.. highlight:: c

.. _pragma_interface_scalar_argument:

Configure Scalar Argument Interface
-----------------------------------

**Syntax**


``#pragma LEGUP interface argument(<arg_name>) type(simple) stable(<false|true>)``

**Description**


This pragma configures the scalar input port.
The ``stable`` option informs LegUp that the port can be hold valid and unchanged throughout the whole
iteration of the execution and potentially can save register usage in the
generated module.
Note that the ``type`` option is not configurable in the current release but
still needs to be specified if you wish to add the stable option.
If 'stable' is false, the pragma is not necessary because LegUp assumes not stable by default.
More details in :ref:`rtl_interface` section.

**Parameters**


+--------------+----------------+----------+-----------+------------------------------------+
|  Parameter   |      Type      | Optional |  Default  |            Description             |
+==============+================+==========+===========+====================================+
| ``argument`` | String         | No       |           | Argument name                      |
+--------------+----------------+----------+-----------+------------------------------------+
| ``type``     | ``simple``     | No       |           | Interface type                     |
+--------------+----------------+----------+-----------+------------------------------------+
| ``stable``   | ``true|false`` | Yes      | ``false`` | ``true`` if the argument is stable |
+--------------+----------------+----------+-----------+------------------------------------+

**Position**

At the beginning of the function definition block.


**Examples**


.. code-block:: c

  int fun(int a) {
  #pragma LEGUP interface argument(a) type(simple) stable(true)
    ...
  }

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