OUTB


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OUTB

NAME
SYNOPSIS
DESCRIPTION
CONFORMING TO
SEE ALSO
COLOPHON

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

SYNOPSIS

#include <sys/io.h>

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

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

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

CONFORMING TO

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.

SEE ALSO

ioperm(2), iopl(2)

COLOPHON

This page is part of release 3.69 of the Linux man-pages project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at http://www.kernel.org/doc/man−pages/.







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