### _inp -- Read Byte from Input Port

Format

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

Language Level: Extension
_inp reads a byte from the specified input port. The port number must be an unsigned int value in the range 0 to 65 535 inclusive.

Note: _inp 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 _inp.
- You cannot parenthesize a call to _inp. (Parentheses specify a call to the function's backing code, and _inp has none.)

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

Return Value
_inp returns the byte value as an integer that was read from the specified port. There is no error return value, and _inp does not set errno.

Example

_inpw -- Read Unsigned Short from Input Port
_inpd -- Read Doubleword from Input Port
isatty -- Test Handle for Character Device
_outp -- Write Byte to Output Port
_outpw -- Write Word to Output Port
_outpd -- Write Double Word to Output Port
<builtin.h>
<conio.h>