# OS_EnableIrqMask

## C Specification

  `#include <nitro/os.h>`
  `OSIrqMask OS_EnableIrqMask( OSIrqMask intr );`

## Arguments

intr | The IRQ interrupt cause to be enabled (expressed as a logical sum)

## Return Values

This is the IRQ interrupt cause that was set before this function is called.

## Description

Sets IRQ interrupt parameters. In addition to the current setting, the designated cause's enable bit is enabled. Refer to `OS_SetIrqMask` for a description of each cause and its corresponding value.

Note: Adds the specified causes in addition to the current settings. `OS_SetIrqMask` is used to overwrite and set a specific cause. However, since there may be interrupt cause settings defined by the system which we do not want to change, it is best not to use the `OS_SetIrqMask` function, since that overwrites all settings. In most cases, the `OS_EnableIrqMask` function should be used to set the specific cause.

## Internal Operation

Operates on one of the IO registers, IE (Interrupt Enable).

## See Also

`OS_DisableIrqMask`, `OS_SetIrqMask`

## Revision History

03/08/2005 Standardized the Japanese term for of "interrupt."
03/12/2004 Emphasized the differences with `OS_SetIrqMask()`.
12/01/2003 Initial version.

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