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Keyboard interrupts

 
 
Victor Bazarov
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      03-28-2005
Cyber wrote:
> I want to catch any event on a PC by the interrupts (C++ under Linux).
> My first step is to catch everything from the keyboard. I have:
> [...]
> It do not works... If this part can work, after, I will add more signal
> definition (for other events, mouse, etc...);
>
> If anyone have an idea ?


There is no way to do what you want using only Standard C++. Please
ask your platform-specific question in a newsgroup dedicated to your
platform (comp.os.linux.development.apps is probably it). They should
have an idea or two.

V
 
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Cyber
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      03-28-2005
Hello !

I want to catch any event on a PC by the interrupts (C++ under Linux).
My first step is to catch everything from the keyboard. I have:

---------------------------------------------------

#include <iostream>
#include <csignal>
using namespace std;

void the_keyboard (int sig)
{
cout << "handling signal no. " << sig << endl;
}

main ()
{
int cont = 1;
while (cont) {
signal (1, the_keyboard); // catch interrupt No.1 (keyboard)
}
}

---------------------------------------------------

It do not works... If this part can work, after, I will add more signal
definition (for other events, mouse, etc...);

If anyone have an idea ?

Thanks,

Cyber
 
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Phlip
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      03-28-2005
Cyber wrote:

> I want to catch any event on a PC by the interrupts (C++ under Linux).


Your questions is about Linux, not C++, so you'd get much better results on
a Linux newsgroup.

> while (cont) {
> signal (1, the_keyboard); // catch interrupt No.1 (keyboard)
> }


> It do not works... If this part can work, after, I will add more signal
> definition (for other events, mouse, etc...);


What are you _really_ trying to do? If you want to affect keystrokes, you
should program to the layer of Linux that handles them the way you need. For
example, if you use X Windows (via Gnome, KDE, or the various others), then
you should research how their keyboard handlers work, and how to extend
them.

--
Phlip
http://industrialxp.org/community/bi...UserInterfaces


 
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Ioannis Vranos
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      03-28-2005
Victor Bazarov wrote:

> There is no way to do what you want using only Standard C++. Please
> ask your platform-specific question in a newsgroup dedicated to your
> platform (comp.os.linux.development.apps is probably it). They should
> have an idea or two.


However we must keep in mind that C++ provides <csignal>.




--
Ioannis Vranos

http://www23.brinkster.com/noicys
 
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Victor Bazarov
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      03-28-2005
Ioannis Vranos wrote:
> Victor Bazarov wrote:
>
>> There is no way to do what you want using only Standard C++. Please
>> ask your platform-specific question in a newsgroup dedicated to your
>> platform (comp.os.linux.development.apps is probably it). They should
>> have an idea or two.

>
>
> However we must keep in mind that C++ provides <csignal>.


We must. Does it have anything to do with a keyboard?
 
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Ioannis Vranos
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Posts: n/a
 
      03-28-2005
Cyber wrote:

> Hello !
>
> I want to catch any event on a PC by the interrupts (C++ under Linux).
> My first step is to catch everything from the keyboard. I have:
>
> ---------------------------------------------------
>
> #include <iostream>
> #include <csignal>
> using namespace std;
>
> void the_keyboard (int sig)
> {
> cout << "handling signal no. " << sig << endl;
> }
>
> main ()
> {
> int cont = 1;
> while (cont) {
> signal (1, the_keyboard); // catch interrupt No.1 (keyboard)
> }
> }
>
> ---------------------------------------------------
>
> It do not works... If this part can work, after, I will add more signal
> definition (for other events, mouse, etc...);
>
> If anyone have an idea ?



signal assigns a function handler to a signal, so you should use it once in the above.

Interrupt values are system-specific. Here is a program that handles ctrl-c by displaying
its int value:



#include <iostream>
#include <csignal>


void sigint_handler(int sig)
{
std::cout << "handling signal no. " << sig << "\n";
}


int main ()
{
using namespace std;

signal(SIGINT, sigint_handler);

while(true)
;
}



Of course you can displays the system-specific values of each of the standard ones with
this way:


#include <iostream>
#include <csignal>

int main ()
{
using namespace std;

cout<<"SIGABRT: "<<SIGABRT<<"\n"
<<"SIGFPE: "<<SIGFPE<<"\n"
<<"SIGILL: "<<SIGILL<<"\n"
<<"SIGINT: "<<SIGINT<<"\n"
<<"SIGSEGV: "<<SIGSEGV<<"\n"
<<"SIGTERM: "<<SIGTERM<<"\n";
}


which in my system are:

C:\c>temp
SIGABRT: 22
SIGFPE: 8
SIGILL: 4
SIGINT: 2
SIGSEGV: 11
SIGTERM: 15

C:\c>



--
Ioannis Vranos

http://www23.brinkster.com/noicys
 
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Ioannis Vranos
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      03-28-2005
Here is what the last draft of C90 was saying:


"4.7 SIGNAL HANDLING <signal.h>

The header <signal.h> declares a type and two functions and defines
several macros, for handling various signals (conditions that may be
reported during program execution).

The type defined is

sig_atomic_t

which is the integral type of an object that can be accessed as an
atomic entity, even in the presence of asynchronous interrupts.

The macros defined are

SIG_DFL
SIG_ERR
SIG_IGN

which expand to distinct constant expressions that have type
compatible with the second argument to and the return value of the
signal function, and whose value compares unequal to the address of
any declarable function; and the following, each of which expands to a
positive integral constant expression that is the signal number
corresponding to the specified condition:

SIGABRT abnormal termination, such as is initiated by the abort function

SIGFPE an erroneous arithmetic operation, such as zero divide or an
operation resulting in overflow

SIGILL detection of an invalid function image, such as an illegal
instruction

SIGINT receipt of an interactive attention signal

SIGSEGV an invalid access to storage

SIGTERM a termination request sent to the program

An implementation need not generate any of these signals, except as
a result of explicit calls to the raise function. Additional signals
and pointers to undeclarable functions, with macro definitions
beginning, respectively, with the letters SIG and an upper-case letter
or with SIG_ and an upper-case letter,/97/ may also be specified by
the implementation. The complete set of signals, their semantics, and
their default handling is implementation-defined; all signal values
shall be positive.


4.7.1 Specify signal handling

4.7.1.1 The signal function

Synopsis

#include <signal.h>
void (*signal(int sig, void (*func)(int)))(int);

Description

The signal function chooses one of three ways in which receipt of
the signal number sig is to be subsequently handled. If the value of
func is SIG_DFL , default handling for that signal will occur. If the
value of func is SIG_IGN , the signal will be ignored. Otherwise,
func shall point to a function to be called when that signal occurs.
Such a function is called a signal handler .

When a signal occurs, if func points to a function, first the
equivalent of signal(sig, SIG_DFL); is executed or an
implementation-defined blocking of the signal is performed. (If the
value of sig is SIGILL, whether the reset to SIG_DFL occurs is
implementation-defined.) Next the equivalent of (*func)(sig); is
executed. The function func may terminate by executing a return
statement or by calling the abort , exit , or longjmp function. If
func executes a return statement and the value of sig was SIGFPE or
any other implementation-defined value corresponding to a
computational exception, the behavior is undefined. Otherwise, the
program will resume execution at the point it was interrupted.

If the signal occurs other than as the result of calling the abort
or raise function, the behavior is undefined if the signal handler
calls any function in the standard library other than the signal
function itself or refers to any object with static storage duration
other than by assigning a value to a static storage duration variable
of type volatile sig_atomic_t . Furthermore, if such a call to the
signal function results in a SIG_ERR return, the value of errno is
indeterminate.

At program startup, the equivalent of

signal(sig, SIG_IGN);

may be executed for some signals selected in an implementation-defined
manner; the equivalent of

signal(sig, SIG_DFL);

is executed for all other signals defined by the implementation.

The implementation shall behave as if no library function calls the
signal function.

Returns

If the request can be honored, the signal function returns the
value of func for the most recent call to signal for the specified
signal sig . Otherwise, a value of SIG_ERR is returned and a positive
value is stored in errno .

Forward references: the abort function ($4.10.4.1).


4.7.2 Send signal

4.7.2.1 The raise function

Synopsis

#include <signal.h>
int raise(int sig);

Description

The raise function sends the signal sig to the executing program.

Returns

The raise function returns zero if successful, nonzero if unsuccessful."




--
Ioannis Vranos

http://www23.brinkster.com/noicys
 
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Stephen Howe
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      03-29-2005
> However we must keep in mind that C++ provides <csignal>.

Please develope your ideas.
Where do we go with the fact that C++ provides <csignal>?

Stephen Howe



 
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Ioannis Vranos
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      03-29-2005
Stephen Howe wrote:

> Please develope your ideas.
> Where do we go with the fact that C++ provides <csignal>?



That the question is about inside the limits of ISO C++.




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Ioannis Vranos

http://www23.brinkster.com/noicys
 
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