Backgrond
I am very experienced in C and pretty new to Android and Java, but this is rather environmental issues that programming.
I have developed an administrative application in ANSI-C to be ported to any OS, just adding a UI in OS-dependent code. Well it uses quite some memory, especially for huge user files. I have a working Win32 program, trying to make an Android app using Android Studio with NDK.
Android studio bundle NDK installation works fine
I have installed and made a Win7 ultimate Android Studio 1.3 with bundle NDK and made compiling and running the ActionbarStyled (non NDK) hello-jni (NDK) sample in the emulators, smooth and nice. I also in the emulator been successfully running Hello-jni sample with a bunch of extra c-files (not called, at present just garbage, compiled without errors, in this step)
Then I tried to connect my Samsung TAB3 SM-T110 template (one need a Win7 Samsung driver SAMSUNG_USB_Driver_for_Mobile_Phones.zip) to my Win7 and tried it. ActionbarStyled sample works just fine. So does the Hello-JNI sample.
But
Running Hello-jni sample with a bunch of extra c-files I get this error message:
Error while starting native debug session: java.lang.IllegalArgumentException: Unable to find process for com.example.hellojni on device samsung-sm_t110-47900bc50c0c3100
I try to understand what is the issue? Is it lack of memory, the Samsung is full of active running apps, the emulator obviously not.
What makes the Samsung unit to halt the application? Error message is not that describing?
Some more questions supporting handling this kind of issues
We are talking about Android studio 1.3 bundle NDK, how much from earlier setups (in articles) are applicable for this new future NDK standard use?
Memory?
Running the pure Hello-jni sample I have about 6Mb memory (where 5Mb are used), that is pretty poor for my needs, is there something I need to do have my app getting more memory allocated? Is the error message due to running out of memory?
How large Android Apps are possible to do? Are we in a world like the 8-bit DOS 64Kb segment business again? I know it from past but that isen't the case? And if need to know to handle it. The Library for unrestricted heap memory for bitmaps using NDK on Android question is interesting to read, but here we are talking about the jni (C-)code rather than java.
Compiler optimisation?
I have some really huge C-files due to that they are machine generated converting an XML library of documents to C-code (made a program writing C-code from the XSD definitions). In an application I most of the time use only say 5% of all the C-function, the rest are in Windows dev studio/compiler optimised away. Certainly I can reorganise my source code to quite some extra work, but I need to know. How is the optimisation in the Android Studio NDK support?
Thing is in this test no extra C-functions are called except the same regular as in the hello-jni sample. Actually the compiler should make exactly the same in both cases (the modified and the original hello-jni). But obviously it don't. Please explain a bit more how the environment works so I know?
General interest
I tried to find any spot in the Android developers that describe things like compiler behaviour, memory management and environment (the Java handles such completely different, but in C-programming on need to be aware). I think for NDK use it would be interesting getting a good answer here, for the general understanding of the environment, somewhere in the Android developer pages, rather than here. That also includes how the compiler optimises in different situations. But also how to make environmental settings.
Related
Currently our Xamarin Android app (PCL) is huge in my opinion, even in release mode. I suspect it is due to supported architectures. Currently we have them all selected. Does anyone know if we have to select all of these? We are not using the Android NDK at all as well.
I will copy part of my answer from here.
Make sure you are at least checking the following architectures: armeabi-v7a and x86. You could do the other three but we do not since we use LLVM compiling in release mode, which is not compatible with the 64 bit architectures (except for armeabi, which is deprecated). The good thing about that is that all of the 64 bit architectures can still use 32 bit builds so they all still get covered if you check those 3.
So I would just check those 3 unless you have a specific reason to check the other ones. We have had 0 problems installing our app on devices using those 3 only.
On a side note, turning on LLVM compiling and optimizing your icons/images will help with the final APK size.
*Edit: Since writing this we ran into a bug only on certain devices (Android Nexus 9) which leads to app crashes when launching the app. The solution is to check the arm64-v8a architecture. This will probably increase app size so weigh the pros and cons and see how much of a difference it makes in your APK size after including the architecture or split your APK for each architecture if necessary.
No you do not have to select all of them. You can create an .apk per ABI if you wanted to to reduce the size of your .apk. Note: The encouraged method is that you develop and publish a single .apk. However this is not always practical, and sometimes it's better to create separate ones. Although this answer only goes into depth about different CPU Architectures (ABI), you could also create different .apk for screen size, device features, and API levels.
https://developer.xamarin.com/guides/android/advanced_topics/build-abi-specific-apks/
http://developer.android.com/google/play/publishing/multiple-apks.html
I would recommend grabbing a tool like WinDirStat(https://windirstat.info/) or Disk Inventory X(http://www.derlien.com/) to investigate why your .apk is so large. You might find other reasons why your .apk is large such as resources(images, raw files), assemblies, etc.
I have an embedded device with WinCE 6.0 as OS. The manufacturer provides an IDE for 3rd party development to it. The IDE pretty much allows nothing else than
.NET 3.5 Compact Framework scripting that's invoked from various events from the main application
Adding files to the device.
The included mediaplayer seems to be using DirectShow and the OS has media codec only for mpeg-1 encoded video playback. My goal is to to be able to play media encoded with some other codecs as well inside that main application.
I've already managed to use DirectShowNETCF (DirectShow wrapper for .NET Compact Framework) and successfully playback mpeg-1 encoded video.
I'm totally new with this stuff and I have tons of (stupid) questions. I'll try to narrow them down:
The OS is based on WinCE, but as far as I've understood, it's actually always some customized version of it (via Platform Builder). Only "correct way" of developing anything for it afterwards is to use the SDK the manufacturer usually provides. Right? In my case, the SDK is extremely limited and tightly integrated into IDE as noted above. However, .NET CF 3.5 is capable for interop so its possible to call native libraries -as long as they are compiled for correct platform.
Compiled code is pretty much just instructions for the processor (assembler code) and the compiler chooses the correct instructions based on the target processor setting. Also there's the PE-header that defines under which platform the program is meant to be run. If I target my "helloworld.exe" (does nothing but returns specific exit code) to x86 and compile it with VC, should it work?
If the PE-header is in fact the problem, is it possible to setup for WINCE without the SDK? Do I REALLY need the whole SDK for creating a simple executable that uses only base types? I'm using VS2010, which doesn't even support smart device dev anymore and I'd hate to downgrade just for testing purposes.
Above questions are prequel to my actual idea: Porting ffmpeg/ffdshow for WinCE. This actually already exists, but not targeted nor built for Intel Atom. Comments?
If the native implementation is not possible and I would end up implementing some specific codec with C#...well that would probably be quite a massive task. But having to choose C# over native, could I run into problems with codec performance? I mean.. is C# THAT much slower?
Thank you.
I've not seen an OEM that shipped their own IDE, but it's certainly possible. That shouldn't change how apps can created, however. It's possible that they've done a lot of work to make sure only things from their IDE work, but that would be a serious amount of work for not that much benefit, so I'd think it's unlikely.
As for your specific questions:
The OS is Windows CE, not "based on" it. The OS is, however, componentized, so not all pieces are going to be available. An SDK generally provides a mechanism to filter out what isn't available. You can actually use any SDK that targets the right processor architecture, but if your app calls into a library for something that isn't in the OS, then you'll get at the very least an error. For managed code this is all not relevant because the CF isn't componentized. If it's there, and CF app can run (and if it's not, you can often install it after the fact). This means that if the platform supports the CF, then you can write a CF app and run it. That app can then call native stuff via P/Invoke (unless, of course, the OS creator decided to add security to prevent that. This is possible in the OS, though I've never seen it implemented).
Yes, compiled code is just "instructions". For native, yes, they are processor instructions. For managed, they are MSIL instructions that the managed runtime in turn converts to processor instructions at JIT time. If your target is an ARM platform, you cannot use an x86 compiler. Broadly speaking, you need to use the correct Microsoft compiler that support Windows CE, and call that compiler with the proper switches to tell it not only the processor architecture, but also the target OS because the linking that needs to be done will be different for OS-level APIs and even the C runtimes. The short of this is that for your platform, you need to use Visual Studio 2008 Pro.
For native apps, you need some SDK that targets the same OS version (CE 6.0) and processor architecture (e.g. ARMv4I). Having it match the OS feature set is also useful but not a requirement. For managed code, you can just use the SDKs that ship with Studio because managed code is not processor-dependent. Still, you have to go back to Studio 2008 because 2010 doesn't have any WinCE compilers.
If you've found an existing library, then you can try to use it. Things that might impede your progress are A) it's unlikely to use an SDK you have so you probably have to create new project files (painful, but workable) and B) if it uses features not available in your OS, then you'd have to work around those. If you're missing OS features, you're probably out of luck but if it already has a media player and codec, I suspect you'll be ok.
Don't implement this in managed code. Seriously, just don't do it. Could you? Yes. Performance could probably be made to be nearly the same except to avoid GC stuttering you're going to have to basically create your own memory manager. The amount of work involved in this path is very, very large.
How to debug mingw built binaries to detect heap errors? I see there are several questions on the topic, but they are general and it's hard to find the tool that would work well with MinGW. I spent much time on finding the solution, I hope the combined topic will be helpful.
Such a tool becomes necessary when for example someone reports a bug in your library while running it under Visual Studio debugger, which stops with a "Heap Error".
There is a tool provided by Microsoft called Application Verifier. It is a gui tool that changes system settings to run selected applications in a controlled environment. This makes it possible to crash your program if it causes detectable memory errors. This is a controlled crash that can be debugged.
Fortunately it is obtainable from Microsoft as a separate download. Another way to get it is to have Windows SDK installed with checked Application Verifier checkbox. SDK offers also an option Application Verifier redistributable.
After you configure Application Verifier to have an eye for your app, you need to debug it. Debugging under MinGW is a more common subject, already explained on stackoverflow. [mingw] [debugging] query on stackoverflow gives interesting articles. One of them is How do I use the MinGW gdb debugger to debug a C++ program in Windows?. Gdb is the one I used.
The general questions How to debug heap corruption errors? and Heap corruption detection tool for C++ were helpful to find this tool, but I wasn't sure if it is compatible with MinGW. It is.
I have a few years of experience writing Unix command line tools (no GUI experience) in python, C and C++, and only recently crossed into the GUI world (Cocoa and IOS only). I've learned quite a bit of objective-C and am getting to understand how cocoa MVC works. However, one of the apps I am developing needs a Windows version and I was wondering what a good place to start would be given that I have absolutely no Windows development experience.
I was thinking about using Visual C++ 2010 Express as my development platform (because it's free and because I don't need to learn C++). My application is relatively simple, it will have only two windows and spend most of the time running in the background. It will however need to communicate with the OS (load dll's etc) and an online server (HTTP methods) and I'm not sure whether Visual C++ Express edition gives me access to the required API's. Would a Windows Forms application suffice? Am I going about this the wrong way? Do I need to learn C#? Any advice will be appreciated.
If you are already happy with proper c++, visual Studio C++ express should suit you fine. Given that you are not making a complicated GUI, you don't even need to dip into the managed code - C++ express allows you to create proper c++ console and GUI apps. You also don't need to install the platform SDK - it is part of VS C++ express.
Not being managed C++, you will be able to share source files between your various projects. managed c++, despite the c++ in the name, really is a different enough language that it will be annoying to work with if you simultaneously have to deal with iso C++.
--
Note: The native windows API is a C api, not a C++ framework. So it does not provide a rich set of classes in a coherent framework to deal with. On the other hand, while, large, it is actually quite simple to work with.
Also: Given that you are already familiar with Mac development, there is a LGPL (iirc) package called CFLite that builds on windows and that implements the C api that underlays the Objective-C Cocoa API.
If you use its abstratcions you can share a greater part of code between windows and Mac (and other platforms).
Other C++ IDE's you might want to consider:
Code::Blocks
QT Creator
both of which can be configured to use the MINGW port of GCC to windows.
you'll be better off with c++ than c# if you need more "low-level" stuff. Loading dlls (that is, libs) is simple (pragma comment lib...), as is pure HTTP transfer and communication.
So, VC++ with windows form will suffice, and it is "very c++".
You have access to all global APIs, and loading specific apis like http requires only two lines: one to include wininet header, and other lib (libs are actually "references" to dlls).
If you go the C++ Express way then you need to install Windows SDK separately, and set it up for Visual Studio to use it. And you can't use MFC.
I would however, suggest C#, because it feels like putting little toy bricks together. Easier to debug and maintain. Problem with C# is that it has so many library functions that you can not possibly know if what you want is already made to a function. But that's why we are here :-) If you feel that something you want to do should already exist then ask a question about it. One notable feature that C# lacks is zip archives (it has something similar, but not quite). For zips you can use public libraries, like SharpZipLib or DotNetZip.
If I were you, I wouldn't jump into a whole new API so quickly. Have you considered using Python on Windows? Most of the Python packages I've seen are also available for Windows, so you'll feel at home. And if you need some GUI, you can opt for wxPython, pyGTK or something similar.
For Windows specific things, you can always use ctypes. Especially if they're as simple as loading a DLL.
have you considered approaching Adobe AIR? it allows you to deploy on Mac, Linux, Windows, iOS, etc. communicating with and launching native processes has been possible since 2.0 and the the latest 2.5 SDK can target Android OS and TVs. with your experience you should be able to pick up ActionScript3 / MXML in no time.
additionally, there are a handful of free IDEs you can use with the Flex and AIR SDKs. or, if you're a student or low-income developer, you can get a free copy of Flash Builder 4 from Adobe: http://www.adobe.com/devnet-archive/flex/free/
edit: i believe deploying AIR applications on iPhone requires Flash Professional CS5, which includes the packager for iPhone options. at the same time, i've read that AIR and other cross-compilers for iOS are painfully slow, so it's perhaps best to develop natively in Objective-C for iOS.
In a nutshell, I want to write my own device driver for windows, so that I can emulate a piece of hardware. I know very little about writing device drivers for windows, but I have a very firm understanding of the C and C++ languages, and I know enough x86(_64) assembly to get around.
I'm not really sure how one would go about even compiling a device driver, or what is required to create one. I'm certainly not against coding the entire thing in assembly if that needs to be done, but does it?
I'd like to do this using Windows tools obviously, I'm planning on trying to put it together using a windows GCC compiler, but I've got access to Visual Studio if that's needed. Can someone point me at resources that would be helpful, like reference manuals, tutorials, specs?
Oh: My target OS here is Windows 7, 64bit, which if I understand should be the same as Windows Vista 64bit, but correct my wrongness if it exists.
Thanks.
Everything you need to build your driver (including the compiler) comes from the WDK. Everything you need to know what to write comes from Walter Oney's books. Be prepared for a rough ride.