I'm looking for some more detailed informaion about the latest 10.8.5 update related to kexts.
There is, so far, no IOUSBFamily Log Version available for 10.8.5,
but don't know if this would help.
My kext (virtuall usb bus, derived from IOUSBControllerV3) works with all predecessors,
but there must be a significant diff with 10.8.5 thats lets kextunload fail
by typicall "class have 1 instance" error.
Thanks in advance for any hint,
regards
Markus
Yes, I've overload the three
virtual void taggedRetain(const void *tag) const;
virtual void taggedRelease(const void *tag) const;
virtual void taggedRelease(const void * tag, const int freeWhen) const;
functions and see the outputs but get no idea who doesn't release his tag under 10.8.5?
Related
I'm optimizing a very time-critical CUDA kernel. My application accepts a wide range of switches that affect the behavior (for instance, whether to use 3rd or 5th order derivative). Consider as an approximation a set of 50 switches, where every switch is an integer variable (a bool sometimes, or a float, but this case is not so relevant for this question).
All these switches are constant during the execution of the application. Most of these switches are run-time and I store them in constant memory, so to exploit the caching mechanism. Some other switches can be compile-time and the customer is fine with having to re-compile the application if he wants to change the value in the switch. A very simple example could be:
__global__ void mykernel(const float* in, float *out)
{
for ( /* many many times */ )
if (compile_time_switch)
do_this(in, out);
else
do_that(in, out);
}
Assume that do_this and do_that are compute-bound and very cheap, that I optimize the for loop so that its overhead is negligible, that I have to place the if inside the iteration. If the compiler recognizes that compile_time_switch is static information it can optimize out the call to the "wrong" function and create code that is just as optimized as if the if weren't there. Now the real question:
In which ways can I provide the compiler with the static value of this switch? I see two such ways, listed below, but none of them work for me. What other possibilities remain?
Template parameters
Providing a template parameter enables this static optimization.
template<int compile_time_switch>
__global__ void mykernel(const float* in, float *out)
{
for ( /* many many times */ )
if (compile_time_switch)
do_this(in, out);
else
do_that(in, out);
}
This simple solution does not work for me, since I don't have direct access to the code that calls the kernel.
Static members
Consider the following struct:
struct GlobalParameters
{
static const bool compile_time_switch = true;
};
Now GlobalParameters::compile_time_switch contains the static information as I want it, and that compiler would be able to optimize the kernel. Unfortunately, CUDA does not support such static members.
EDIT: the last statement is apparently wrong. the definition of the struct is of course legit and you are able to use the static member GlobalParameters::compile_time_switch in device code. The compiler inlines the variable, so that the final code will directly contain the value, not a run-time variable access, which is the behavior you would expect from an optimizer compiler. So, the second options is actually suitable.
I consider my problem solved both thanks to this fact and to kronos' answer. However, I'm still looking for other alternative methods to provide compile-time information to the compiler.
Yor third options are preprocessor definitions:
#define compile_time_switch 1
__global__ void mykernel(const float* in, float *out)
{
for ( /* many many times */ )
if (compile_time_switch)
do_this(in, out);
else
do_that(in, out);
}
The preprocessor will discard the else case compleatly and the compiler has nothing to optimize in his dead code elemination pass, because there is no dead code.
Furthermore, you can specify the definition with the -D comand line switch and (I think) any by nvidia supported compiler will accept -D (msvc may use a different switch).
I am reading Apple's recently (Dec 5, 2013) updated sample code for camera control using AV Foundation (here is the link). And I come across the following lines in the file AVCamViewController.m which I don't understand.
static void * CapturingStillImageContext = &CapturingStillImageContext;
static void * RecordingContext = &RecordingContext;
static void * SessionRunningAndDeviceAuthorizedContext = &SessionRunningAndDeviceAuthorizedContext;
What does it mean to assign the pointer of itself? Why do we need this?
Update (2015-10-02): Now the AVCam is updated and rename to AVCam-iOS, if you are still insterest in this code AVCamViewController.m.
Well, so idea for these constants is to have some unique value, that will not repeat anywhere in the program, but we don't really care about its content.
Now, instead of coming up with some random string/number etc, we just create a pointer, and put its address as content, this way it's unique and the code is simple is nice :)
I am porting my windows code to linux.
when i am using ACE_Atomic_Op api, compiler is throwing some error as shown below
variable "ACE_Atomic_Op<ACE_Thread_Mutex, unsigned int> AcsHcs::Cache::cnt"
has initializer but incomplete type"
my code is as follows:
in Cache.h file i have
static ACE_Atomic_Op<ACE_Thread_Mutex, unsigned int> cnt;
and in cache.cpp i am declaring cnt as
ACE_Atomic_Op<ACE_Thread_Mutex, unsigned int> Cache::cnt = 0;
this works fine in windows, but it is throwing error in linux
can anyone tell me whats the problem is?
thanks in advance
You are lacking an include, please add ace/Atomic_Op.h to your source file. Because of platform differences it sometimes happens that on a platform your get an include for free, when porting to another platform you have to add an explicit include.
Background info
I have a query regarding a questions from Sierra & Bates, SCJP v6 book. Namely Chapter 2 question 2. The answer given is that the "compilation fails". However when I tried this in neBeans, the code compiled and ran without error. It also returned a output of "D" which was not one of the alternatives. There are some other discussions on this same question in various forums, regarding the need to insert super() etc. However none seem to have recognised it can compile.
Question
1. I expected the constructor "Bottom2(String s)...to have called the super constructor "Top(String s)...". In which case the output would have been "BD" (which happens to be an option for the question. Why does the "Top(String s)..." not get called.
2. As there is a Top constructor then would the default compiler constructor still be implicitly created. ie in effect a "Top() {}" constructor which can be called by "Bottom2(String s)". This not how I understood this to happen - ie the compiler only creates this default if no other constructor is created.
3. Is there and error in this question, or is this a carry over question from the Java 5 version and somehow in Java 6 the compiler can now handle this.
4. Could netBeans have a means to "solve" the compiler problem. This is quite important as I am studying for the SCJP and I find not all the questions can be duplicated in netBeans. In which case I may learn to believe some code works when (for exam purposes) it does not.
Code included for ease of reference.
class Top {
public Top(String s) { System.out.print("B"); }
}
public class Bottom2 extends Top {
public Bottom2(String s) { System.out.print("D"); }
public static void main(String [] args) {
new Bottom2("C");
System.out.println(" ");
}
}
Top doesn't have a default constructor (a default constructor is a public constructor with empty argument list. Therefore, the constructor of Bottom2 must explicitly invoke the super constructor (and pass its argument), but doesn't, and hence compilation fails.
Indeed, eclipse helios says:
Implicit super constructor Top() is undefined. Must explicitly invoke another constructor
and javac says:
cannot find symbol
symbol : constructor Top()
location: class tools.Top
public Bottom2(String s) { System.out.print("D"); }
^
Are you really sure you have tried the same code in Netbeans?
I read this article and try to do the exercise in D Programming Language, but encounter a problem in the first exercise.
(1) Display series of numbers
(1,2,3,4, 5....etc) in an infinite
loop. The program should quit if
someone hits a specific key (Say
ESCAPE key).
Of course the infinite loop is not a big problem, but the rest is. How could I grab a key hit in D/Tango? In tango FAQ it says use C function kbhit() or get(), but as I know, these are not in C standard library, and does not exist in glibc which come with my Linux machine which I use to programming.
I know I can use some 3rd party library like ncurses, but it has same problem just like kbhit() or get(), it is not standard library in C or D and not pre-installed on Windows. What I hope is that I could done this exercise use just D/Tango and could run it on both Linux and Windows machine.
How could I do it?
Here's how you do it in the D programming language:
import std.c.stdio;
import std.c.linux.termios;
termios ostate; /* saved tty state */
termios nstate; /* values for editor mode */
// Open stdin in raw mode
/* Adjust output channel */
tcgetattr(1, &ostate); /* save old state */
tcgetattr(1, &nstate); /* get base of new state */
cfmakeraw(&nstate);
tcsetattr(1, TCSADRAIN, &nstate); /* set mode */
// Read characters in raw mode
c = fgetc(stdin);
// Close
tcsetattr(1, TCSADRAIN, &ostate); // return to original mode
kbhit is indeed not part of any standard C interfaces, but can be found in conio.h.
However, you should be able to use getc/getchar from tango.stdc.stdio - I changed the FAQ you mention to reflect this.
D generally has all the C stdlib available (Tango or Phobos) so answers to this question for GNU C should work in D as well.
If tango doesn't have the needed function, generating the bindings is easy. (Take a look at CPP to cut through any macro junk.)
Thanks for both of your replies.
Unfortunately, my main development environment is Linux + GDC + Tango, so I don't have conio.h, since I don't use DMC as my C compiler.
And I also found both getc() and getchar() is also line buffered in my development environment, so it could not achieve what I wish I could do.
In the end, I've done this exercise by using GNU ncurses library. Since D could interface C library directly, so it does not take much effort. I just declare the function prototype that I used in my program, call these function and linking my program against ncurses library directly.
It works perfectly on my Linux machine, but I still not figure out how could I do this without any 3rd party library and could run on both Linux and Windows yet.
import tango.io.Stdout;
import tango.core.Thread;
// Prototype for used ncurses library function.
extern(C)
{
void * initscr();
int cbreak ();
int getch();
int endwin();
int noecho();
}
// A keyboard handler to quit the program when user hit ESC key.
void keyboardHandler ()
{
initscr();
cbreak();
noecho();
while (getch() != 27) {
}
endwin();
}
// Main Program
void main ()
{
Thread handler = new Thread (&keyboardHandler);
handler.start();
for (int i = 0; ; i++) {
Stdout.format ("{}\r\n", i).flush;
// If keyboardHandler is not ruuning, it means user hits
// ESC key, so we break the infinite loop.
if (handler.isRunning == false) {
break;
}
}
return 0;
}
As Lars pointed out, you can use _kbhit and _getch defined in conio.h and implemented in (I believe) msvcrt for Windows. Here's an article with C++ code for using _kbhit and _getch.