MATLAB: How to solve “unsupported unbounded loop structure”

fbmcHDL Coderoqam modulation

Hello, I'm trying to generate VHDL code for OQAM modulation. In this I got error for loop which unsupported and unbounded because of for loop. I also tried while loop to bound the loop as given in some solutions but still it is not working.

The HDL coder gives below error:

"Found an unsupported unbounded loop structure. This loop may be user written or automatically generated due to the use of specific vector expressions or functions. For more information on unsupported loop structures, please refer to the documentation."

thanks in advance.

Best Answer

Does your code have a while loop, a for loop with a non-static limit, or something similar? This sort of construct is what the error message is referring to. The number of loop iterations must be static for HDL code generation.

Related Solutions

MATLAB: Problem with a loop in the hdl coder

I'm still learning vhdl and HDL coder, myself - you can use while loops, it just sounds like you need to provide some information on a variable. For example, if you have something like, "while x< 1," the synthesis program needs to know the range of x. So if you defined x as, say 1:10, then that should fix it.

MATLAB: Problem found in hdl coder

You have a loop from 1:n-1 , where n is length(x) . You also have an inner loop from 1:(n-m) , where m is the current index of the outer loop. This inner loop does not have a well-defined upper bound. It's not generally possible to determine how many loops you need with code like this. Since the number of loops dictates what sort of hardware gets created, HDL Coder cannot generate synthesizable HDL from such a design.

The most obvious rewrite of the inner loop, to give it a static bound, is:

 for n1 = 1:n
   if n1 <= (n-m)
      <...>
   end
 end

In software, you'll execute the loop m extra times. In hardware, the loop will be unrolled (in general) and the extra empty loops will cause no hardware to be created.

You may run into the same issue with the outer loop, if length(x) is not statically determinable.

Best Answer

Related Solutions

MATLAB: Problem with a loop in the hdl coder

MATLAB: Problem found in hdl coder

Related Question