Getting Alchemy65 to work with Mesen 2

[DoctorMikeReddy]

Trying to update Alchemy65 (for VS Code) to debug with Mesen 2. I have enabled "Allow access to I/O and OS functions" and "Allow network access" (which is required for sockets), thanks to a tip on NesDev, but now getting the following error:

adapter.lua:247: attempt to index a nil value (field 'cpu')

The adapter.lua file is stored in c:\Users/XXX.vscode\extensions\alchemic-raker-alchemy65-1.0.8\lua and so is clearly Alchemy65 code that is run from within Mesen. This works with Mesen-X, of course, but this code:

    if command == "getcpuvars" then
      local state = emu.getState()
      local pc_prg = emu.getPrgRomOffset(state.cpu.pc) <- *** HERE
      connection:send("cpuvars " .. tostring(state.cpu.status) .. " " .. tostring(state.cpu.a) .. " " .. tostring(state.cpu.x) .. " " .. tostring(state.cpu.y) .. " " .. tostring(state.cpu.pc) .. " " .. tostring(state.cpu.sp) .. " " .. tostring(pc_prg) .. "\n")
      --log("cpuvars")
      return true -- keep processing messages
    end

doesn't seem to like the 'cpu' bit

Any thoughts?

[DoctorMikeReddy]

It appears that state.anything.anything does not work with Mesen2. state.region is fine, but state.cpu.pc returns 'nil' as does any other nested table item

[DoctorMikeReddy]

It looks like various elements from https://www.mesen.ca/docs/apireference/emulation.html#getstate have not been implemented in Mesen2, so closing this now

[DoctorMikeReddy]

Ok, it appears I was wrong, and it was just a different way of accessing: Instead of state.cpu.pc we need state["cpu.pc"] in the code

[DoctorMikeReddy]

So, I am looking at altering the adapter.lua script to work with Mesen2 with the revised syntax. emu.getPrgRomOffset doesn't appear to be implemented in Mesen2, so it may need extending, like Mesen-X was UPDATE: dumping the value of the PrgRomOffset for a test rom gave back -1 (the default, as the test rom I am using doesn't have a mapper), so for now we can just send this. I think that ConvertAddress is what replaced it, but it is a bit more complex, doing more than the old one

[DoctorMikeReddy]

Right, cpu.status isn't available in Mesen2 yet, and is not implemented. Have gone back to the author of Mesen2 to see if we can get these. Doing some digging, cpu.status is cpu.ps in the new emulator

[DoctorMikeReddy]

StepOver StepInto and StepOut in VSCode cause errors in Mesen2. The execute command in Mesen-X has been replaced by a Step function; I think this is the StepInto that is missing. Mesen 2 also doesn't have Lua calls for StepOver and StepOut. Break has been renamed BreakExecution, but uses the same local call, so isn't an issue.

[JeffAlyanak]

@DoctorMikeReddy You may have already found this, but Mesen2 has the following document on the new Lua implementation: LuaDocumentation.json

Looks like the step function now takes a stepType param:

{
    "name": "step",
    "description": "Breaks the emulation's execution when the step conditions are reached.",
    "parameters": [
        { "name": "count", "type": "Int", "description": "Number of cycles/frames/etc." },
        { "name": "stepType", "type": "Enum", "enumName": "stepType", "description": "Step type" },
        { "name": "cpuType", "type": "Enum", "enumName": "cpuType", "description": "CPU type", "defaultValue": "main CPU" }
    ]
}

And that stepType enum includes stepOver and StepOut:

{
    "name": "stepType",
    "description": "Used by emu.step()",
    "enumValues": [
        { "name": "step", "description": "Steps the specified number of instructions" },
        { "name": "stepOut", "description": "Steps out of the current subroutine (not available for all CPUs)" },
        { "name": "stepOver", "description": "Steps over the current subroutine call (not available for all CPUs)" },
        { "name": "cpuCycleStep", "description": "Steps the specified number of CPU cycles (not available for all CPUs)" },
        { "name": "ppuStep", "description": "Steps the specified number of scanline cycles" },
        { "name": "ppuScanline", "description": "Steps the specified number of scanlines" },
        { "name": "ppuFrame", "description": "Steps the specified number of video frames" },
        { "name": "specificScanline", "description": "Breaks on the specified scanline number" },
        { "name": "runToNmi", "description": "Breaks on the next NMI event" },
        { "name": "runToIrq", "description": "Breaks on the next IRQ event" }
    ]
}

[DoctorMikeReddy]

Excellent. This had been in the back burner, but will be using this next academic year, so thank you

[AlchemicRaker]

Wanted to know that while I'm not in a position to implement and test these updates currently, if someone is able to create the necessary PR for this, I will get it approved quickly. I appreciate the contributions!

[JeffAlyanak]

@AlchemicRaker I'll look at it over the next few days and see if I can put together a PR.

[JeffAlyanak]

Starting work on the PR over here: https://github.com/AlchemicRaker/alchemy65/pull/12

[JeffAlyanak]

I'm still filling this table out, but in case anyone is working on this in parallel or wants to contribute to this PR, I've put together the documentation below on the table returned by emu.getState.

From what I can tell, the only function missing that was used in @AlchemicRaker 's original script is a lack emu.eventType.whilePaused of used in the emu.addEventCallback on line 316.

The main hurdle now is just the lack of a callback or state value for isPaused. For now I've added that in a fork for testing purposes.

Key	Lua type	Description
General
consoleType	string (Nes, Snes, Gameboy, PcEngine, Sms, Gba)
region	string (Ntsc, Pal, Dendy, NtscJapan)
clockRate	number
frameCount	number
masterClock	number
paused	bool	currently only available in my fork
CPU
cpu.cycleCount	number
cpu.pc	number	Program Counter
cpu.ps	number	Processor Status (flags)
cpu.sp	number	Stack Pointer
cpu.a	number	Accumulator
cpu.x	number	X Register
cpu.y	number	Y Register
PPU
ppu.cycle	number
ppu.control.backgroundPatternAddr	number
ppu.control.largeSprites	bool
ppu.control.nmiOnVerticalBlank	bool
ppu.control.spritePatternAddr	number
ppu.control.verticalWrite	bool
ppu.frameCount	number
ppu.highBitShift	number
ppu.intensifyColorBits	number
ppu.lowBitShift	number
ppu.mask.backgroundEnabled	bool
ppu.mask.backgroundMask	bool
ppu.mask.grayscale	bool
ppu.mask.intensifyBlue	bool
ppu.mask.intensifyGreen	bool
ppu.mask.intensifyRed	bool
ppu.mask.spriteMask	bool
ppu.mask.spritesEnabled	bool
ppu.masterClock	number
ppu.memoryReadBuffer	number
ppu.paletteRamMask	number
ppu.ppuBusAddress	number
ppu.scanline	number
ppu.spriteRamAddr	number
ppu.statusFlags.sprite0Hit	bool
ppu.statusFlags.spriteOverflow	bool
ppu.statusFlags.verticalBlank	bool
ppu.tmpVideoRamAddr	number
ppu.videoRamAddr	number
ppu.writeToggle	bool
ppu.xScroll	number
APU
apu.dmc.bitsRemaining	number
apu.dmc.bufferEmpty	bool
apu.dmc.bytesRemaining	number
apu.dmc.currentAddr	number
apu.dmc.irqEnabled	bool
apu.dmc.loopFlag	bool
apu.dmc.needToRun	bool
apu.dmc.outputLevel	number
apu.dmc.readBuffer	number
apu.dmc.sampleAddr	number
apu.dmc.sampleLength	number
apu.dmc.shiftRegister	number
apu.dmc.silenceFlag	bool
apu.dmc.timer.lastOutput	number
apu.dmc.timer.period	number
apu.dmc.timer.timer	number
apu.frameCounter.blockFrameCounterTick	number
apu.frameCounter.currentStep	number
apu.frameCounter.inhibitIRQ	bool
apu.frameCounter.newValue	number
apu.frameCounter.previousCycle	number
apu.frameCounter.stepMode	number
apu.frameCounter.writeDelayCounter	number
apu.noise.envelope.constantVolume	bool
apu.noise.envelope.counter	number
apu.noise.envelope.divider	number
apu.noise.envelope.lengthCounter.counter	number
apu.noise.envelope.lengthCounter.enabled	bool
apu.noise.envelope.lengthCounter.halt	bool
apu.noise.envelope.lengthCounter.newHaltValue	bool
apu.noise.envelope.lengthCounter.previousValue	number
apu.noise.envelope.lengthCounter.reloadValue	number
apu.noise.envelope.start	bool
apu.noise.envelope.volume	number
apu.noise.modeFlag	bool
apu.noise.shiftRegister	number
apu.noise.timer.lastOutput	number
apu.noise.timer.period	number
apu.noise.timer.timer	number
apu.square1.duty	number
apu.square1.dutyPos	number
apu.square1.envelope.constantVolume	bool
apu.square1.envelope.counter	number
apu.square1.envelope.divider	number
apu.square1.envelope.lengthCounter.counter	number
apu.square1.envelope.lengthCounter.enabled	bool
apu.square1.envelope.lengthCounter.halt	bool
apu.square1.envelope.lengthCounter.newHaltValue	bool
apu.square1.envelope.lengthCounter.previousValue	number
apu.square1.envelope.lengthCounter.reloadValue	number
apu.square1.envelope.start	bool
apu.square1.envelope.volume	number
apu.square1.realPeriod	number
apu.square1.reloadSweep	bool
apu.square1.sweepDivider	number
apu.square1.sweepEnabled	bool
apu.square1.sweepNegate	bool
apu.square1.sweepPeriod	number
apu.square1.sweepShift	number
apu.square1.sweepTargetPeriod	number
apu.square1.timer.lastOutput	number
apu.square1.timer.period	number
apu.square1.timer.timer	number
apu.square2.duty	number
apu.square2.dutyPos	number
apu.square2.envelope.constantVolume	bool
apu.square2.envelope.counter	number
apu.square2.envelope.divider	number
apu.square2.envelope.lengthCounter.counter	number
apu.square2.envelope.lengthCounter.enabled	bool
apu.square2.envelope.lengthCounter.halt	bool
apu.square2.envelope.lengthCounter.newHaltValue	bool
apu.square2.envelope.lengthCounter.previousValue	number
apu.square2.envelope.lengthCounter.reloadValue	number
apu.square2.envelope.start	bool
apu.square2.envelope.volume	number
apu.square2.realPeriod	number
apu.square2.reloadSweep	bool
apu.square2.sweepDivider	number
apu.square2.sweepEnabled	bool
apu.square2.sweepNegate	bool
apu.square2.sweepPeriod	number
apu.square2.sweepShift	number
apu.square2.sweepTargetPeriod	number
apu.square2.timer.lastOutput	number
apu.square2.timer.period	number
apu.square2.timer.timer	number
apu.triangle.lengthCounter.counter	number
apu.triangle.lengthCounter.enabled	bool
apu.triangle.lengthCounter.halt	bool
apu.triangle.lengthCounter.newHaltValue	bool
apu.triangle.lengthCounter.previousValue	number
apu.triangle.lengthCounter.reloadValue	number
apu.triangle.linearControlFlag	bool
apu.triangle.linearCounter	number
apu.triangle.linearCounterReload	number
apu.triangle.linearReloadFlag	bool
apu.triangle.sequencePosition	number
apu.triangle.timer.lastOutput	number
apu.triangle.timer.period	number
apu.triangle.timer.timer	number
Control Manager
controlManager.controlDevices[0].strobe	bool
controlManager.controlDevices[1].microphoneEnabled	bool
controlManager.controlDevices[1].stateBuffer	number
controlManager.controlDevices[1].strobe	bool
controlManager.lagCounter	number
controlManager.pollCounter	number