InterruptCharacteristic(), InterruptCharacteristic_r()

Get or set a characteristic associated with an interrupt

Synopsis:

#include <sys/neutrino.h>

int InterruptCharacteristic( int type,
                             int id,
                             unsigned *new,
                             unsigned *old );

int InterruptCharacteristic_r( int type,
                               int id,
                               unsigned *new,
                               unsigned *old );

Library:

libc

Use the -l c option to qcc to link against this library. This library is usually included automatically.

Arguments:

type
The type of characteristic; the only type that's currently defined is:
  • _NTO_IC_LATENCY — set or get the interrupt's latency.
id
The identifier for the interrupt function, as returned by InterruptAttach(), InterruptAttachArray(), or InterruptAttachEvent().
new
NULL, or a pointer to the new value.
old
NULL, or a pointer to a location where the function can store the old value.

Description:

The InterruptCharacteristic() and InterruptCharacteristic_r() kernel calls set or get a characteristic of an interrupt.

These functions are identical except in the way they indicate errors. See the Returns section for details.

The only type currently defined is _NTO_IC_LATENCY. If the new argument is non-NULL, it points to an unsigned that contains the new latency value for the interrupt, in nanoseconds. If the old argument is non-NULL, it's filled in with the old latency value for the interrupt. The default latency value is zero. In order to set a latency, the calling thread must:

The id argument can be -1. In this case, you're setting the global latency value for the system. If an interrupt attachment doesn't specify a latency value, the global latency number is used when calculating how deep a sleep state the kernel may use. You need to have I/O privileges to set the global latency value.

Returns:

0 on success. If an error occurs:

Errors:

EFAULT
The function couldn't read from the new pointer, or it couldn't write to the old.
EINVAL
The type isn't _NTO_IC_LATENCY.
EPERM
You're trying to set a new latency, but the calling thread isn't in the attaching process or doesn't have I/O privileges.
ESRCH
The id isn't either a valid interrupt attachment identifier or -1.

Classification:

QNX Neutrino

Safety:  
Cancellation point No
Interrupt handler Yes
Signal handler Yes
Thread Yes