Section 2 · System calls

outl.2

Package: man-pages

outb

NAME
LIBRARY
SYNOPSIS
DESCRIPTION
VERSIONS
STANDARDS
SEE ALSO

NAME

outb, outw, outl, outsb, outsw, outsl, inb, inw, inl, insb, insw, insl, outb_p, outw_p, outl_p, inb_p, inw_p, inl_p − port I/O

LIBRARY

Standard C library (libc, −lc)

SYNOPSIS

#include <sys/io.h>

unsigned char inb(unsigned short port**);
unsigned char inb_p(unsigned short** port**);
unsigned short inw(unsigned short** port**);
unsigned short inw_p(unsigned short** port**);
unsigned int inl(unsigned short** port**);
unsigned int inl_p(unsigned short** port**);**

void outb(unsigned char value**, unsigned short** port**);
void outb_p(unsigned char** value**, unsigned short** port**);
void outw(unsigned short** value**, unsigned short** port**);
void outw_p(unsigned short** value**, unsigned short** port**);
void outl(unsigned int** value**, unsigned short** port**);
void outl_p(unsigned int** value**, unsigned short** port**);**

void insb(unsigned short port**, void** addr**[.count],
unsigned long** count**);
void insw(unsigned short** port**, void** addr**[.count],
unsigned long** count**);
void insl(unsigned short** port**, void** addr**[.count],
unsigned long** count**);
void outsb(unsigned short** port**, const void** addr**[.count],
unsigned long** count**);
void outsw(unsigned short** port**, const void** addr**[.count],
unsigned long** count**);
void outsl(unsigned short** port**, const void** addr**[.count],
unsigned long** count**);**

DESCRIPTION

This family of functions is used to do low-level port input and output. The out* functions do port output, the in* functions do port input; the b-suffix functions are byte-width and the w-suffix functions word-width; the _p-suffix functions pause until the I/O completes.

They are primarily designed for internal kernel use, but can be used from user space.

You must compile with −O or −O2 or similar. The functions are defined as inline macros, and will not be substituted in without optimization enabled, causing unresolved references at link time.

You use ioperm(2) or alternatively iopl(2) to tell the kernel to allow the user space application to access the I/O ports in question. Failure to do this will cause the application to receive a segmentation fault.

VERSIONS

outb() and friends are hardware-specific. The value argument is passed first and the port argument is passed second, which is the opposite order from most DOS implementations.

STANDARDS

None.