what the use of the static and dynamic L-PDUS in the com stack of AUTOSAR, and when will be using (please provide one example), if i was not configured how will i know its dynamic or static L-PDU.
Static L-PDUs are defined with their ID and can not be changed later. Dynamic L-PDUs can be changed at runtime regarding their CanId. For Dynamic L-PDUs you need to also enable the DynamicTx API e.g. CanIf_SetDynamicTxId() and use it for setting the actual CanId.
I would suggest, reading chapters 7.3, 7.4 (and also the Abbreviation/Acronyms) in the AUTOSAR_SWS_CanInterface.pdf.
Also, ch. 10 usually explains the configuration elements.
Related
Im trying to accomplish a twincat 3 library which does things using global constants defined in the main project, like creating arrays the size of those constants and cycling trough them. However I've been unsuccessful and I wonder if this can be done. I just get this error "Error 4 Border 'cPassedConstant' of array is no constant value" when I try to build the main project. The error comes from the array defined in the library.
I've tried making a GVL with a constant of the same name to the library and then setting the "external implementation" property true but that does not help.
My goal here is to make a IO management library with filtering and such. And then I could just add it to the main project and define some constants like "cDigitalIputsCount","cAnalogInputCount" and so on.
Maybe you can get along with the new ARRAY[*] feature instead, although it is still very limited. There is no other way than to define the constant in the library.
The library concept is the same as in other environments. A library provides you reusable components. Your main project depends on the library and not the other way around. Therefore your library cannot know a thing about the project where it is used.
A confusing thing in TwinCat3 is, that you can build projects successful with programming errors inside. The TwinCat3 compiler allows broken code inside a project as long as it is not called. Therefore when you ship libraries you should always use "Check all objects".
You should check Beckhoff's feature called Parameter List. By adding a parameter list to the library project, you can re-define library constants in the project that uses the library. The definition happens in the library manager.
Image from Beckhoff's site:
I think that should do it. Of course, the other option is to use the ARRAY[*] option, which is awesome too (for a PLC programming world). The problem with parameter lists is that it is a project-wide re-definition. Using the ARRAY[*] allows the size be changed dynamically.
I would suggest using a variable length ARRAY[*], as explained in the link below (and also in the Beckhoff/Infosys, section DataTypes/Array).
The point is that you should declare the ARRAY[1..cAINs] of FB_AnalogIO in your main program (it knows the FB_AnalogIO from your analog library and can declare it with a constant size).
The PRG_IO should then be changed to either a function or function block, so that it accepts the ARRAY[*] as a VAR_IN_OUT without knowing the exact size.
https://stefanhenneken.wordpress.com/2016/09/27/iec-61131-3-arrays-with-variable-length/
I'd like to extend String's asType method to handle LocalDateTime. I know how to override this method, however I've no idea where should I put it in project structure to work globally - for all strings in my project. Is it enough to put such extension wherever in the classpath? I know that there's a special convention for extensions (META-INF/services), how does it work for method overriding?
All documentation regarding this topic can be found here. And here exactly the relevant part can be found.
Module extension and module descriptor
For Groovy to be able to load your extension methods, you must declare
your extension helper classes. You must create a file named
org.codehaus.groovy.runtime.ExtensionModule into the META-INF/services
directory:
org.codehaus.groovy.runtime.ExtensionModule moduleName=Test module for
specifications moduleVersion=1.0-test
extensionClasses=support.MaxRetriesExtension
staticExtensionClasses=support.StaticStringExtension The module
descriptor requires 4 keys:
moduleName : the name of your module
moduleVersion: the version of your module. Note that version number is
only used to check that you don’t load the same module in two
different versions.
extensionClasses: the list of extension helper classes for instance
methods. You can provide several classes, given that they are comma
separated.
staticExtensionClasses: the list of extension helper classes for
static methods. You can provide several classes, given that they are
comma separated.
Note that it is not required for a module to define both static
helpers and instance helpers, and that you may add several classes to
a single module. You can also extend different classes in a single
module without problem. It is even possible to use different classes
in a single extension class, but it is recommended to group extension
methods into classes by feature set.
Module extension and classpath
It’s worth noting that you can’t use an extension which is compiled at
the same time as code using it. That means that to use an extension,
it has to be available on classpath, as compiled classes, before the
code using it gets compiled. Usually, this means that you can’t have
the test classes in the same source unit as the extension class
itself. Since in general, test sources are separated from normal
sources and executed in another step of the build, this is not an
issue.
I have built a linux shared object which I inject into a 3rd party program to intercept some dynamic function calls using LD_PRELOAD.
The 3rd party program uses a SO "libabc.so" located at some path. My injected SO uses another SO, also called "libabc.so" located at another path (essentially identical but slight code differences).
My problem is now, that calls to a function "def" which appear in both libabc.so are always resolved by the first. (Presumably because it is loaded first?!) How can I get them to be resolved with the second libabc.so?
Many thanks!
Unless something changed since I used to do this, you will need to dlopen() the library you want to pass calls on to and call the function manually, something like;
handle = dlopen("/path/to/libabc.so", RTLD_LAZY);
otherDef = dlsym(handle, "def");
orderDef(parameter);
There is a complete example how to do this very thing at LinuxJournal.
If you only want to use one libabc.so version, you can always use LD_PRELOAD to load it along with your own shared object before anything else.
If you want to use multiple versions, you have a few alternatives:
Use dlopen() in your shared object to load that library. Since you have created a function injection object you should be familiar with this procedure. This is the more generic and powerful way - you could even mix & match functions from different library versions.
Use a different DT_SONAME for the library version your shared object links against. Unfortunately this requires (slightly) changing the build system of that library and recompiling.
Link your shared object statically against the library in question. Not always possible but it does not require modifying the library in question. The main issue with this alternative is that any change in the library should be followed by a relinking of your shared object for the changes to be pulled in.
Warning: you may need to use a custom linker script or specific linker options to avoid symbol conflicts.
I am using the GNU autotools (including automake!) for my project. I would like to know if I could create a static and a shared library using libtool? Or would the declarations be separate? Would this:
LT_INIT(shared static)
work?
Nothing besides LT_INIT is needed, it defaults to building both static and shared libraries. If you like, you can again explicitly state the defaults (but it is sort of redundant)
LT_INIT
AC_ENABLE_SHARED
AC_ENABLE_STATIC
edit: manual says LT_INIT([shared]) and LT_INIT([static]) (combined to LT_INIT([shared static]) shall also work. Also manual's more precise wording on what's default when LT_INIT is given:
this macro turns on shared libraries if they are
available, and also enables static libraries if they don't
conflict with the shared libraries.
I'm working on a cross platform project that uses STL. The other compiler includes STL support by default, but in VS2005 I need to add the following before the class definitions that use STL items:
#include <cstdlib>
using namespace std;
Is there a VS2005 option that would set this automatically? It's just a bit tedious to work around. I'm just trying to avoid lots of #ifdefs in the source -
EDIT: The other compiler is the IAR workbench for the ARM 926x family. Perhaps I should get them to explicitly do the includes?
Also - is "std::map<>" preferred over "using namespace std; map<>" ?
All compilers should require you to include those lines. If they don't, then they're just encouraging you to write non-portable code because you're relying on certain headers to be included automatically and you're relying on certain names to be in scope implicitly.
I don't mean to say that those two lines should always be required, though. I only mean that if the rest of your code is written to use things declared in the cstdlib header and in the std namespace, then those two lines need to appear first, and the compiler shouldn't act as though they are there when they really aren't.
Check whether your other compiler has some settings to disable this implicit code. If it doesn't, then it's probably a very, very old compiler, and you should consider not using it and not supporting it anymore.
Try refering to STL components by their namespace-qualified name (i.e. std::vector).
Doing a global 'using namespace std' is usually a bad idea.
Or maybe I'm not understanding the question.
The IAR compiler does not support the std namespace (I'm not sure why, because it does support namespaces in general if I remember right).
If you look in the runtime headers for IAR you'll see that they do some macro gymnastics to work around that (the runtime is licensed from Dinkumware, who provide runtimes for quite a few compilers).
You may need to do something similar if you want your stuff to work in multiple environments. A possible cleaner alternative is to just include the "using namespace std;" directive. I might be wrong, but I think the IAR compiler essentially ignored it (it didn't mind that you were using a namespace it didn't know about). A lot of people will think that's ugly, but sometimes you gotta do what the compiler you have wants you to do.
In general you should avoid "using namespace X", especially in header files (because everyone who includes your header gets that namespace too whether they want it or not), and especially for namespace std (because it's so big and the potential for name collisions is big).
Instead, in header files refer to names by their fully qualified form, e.g.:
// for plain functions
void foo(std::map<int> intMap);
// for classes
class person {
std::string name_;
public:
person(std::string name);
// ...
};
Then, in code files, you can do "using", but prefer using specific items in the namespace rather than pulling in the entire namespace. e.g.:
using std::map;
using std::string;
void foo(map<int> intMap) { ... };
person::person(string name) : name_(name) { ... };
etc. This way you avoid impacting others including your headers, and you avoid pulling in potentially zillions of names that might cause a collision with other stuff.