Why do I get an error with system object calls in HDL Code Generation?
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Pablo Medina
on 16 Jul 2016
Commented: Pablo Medina
on 22 Jul 2016
error: hdlcoder:pirudd:systemobjectmultipleuse: System object methods can only be called once
My Code:
main fucntion:
[x,validOut] = mainfc(data_in,st)
persistent var ifft128 out1
if isempty(var)
var=0;
ifft128 = dsp.HDLIFFT('FFTLength',128);
end
if st==1
[out1] = func1(data);
%IFFT calculation
[Xt,validOut]=ifft128_fc(ifft128,out1,true)
elseif st==0
%To complete the IFFT calculation
[Xt,validOut]=ifft128_fc(ifft128,out1,false)
end
%ifft128_fc
function [yOut,validOut] = ifft128_fc(objeto,yIn,validIn)
[yOut,validOut] = step(objeto,yIn,validIn);
end
%My test bench for the main function
N = 128;
for i=1:1:N
[X,V] = main_fc(data_in,1);
end
for i = N+1:1:3*N
[X,V] = main_fv(data_in,0)
end
0 Comments
Accepted Answer
Tim McBrayer
on 18 Jul 2016
I'm not an expert in the DSP side of the product, but my understanding of your code is that you are invoking the same object twice in a single time step. You have a single dsp.HDLIFFT named ifft128 in your design. Each time that your function mainfc is called will correspond (in the simple case) to a single hardware clock cycle. In this single cycle you are calling the step function on ifft128 twice. This function can be thought of as the behavior of the IFFT implementation. So, in essence, you are attempting to run the same FFT twice in one cycle. This is not supported for HDL code generation for fairly straightforward reasons, although MATLAB has no issues executing the code that you have written. HDL Coder does not perform enough semantic analysis to notice that the two calls to step() are mutually exclusive from each other.
Your code looks easy to update. You need to make one call to your wrapper function:
[Xt,validOut]=ifft128_fc(ifft128,out1, st == 0);
If st can be any value besides 0 or 1, you may want to enclose this call inside the appropriate if statement:
if st == 0 || st == 1
[Xt,validOut]=ifft128_fc(ifft128,out1, st == 0);
end
More Answers (1)
Walter Roberson
on 16 Jul 2016
You have
if isempty(var)
but you never assign to var so isempty will continue to be true, resulting in the next line being executed every pass.
2 Comments
Walter Roberson
on 17 Jul 2016
Please post the actual code. For example should the first bit you posted a function definition where the "function" keyword has wandered off to the washroom, or is that code part of a script file? I don't think HDL can compile script files as the main entry.
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