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sem_post funkiness on Linux | |
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Date: 9/8/2017 Tags: linux | I moved the Linux implementation of the GThreadEvent class (.h,
.cpp) over to the sem_open,
sem_post,
sem_wait calls a little while back. Initially I used named semaphores and that seemed to work ok. But after a few weeks I noticed that sometimes the call to sem_post would just quietly NOT increment the semaphore count, while still returning 0 (Success). Which causes the listening thread blocking in sem_wait to never wake up. Crucially this would break the destructor / exit loop of GEventTargetThread. Googling this didn't turn up anything useful. I believe I was using the API correctly and the documentation is very sparse. Anyway I implemented the semaphores using the sem_init/sem_destroy (anonymous) and it seems to be robust. Still, I'd like to know what the deal is with the named ones. The general pattern of behaviour I would see is:
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Ho ho ho | |
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Date: 21/12/2016 Tags: scribe html-editor | The merry little elves at Memecode have been working away at all hours of the night to bring you a working Rich Text (HTML) editor in Scribe to put in your Christmas stockings. With the release of Scribe v2.1.33 there is enough functionality to write email with styles. The reply/forwarding side of things isn't as good as the composition of new email. For a variety of reasons. And the control is still definitely in "Alpha" (i.e. incomplete functionality, still contains bugs, possibly show stopping ones). It would be a excellent idea to reset the reply/forward formats to their default values, because I've updated the default template for HTML reply/forward. If you have a custom template for plain text, save that before you reset the templates in File -> Options -> General -> Reply / Fwd templates -> Reset. Also go into your signature settings and configure a HTML sig for each account with an identity. I'll set some expectations first... with the pros:
To switch between plain text and HTML quickly use Edit -> Use HTML Editor. Do not use the HTML control for production emails. If it matters, use the plain text compose control. Otherwise I'd like to hear how it goes. |
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Rich Text / HTML support in Scribe | |
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Date: 5/12/2016 Tags: scribe | There has been a lot of people asking about the Rich Text / HTML editing support in Scribe and so while not fixing crash bugs I'm actively developing a new control to support styled text editing. So that those that are interested can track the progress I'm publishing my internal spreadsheet of bugs and features: Broadly speaking my hope is to have a very basic control working by the end of the year. Good enough that you can write and reply to email with, even if there isn't a lot of support for styling. Maybe some basic stuff like bold, colours and font size. |
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Refactoring for performance | |
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Date: 26/8/2016 Tags: mc2 | A few weeks into actually using the MC2 I realized that the response time of the expression pedal was quite poor, running in the 100-200ms range. After doing some tests I worked out that it was because of the way messages were passed from the hardware thread that received the events, like analog to digital reads for the expression pedal, to the user interface thread, where they would be processed and sent back out the hardware thread to the Axefx. The problem with this was the the Raspberry PI is quite slow (or at least the version I'm using) and the user interface update speed was lagging. If the user interface is being updated, it's not processing messages. Hence the delay. But fixing it wasn't straight forward, because all the user interface code and Axefx code were all jumbled up like this: So I took all the code that relates to the Axefx, and all the code that updates the user interface and separated them out into their own source code files. I called the Axefx specific code the "logic". Now I had 3 separate bits of code:
So hardware events, like the expression pedal value changing, would by processed immediately in the same thread and an outgoing MIDI message could be sent almost immediately, even if the UI was busy doing something. The latency was hugely improved. It's got to the point that it no longer has an impact musically. It seems to respond instantly. In doing this I realized that I could hide all the details of each block of code behind a message passing interface. Which is excellent for thread safety. There was a little shared data that I wrapped in a mutex. But all in all the design feels nice and clean. In fact I loved the design so much I'm rewriting i.Ftp to use the same architecture. Oh yeah, and because it was kinda badly written and wouldn't port to modern UI systems that don't have thread safe UI APIs. |
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Negative ADS1115 readings | |
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Date: 1/8/2016 Tags: mc2 | I've been using an ADS1115 to convert the analog voltage from the expression pedal input, which is just a potentiometer really, to a 16 bit value. On the weekend I had a gig and both at the rehearsal and the set the expression pedal would flip to 127 (the maximum) when in the minimum position. It was also behaving erratically, the full range of output values was compressed into a very short throw of physical movement. I didn't technically need it for the gig so I just unplugged it. So today I thought I'd get to the bottom of it. After switching on the logging and reproducing the issue it was apparent that a lot of "plugged" / "unplugged" events were happening. This was due to the values coming from the ADS1115 were bouncing between very low values (say 0 - 100) to very high values (65530 - 65535). I started by putting the multi-meter in voltage mode over the input pin of the ADS1115 and ground and found that the lowest voltage was about 0.1V which is, well, correct for the minimum position. So that led me to believe it was solely a software issue. Looking at the code that does the read, I found it was assuming the 16bit value was a unsigned integer. But that fact that the value was jumping to 65500 made me wonder if maybe the ADS1115 was giving me a signed value instead. So I changed the code to assume signed behaviour and now the values all seemed to follow each other as the pedal moves back and forth. Then checking with the data sheet: The ADS1113/4/5 provide 16 bits of data in binary twos complement formatUgh, ok so I should read that more carefully. Still it going slightly negative like that even with a positive voltage is a bit weird to me. Oh well, I'm just going with max(0, AdcReadValue) for the moment and it seems to be working just fine now. |
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Scribe: Installer script hooks | |
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Date: 14/7/2016 Tags: scribe scripting | So you know those red bars that appear in Scribe when it wants to install something? I've just added the spell check dictionaries to that so you have to confirm there install. This allows you to make sure you have a working internet connection before download a dictionary. But I thought it would be cool to add some scripting hooks for the install bar and the actual install itself. So take an example script like this:
function BeforeInstall(App, Msg, Actions) { Actions.Add("Scare"); Msg = Msg + " (BeforeInstall was here)"; return true; } function Install(App, Action) { if (Action == "Scare") { MsgBox(App, "Boo!"); return false; } return true; } function Main(App) { if (!AddCallback("OnBeforeInstallBar", "BeforeInstall")) MsgBox(App, "Couldn't add BeforeInstall"); if (!AddCallback("OnInstallComponent", "Install")) MsgBox(App, "Couldn't add Install"); return 1; }What it does is install 2 callbacks, one for the missing capability bar, and one for the install itself. It messes with the message and buttons available to the install bar. Then adds a new "action" that is caught later in the "Install" function to put up a dialog box. Might be useful for managed installs of Scribe. |
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