work. And indeed, that increases my framerate of Zelda
3 uncapped from 133fps to 142fps. Yay. But it's not a "real" speedup,
as it only helps you when you exceed 100% speed (theoretically, you'd
need to crack 300% speed since the game itself will poll at 16ms at 100%
speed, but yet it sped up Zelda 3, so who am I to complain?)

I threw the latency value into the settings file. It should be 16,
but I set it to 5 since that was the lowest before it started negatively
impacting uncapped speeds. You're wasting your time and CPU cycles setting
it lower than 5, but if people like placebo effects it might work. Maybe
I should let it be a signed integer so people can set it to -16 and think
it's actually faster :P (I'm only joking. I took out the 96000hz audio
placebo effect as well. Not really into psychological tricks anymore.)

But yeah seriously, I didn't do this to start this discussion again for
the billionth time. Please don't go there. And please don't tell me this
WIP has higher/lower latency than before. I don't want to hear it.

The only reason I bring it up is for the fun part that is worth
discussing: put up or shut up time on how sensitive you are to
latency! You can set the value above 5 to see how games feel.

I personally can't really tell a difference until about 50. And I can't
be 100% confident it's worse until about 75. But ... when I set it to
150, games become "extra difficult" ... the higher it goes, the worse
it gets :D

For this WIP, I've left no upper limit cap. I'll probably set a cap of
something like 500ms or 1000ms for the official release. Need to balance
user error/trolling with enjoyability. I'll think about it.

[...]

Now, what I worry about is stupid people seeing it and thinking it's an
"added latency" setting, as if anyone would intentionally make things
worse by default. This is a limiter. So if 5ms have passed since the
game last polled, and that will be the case 99.9% of the time in games,
the next poll will happen just in time, immediately when the game polls
the inputs. Thus, a value below 1/<framerate>ms is not only pointless,
if you go too low it will ruin your fast forward max speeds.

I did say I didn't want to resort to placebo tricks, but I also don't
want to spark up public discussion on this again either. So it might
be best to default Input/Latency to 0ms, and internally have a max(5,
latency) wrapper around the value.
2016-08-03 22:32:40 +10:00
Tim Allen c50723ef61 Update to v100r15 release.
byuu wrote:

Aforementioned scheduler changes added. Longer explanation of why here:
http://hastebin.com/raw/toxedenece

Again, we really need to test this as thoroughly as possible for
regressions :/
This is a really major change that affects absolutely everything: all
emulation cores, all coprocessors, etc.

Also added ADDX and SUB to the 68K core, which brings us just barely
above 50% of the instruction encoding space completed.

[Editor's note: The "aformentioned scheduler changes" were described in
a previous forum post:

    Unfortunately, 64-bits just wasn't enough precision (we were
    getting misalignments ~230 times a second on 21/24MHz clocks), so
    I had to move to 128-bit counters. This of course doesn't exist on
    32-bit architectures (and probably not on all 64-bit ones either),
    so for now ... higan's only going to compile on 64-bit machines
    until we figure something out. Maybe we offer a "lower precision"
    fallback for machines that lack uint128_t or something. Using the
    booth algorithm would be way too slow.

    Anyway, the precision is now 2^-96, which is roughly 10^-29. That
    puts us far beyond the yoctosecond. Suck it, MAME :P I'm jokingly
    referring to it as the byuusecond. The other 32-bits of precision
    allows a 1Hz clock to run up to one full second before all clocks
    need to be normalized to prevent overflow.

    I fixed a serious wobbling issue where I was using clock > other.clock
    for synchronization instead of clock >= other.clock; and also another
    aliasing issue when two threads share a common frequency, but don't
    run in lock-step. The latter I don't even fully understand, but I
    did observe it in testing.

    nall/serialization.hpp has been extended to support 128-bit integers,
    but without explicitly naming them (yay generic code), so nall will
    still compile on 32-bit platforms for all other applications.

    Speed is basically a wash now. FC's a bit slower, SFC's a bit faster.

The "longer explanation" in the linked hastebin is:

    Okay, so the idea is that we can have an arbitrary number of
    oscillators. Take the SNES:

    - CPU/PPU clock = 21477272.727272hz
    - SMP/DSP clock = 24576000hz
    - Cartridge DSP1 clock = 8000000hz
    - Cartridge MSU1 clock = 44100hz
    - Controller Port 1 modem controller clock = 57600hz
    - Controller Port 2 barcode battler clock = 115200hz
    - Expansion Port exercise bike clock = 192000hz

    Is this a pathological case? Of course it is, but it's possible. The
    first four do exist in the wild already: see Rockman X2 MSU1
    patch. Manifest files with higan let you specify any frequency you
    want for any component.

    The old trick higan used was to hold an int64 counter for each
    thread:thread synchronization, and adjust it like so:

    - if thread A steps X clocks; then clock += X * threadB.frequency
      - if clock >= 0; switch to threadB
    - if thread B steps X clocks; then clock -= X * threadA.frequency
      - if clock <  0; switch to threadA

    But there are also system configurations where one processor has to
    synchronize with more than one other processor. Take the Genesis:

    - the 68K has to sync with the Z80 and PSG and YM2612 and VDP
    - the Z80 has to sync with the 68K and PSG and YM2612
    - the PSG has to sync with the 68K and Z80 and YM2612

    Now I could do this by having an int64 clock value for every
    association. But these clock values would have to be outside the
    individual Thread class objects, and we would have to update every
    relationship's clock value. So the 68K would have to update the Z80,
    PSG, YM2612 and VDP clocks. That's four expensive 64-bit multiply-adds
    per clock step event instead of one.

    As such, we have to account for both possibilities. The only way to
    do this is with a single time base. We do this like so:

    - setup: scalar = timeBase / frequency
    - step: clock += scalar * clocks

    Once per second, we look at every thread, find the smallest clock
    value. Then subtract that value from all threads. This prevents the
    clock counters from overflowing.

    Unfortunately, these oscillator values are psychotic, unpredictable,
    and often times repeating fractions. Even with a timeBase of
    1,000,000,000,000,000,000 (one attosecond); we get rounding errors
    every ~16,300 synchronizations. Specifically, this happens with a CPU
    running at 21477273hz (rounded) and SMP running at 24576000hz. That
    may be good enough for most emulators, but ... you know how I am.

    Plus, even at the attosecond level, we're really pushing against the
    limits of 64-bit integers. Given the reciprocal inverse, a frequency
    of 1Hz (which does exist in higan!) would have a scalar that consumes
    1/18th of the entire range of a uint64 on every single step. Yes, I
    could raise the frequency, and then step by that amount, I know. But
    I don't want to have weird gotchas like that in the scheduler core.

    Until I increase the accuracy to about 100 times greater than a
    yoctosecond, the rounding errors are too great. And since the only
    choice above 64-bit values is 128-bit values; we might as well use
    all the extra headroom. 2^-96 as a timebase gives me the ability to
    have both a 1Hz and 4GHz clock; and run them both for a full second;
    before an overflow event would occur.

Another hastebin includes demonstration code:

    #include <libco/libco.h>

    #include <nall/nall.hpp>
    using namespace nall;

    //

    cothread_t mainThread = nullptr;
    const uint iterations = 100'000'000;
    const uint cpuFreq = 21477272.727272 + 0.5;
    const uint smpFreq = 24576000.000000 + 0.5;
    const uint cpuStep = 4;
    const uint smpStep = 5;

    //

    struct ThreadA {
      cothread_t handle = nullptr;
      uint64 frequency = 0;
      int64 clock = 0;

      auto create(auto (*entrypoint)() -> void, uint frequency) {
        this->handle = co_create(65536, entrypoint);
        this->frequency = frequency;
        this->clock = 0;
      }
    };

    struct CPUA : ThreadA {
      static auto Enter() -> void;
      auto main() -> void;
      CPUA() { create(&CPUA::Enter, cpuFreq); }
    } cpuA;

    struct SMPA : ThreadA {
      static auto Enter() -> void;
      auto main() -> void;
      SMPA() { create(&SMPA::Enter, smpFreq); }
    } smpA;

    uint8 queueA[iterations];
    uint offsetA;
    cothread_t resumeA = cpuA.handle;

    auto EnterA() -> void {
      offsetA = 0;
      co_switch(resumeA);
    }

    auto QueueA(uint value) -> void {
      queueA[offsetA++] = value;
      if(offsetA >= iterations) {
        resumeA = co_active();
        co_switch(mainThread);
      }
    }

    auto CPUA::Enter() -> void { while(true) cpuA.main(); }

    auto CPUA::main() -> void {
      QueueA(1);
      smpA.clock -= cpuStep * smpA.frequency;
      if(smpA.clock < 0) co_switch(smpA.handle);
    }

    auto SMPA::Enter() -> void { while(true) smpA.main(); }

    auto SMPA::main() -> void {
      QueueA(2);
      smpA.clock += smpStep * cpuA.frequency;
      if(smpA.clock >= 0) co_switch(cpuA.handle);
    }

    //

    struct ThreadB {
      cothread_t handle = nullptr;
      uint128_t scalar = 0;
      uint128_t clock = 0;

      auto print128(uint128_t value) {
        string s;
        while(value) {
          s.append((char)('0' + value % 10));
          value /= 10;
        }
        s.reverse();
        print(s, "\n");
      }

      //femtosecond (10^15) =    16306
      //attosecond  (10^18) =   688838
      //zeptosecond (10^21) = 13712691
      //yoctosecond (10^24) = 13712691 (hitting a dead-end on a rounding error causing a wobble)
      //byuusecond? ( 2^96) = (perfect? 79,228 times more precise than a yoctosecond)

      auto create(auto (*entrypoint)() -> void, uint128_t frequency) {
        this->handle = co_create(65536, entrypoint);

        uint128_t unitOfTime = 1;
      //for(uint n : range(29)) unitOfTime *= 10;
        unitOfTime <<= 96;  //2^96 time units ...

        this->scalar = unitOfTime / frequency;
        print128(this->scalar);
        this->clock = 0;
      }

      auto step(uint128_t clocks) -> void { clock += clocks * scalar; }
      auto synchronize(ThreadB& thread) -> void { if(clock >= thread.clock) co_switch(thread.handle); }
    };

    struct CPUB : ThreadB {
      static auto Enter() -> void;
      auto main() -> void;
      CPUB() { create(&CPUB::Enter, cpuFreq); }
    } cpuB;

    struct SMPB : ThreadB {
      static auto Enter() -> void;
      auto main() -> void;
      SMPB() { create(&SMPB::Enter, smpFreq); clock = 1; }
    } smpB;

    auto correct() -> void {
      auto minimum = min(cpuB.clock, smpB.clock);
      cpuB.clock -= minimum;
      smpB.clock -= minimum;
    }

    uint8 queueB[iterations];
    uint offsetB;
    cothread_t resumeB = cpuB.handle;

    auto EnterB() -> void {
      correct();
      offsetB = 0;
      co_switch(resumeB);
    }

    auto QueueB(uint value) -> void {
      queueB[offsetB++] = value;
      if(offsetB >= iterations) {
        resumeB = co_active();
        co_switch(mainThread);
      }
    }

    auto CPUB::Enter() -> void { while(true) cpuB.main(); }

    auto CPUB::main() -> void {
      QueueB(1);
      step(cpuStep);
      synchronize(smpB);
    }

    auto SMPB::Enter() -> void { while(true) smpB.main(); }

    auto SMPB::main() -> void {
      QueueB(2);
      step(smpStep);
      synchronize(cpuB);
    }

    //

    #include <nall/main.hpp>
    auto nall::main(string_vector) -> void {
      mainThread = co_active();

      uint masterCounter = 0;
      while(true) {
        print(masterCounter++, " ...\n");

        auto A = clock();
        EnterA();
        auto B = clock();
        print((double)(B - A) / CLOCKS_PER_SEC, "s\n");

        auto C = clock();
        EnterB();
        auto D = clock();
        print((double)(D - C) / CLOCKS_PER_SEC, "s\n");

        for(uint n : range(iterations)) {
          if(queueA[n] != queueB[n]) return print("fail at ", n, "\n");
        }
      }
    }

...and that's everything.]
2016-07-31 12:11:20 +10:00
Tim Allen ca277cd5e8 Update to v100r14 release.
byuu says:

(Windows: compile with -fpermissive to silence an annoying error. I'll
fix it in the next WIP.)

I completely replaced the time management system in higan and overhauled
the scheduler.

Before, processor threads would have "int64 clock"; and there would
be a 1:1 relationship between two threads. When thread A ran for X
cycles, it'd subtract X * B.Frequency from clock; and when thread B ran
for Y cycles, it'd add Y * A.Frequency from clock. This worked well
and allowed perfect precision; but it doesn't work when you have more
complicated relationships: eg the 68K can sync to the Z80 and PSG; the
Z80 to the 68K and PSG; so the PSG needs two counters.

The new system instead uses a "uint64 clock" variable that represents
time in attoseconds. Every time the scheduler exits, it subtracts
the smallest clock count from all threads, to prevent an overflow
scenario. The only real downside is that rounding errors mean that
roughly every 20 minutes, we have a rounding error of one clock cycle
(one 20,000,000th of a second.) However, this only applies to systems
with multiple oscillators, like the SNES. And when you're in that
situation ... there's no such thing as a perfect oscillator anyway. A
real SNES will be thousands of times less out of spec than 1hz per 20
minutes.

The advantages are pretty immense. First, we obviously can now support
more complex relationships between threads. Second, we can build a
much more abstracted scheduler. All of libco is now abstracted away
completely, which may permit a state-machine / coroutine version of
Thread in the future. We've basically gone from this:

    auto SMP::step(uint clocks) -> void {
      clock += clocks * (uint64)cpu.frequency;
      dsp.clock -= clocks;
      if(dsp.clock < 0 && !scheduler.synchronizing()) co_switch(dsp.thread);
      if(clock >= 0 && !scheduler.synchronizing()) co_switch(cpu.thread);
    }

To this:

    auto SMP::step(uint clocks) -> void {
      Thread::step(clocks);
      synchronize(dsp);
      synchronize(cpu);
    }

As you can see, we don't have to do multiple clock adjustments anymore.
This is a huge win for the SNES CPU that had to update the SMP, DSP, all
peripherals and all coprocessors. Likewise, we don't have to synchronize
all coprocessors when one runs, now we can just synchronize the active
one to the CPU.

Third, when changing the frequencies of threads (think SGB speed setting
modes, GBC double-speed mode, etc), it no longer causes the "int64
clock" value to be erroneous.

Fourth, this results in a fairly decent speedup, mostly across the
board. Aside from the GBA being mostly a wash (for unknown reasons),
it's about an 8% - 12% speedup in every other emulation core.

Now, all of this said ... this was an unbelievably massive change, so
... you know what that means >_> If anyone can help test all types of
SNES coprocessors, and some other system games, it'd be appreciated.

----

Lastly, we have a bitchin' new about screen. It unfortunately adds
~200KiB onto the binary size, because the PNG->C++ header file
transformation doesn't compress very well, and I want to keep the
original resource files in with the higan archive. I might try some
things to work around this file size increase in the future, but for now
... yeah, slightly larger archive sizes, sorry.

The logo's a bit busted on Windows (the Label control's background
transparency and alignment settings aren't working), but works well on
GTK. I'll have to fix Windows before the next official release. For now,
look on my Twitter feed if you want to see what it's supposed to look
like.

----

EDIT: forgot about ICD2::Enter. It's doing some weird inverse
run-to-save thing that I need to implement support for somehow. So, save
states on the SGB core probably won't work with this WIP.
2016-07-30 13:56:12 +10:00
Tim Allen 306cac2b54 Update to v100r13 release.
byuu says:

Changelog: M68K improvements, new instructions added.
2016-07-26 20:46:43 +10:00
Tim Allen f230d144b5 Update to v100r12 release.
byuu says:

All of the above fixes, plus I added all 24 variations on the shift
opcodes, plus SUBQ, plus fixes to the BCC instruction.

I can now run 851,767 instructions into Sonic the Hedgehog before hitting
an unimplemented instruction (SUB).

The 68K core is probably only ~35% complete, and yet it's already within
4KiB of being the largest CPU core, code size wise, in all of higan. Fuck
this chip.
2016-07-25 23:15:54 +10:00
Tim Allen 7ccfbe0206 Update to v100r11 release.
byuu says:

I split the Register class and read/write handlers into DataRegister and
AddressRegister, given that they have different behaviors on byte/word
accesses (data tends to preserve the upper bits; address tends to
sign-extend things.)

I expanded EA to EffectiveAddress. No sense in abbreviating things
to death.

I've now implemented 26 instructions. But the new ones are just all the
stupid from/to ccr/sr instructions.

Ryphecha confirmed that you can't set the undefined bits, so I don't
think the BitField concept is appropriate for the CCR/SR. Instead, I'm
just storing direct flags and have (read,write)(CCR,SR) instead. This
isn't like the 65816 where you have subroutines that push and pop the
flag register. It's much more common to access individual flags. Doesn't
match the consistency angle of the other CPU cores, but ... I think this
is the right thing to for the 68K specifically.
2016-07-23 12:32:35 +10:00
Tim Allen 4b897ba791 Update to v100r10 release.
byuu says:

Redesigned the handling of reading/writing registers to be about eight
times faster than the old system. More work may be needed ... it seems
data registers tend to preserve their upper bits upon assignment; whereas
address registers tend to sign-extend values into them. It may make
sense to have DataRegister and AddressRegister classes with separate
read/write handlers. I'd have to hold two Register objects inside the
EffectiveAddress (EA) class if we do that.

Implemented 19 opcodes now (out of somewhere between 60 and 90.) That gets
the first ~530,000 instructions in Sonic the Hedgehog running (though
probably wrong. But we can run a lot thanks to large initialization
loops.)

If I force the core to loop back to the reset vector on an invalid opcode,
I'm getting about 1500fps with a dumb 320x240 blit 60 times a second and
just the 68K running alone (no Z80, PSG, VDP, YM2612.) I don't know if
that's good or not. I guess we'll find out.

I had to stop tonight because the final opcode I execute is an RTS
(return from subroutine) that's branching back to address 0; which is
invalid ... meaning something went terribly wrong and the system crashed.
2016-07-22 22:03:25 +10:00
Tim Allen be3f6ac0d5 Update to v100r09 release.
byuu says:

Another six hours in ...

I have all of the opcodes, memory access functions, disassembler mnemonics
and table building converted over to the new template<uint Size> format.

Certainly, it would be quite easy for this nightmare chip to throw me
another curveball, but so far I can handle:

- MOVE (EA to, EA from) case
  - read(from) has to update register index for +/-(aN) mode
- MOVEM (EA from) case
  - when using +/-(aN), RA can't actually be updated until the transfer
    is completed
- LEA (EA from) case
  - doesn't actually perform the final read; just returns the address
    to be read from
- ANDI (EA from-and-to) case
  - same EA has to be read from and written to
  - for -(aN), the read has to come from aN-2, but can't update aN yet;
    so that the write also goes to aN-2
- no opcode can ever fetch the extension words more than once
- manually control the order of extension word fetching order for proper
  opcode decoding

To do all of that without a whole lot of duplicated code (or really
bloating out every single instruction with red tape), I had to bring
back the "bool valid / uint32 address" variables inside the EA struct =(

If weird exceptions creep in like timing constraints only on certain
opcodes, I can use template flags to the EA read/write functions to
handle that.
2016-07-19 19:12:05 +10:00
Tim Allen 92fe5b0813 Update to v100r08 release.
byuu says:

Six and a half hours this time ... one new opcode, and all old opcodes
now in a deprecated format. Hooray, progress!

For building the table, I've decided to move from:

    for(uint opcode : range(65536)) {
      if(match(...)) bind(opNAME, ...);
    }

To instead having separate for loops for each supported opcode. This
lets me specialize parts I want with templates.

And to this aim, I'm moving to replace all of the
(read,write)(size, ...) functions with (read,write)<Size>(...) functions.

This will amount to the ~70ish instructions being triplicated ot ~210ish
instructions; but I think this is really important.

When I was getting into flag calculations, a ton of conditionals
were needed to mask sizes to byte/word/long. There was also lots of
conditionals in all the memory access handlers.

The template code is ugly, but we eliminate a huge amount of branch
conditions this way.
2016-07-18 08:11:29 +10:00
Tim Allen 059347e575 Update to v100r07 release.
byuu says:

Four and a half hours of work and ... zero new opcodes implemented.

This was the best job I could do refining the effective address
computations. Should have all twelve 68000 modes implemented now. Still
have a billion questions about when and how I'm supposed to perform
certain edge case operations, though.
2016-07-17 13:24:28 +10:00
Tim Allen 0d6a09f9f8 Update to v100r06 release.
byuu says:

Up to ten 68K instructions out of somewhere between 61 and 88, depending
upon which PDF you look at. Of course, some of them aren't 100% completed
yet, either. Lots of craziness with MOVEM, and BCC has a BSR variant
that needs stack push/pop functions.

This WIP actually took over eight hours to make, going through every
possible permutation on how to design the core itself. The updated design
now builds both the instruction decoder+dispatcher and the disassembler
decoder into the same main loop during M68K's constructor.

The special cases are also really psychotic on this processor, and
I'm afraid of missing something via the fallthrough cases. So instead,
I'm ordering the instructions alphabetically, and including exclusion
cases to ignore binding invalid cases. If I end up remapping an existing
register, then it'll throw a run-time assertion at program startup.

I wanted very much to get rid of struct EA (EffectiveAddress), but
it's too difficult to keep track of the internal effective address
without it. So I split out the size to a separate parameter, since
every opcode only has one size parameter, and otherwise it was getting
duplicated in opcodes that take two EAs, and was also awkward with the
flag testing. It's a bit more typing, but I feel it's more clean this way.

Overall, I'm really worried this is going to be too slow. I don't want
to turn the EA stuff into templates, because that will massively bloat
out compilation times and object sizes, and will also need a special DSL
preprocessor since C++ doesn't have a static for loop. I can definitely
optimize a lot of EA's address/read/write functions away once the core
is completed, but it's never going to hold a candle to a templatized
68K core.

----

Forgot to include the SA-1 regression fix. I always remember immediately
after I upload and archive the WIP. Will try to get that in next time,
I guess.
2016-07-16 18:39:44 +10:00
Tim Allen b72f35a13e Update to v100r05 release.
byuu says:

Alright, I'm definitely going to need to find some people willing to
tolerate my questions on this chip, so I'm going to go ahead and announce
I'm working on this I guess.

This core is way too big for a surprise like the NES and WS cores
were. It'll probably even span multiple v10x releases before it's
even ready.
2016-07-13 08:47:04 +10:00
Tim Allen 1c0ef793fe Update to v100r04 release.
byuu says:

I now have enough of three instructions implemented to get through the
first four instructions in Sonic the Hedgehog.

But they're far from complete. The very first instruction uses EA
addressing, which is similar to x86's ModRM in terms of how disgustingly
complex it is. And it also accesses Z80 control registers, which obviously
isn't going to do anything yet.

The slow speed was me being stupid again. It's not 7.6MHz per frame,
it's 7.67MHz per second. So yeah, speed is so far acceptable again. But
we'll see how things go as I keep emulating more. The 68K decode is not
pretty at all.
2016-07-12 20:19:31 +10:00
Tim Allen 76a8ecd32a Update to v100r03 release.
byuu says:

Changelog:
- moved Thread, Scheduler, Cheat functionality into emulator/ for
  all cores
- start of actual Mega Drive emulation (two 68K instructions)

I'm going to be rather terse on MD emulation, as it's too early for any
meaningful dialogue here.
2016-07-10 15:28:26 +10:00
Tim Allen 3dd1aa9c1b Update to v100r02 release.
byuu says:

Sigh ... I'm really not a good person. I'm inherently selfish.

My responsibility and obligation right now is to work on loki, and
then on the Tengai Makyou Zero translation, and then on improving the
Famicom emulation.

And yet ... it's not what I really want to do. That shouldn't matter;
I should work on my responsibilities first.

Instead, I'm going to be a greedy, self-centered asshole, and work on
what I really want to instead.

I'm really sorry, guys. I'm sure this will make a few people happy,
and probably upset even more people.

I'm also making zero guarantees that this ever gets finished. As always,
I wish I could keep these things secret, so if I fail / give up, I could
just drop it with no shame. But I would have to cut everyone out of the
WIP process completely to make it happen. So, here goes ...

This WIP adds the initial skeleton for Sega Mega Drive / Genesis
emulation. God help us.

(minor note: apparently the new extension for Mega Drive games is .md,
neat. That's what I chose for the folders too. I thought it was .smd,
so that'll be fixed in icarus for the next WIP.)

(aside: this is why I wanted to get v100 out. I didn't want this code in
a skeleton state in v100's source. Nor did I want really broken emulation,
which the first release is sure to be, tarring said release.)

...

So, basically, I've been ruminating on the legacy I want to leave behind
with higan. 3D systems are just plain out. I'm never going to support
them. They're too complex for my abilities, and they would run too slowly
with my design style. I'm not willing to compromise my design ideals. And
I would never want to play a 3D game system at native 240p/480i resolution
... but 1080p+ upscaling is not accurate, so that's a conflict I want
to avoid entirely. It's also never going to emulate computer systems
(X68K, PC-98, FM-Towns, etc) because holy shit that would completely
destroy me. It's also never going emulate arcade machines.

So I think of higan as a collection of 2D emulators for consoles
and handhelds. I've gone over every major 2D gaming system there is,
looking for ones with games I actually care about and enjoy. And I
basically have five of those systems supported already. Looking at the
remaining list, I see only three systems left that I have any interest
in whatsoever: PC-Engine, Master System, Mega Drive. Again, I'm not in
any way committing to emulating any of these, but ... if I had all of
those in higan, I think I'd be content to really, truly, finally stop
writing more emulators for the rest of my life.

And so I decided to tackle the most difficult system first. If I'm
successful, the Z80 core should cover a lot of the work on the SMS. And
the HuC6280 should land somewhere between the NES and SNES in terms of
difficulty ... closer to the NES.

The systems that just don't appeal to me at all, which I will never touch,
include, but are not limited to:
* Atari 2600/5200/7800
* Lynx
* Jaguar
* Vectrex
* Colecovision
* Commodore 64
* Neo-Geo
* Neo-Geo Pocket / Color
* Virtual Boy
* Super A'can
* 32X
* CD-i
* etc, etc, etc.

And really, even if something were mildly interesting in there ... we
have to stop. I can't scale infinitely. I'm already way past my limit,
but I'm doing this anyway. Too many cores bloats everything and kills
quality on everything. I don't want higan to become MESS v2.

I don't know what I'll do about the Famicom Disk System, PC-Engine CD,
and Mega CD. I don't think I'll be able to achieve 60fps emulating the
Mega CD, even if I tried to.

I don't know what's going to happen here with even the Mega Drive. Maybe
I'll get driven crazy with the documentation and quit. Maybe it'll end
up being too complicated and I'll quit. Maybe the emulation will end up
way too slow and I'll give up. Maybe it'll take me seven years to get
any games playable at all. Maybe Steve Snake, AamirM and Mike Pavone
will pool money to hire a hitman to come after me. Who knows.

But this is what I want to do, so ... here goes nothing.
2016-07-09 14:21:37 +10:00
Tim Allen 88c79e56a0 Update to v100r01 release.
[This version, with the internal version number changed back to "v100",
replaced the original v100 source archive on byuu.org soon after v100's
release, because it fixes important bugs in that version. --Ed]

byuu says:

Changelog:
- fixed default paths for Sufami Turbo slotted games
- moved WonderSwan orientation controls to the port rather than the device
  - I do like hex_usr's idea here; but that'll need more consideration;
    so this is a temporary fix
- added new debugger interface (see the public topic for more on that)
2016-07-08 22:31:35 +10:00
Tim Allen 07995c05a5 Update to v100 release.
byuu says:

higan has finally reached v100!

I feel it's important to stress right away that this is not "version
1.00", nor is it a major milestone release. Rather than arbitrary version
numbers, all of my software simply bumps version numbers by one for each
official release. As such, higan v100 is simply higan's 100th release.

That said, the primary focus of this release has been code
clean-ups. These are always somewhat dangerous in that regressions are
possible. We've tested through sixteen WIP revisions, one of which was
open to the public, to try and minimize any regressions. But all the same,
please report any regressions if you discover any.

Changelog (since v099):
FC: render during pixels 1-256 instead of 0-255 [hex_usr]
FC: rewrote controller emulation code
SFC: 8% speedup over the previous release thanks to PPU optimizations
SFC: fixed nasty DB address wrapping regression from v099
SFC: USART developer controller removed; superseded by 21fx
SFC: Super Multitap option removed from controller port 1; ports
    renamed 2-5
SFC: hidden option to experiment with 128KB VRAM (strictly for novelty)
higan: audio volume no longer divided by number of audio streams
higan: updated controller polling code to fix possible future mapping
    issues
higan: replaced nall/stream with nall/vfs for file-loading subsystem
tomoko: can now load multi-slotted games via command-line
tomoko: synchronize video removed from UI; still available in the
    settings file
tomoko, icarus: can navigate to root drive selection on Windows
all: major code cleanups and refactoring (~1MB diff against v099)

Note 1: the audio volume change means that SGB and MSU1 games won't
lose half the volume on the SNES sounds anymore. However, if one goes
overboard and drives the sound all the way to max volume with the MSU1,
clamping may occur. The obvious solution is not to drive volume that high
(it will vastly overpower the SNES audio, which usually never exceeds
25% volume.) Another option is to lower the volume in the audio settings
panel to 50%. In general, neither is likely to ever be necessary.

Note 2: the synchronize video option was hidden from the UI because it
is no longer useful. With the advent of compositors, the loss of the
complicated timing settings panel, support for the WonderSwan and its
75hz display, the need to emulate variable refresh rate behaviors in the
Game Boy, the unfortunate latency spike and audio distortion caused by
long Vsync pauses, and the arrival of adaptive sync technology ... it
no longer makes sense to present this option. However, as stated, you
can edit settings.bml to enable this option anyway if you insist and
understand the aforementioned risks.

Changelog (since v099r16 open beta):

- fixed MSU1 audio sign extension
- fixed compilation with SGB support disabled
- icarus can now navigate to root directory
- fixed compilation issues with OS X port
- (hopefully) fixed label height issue with hiro that affected icarus
  import dialog
- (mostly) fixed BS Memory, Sufami Turbo slot loading

Errata:

- forgot to remove the " - Slot A", " - Slot B" suffixes for Sufami
  Turbo slot loading
  - this means you have to navigate up one folder and then into Sufami
    Turbo/ to load games for this system
- moving WonderSwan orientation controls to the device slot is causing
  some nastiness
  - can now select orientation from the main menu, but it doesn't rotate
    the display
2016-07-08 22:04:59 +10:00
Tim Allen 13ad9644a2 Update to v099r16 release (public beta).
byuu says:

Changelog:
- hiro: BrowserDialog can navigate up to drive selection on Windows
- nall: (file,path,dir,base,prefix,suffix)name =>
  Location::(file,path,dir,base,prefix,suffix)
- higan/tomoko: rename audio filter label from "Sinc" to "IIR - Biquad"
- higan/tomoko: allow loading files via icarus on the command-line
  once again
- higan/tomoko: (begrudging) quick hack to fix presentation window focus
  on startup
- higan/audio: don't divide output audio volume by number of streams
- processor/r65816: fix a regression in (read,write)DB; fixes Taz-Mania
- fixed compilation regressions on Windows and Linux

I'm happy with where we are at with code cleanups and stability, so I'd
like to release v100. But even though I'm not assigning any special
significance to this version, we should probably test it more thoroughly
first.
2016-07-04 21:53:24 +10:00
Tim Allen 8d5cc0c35e Update to v099r15 release.
byuu says:

Changelog:
- nall::lstring -> nall::string_vector
- added IntegerBitField<type, lo, hi> -- hopefully it works correctly...
- Multitap 1-4 -> Super Multitap 2-5
- fixed SFC PPU CGRAM read regression
- huge amounts of SFC PPU IO register cleanups -- .bits really is lovely
- re-added the read/write(VRAM,OAM,CGRAM) helpers for the SFC PPU
  - but they're now optimized to the realities of the PPU (16-bit data
    sizes / no address parameter / where appropriate)
  - basically used to get the active-display overrides in a unified place;
    but also reduces duplicate code in (read,write)IO
2016-07-04 21:48:17 +10:00
Tim Allen 82293c95ae Update to v099r14 release.
byuu says:

Changelog:
- (u)int(max,ptr) abbreviations removed; use _t suffix now [didn't feel
  like they were contributing enough to be worth it]
- cleaned up nall::integer,natural,real functionality
  - toInteger, toNatural, toReal for parsing strings to numbers
  - fromInteger, fromNatural, fromReal for creating strings from numbers
  - (string,Markup::Node,SQL-based-classes)::(integer,natural,real)
    left unchanged
  - template<typename T> numeral(T value, long padding, char padchar)
    -> string for print() formatting
    - deduces integer,natural,real based on T ... cast the value if you
      want to override
    - there still exists binary,octal,hex,pointer for explicit print()
      formatting
- lstring -> string_vector [but using lstring = string_vector; is
  declared]
  - would be nice to remove the using lstring eventually ... but that'd
    probably require 10,000 lines of changes >_>
- format -> string_format [no using here; format was too ambiguous]
- using integer = Integer<sizeof(int)*8>; and using natural =
  Natural<sizeof(uint)*8>; declared
  - for consistency with boolean. These three are meant for creating
    zero-initialized values implicitly (various uses)
- R65816::io() -> idle() and SPC700::io() -> idle() [more clear; frees
  up struct IO {} io; naming]
- SFC CPU, PPU, SMP use struct IO {} io; over struct (Status,Registers) {}
  (status,registers); now
  - still some CPU::Status status values ... they didn't really fit into
    IO functionality ... will have to think about this more
- SFC CPU, PPU, SMP now use step() exclusively instead of addClocks()
  calling into step()
- SFC CPU joypad1_bits, joypad2_bits were unused; killed them
- SFC PPU CGRAM moved into PPU::Screen; since nothing else uses it
- SFC PPU OAM moved into PPU::Object; since nothing else uses it
  - the raw uint8[544] array is gone. OAM::read() constructs values from
    the OAM::Object[512] table now
  - this avoids having to determine how we want to sub-divide the two
    OAM memory sections
  - this also eliminates the OAM::synchronize() functionality
- probably more I'm forgetting

The FPS fluctuations are driving me insane. This WIP went from 128fps to
137fps. Settled on 133.5fps for the final build. But nothing I changed
should have affected performance at all. This level of fluctuation makes
it damn near impossible to know whether I'm speeding things up or slowing
things down with changes.
2016-07-01 21:50:32 +10:00
Tim Allen 67457fade4 Update to v099r13 release.
byuu says:

Changelog:
- GB core code cleanup completed
- GBA core code cleanup completed
- some more cleanup on missed processor/arm functions/variables
- fixed FC loading icarus bug
- "Load ROM File" icarus functionality restored
- minor code unification efforts all around (not perfect yet)
  - MMIO->IO
  - mmio.cpp->io.cpp
  - read,write->readIO,writeIO

It's been a very long work in progress ... starting all the way back with
v094r09, but the major part of the higan code cleanup is now completed! Of
course, it's very important to note that this is only for the basic style:

- under_score functions and variables are now camelCase
- return-type function-name() are now auto function-name() -> return-type
- Natural<T>/Integer<T> replace (u)intT_n types where possible
- signed/unsigned are now int/uint
- most of the x==true,x==false tests changed to x,!x

A lot of spot improvements to consistency, simplicity and quality have
gone in along the way, of course. But we'll probably never fully finishing
beautifying every last line of code in the entire codebase. Still,
this is a really great start. Going forward, WIP diffs should start
being smaller and of higher quality once again.

I know the joke is, "until my coding style changes again", but ... this
was way too stressful, way too time consuming, and way too risky. I'm
too old and tired now for extreme upheavel like this again. The only
major change I'm slowly mulling over would be renaming the using
Natural<T>/Integer<T> = (u)intT; shorthand to something that isn't as
easily confused with the (u)int_t types ... but we'll see. I'll definitely
continue to change small things all the time, but for the larger picture,
I need to just accept the style I have and live with it.
2016-06-29 21:10:28 +10:00
Tim Allen 7a68059f78 Update to v099r12 release.
byuu says:

Changelog:
- fixed FC AxROM / VRC7 regression
- BitField split to BooleanBitField/NaturalBitField (in preparation
  for IntegerBitField)
- BitFieldReference removed
- GB CPU cleaned up
- GB Cartridge + Mappers cleaned up
- SFC CGRAM is now emulated as uint15[256] instead of uint[512]
- sfc/ppu/memory.cpp no longer needed; removed
- purged SFC Debugger hooks for now (some of the operator[] calls were
  bypassing them anyway)

Unfortunately, for reasons that defy all semblance of logic, the CGRAM
change caused a slight speed hit. As have the last few changes. We're
now down to around 129.5fps compared to 123.fps for v099 and 134.5fps
at our peak (v099r01-r02).

I really like the style I came up with for the Game Boy mappers to settle
the purpose(ROM,RAM) vs (rom,ram)Purpose naming convention. If I ever get
around to redoing the NES mappers, that's likely the approach I'll take.
2016-06-28 20:43:47 +10:00
Tim Allen 3e807946b8 Update to v099r11 release.
byuu says:

Changelog:
- NES PPU core updated to use BitFields (absolutely massive improvement
  in code readability)
- NES APU core updated to new coding style
- NES cartridge/board and cartridge/chip updated to new coding style
- pushed NES PPU rendering one dot forward (doesn't fix King's Quest V
  yet, sadly)
- fixed SNES PPU BG tilemask for 128KiB VRAM mode (doesn't fix Yoshi's
  Island, though)

So ... I kind of went overboard with the fc/cartridge changes. This WIP
diff is 185KiB >_>
I didn't realize it was going to be as big a task as it was, but once
I started everything broke in a chain reaction, so I had to do it all
at once.

There's a massive chance we've broken a bunch of NES things. Any typos
in this WIP are going to be absolutely insidious to track down =(

But ... supposing I pulled it off, this means the Famicom core is now
fully converted to the new coding style as well. That leaves only the
GB and GBA cores. Once those are finished, then we'll finally be free
of these gigantic hellspawn diffs.
2016-06-27 23:07:57 +10:00
Tim Allen a816998122 Update to v099r10 release.
byuu says:

Changelog:
- higan/profile/ => higan/systems/ [temporary; unless we can't think of
  a better base folder name]
- god-damn-better-have fixed the input polling bug
- re-added command-line and drag-and-drop loading
  - command-line loading can now load multiple folders at once (SGB+GB
    game; Sufami Turbo+Slot A+Slot B; etc)
  - if you load just the base cart, it'll present you with a dialog to
    optionally load slotted cart(s)
- MSU1 now goes through nall/vfs instead of directly accessing the
  filesystem
- Famicom Cartridge, PPU cores updated to newer programming style
  - there's countless opportunity for BitField and .bits() in the PPU
    ... but I'm worried about breaking things

If anyone has a working MSU1 game and can test the changes out, that'd
be appreciated. I still don't have a test ROM on my dev box.

I wouldn't worry too much about extensively testing the Famicom PPU
changes just yet ... I'm still struggling with what to name the structs
inside the classes between all of my emulators, and the BitField/.bits()
changes will be much more important to test at a later date.

The only use case left for Emulator::Interface::path(uint id) is for
21fx emulation. This peripheral loads a DLL/SO via LoadLibrary/dlopen,
which do not have any official ways to open a file in RAM. I'm
very hesitant to use the portable trick of writing the memory to a
temporary file, loading it, and deleting the temporary file once done
... it's a real waste of disk activity. I might make something like
vfs::file::isVirtual->bool,path()->string to get around this. But even
once I do, the underlying LoadLibrary/dlopen call is still going to be
direct disk access.
2016-06-26 18:54:12 +10:00
Tim Allen 3a9c7c6843 Update to v099r09 release.
byuu says:

Changelog:
- Emulator::Interface::Medium::bootable removed
- Emulator::Interface::load(bool required) argument removed
  [File::Required makes no sense on a folder]
- Super Famicom.sys now has user-configurable properties (CPU,PPU1,PPU2
  version; PPU1 VRAM size, Region override)
- old nall/property removed completely
- volatile flags supported on coprocessor RAM files now (still not in
  icarus, though)
- (hopefully) fixed SNES Multitap support (needs testing)
- fixed an OAM tiledata range clipping limit in 128KiB VRAM mode (doesn't
  fix Yoshi's Island, sadly)
- (hopefully, again) fixed the input polling bug hex_usr reported
- re-added dialog box for when File::Required files are missing
  - really cool: if you're missing a boot ROM, BIOS ROM, or IPL ROM,
    it warns you immediately
  - you don't have to select a game before seeing the error message
    anymore
- fixed cheats.bml load/save location
2016-06-25 18:53:11 +10:00
Tim Allen f48b332c83 Update to v099r08 release.
byuu says:

Changelog:
- nall/vfs work 100% completed; even SGB games load now
- emulation cores now call load() for the base cartridges as well
- updated port/device handling; portmask is gone; device ID bug should
  be resolved now
- SNES controller port 1 multitap option was removed
- added support for 128KiB SNES PPU VRAM (for now, edit sfc/ppu/ppu.hpp
  VRAM::size=0x10000; to enable)

Overall, nall/vfs was a huge success!! We've substantially reduced
the amount of boilerplate code everywhere, while still allowing (even
easier than before) support for RAM-based game loading/saving. All of
nall/stream is dead and buried.

I am considering removing Emulator::Interface::Medium::id and/or
bootable flag. Or at least, doing something different with it. The
values for the non-bootable GB/BS/ST entries duplicate the ID that is
supposed to be unique. They are for GB/GBC and WS/WSC. Maybe I'll use
this as the hardware revision selection ID, and then gut non-bootable
options. There's really no reason for that to be there. I think at one
point I was using it to generate library tabs for non-bootable systems,
but we don't do that anymore anyway.

Emulator::Interface::load() may not need the required flag anymore ... it
doesn't really do anything right now anyway.

I have a few reasons for having the cores load the base cartridge. Most
importantly, it is going to enable a special mode for the WonderSwan /
WonderSwan Color in the future. If we ever get the IPLROMs dumped ... it's
possible to boot these systems with no games inserted to set user profile
information and such. There are also other systems that may accept being
booted without a cartridge. To reach this state, you would load a game and
then cancel the load dialog. Right now, this results in games not loading.

The second reason is this prevents nasty crashes when loading fails. So
if you're missing a required manifest, the emulator won't die a violent
death anymore. It's able to back out at any point.

The third reason is consistency: loading the base cartridge works the
same as the slot cartridges.

The fourth reason is Emulator::Interface::open(uint pathID)
values. Before, the GB, SB, GBC modes were IDs 1,2,3 respectively. This
complicated things because you had to pass the correct ID. But now
instead, Emulator::Interface::load() returns maybe<uint> that is nothing
when no game is selected, and a pathID for a valid game. And now open()
can take this ID to access this game's folder contents.

The downside, which is temporary, is that command-line loading is
currently broken. But I do intend on restoring it. In fact, I want to do
better than before and allow multi-cart booting from the command-line by
specifying the base cartridge and then slot cartridges. The idea should
be pretty simple: keep a queue of pending filenames that we fill from
the command-line and/or drag-and-drop operations on the main window,
and then empty out the queue or prompt for load dialogs from the UI
when booting a system. This also might be a bit more unorthodox compared
to the traditional emulator design of "loadGame(filename)", but ... oh
well. It's easy enough still.

The port/device changes are fun. We simplified things quite a bit. The
portmask stuff is gone entirely. While ports and devices keep IDs,
this is really just sugar-coating so UIs can use for(auto& port :
emulator->ports) and access port.id; rather than having to use for(auto
n : range(emulator->ports)) { auto& port = emulator->ports[n]; ... };
but they should otherwise generally be identical to the order they appear
in their respective ranges. Still, don't rely on that.

Input::id is gone. There was no point since we also got rid of the nasty
Input::order vector. Since I was in here, I went ahead and caved on the
pedantics and renamed Input::guid to Input::userData.

I removed the SNES controller port 1 multitap option. Basically, the only
game that uses this is N-warp Daisakusen and, no offense to d4s, it's
not really a good game anyway. It's just a quick demo to show 8-players
on the SNES. But in the UI, all it does is confuse people into wasting
time mapping a controller they're never going to use, and they're going
to wonder which port to use. If more compelling use cases for 8-players
comes about, we can reconsider this. I left all the code to support this
in place, so all you have to do is uncomment one line to enable it again.

We now have dsnes emulation! :D
If you change PPU::VRAM::size to 0x10000 (words), then you should now
have 128KiB of VRAM. Even better, it serializes the used-VRAM size,
so your save states shouldn't crash on you if you swap between the two
(though if you try this, you're nuts.)

Note that this option does break commercial software. Yoshi's Island in
particular. This game is setting A15 on some PPU register writes, but
not on others. The end result of this is things break horribly in-game.

Also, this option is causing a very tiny speed hit for obvious reasons
with the variable masking value (I'm even using size-1 for now.) Given
how niche this is, I may just leave it a compile-time constant to avoid
the overhead cost. Otherwise, if we keep the option, then it'll go into
Super Famicom.sys/manifest.bml ... I'll flesh that out in the near-future.

----

Finally, some fun for my OCD ... my monitor suddenly cut out on me
in the middle of working on this WIP, about six hours in of non-stop
work. Had to hit a bunch of ctrl+alt+fN commands (among other things)
and trying to log in headless on another TTY to do issue commands,
trying to recover the display. Finally power cycled the monitor and it
came back up. So all my typing ended up going to who knows where.

Usually this sort of thing terrifies me enough that I scrap a WIP and
start over to ensure I didn't screw anything up during the crashed screen
when hitting keys randomly.

Obviously, everything compiles and appears to work fine. And I know
it's extremely paranoid, but OCD isn't logical, so ... I'm going
to go over every line of the 100KiB r07->r08 diff looking for any
corruption/errors/whatever.

----

Review finished.

r08 diff review notes:
- fc/controller/gamepad/gamepad.cpp:
  use uint device = ID::Device::Gamepad; not id = ...;
- gb/cartridge/cartridge.hpp:
  remove redundant uint _pathID; (in Information::pathID already)
- gb/cartridge/cartridge.hpp:
  pull sha256 inside Information
- sfc/cartridge/load/cpp:
  add " - Slot (A,B)" to interface->load("Sufami Turbo"); to be more
  descriptive
- sfc/controller/gamepad/gamepad.cpp:
  use uint device = ID::Device::Gamepad; not id = ...;
- sfc/interface/interface.cpp:
  remove n variable from the Multitap device input generation loop
  (now unused)
- sfc/interface/interface.hpp:
  put struct Port above struct Device like the other classes
- ui-tomoko:
  cheats.bml is reading from/writing to mediumPaths(0) [system folder
  instead of game folder]
- ui-tomoko:
  instead of mediumPaths(1) - call emulator->metadataPathID() or something
  like that
2016-06-24 22:16:53 +10:00
Tim Allen ccd8878d75 Update to v099r07 release.
byuu says:

Changelog:
- (hopefully) fixed BS Memory and Sufami Turbo slot loading
- ported GB, GBA, WS cores to use nall/vfs
- completely removed loadRequest, saveRequest functionality from
  Emulator::Interface and ui-tomoko
  - loadRequest(folder) is now load(folder)
- save states now use a shared Emulator::SerializerVersion string
  - whenever this is bumped, all older states will break; but this makes
    bumping state versions way easier
  - also, the version string makes it a lot easier to identify
    compatibility windows for save states
- SNES PPU now uses uint16 vram[32768] for memory accesses [hex_usr]

NOTE: Super Game Boy loading is currently broken, and I'm not entirely
sure how to fix it :/
The file loading handoff was -really- complicated, and so I'm kind of
at a loss ... so for now, don't try it.
Everything else should theoretically work, so please report any bugs
you find.

So, this is pretty much it. I'd be very curious to hear feedback from
people who objected to the old nall/stream design, whether they are
happy with the new file loading system or think it could use further
improvements.

The 16-bit VRAM turned out to be a wash on performance (roughly the same
as before. 1fps slower on Zelda 3, 1fps faster on Yoshi's Island.) The
main reason for this was because Yoshi's Island was breaking horribly
until I changed the vramRead, vramWrite functions to take uint15 instead
of uint16.

I suspect the issue is we're using uint16s in some areas now that need
to be uint15, and this game is setting the VRAM address to 0x8000+,
causing us to go out of bounds on memory accesses.

But ... I want to go ahead and do something cute for fun, and just because
we can ... and this new interface is so incredibly perfect for it!! I
want to support an SNES unit with 128KiB of VRAM. Not out of the box,
but as a fun little tweakable thing. The SNES was clearly designed to
support that, they just didn't use big enough VRAM chips, and left one
of the lines disconnected. So ... let's connect it anyway!

In the end, if we design it right, the only code difference should be
one area where we mask by 15-bits instead of by 16-bits.
2016-06-24 22:09:30 +10:00