CODEWITHSUNDEEP
clinuxgosystem-calls
Pavel S
Pavel S

Reputation: 25

Wrappers for inb() and outb() linux syscalls

Are there any Go wrappers for the following Linux syscalls used for low-level port input-output? 

#include <sys/io.h>

unsigned char inb(unsigned short int port);
void outb(unsigned char value, unsigned short int port);

I have only managed to find a wrapper for sister call:

int ioperm(unsigned long from, unsigned long num, int turn_on);

which sets access to aforementioned ports. Wrapper is in syscall Go package:

func Ioperm(from int, num int, on int) (err error)

but not a trace of inb() and outb(). I do not want to use cgo for this calls to not lose easy cross-compilation.

Upvotes: 0

Views: 1234

Answers (1)

S.S. Anne
S.S. Anne

Reputation: 15576

inb and outb are not system calls, they are processor instructions. You can write wrapper functions in C for these and call them with cgo.

Here's the C functions (unless you do have them available in sys/io.h):

unsigned char inb(unsigned short port)
{
    unsigned char ret;
    asm volatile("in %%dx, %%al" : "=a"(ret) : "d"(port) : "memory");
    return ret;
}

void outb(unsigned char value, unsigned short port)
{
    asm volatile("out %%al, %%dx" : : "a"(value), "d"(port) : "memory");
}

And a little header file you can use with cgo:

#ifndef IOPORT_H_
#define IOPORT_H_ 1

unsigned char inb(unsigned short port);
void outb(unsigned char value, unsigned short port);

#endif

Upvotes: 2

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