inb() and outb()

inb() and outb()

[Belinda]

Hi, all

I wrote a simple program with inb() and outb().
However, it reports the segmentation error when
running it. 

The code follows as: 
---------------------------------
#include <asm/io.h>

#define LPT 0x378

void write_LPT(unsigned char byte) 
{
    outb(byte, LPT);
}

int main()
{
   write_LPT(LPT);
   printf("Value:%c", inb(LPT));

}
------------------------------------------------------

Thanks,

Belinda

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Re: inb() and outb()

[Ben Greear]

Belinda wrote:
> 
> Hi, all
> 
> I wrote a simple program with inb() and outb().
> However, it reports the segmentation error when
> running it.
> 
> The code follows as:
> ---------------------------------
> #include <asm/io.h>
> 
> #define LPT 0x378
>    

You need to add something like this in your main method before
calling write_LPT.

See 'man ioperm' for more info..

if (ioperm(LPT, 3, 1)) {
      printf("Sorry, you were not able to gain access to the ports\n");
      printf("You must be root to run this program\n");
      exit(1);
}


> void write_LPT(unsigned char byte)
> {
>     outb(byte, LPT);
> }
> 
> int main()
> {
>    write_LPT(LPT);
>    printf("Value:%c", inb(LPT));
> 
> }
> ------------------------------------------------------
> 
> Thanks,
> 
> Belinda
> 
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