Structure or array for S-function input, output and parameters?
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Hi,
What is faster and what do you recommend?
I have a C S-function with 14 inputs. 1. Right now I am using a single port and I see the input as an array. I have 14 #define in order to help selecting the right input: for example #define U_IDX_FLOW_WATER 0 and then I select it as u[U_IDX_FLOW_WATER]. It helps understanding the code better than using a plain number.
2. I just came across passing structures to S-functions and, I guess, I could select my input like u->flow_water and forget about the hardcoding that I did before.
Is there a performance penalty when using approach 2?
Thanks, Remus.
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Answers (1)
Kaustubha Govind
on 25 Jul 2012
I can't imagine there being a major difference in Simulink performance between #1 and #2 - they are equivalent to writing two C functions - one that takes several function arguments and the other takes one structure argument with each field represent arguments from the first function. So it boils down to more of a C question - is one more efficient that the other in C?
However, from my experience, using structure/bus signals to combine similar signals is good modeling practice.
3 Comments
Remus Mihail Prunescu
on 25 Jul 2012
Edited: Remus Mihail Prunescu
on 25 Jul 2012
Kaustubha Govind
on 25 Jul 2012
Structure types are only supported for inputs, output and parameters, not states. But looks like you've found a solution anyway. :)
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