I've been working with a teensy for a multithreaded project using openmp compiling with gcc, however I'm joining a project that uses avr-gcc which doesn't seem to want to compile or recognize omp.h . I get the error "avr-gcc: error: unrecognized command line option '-pthread' " when I attempt to compile and am having trouble finding more information. I found this question about gcc-avr having slower updates AVR gcc version < gcc release versions -- why? but am wondering if avr-gcc hasn't yet added openmp support or doesn't for one reason or another and if there's a work around without requiring the team to switch compilers.
thanks for the direction it appears that avr-gcc doesn't provide headers that interact with operating systems which apparently pthreads does.
"Since sockets are a feature provided by the operating system, and you are compiling code that runs bare-metal on an Arduino microcontroller, which has no operating system running on top, the whole purpose of the sys/socket.h header is nullified.
This applies to any other kind of header or library function that interacts with the operating system, such as unistd.h, fcntl.h, pthread.h etc. In fact, avr-libc, the Standard C library for AVR-GCC, does not provide such headers.
You will need to look at the avr-libc documentation to find out more about the headers and functions that are provided and their usage."
Related
Well, I am going to do some deep learning stuff with opencv.
I have already installed scikit-image and scikit-learn.
No, but you could install some C++ compiler on MacOSX.
Visual C++ is a C++ compiler and IDE for Windows (don't confuse it with Visual Studio Code, which is a cross-platform IDE). You need some compiler for MacOSX, which is a Unix variant and nearly POSIX (it could be certified to some specific POSIX standard, but I don't know which).
Probably, both GCC and Clang are available on MacOSX (see this). You need to find some packaged version of them, perhaps with brew; both compilers work really well. Apple is partly funding Clang. GCC is funded by many other corporations. They both are open source compilers, but with a different license (GCC is mostly GPLv3+). GCC is probably producing some faster code (when optimizing, faster by a few percents only). Clang is probably giving better diagnostics. I actually recommend installing both of them (and using occasionally both of them too).
Take care to install recent versions of GCC & Clang. Both are very active projects, and are progressing quite well.
You probably need to install other things too. E.g. a build automation tool (like GNU make), a version control system (like git), a source code editor (like emacs or vim).
You might even install some fancy IDE like Clion, Code::Blocks, XCode, etc.. I recommend avoiding that, because you need to learn how to compile on the command line. These fancy tools are running the command line compiler under the hoods, and you really need to understand what they are doing (and hiding from you). Actually C and C++ are somehow not IDE friendly (you really need to understand what the compiler is doing). In both C11 specification (n1570) and in C++11 specification (n3337) the notion of translation unit and of preprocessing is important (and sadly, IDEs tend to hide these notions).
As remarked in comments, you could install the XCode package (which pulls useful packages like GCC or Clang, etc...), but avoid using the XCode IDE.
Whats the best procedure to cross compile lua and libs (luasockets, orbit, etc) for an embedded arm device.
Im able to succesfully cross compile lua interpreter, but from there im a little bit lost.
I started using this repo as a base some years ago: https://github.com/johnhw/luajitpi
The whole process depends on what OS your device is running and how POSIX-ish it is. If your system provides a BSD-like-socket API the process should be trivial.
The same applies for pthreads and other APIs your OS should provide. We're running eCos for example, which has a small POSIX layer so the porting of libs like luasocket was easy.
I've been searching around the Lazarus IDE documentation for a bit, and thus far only found information related to cross compiling, so I was hoping someone could give me a straight answer on this. I'm currently working on a project that will require compilation for 32-bit Windows as well as 64-bit Windows. Additionally, I've already set up both versions of the Free Pascal Compiler. Does Lazarus have any built in functionality for configuring in both compilers, and then based on the build target, using the appropriate compiler? Ideally, this would be done at a global level, so that the configuration persists across projects, but if it can only be done at the project level, I don't mind doing it that way.
On further reading, I think I found my answer. I didn't realize it, but fpc has the same sort of front-end functionality as gcc. With that said, implementing the functionality described in my question is just a matter of installing the compiler as a cross compiler, rather than as an independent compiler. Since it doesn't look like you can use the x86_64 compiler to create a 32-bit version, you'll have to compile the 32-bit version, and then crosscompile the 64-bit version. In my case, I first compiled and installed the Win32 compiler using:
make all install INSTALL_PREFIX=C:\path\to\lazarus\1.0.8\fpc\2.6.3 OS_TARGET=win32 CPU_TARGET=i686 PP=ppc386.exe
Next, I compiled and crossinstalled the 64-bit compiler:
make crossall crossinstall INSTALL_PREFIX=C:\path\to\lazarus\1.0.8\fpc\2.6.3 OS_TARGET=win64 CPU_TARGET=x86_64
To confirm that it worked, you can find an executable called, ppcrossx64 in your C:\path\to\lazarus\1.0.8\fpc\2.6.3\bin\i386-win32 folder.
How can I build and compile my own Lua files on Windows? And make them executable.
I am reading Beginning Lua programming, and I have Windows 7 and MacOS Lion both installed. I am having the hard time to follow the instructions. They do not work for me.
On MacOS I open the terminal and put these in:
export LUA_DIR=/usr/local/lib/lua/5.1
mkdir -p /usr/local/lib/lua/5.1 (it tells me, mkdir: illegal option) and I can not follow from here
SET LUA_DIR=”c:\program files\lua\5.1”
As for Windows I do this according to the book.
This what I see in my shell c:\Users\bd>
mkdir "c:\program files\utility" and it tells me access is denied
I have tried to right click on this folder and check off read only, but it does not work.
Any clues would be appreciated, this part has been really confusing for me.
To package your Lua files into an executable on Windows you have several options. There is srlua, there is wxLuaFreeze from wxLua (available as a binary for Windows), and there are more options in this SO answer.
Essentially, the main two options are: (1) append your Lua code to a precompiled exe file, such that it will be loaded and executed when that exe file is run, and (2) convert your Lua code into real executable by compiling it to bytecode, then to C, and then to your target platform.
As to your MacOS issue, mkdir -p means that mkdir is asked to create intermediate directories (for example, you asked to create /a/b/c, it will also create /a/b if those don't exist). As you don't say which version of MacOS you run, it's difficult to provide more detailed answer.
For now the standard distribution of Lua does not compile a script to native executable code; it execute your scripts by first compiling it to bytecode, then by interpreting the bytecode with a reasonnably fast static interpret (this also means that it is easily portable across native or virtual systems, and very resistant to attacks (that could be targetting bugs in the native compiler itself).
Also Lua still does not feature a runtime JIT compiler like Java and .Net: Lua still does not features a VM to produce a safe sandbox.
There exists Lua packages that convert your bytecode (or directly a source script) to a C source that can be used to convert a Lua library into native mode via the same C compiler used to compile the Lua engine itself (this is how the builtin libraries are produced, though they are slightly optimized manually in some time-critical parts).
However it is possible to compile Lua to a javascript source, and run it with fast performance using Javascript, because today's Javascript interprets do have good performance with their implemented VM featuring a JIT compiler for their own bytecodes.
It is also possible by converting it the Lua bytecode to a .Net or Java source that can then be executed directly from Lua (for that you need a version of Lua that has been ported to .Net or Java or Javascript, something that is not so complicate than developing in C/C++ directly a VM with a JIT compiler (a moderately complex part is the bytecode verifier, but the really complex part is the memory manager its garbage collector and its sandbox so that your Lua script will be fully isolated from the Lua engine itself for itw own memory, but the most complex part if the runtime optimizer and collection of profiling statistics: this has been done in the modern VMs for Java, .Net, Javascript, PHP/Zend, Python, Perl...).
I dont know which other language VM would offer the best performance to port Lua and implement on it a compiler to their own bytecode running at near native speed in their VM. But my own small experience with programs (in a much simpler language) self-generating a bytecode that they can run themselves, has always shown me Java winning in performance over .Net and Javascript. This is most probably because Java features an profiling-based dynamic code optimizer
(On the opposite the .Net optimizer runs only once during program installation, using some profiling data collected during the installation of the .Net VM itself, or at first instanciation of the script, without really knowing any profiling data collected during execution of the compiled program itself, and based on some cheked assumptions about the platform capabilities).
I also don't if would be faster in PHP, Python or Perl; the comparison with newer Javascript engines was never attempted though. Porting/compiling a Lua program to Javascript is relatively easy because it implements closures relatively easy for the resolution of linkages. Then the generated Javascript will compile to native code with the excellent Javascript's JIT compilers we have today (and never cease to improve in performance, so much that I've seen various appliactions running now faster in Javascript than before when they were written in C++ or plain C; as well the memory footprint has largely been reduced, we no longer have memory leaks, and even if there's a garbage collector, today's Javascript VM have a very efficient one, which is even better than the GC implemented in the native Lua).
But Lua remains useful as it is easy to secure and sandbox and offers various security benefits (but there are security issues in Lua as well for some kinds of applications, where Javascript offers some solutions, notably for side-channel attacks based on variation of time of execution; but these side-channel attacks are very hard to solve and can affect any system, any program, any programming language, and this starts becoming a critical issue because they are now more esily exploitable; the reason of that comes from hardware optimizations that we depend more and more today when we want to maximize the performances). And with Lua you may be more immune to these problems that a sandboxing sofware environment cannot solve alone.
Probably later we'll see a true VM implementation of Lua with a JIT and self-generating code and the possibility to instanciate new sandboxed VMs to run their self-generated code. It will take more time to generate an EXE file for distribution; notably because it generally requires adding also an installer and a distribution manager.
So for now we could imagine distributing Lua applications compiled to the bytecode of another JIT-capable VM: this generated bytecode would be faster than the Lua bytecode, and would then be extremely complex to reverse-engineer to the semantics of Lua because it would require two separate reverse engineering first from the bytecode of the other VM to the bytecode of Lua, both bytecodes loosing some easiy inferable rules and options tested and foll, and then again to sme Lua source
For the OSX terminal issue:
This command should work
export LUA_DIR=/usr/local/lib/lua/5.1
This command will probably give you permission problems:
mkdir -p /usr/local/lib/lua/5.1
You may try this to solve that. You will be prompted for your password:
sudo mkdir -p /usr/local/lib/lua/5.1
This command has nothing to do with OSX and will not work. This is a windows command:
SET LUA_DIR=”c:\program files\lua\5.1”
You have a permissions problem with Windows- try creating your cmd or PowerShell in Administrator mode. C:\Program Files is a protected directory that a regular user account doesn't have permission to write to.
As for the OS X issue, check out the mkdir OS X manual page to make sure you have the command correct.
So, if I understood your question correctly, you are trying to build Lua on Windows.
This is of course possible, but not easy for beginners. I would highly recommend you to use a binary distribution, which is much easier to install, unless you have special requirements.
Here are several Windows distributions :
Lua Binaries (Lua 5.1 and 5.2)
LuaForWindows (Lua 5.1)
LuaDist (Lua 5.2)
I'm using flex (lexical analyzer, not Adobe Flex) on a project. However, I want to be able to compile on Windows platforms as well, but the Windows version's newest version is only 2.5.4a, so it won't compile my file for version 2.5.35. And no, I can't downgrade to the highest supported Windows version.
Anyone know about plans to upgrade the windows version, or have a suggestion to compile on windows anyway?
You can ask on the mailing list, or get involved in the Flex project yourself. I think the code-base for Flex has remained static for a while, but I don't know who maintains the Windows port. In the interim...
I would recommend including the produced source in your project.
Generate the lexer on a Linux system to produce your lex.c/lex.h files (or whatever)
Include those files in your Win32 C source before you build
If you don't have direct access to a Linux system, a virtual machine might be a good idea. The Flex source should be complaint to some C standard that builds on Windows, but most of the POSIX differences can be altered to use Win32 API fairly easily.
Maybe distribute as:
/src/source_files.c
/src/lex.l
/src/win32_lex/lex.c
This way systems with a modern flex can generate the source from the lex file, and Windows systems compiling the source can use the complementary pre-processed C files.
Short of using some user-space POSIX (Cygwin or whatever).
A little bit of tweaking required, but isn't that portability for you!
Windows builds of flex 2.5.35 do exist, but unfortunately they are not self contained. You can download the MINGW build here, and the Cygwin build here; see also another stackoverflow question. Each build requires that its respective (MINGW or Cygwin) kernel be installed.