I just started using FPC to practice more my old knowledge of Pascal, but now for Linux, then I started seeing much this comment after the 'program' declaration:
{$apptype console}
But is this a best practice comment or a type of declaration?
{$ ...} are not just comments but they are compiler directives.
Here is a list of compiler directives.
Specifically, {$apptype console} tells the compiler to make a console instead of a gui application.
Yes, but contrary to Delphi, in FPC console is default. Delphi has GUI default (*)
Because the defaults vary between Delphi and FPC, it is a reasonable practice to add it, if there is a chance the code must run under Delphi.
(*) strictly speaking not, since the console app flag can also be set using the cmdline. But while thus not 100% mandatory, it is smart to add it in 99.9% of the cases in Delphi.
Related
I'm developing a c++ application with Xcode 3.1.4
while debugging, if i step into a constructor, i see only the membervariables, but no locals used in the constructor.
does anyone know that problem and how to solve it?
I saw somewhere else that -gstabs+ solves a similar problem specific to locals in constructors. I didn't try it but the solution that worked for me was to move the body of the code into a private function with the same arguments, and call that function from the constructor. Same behavior, but now you can debug the code...
It may be a bug in the compiler such as this one. You could try upgrading your g++ or using a different compiler.
Obvious question: you're running with no optimizations (-O0), correct? With optimizations, it is very common for local variables to be optimized out. Even without optimizations, I have found that a lot of simple C++ seems to get hidden. For instance, you can't always call get() on a shared_ptr because it gets inlined.
I recommend upgrading to Xcode 3.2. I feel that C++ support improved somewhat between 3.1 and 3.2. That said, C++ support within Xcode is still very weak. Unless you need the portability of C++ (as I do), I do not recommend developing Mac or iPhone apps in C++. You will fight the system all day. It is far better to just learn ObjC and use it (besides, ObjC really is a very powerful language and works extremely well with Cocoa). Even when you need the portability of C++, I recommend isolating the C++ code into a core and wrapping it up in Objective-C.
In no case should you use much ObjC++. gdb gets extremely confused in my experience with ObjC++. If you're going to write in C++, wrap your ObjC. If you're going to write in ObjC, wrap your C++. But don't try to write in both at the same time if you ever plan to use the debugger.
I'm pretty sure this is possible but I'm not sure how to go about it. I'm very new to building with GCC in general and I have never used FreeRTOS, but I'd like to try getting the OS up and running on a TI ARM Cortex MCU but with a slight twist: I'd like to get it up and running with Pascal. I'm curious:
Is this even possible to get work? If not, the next issues are kind of moot points.
From my Delphi days, I vaguely recall the ability to access functions in C libraries. I'm wondering if I would have access to the C routines in FreeRTOS.
If I use the GCC version (preferable) would I be able to debug using OpenOCD on the target? I'm not quite sure how debug symbols work and if it's more or less language agnostic (hopefully, in this case).
As kind of a bonus question a bit outside the scope of the original query, can I simulate FreeRTOS on an x86 processor (e.g. my development PC) for easier debugging during development? (With a Pascal program, of course..)
I haven't found any documentation on achieving this, so hopefully someone here can shed some light! Any resources would be most helpful. Like I said, I'm very new to this kind of development. I'm also open to suggestions if you think there is a better alternative.
FYI, my preferred host configuration would be something similar to:
Linux (Ubuntu/Debian)
Eclipse IDE for development, unit testing, and hopefully simulation / debugging
OpenOCD for target debugging
GNU Pascal + FreeRTOS on target
FreeRTOS is C source code, so like you say you would have to have some mechanism for linking C with your Pascal programs. Also, FreeRTOS relies on certain registers to be used for things like passing a parameter into a task (as a hypothetical example, the task might always expect the parameter to be in register R0) so you would have to ensure the ABI for the C compiler and the Pascal compiler was the same - or have your task entry in C then have it call a Pascal function (very nasty). Then there is the issue of interrupts, calling inline macros, etc. I would say this would be extremely difficult to achieve.
Both GNU Pascal and Free Pascal support linking to C (gcc) and ARM, as well as calling pascal code from C etc. Writing a header and declaring the prototypes with cdecl is all there is to it.
Macros are a bit bigger problem. Usually I just rewrite them to inline functions (what they should have been anyway). Except for the macro/header issue, the problems are more compiler specific functionality (which you also would have a problem with when porting from one C compiler to the next)
If you prefer TP/Delphi dialect, Free Pascal is the better choice.
I run my old Delphi code fine on my sheevaplug.
There is already an example for FreeRTOS/GCC/OpenOCD on a TI Cortex-M3 (was Luminary Micro Cortex-M3). Be aware though that this is a really old example and both the Eclipse and OpenOCD versions used are out of date.
Although there is an Eclipse project provided, the project is configured as a standard make (as opposed to a managed make) project, so there is a standard makefile that can be just as easily executed from the command line as from within Eclipse.
http://www.freertos.org/portLM3Sxxxx_Eclipse.html
In both Haskell and OCaml, it's possible to call into the language from C programs. How feasible would it be to create Native applications for either Windows, Mac, or Linux which made extensive use of this technique?
(I know that there are GUI libraries like wxHaskell, but suppose one wanted to just have a portion of your application logic in the foreign language.)
Or is this a terrible idea?
Well, the main risk is that while facilities exist, they're not well tested -- not a lot of apps do this. You shouldn't have much trouble calling Haskell from C, looks pretty easy:
http://www.haskell.org/haskellwiki/Calling_Haskell_from_C
I'd say if there is some compelling reason to use C for the front end (e.g. you have a legacy app) and you really need a Haskell library, or want to use Haskell for some other reason, then, yes, go for it. The main risk is just that not a lot of people do this, so less documentation and examples than for calling the other way.
You can embed OCaml in C as well (see the manual), although this is not as commonly done as extending OCaml with C.
I believe that the best approach, even if both GUI and logic are written in the same language, is to run two processes which communicates via a human-readable, text-based protocol (a DSL of some sort). This architecture applies to your case as well.
Advantages are obvious: GUI is detachable and replaceable, automated tests are easier, logging and debugging are much easier.
I make extensive use of this by compiling haskell shared libs that are called outside Haskell.
usually the tasks involved would be to
create the proper foreign export declarations
create Storable instances for any datatypes you need to marshal
create the C structures (or structures in the language you're using) to read this information
since I don't want to manually initialize the haskell RTS, i add initiallisation/termination code to the lib itself. (dllmain in windows __attribute__ ((constructor)) on unix)
since I no longer need any of them, I create a .def file to hide all the closure and rts functions from being in the export table (windows)
use GHC to compile everything together
These tasks are rather robotic and structured, to a point you could write something to automate them. Infact what I use myself to do this is a tool I created which does dependency tracing on functions you marked to be exported, and it'll wrap them up and compile the shared lib for you along with giving you the declarations in C/C++.
(unfortunately, this tool is not yet on hackage, because there is something I still need to fix and test alot more before I'm comfortable doing so)
Tool is available here http://hackage.haskell.org/package/Hs2lib-0.4.8
Or is this a terrible idea?
It's not a terrible idea at all. But as Don Stewart notes, it's probably a less-trodden path. You could certainly launch your program as Haskell or OCaml, then have it do a foreign-function call right out of the starting gate—and I recommend you structure your code that way—but it doesn't change the fact that many more people call from Haskell into C than from C into Haskell. Likewise for OCaml.
I have a desktop program I downloaded and installed. It runs from an .exe file.
Is there some way from the .exe file to tell what programming language was used to write the program?
Are there any tools are available to help with this?
What languages can be determined and which ones cannot?
Okay here are two of the sort of things I'm looking for:
Tips to Determine Whether an App is Written in Delphi or Not
This "IsDelphi" program by Bruce McGee will find all applications built with Delphi, Delphi for .Net or C++ Builder that are on your hard drive.
I use WinDowse (a small freeware utility written in Delphi) to spy the windows of the program.. for example if you look at the "Class" TabSheet you can discover the "Class" Name of the control..
For example:
TFormXX, TEditYY, TPanelZZZ for delphi apps
WindowsForms10.XXXX.yyy, for .NET apps
wxWindowsXXX for wxWindows apps
AfxWndXX for MFC/VC++ apps (I think)
I think this is the fastest way (although not the most accurate) to find information about apps..
I understand your curiosity.
You can identify Delphi and C++ Builder apps and their SKU by looking for a couple of specific resources that the linker adds. Specifically RC Data\DVCLAL and RC DATA\PACKAGEINFO. The XN Resource Editor makes this a lot easier, but it might choke on compressed EXEs.
EXE compressors complicate things a little. They can hide or scramble the contents of the resources. Programs compressed with UPX are easy to identify with a HEX editor because the first 2 sections in the PE header are named UPX0 and UPX1. You can use the app to decompress these.
Applications compiled with .Net aren't difficult to detect. Recent versions of Delphi even include an IsAssembly function, or you could do a little spelunking in the PE header. Check out the IsManaged function in IsDelphi.
Telling which .Net language was used is trickier. By default, VB.Net includes a reference to Microsoft.VisualBasic, and VCL.Net apps included Borland specific references. However, VCL.Net is defunct in favour of Delphi Prism, and you can add a reference to the VB assembly to any managed language.
I haven't looked at some of the apps that use signatures to identify the the compiler, so I don't know how well they work.
I hope this helps.
First, look to see what run time libraries it loads. A C program won't normally load Visual Basic's library.
Also, examine the executable for telltale strings. In most executables, this is near the end. If the program uses string constants, there might be a clue in how they are stored.
A good disassembler, plus of course an excellent understanding of the underlying CPU architecture, can often help you identify the runtime libraries that are in play. Unless the exe has been carefully "stripped" of symbols and/or otherwise masked, the names of symbols seen in runtime libraries will often provide you with programming-language hints, because different languages' standards specify different names, and vendors of compilers and accompanying runtime libraries usually respect those standards pretty closely.
Of course, you won't get there without knowledge of the various possible languages and their library standards -- and if the code's author was intent to mask the information, that's not too hard for them to do, either.
If you have available a large set of samples from known compilers, I should think this would be an excellent application for machine learning. I believe so-called "supervised learning" is relevant here. Unfortunately I know next to nothing about the topic—only that I have heard some impressive results presented at conferences.
You might dig through the proceedings of the Working Conference on Reverse Engineering to see if anyone else is interested in this problem.
Assuming this is an application for Windows...
Does Reflector recognize it as a .NET assembly? Then it's MSIL, 99% either VB or C#, but you'll likely never know which, nor does it matter.
Does it need an intrepreter (like Java?)? Then it's Java (or whatever the interpreter is.)
Check what runtime DLLs it requires.
Does it require the VB runtime dlls? Congratulations, VB from VisualStudio 6.0 or earlier.
Does it require the Delphi dlls? Congratulations, Delphi.
Did you make it this far? C/C++. Assume C++ unless it requires msys or cygwin dlls, in which case C has maybe a 25% chance.
Congratulations, this should come out correct for the vast majority of Windows software. This probably doesn't actually help you though, as a lot of the same things can be done in all of these languages.
IDA Pro Free (http://www.hex-rays.com/idapro/idadownfreeware.htm) may be helpful. Even if you don't understand assembly language, if you load the EXE into IDA Pro then its initial progress output might (if there are any telltale signs) include its best guess as to which compiler was used.
Start with various options to dumpbin. The symbol names, if not carefully erased, will give you all kinds of hints as to whether it is C, C++, CLR, or something else.
Other tools use signatures to identify the compiler used to create the executable, like PEiD, CFF Explorer and others.
They normally scan the entry point of the executable vs the signature.
Signature Explorer from CFF Explorer can give you an understanding of how one signature is constructed.
It looks like the VC++ linker from V6 up adds a signature to the PE header which youcan parse.
i suggest PEiD (freeware, closed source). Has all of Delphi for Win32 signatures, also can tell you which was packer used (if any).
For certain programs nothing beats the command line. Unfortunately, I have never seen good documentation or examples on how to write console applications that go beyond "Hello World". I'm interested in making console apps like Vim or Emacs. Well not exactly like Vim or Emacs but one that takes over the entire command prompt while it is in use and then after you exit it leaves no trace behind. I know that on Unix there is the curses library but for Windows? ...
PDCurses works on Win32.
I found List of Console Functions on msdn, PDCurses, and The Console Module.
You can certainly write that kind of application with Delphi, which has reasonable commandline support. People often overlook that Delphi can build any kind of Windows executable, not just GUI apps.
I don't know off-hand if the free 'Turbo' edition of Delphi has anything cobbled into it to PREVENT you from using it to build console apps - I would have thought it would be fine for this kind of thing.
There is a small but good tutorial on using C++ for the Windows console at www.benryves.com/tutorials/?t=winconsole&c=all going as far as coding a simple painting program.
You could also try Free Pascal. It is a free ((L)GPL) Object Pascal compiler which is compatible with the Delphi-compiler. It has an console-based IDE, which proves that you can make very good console-applications with it, and which you can use as an example.
If you want to use a graphical IDE to build your console-application, you can download the Lazarus IDE.
As a bonus your application will run on Windows (32/64 bit), Linux, Mac OS X, FreeBSD, Solaris etc...
In Windows or DOS, I used the conio library from Borland. It's very old but fine enough for a beginner like me.
As Robsoft says Delphi would be a good start. There is Turbo Delphi (Pascal based) or Turbo C++ both free editions.
web site here.
http://www.turboexplorer.com/
Check out some of the mono libs. They have a great one to parse command line arguments but can't remember the namespace.
Miguel just posted some terminal code as well.
For ncurses-like library/framework on Windows, I'll highly suggest to get your hand dirty with PDCurses.
If you trying/using C#, there's Curses-Sharp.
This is the best tool for it I've ever seen!!
1) Create any application using VB6 IDE
2) Convert it to Console Application, using THIS!