### _outp -- Write Byte to Output Port

Format

>     #include <conio.h>  /* also in <builtin.h> */
>     int _outp( const unsigned int port, const int value );

Language Level: Extension
_outp writes a byte value to the specified port. The port number must be an unsigned integer value within the range 0 to 65 535 inclusive. The byte value must be within the range 0 to 255 inclusive.

Note: _outp is a built-in function, which means it is implemented as an inline instruction and has no backing code in the library. For this reason:

- You cannot take the address of _outp.
- You cannot parenthesize a call to _outp. (Parentheses specify a call to the function's backing code, and _outp has none.)

You can run code containing this function only at ring zero. Otherwise, an invalid instruction exception is generated.

Return Value
_outp returns the integer value that was output to the specified port. There is no error return value, and _outp does not set errno.

Example

_inp -- Read Byte from Input Port
_inpw -- Read Unsigned Short from Input Port
_inpd -- Read Doubleword from Input Port
_outpw -- Write Word to Output Port
_outpd -- Write Double Word to Output Port
<builtin.h>
<conio.h>