HDLcoder ignores coder.const

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Anze Slosar
Anze Slosar on 13 Sep 2022
Answered: Kiran Kintali on 25 Sep 2022
I'm tryint to compile some code into HDL. There are weights used in digital filter which I want to precompute at the compile time.
The way I did this is
persistent c buf tout pfb_weights;
if isempty(c)
pfb_weights = coder.const(get_pfb_weights(settings_Nfft,settings_Ntaps));
The reason I think it is not working is that the coding report says:
  • It lists sin function under Toolbox Function Usage: Supported List. Sin function is only used in get_pfb_weights function
  • It lists coder/matlabcoder under Toolbox Function Usage: Unsupported List
  • If I attempt fixedpoint conversion it complains that function "double" inside get_pfb_weights is not suitable for fixed point conversion and wouldn't proceed.
How do we fix this?

Accepted Answer

David Fink
David Fink on 14 Sep 2022
By making the call to get_pfb_weights opaque to code generation (so fixed-point conversion won't try to process it), you can call it extrinsically (in MATLAB), at compile-time, via coder.const and coder.extrinsic.
See the coder.extrinsic documentation for a coder.const example.

More Answers (1)

Kiran Kintali
Kiran Kintali on 25 Sep 2022
You can find examples of HDL Coder friendly designs with coder.load and coder.const in the attachment.


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