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SubjectRe: Direct access to parport

On Tue, 4 Mar 2003, Uwe Reimann wrote:
> I'd like to connect some self made hardware to the parallel port and
> read the values of the dataline using linux. Can this be done in
> userspace or do I have to write kernel code to do so? I'm currently
> thinking of writing a device like lp, which in turn uses the parport
> device. Does this sound like a good idea?

From userspace it's quite simple:

#include <stdio.h>
#include <sys/io.h>

int main(int argc, char **argv)
{
int addr = 0x378;

if(ioperm(addr, 3, 1) == -1) {
perror("ioperm");
exit(1);
}
printf("0x%02x\n", inb(addr + 1));
}

The ioperm() only works if you're root.

Eric
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