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Eike
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Simulink block to extract signal at index from vector signal doesn't exist?

Asked by Eike
on 21 Mar 2012
Latest activity Answered by Bibek
on 1 Apr 2015
Hey,
I'm looking for a block that takes 2 input signals: One vector signal and one integer index signal. The output would be
vector(index)
Am I just too stupid to find it or does that block really not exist? Any workarounds?
Also see my other question for my personal workaround. (Which I regard as being not so nice.)
I need this for use with the Simulink HDL Coder.
Kind regards and many thanks in advance,
Eike

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4 Answers

Answer by Kaustubha Govind on 21 Mar 2012
 Accepted Answer

You need the Selector block. It is supported for HDL Code Generation.

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Thank you, that is indeed exactly what I was looking for! To be honest, I had seen that block before but did not really understand how it works / in which ways I can configure it.

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Answer by Tim McBrayer on 21 Mar 2012

The block you are looking for is the Multiport Switch block, located in the Simulink->Signal Routing library. This block is supported by Simulink HDL Coder. For your use case you will want to configure it to have one input port. Connect port one to your index signal, and port 2 to your vector signal. The output will be:
vector(index)
You can choose either zero-based or one-based indexing.

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Kaustubha is also correct. Both blocks will generate identical HDL code, when similarly configured:
Multiport_Switch_out1 <= In2(0) WHEN In1_unsigned = 1 ELSE
In2(1) WHEN In1_unsigned = 2 ELSE
In2(2) WHEN In1_unsigned = 3 ELSE
In2(3) WHEN In1_unsigned = 4 ELSE
In2(4) WHEN In1_unsigned = 5 ELSE
In2(5);
Selector_out1 <= In2(0) WHEN In1_unsigned = 1 ELSE
In2(1) WHEN In1_unsigned = 2 ELSE
In2(2) WHEN In1_unsigned = 3 ELSE
In2(3) WHEN In1_unsigned = 4 ELSE
In2(4) WHEN In1_unsigned = 5 ELSE
In2(5);
But how can I configure the Multiport Switch to work on a vector signal?
Configure it to have one data port, and connect a vector to it.

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Answer by David Amor on 10 Jun 2014

Are you trying to get a single bit from a vector at an index? If so bitget would be easier and less verbose.
ans = bitget(vector,index);
but if you are trying to access a vector from an array of vectors then yeah, you need the selector block.

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Answer by Bibek
on 1 Apr 2015

Is there any block which will give the index from the value selected!!

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