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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 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