Problem with a loop in the hdl coder
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Hello,
I have written a matlab code and I try to produce a vhdl code by using the hdl coder. The problem is that the following error is appearing during the procedure of the code generation. "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."
I have in the code a "while loop" and it seems that this error.Does anyone know why this error appears? As I know, the vhdl supports the "while loop".
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Wayne
2013년 9월 10일
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.
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Wayne
2013년 9월 11일
I have had difficulty with HDL coder and multi-dimensional arrays - I'm surprised you didn't get an unsupported matrix type error. This doesn't really help you, but to handle matrices I just broke down and learned vhdl and coded those sections myself. Maybe some HDL Coder gurus can help here, but I found it easier to learn vhdl, heh
추가 답변 (2개)
sin
2014년 2월 24일
i haven't used any loop still am getting the same error. can anyone help me with the solution?
thanks in advance!
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DN
2016년 7월 20일
Hi, have any of you had any joy on this. Can one use a For and While statement in a user defined function block in Simulink and still generate HDL code? Thanks
Tim McBrayer
2016년 7월 21일
For loops are supported, when they have fixed loop indices. While loops in general are not, as there is no way the compiler can determine how many loops will be executed. Keep in mind you are building hardware; no sizes can be left data-dependent, as your hardware cannot reconfigure itself at runtime based off of time-dependent input data.
This situation is the basis of the error message. HDL Coder must be able to statically determine, at compile time, how many times a loop will execute. In general a while loop does not execute a static number of times, so they are not supported. Hence, the "unbounded loop structure" message.
You can map while loops to for loops in many cases. The for loop should loop across the maximum range of iteration, while the body of the for loop has an if statement protecting the rest of the body so that the loop is in essence conditionally executed.
Finally: sometimes you can get an error referencing an unbounded loop when you have not written one explicitly in your code. This is most likely because you are calling a function, possibly even a built-in MATLAB function, that has such a loop in its underlying implementation.
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