Overclock when busy messes up navigation

[BindingOx]

on the app screen when I press left or right it would jump around. When you press the right arrow it's busy and when you press it again it will jump because it's overclocked so this is unintended behavior.

[eanema]

Good morning. Not sure if you looked through any of the other issues, but as I've said there, I do not actively develop on this code base. I just don't have time. I am just another user who didn't like that graph89 wouldn't work on 64 bit android. I came up with a patch and now I have published it so others can make use of this app.

That being said, if you come up with a patch of your own that will fix this issue I am willing to accept pull requests and get your changes into the F-droid stream for others to enjoy.

[josephcsible]

I just ran into this too. Until someone can come up with a proper fix, would you take a PR that makes this option default to off?

[eanema]

I'm not really sure what the problem is. Could you explain it a bit better? On my phone, I don't see any issues...

It seems silly to disable overclocking with such a powerful cpu in your pocket. From the description it says that it only overclocks the CPU when it's "busy" I assume this means when it's executing a command?

[josephcsible]

To reproduce, install a bunch of the apps from https://education.ti.com/software/search/ti-89-ti-89-titanium onto an emulated TI-89 Titanium, then press 2nd -> Var-Link followed by 2nd -> F7, then scroll through the list by tapping, but not holding, the up and down keys. You'll see it jump a bunch of times instead of going one entry at a time. I think the problem is that since it's overclocked while the keys are pressed, the calculator thinks the keys were held down a lot longer than they actually were, so it makes them repeat.

[eanema]

Interesting. I don't have that problem when I have 'overclock when busy' selected, but it does happen when I turned up the 'CPU speed' setting to 250% (I keep mine at the default 100%) What is your CPU speed setting?

From my intuitive understanding of the settings, I would expect the CPU speed setting to be a constant overclocking, and the overclock when busy setting is just overclock when its working on something, not all the time.

[josephcsible]

It happens to me at the default 100%.

[eanema]

Well, the repeat time is determined by the OS and I doubt that the emulator knows the difference between busy waiting for input and busy doing work... Maybe it does? I have no idea how those setting work, and what they do to the emulator. This may date me, but it reminds me of the turbo button on the old 2/3/486s of the 90s... Things just happen quicker on faster CPUs.

I wonder how many people this effects, and why it's effects of you and not me?

[josephcsible]

My guess is that it's looking at whether the CPU usage is low or high, and overclocking when it's at or near 100%. I suspect it could be fixed by making it not overclock while keys are pressed.

[eanema]

I did a bit of digging and found that Graph89 knows if the emulated calculator is busy by looking at the contents of the screen. I didn't figure out the entire mechanism but I believe it is looking for the 'busy' banner/message in the lower right corner of the screen.

For anyone who is interested, the overclock when busy boolean in the ROM configuration menu is used in the TIEmuThread.java and TilEmThread.java. Both of those functions call skin.Screen.isBusy() which is in EmulatorScreen.java. This function essentially just returns the state of the isBusy local variable which is set in the refresh() method by the Flags array which is set by the call just above to EmulatorActivity.nativeReadEmulatedScreen(Flags). This is a JNI native C call to graph89_read_emulated_screen() in wrappercommon.c which just decides to call the _read_emulated_screen() fucntion from TIEmu or TilEm.

That was all to set the turbo flag in the TIEmuThread.java/TilEmThread.java which is then used in just below to call EmulatorActivity.nativeTiEmuRunEngine() or EmulatorActivity.nativeTilemRunEngine()

If anyone has the bandwidth to figure out what's going on here, I believe the problem is that its reading the screen and failing to correctly determine if the busy message is being displayed. IE it believes that the OS is busy but it is not actually busy so it goes and overclocks its when it shouldn't.

[doak]

I even can reproduce it when navigating horizontal through F1…F6 menus. Let's see if somebody has enough motivation to dig into it.

I've just found this emulator today and I really like it. All the usual calculators are quite useless. Having said this, thanks @eanema for your effort providing a working app – even if you can't maintain it. For this we are a FOSS community, aren't we. :)