.TH rtapi_outb "3rtapi" "2006-10-12" "LinuxCNC Documentation" "RTAPI"
.SH NAME

rtapi_outb, rtapi_inb \- Perform hardware I/O

.SH SYNTAX
.HP
void rtapi_outb(unsigned char \fIbyte\fR, unsigned int \fIport\fR)
.HP
unsigned char rtapi_inb(unsigned int \fIport\fR)

.SH  ARGUMENTS
.IP \fIport\fR
The address of the I/O port
.IP \fIbyte\fR
The byte to be written to the port

.SH DESCRIPTION
\fBrtapi_outb\fR writes a byte to a hardware I/O port.  \fBrtapi_inb\fR
reads a byte from a hardware I/O port.

.SH REALTIME CONSIDERATIONS
May be called from init/cleanup code and from within realtime tasks.
Not available in userspace components.

.SH RETURN VALUE
\fBrtapi_inb\fR returns the byte read from the given I/O port

.SH NOTES
The I/O address should be within a region previously allocated by
\fBrtapi_request_region\fR.  Otherwise, another real-time module or the Linux
kernel might attempt to access the I/O region at the same time.

.SH SEE ALSO
\fBrtapi_region(3rtapi)\fR