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<title>Shifter</title>
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<h1><img  align="center" src="../../../../en/icons/shifter.gif" width="32" height="32">
<em>Shifter</em></h1>

<p><table>
<tr><td><strong>Library:</strong></td>
	<td><a href="index.html">Arithmetic</a></td></tr>
<tr><td><strong>Introduced:</strong></td>
	<td>2.3.0</td></tr>
<tr><td valign="top"><strong>Appearance:</strong></td>
	<td valign="top"><img src="../../../../en/img-libs/shifter.png" width="44" height="42"></td></tr>
</table></p>

<h2>Behavior</h2>

<p>This component includes two inputs, <var>data</var> and <var>dist</var>, and
it has one output, which is the result of shifting <var>data</var> by
<var>dist</var> places. Both <var>data</var> and output have the same number of
bits in them. The component supports the following shift types:</p>

<ul>

<li>Logical Left: All bits in <var>data</var> are shifted up <var>dist</var> places,
with the bottom <var>dist</var> places filled with 0's. For example,
11001011 logically shifted left twice is 00101100. (The top two ones are lost.)</li>

<li>Logical Right: All bits in <var>data</var> are shifted down <var>dist</var>
places, with the upper <var>dist</var> places filled with 0's. For example,
11001011 logically shifted right twice is 00110010. (The bottom two ones are
lost.)</li>

<li>Arithmetic Right: All bits in <var>data</var> are shifted down <var>dist</var>
places, with the upper <var>dist</var> places filled with repetitions of
whatever the uppermost bit in <var>data</var>. For example, 11001011
arithmetically shifted right twice is 11110010.</li>

<li>Rotate Left: All bits in <var>data</var> are shifted up <var>dist</var>
places, with the top <var>dist</var> places wrapped around into the bottom.
For example, 11001011 rotated left twice is 00101111.</li>

<li>Rotate Right: All bits in <var>data</var> are shifted down <var>dist</var>
places, with the bottom <var>dist</var> places wrapped around into the top.
For example, 11001011 rotated right twice is 11110010.</li>

</ul> 

<p>Note that if <var>dist</var> contains any floating or error inputs, then
the output is composed entirely of error values, since there is no way to
guess how far to shift the input.</p>

<h2>Pins</h2>

<dl>

<dt>West edge, north end (input, bit width matches the Data Bits attribute)</dt>
<dd>The value to be shifted.</dd>

<dt>West edge, south end (input, bit width is computed as below)</dt>
<dd>The number of bits by which to shift the <var>data</var> input.
This input should have as many bits as is the minimum number to indicate
any shift distance from 0 up to one less than Data Bits; that is, it should
be the ceiling of the base-2 logarithm of Data Bits. For example, if Data Bits
were 8, this input would require 3 bits; but if it were 9, it would require
4 bits.</dd>

<dt>East edge (output, bit width matches the Data Bits attribute)
<dd>The result of shifting the input value by the input distance.</dd>

</dl>

<h2>Attributes</h2>

<p>When the component is selected or being added,
Alt-0 through Alt-9 alter its <q>Data Bits</q> attribute.</p>

<dl>

<dt>Data Bits</dt>
<dd>The bit width of the <var>data</var> input and of the output.</dd>

<dt>Shift Type</dt>
<dd>One of the five possible shift types as outlined above (Logical Left,
Logical Right, Arithmetic Right, Rotate Left, Rotate Right).</dd>

</dl>

<h2>Poke Tool Behavior</h2>

<p>None.</p>

<h2>Text Tool Behavior</h2>

<p>None.</p>

<p><a href="../index.html">Back to <em>Library Reference</em></a></p>

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