.\" Copyright (c) 2014 Jeff Epler
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.TH funct "3rtapi" "2022-11-29" "LinuxCNC Documentation" "RTAPI"
.SH NAME

rtapi_io.h \- RTAPI wrappers for linux kernel functionality

.SH SYNTAX
.HP
#include <rtapi_io.h>
.HP
unsigned char rtapi_inb(unsigned short int port);
.HP
unsigned short rtapi_inw(unsigned short int port);
.HP
unsigned int rtapi_inl(unsigned short int port);
.HP
unsigned void rtapi_outb(unsigned char value, unsigned short int port);
.HP
unsigned void rtapi_outw(unsigned short value, unsigned short int port);
.HP
unsigned void rtapi_inl(unsigned int value, unsigned short int port);
.HP
int rtapi_ioperm(unsigned long from, unsigned long num, int turn_on);
.HP
unsigned void rtapi_outl(unsigned int value, unsigned short int port);

.SH DESCRIPTION
In kernel space, each rtapi_xxx or RTAPI_XXX identifier is mapped to the
underlying kernel functionality, if available.

In userspace, or in kernels where the underlying functionality is not provided
by a kernel, generally another implementation--possibly with reduced
functionality--is provided.  (For example, the userspace implementation for
rtapi_device_register and the kernel space implementation of rtapi_ioperm always
succeeds)
.SH REALTIME CONSIDERATIONS
Call from init/cleanup code and from realtime tasks.  These functions will
cause illegal instruction exceptions in userspace components, as well as in
uspace rtapi_app when it is not setuid root.
.SH RETURN VALUE
As in Linux.
.SH SEE ALSO
\fBinb(3)\fR,
\fBinw(3)\fR,
\fBinl(3)\fR,
\fBoutb(3)\fR,
\fBoutw(3)\fR,
\fBoutl(3)\fR,
\fBioperm(3)\fR,
.SH AUTHOR
Jeff Epler