How to use __asm__ in fc6 g++

[ashukla]

Dear All,

#include <iostream>
using namespace std;
int main()
{
  __asm__ int 5; // generate intertupt 5
  return 0;
}

#include <iostream>
using namespace std;
int main()
{
  __asm__ int 5; // generate intertupt 5
  return 0;
}

To copy to clipboard, switch view to plain text mode 

I have comiled this a.cpp file as follows;
g++ a.cpp
a.cpp: In function ‘int main()’:
a.cpp:5: error: expected `(' before ‘int’
a.cpp:5: error: expected unqualified-id before numeric constant
and found the above error
Can any one guide me where I am wrong;
How a way I use interrupts using __asm__ in g++.

[wysota]

Try embedding the assembly code in braces.

[ashukla]

Try embedding the assembly code in braces.

I have spoil whole day for that but nothing get. Is anyone have a link or code for g++4.0.1 compiler.

[wysota]

Try round brackets instead of braces as the compiler suggests.

[ashukla]

Try round brackets instead of braces as the compiler suggests.

#include <iostream>
using namespace std;
int main()
{
  char * am="int 5";
  (__asm__ int 5); // generate intertupt 5
 
    return 0;
}

#include <iostream>
using namespace std;
int main()
{
  char * am="int 5";
  (__asm__ int 5); // generate intertupt 5
  
    return 0;
}

To copy to clipboard, switch view to plain text mode 

and getting
g++ a.c
a.c: In function ‘int main()’:
a.c:6: error: expected primary-expression before ‘asm’
a.c:6: error: expected `)' before ‘asm’

[wysota]

I meant:

__asm__ ( int 5 );

__asm__ ( int 5 );

To copy to clipboard, switch view to plain text mode 

or

__asm__ { int 5 };

__asm__ { int 5 };

To copy to clipboard, switch view to plain text mode 

[ashukla]

I meant:

__asm__ ( int 5 );

__asm__ ( int 5 );

To copy to clipboard, switch view to plain text mode 

or

__asm__ { int 5 };

__asm__ { int 5 };

To copy to clipboard, switch view to plain text mode 

getting the following error respectively

__asm__ ( int 5 );

g++ a.c
a.c: In function ‘int main()’:
a.c:7: error: expected string-literal before ‘int’

__asm__ { int 5 };

g++ a.c
a.c: In function ‘int main()’:
a.c:7: error: expected `(' before ‘{’ token
a.c:7: error: expected unqualified-id before numeric constant

[wysota]

How about this:

asm("int 5");

asm("int 5");

To copy to clipboard, switch view to plain text mode 

[jpn]

Here's an example from qatomic_i386.h:

inline int q_atomic_fetch_and_add_int(volatile int *ptr, int value)
{
    asm volatile("lock\n"
                 "xaddl %0,%1"
                 : "=r" (value), "+m" (*ptr)
                 : "0" (value)
                 : "memory");
    return value;
}

inline int q_atomic_fetch_and_add_int(volatile int *ptr, int value)
{
    asm volatile("lock\n"
                 "xaddl %0,%1"
                 : "=r" (value), "+m" (*ptr)
                 : "0" (value)
                 : "memory");
    return value;
}

To copy to clipboard, switch view to plain text mode 

Searching Google for example "g++ inline asm" would have surely been also productive.

[ashukla]

How about this:

asm("int 5");

asm("int 5");

To copy to clipboard, switch view to plain text mode 

g++ a.c
/tmp/cc8Vc1Ze.s: Assembler messages:
/tmp/cc8Vc1Ze.s:23: Error: suffix or operands invalid for `int'

getting the above error....

[wysota]

This is an assembler error, your assembly code is invalid.

[ashukla]

This is an assembler error, your assembly code is invalid.

Probably, you are saying right!
This is one of my program which is runned successfully;

#include <iostream>
using namespace std;
int a, b;
 
void f1(void)
{
        a = 5;
        b = 30;
 
        asm
        (
                /*"movl $12, %ebx;"
                "movl %ebx, a;"
                "movl %ebx, b;"*/
                "movl %eax, a;"
        );
 
        // cout<<"";
 
        std::cout<<a<<std::endl;
        std::cout<<b<<std::endl;
}
 
int main(){f1();}

#include <iostream>
using namespace std;
int a, b;

void f1(void)
{
        a = 5;
        b = 30;
        
        asm
        (
                /*"movl $12, %ebx;"
                "movl %ebx, a;"
                "movl %ebx, b;"*/
                "movl %eax, a;"
        );
        
        // cout<<"";
        
        std::cout<<a<<std::endl;
        std::cout<<b<<std::endl;
}

int main(){f1();}

To copy to clipboard, switch view to plain text mode 

Thanks for your help & quick response.
But How a way I generate a interrupt no. 5 for print screen which doesn't take any input.

[wysota]

Are you sure the interrupt is handled by Fedora? I never heard of a "print screen" interrupt in Linux. And it is surely doubtful the kernel will let you run one in user mode. Linux uses syscalls and not direct interrupts.

[ashukla]

Are you sure the interrupt is handled by Fedora? I never heard of a "print screen" interrupt in Linux. And it is surely doubtful the kernel will let you run one in user mode. Linux uses syscalls and not direct interrupts.

I have depicted a few days ago that you can call any interrupt in any OS using the asm keyboard on internet by a researcher of MIT. But I have not gotted the code for that. But I am sure it is working on DOS and windows.

[ashukla]

I have depicted a few days ago that you can call any interrupt in any OS using the asm keyboard on internet by a researcher of MIT. But I have not gotted the code for that. But I am sure it is working on DOS and windows.

Can you give me a example as you say it is possible in Linux using with syscall. I have also a need of mouse and keyboard input access.

[wysota]

I have depicted a few days ago that you can call any interrupt in any OS using the asm keyboard on internet by a researcher of MIT.

Provided that a particular OS has this interrupt and allows calling them in user mode.

But I have not gotted the code for that. But I am sure it is working on DOS and windows.

So "any" or "DOS and windows"? DOS and Windows do use interrupts...

Can you give me a example as you say it is possible in Linux using with syscall. I have also a need of mouse and keyboard input access.

man syscall