.. _switchDoc:

.. index:: single: switch

============
Switch Block
============

Declares a **switch block** or a **switch block bundle** using the keyword ``switch``.

* Declaration_
* `Shorthand Declaration`_
* `Ports Table`_
* Description_
* `Code Examples`_

.. figure:: Images/SwitchBlock.png
   :scale: 100%
   :alt: Signal Block
   :align: center

----

Declaration
===========

::
	
	#switch block
	switch LABEL {
		default:	off
		reset:		MasterReset
		meta:		none
	}
	
	#switch block bundle
	switch LABEL [SIZE] {
		default:	off | [ off, ...]
		reset:		MasterReset
		meta:		none
	}

**LABEL**
	:definition: the label of the block
	
**SIZE**
	:definition:	the size of the block bundle
	:type:			constant integer port (CIP)

----
	
Shorthand Declaration
=====================		

::

	# constant block
	Boolean >> LABEL;
	
	# constant block bundle
	BooleanList >> LABEL;

**LABEL**
	:definition: the label of the block

**Boolean**
	:definition:	:ref:`on <On>` or :ref:`off <Off>`

**BooleanList**
	:definition:	a list of :ref:`on <On>` and :ref:`off <Off>`		

----

Ports Table
===========

+------+-------------+-----------+------+------------+------------+-----------------+---------------+
|      |             |           |      |            |            |                 |               |
+------+-------------+-----------+------+------------+------------+-----------------+---------------+
| Port | Name        | Direction | Type | Connection | Access     | Default         | Required      |
+======+=============+===========+======+============+============+=================+===============+
| 1    | input       | input     | CBP  | single     | >> LABEL   | ``none``        | no :sup:`(1)` | 
|      |             |           |      |            +------------+                 |               |
|      |             |           |      |            | assignment |                 |               | 
+------+-------------+-----------+------+------------+------------+-----------------+---------------+
| 2    | output      | output    | CBP  | multiple   | LABEL >>   | ``none``        | no :sup:`(1)` |
|      |             |           |      |            +------------+                 |               |
|      |             |           |      |            | assignment |                 |               | 
+------+-------------+-----------+------+------------+------------+-----------------+---------------+
| 3    | ``default`` | input     | CBP  | single     | property   | ``off``         | yes           |
+------+-------------+-----------+------+------------+------------+-----------------+---------------+
| 4    | ``reset``   | input     | CBP  | single     | property   | ``MasterReset`` | yes           |
+------+-------------+-----------+------+------------+------------+-----------------+---------------+
| 5    | ``meta``    | input     | CSP  | single     | property   | ``none``        | no            |
+------+-------------+-----------+------+------------+------------+-----------------+---------------+


:CBP:	constant boolean port

:CSBP:	control stream boolean port

:CSP:	constant string port
	
:LABEL:	block label	

:sup:`1` Warning issued during compilation if the port is left unconnected.
	
----
	
Description
===========

Switches are asynchronous blocks. They propegate the rate ``none`` upstream.

----

Code Examples
=============

::

	switch Switch {
		default:	off
		reset:		MasterReset
		meta:		'A switch'
	}
	
	# Shorthand 
	off >> Switch;

::
	
	switch SwitchBundle [2] {
		default:	off
		reset:		MasterReset
		meta:		'A switch'
	}
	
	# Shorthand 
	[off, off] >> SwitchBundle;