Constant requirement in codegen

I am trying to generate code from a function in the signal processing toolbox. I need to generate code for functions "hann" and "fir1". Here is a simple testcase:

function out = test(in)
%#codegen
assert(isa(in, 'double') && isscalar(in))
assert(in<1000)
out = hann(in);

The function above produces an error that indicates the HANN function requires a constant input. I see in the documentation a discussion of this, but the nature of my problem is such that the input is not constant as I am developing a programmable decimation filter. It seems to me that there must be a way to constrain the input such that the coder will know how big to allocate the output. (Hence my attempt to use the second ASSERT statement above).

Am I completely out of luck? Do I need to implement my own versions of HANN and FIR1?

Thanks.

[Sean Little]

I just wrote my own codegen compatible version of the HANN function. But FIR1 looks like it will be more problematic.

Answer 1

[Sean Little]

I am answering this for completeness. The response from technical support indicates that this is not supported and there are no work-arounds.