in8()
Read an 8-bit value from a port
Synopsis:
#include <hw/inout.h>
uint8_t in8( uintptr_t port );
Arguments:
- port
- The port you want to read the value from.
Library:
libc
Use the -l c option to qcc to link against this library. This library is usually included automatically.
Description:
The in8() function reads an 8-bit value from the specified port.
Returns:
An 8-bit value.
Classification:
| Safety: | |
|---|---|
| Cancellation point | No |
| Interrupt handler | Yes |
| Signal handler | Yes |
| Thread | Yes |
Caveats:
The calling thread must have the PROCMGR_AID_IO ability enabled and must have I/O privileges; see procmgr_ability(), and ThreadCtl()'s _NTO_TCTL_IO command for details.
The calling process must also use mmap_device_io() to access the device's I/O registers.