.TH INB 10.2 x86
.SH NAME
inb, ins, inl, outb, outs, outl, insb, inss, insl, outsb, outss, outsl \- programmed I/O
.SH SYNOPSIS
.ta \w'\fLushort 'u
.B
int	inb(int port);
.PP
.B
ushort	ins(int port);
.PP
.B
ulong	inl(int port);
.PP
.B
void	outb(int port, int value);
.PP
.B
void	outs(int port, ushort value);
.PP
.B
void	outl(int port, ulong value);
.PP
.B
void	insb(int port, void *address, int count);
.PP
.B
void	inss(int port, void *address, int count);
.PP
.B
void	insl(int port, void *address, int count);
.PP
.B
void	outsb(int port, void *address, int count);
.PP
.B
void	outss(int port, void *address, int count);
.PP
.B
void	outsl(int port, void *address, int count);
.SH DESCRIPTION
The
.I x86
implementation of Inferno provides functions to allow kernel code
written in C to access the I/O address space.
On several other architectures such as the PowerPC and Strongarm,
Inferno provides similar functions to access
devices with an I/O space interface, even though memory mapped, to encourage portability of device drivers.
.PP
.IR Inb ,
.I ins
and
.I inl
apply the corresponding hardware instruction to fetch the next byte, short or long
from the I/O
.IR port .
.IR Outb ,
.I outs
and
.I outl
output a
.I value
to the I/O
.IR port .
.PP
The remaining functions transfer
.I count
bytes, shorts, or longs using programmed I/O between a memory
.I address
and
.IR port .
Functions
.BI ins x
copy values into memory; functions
.BI outs x
copy values from memory.
The
.I count
is in elements, not bytes.
.SH SOURCE
.B /os/pc/l.s
.SH SEE ALSO
.IR dma (10.2),
.IR isaconfig (10.2)