Read an 8-bit value from a port
#include <hw/inout.h> uint8_t in8( uintptr_t port );
libc
Use the -l c option to qcc to link against this library. This library is usually included automatically.
The in8() function reads an 8-bit value from the specified port.
The calling process must use mmap_device_io() to access the device's I/O registers.
On x86 and x86_64 targets, the process must have the PROCMGR_AID_IO ability enabled, and the calling thread must have I/O privileges, or else it will fault with a SIGSEGV; see procmgr_ability(), and the ThreadCtl() _NTO_TCTL_IO command.
An 8-bit value.
| Safety: | |
|---|---|
| Cancellation point | No |
| Interrupt handler | Yes |
| Signal handler | Yes |
| Thread | Yes |