
VHDL Coder Error: "Found an unsupported unbounded loop structure"
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Abigail Kwan
on 17 Apr 2020
Answered: Kiran Kintali
on 19 Apr 2020
Hello, I am trying to convert this code into HDL. I am getting these errors but it won't tell me the location. I have already changed all the for loops into static ones. What can I do to fix this? I'm new to matLAB and also to HDL Coder so I don't know if the way I'm going through the matrices is supported or not.
OneRVHDLtest_fixpt:0 Error Found an unsupported unbounded loop structure, at Function 'sortIdx' (#53.18405.18482), line 530, column 1 Function 'sortIdx' (#53.17932.18022), line 514, column 5 Function 'sortIdx' (#53.11676.11779), line 333, column 5 Function 'sortIdx' (#53.3899.4005), line 105, column 13 Function 'sort' (#45.3187.3277), line 72, column 5. This loop may be user written or automatically generated due to the use of specific vector expressions or functions.
OneRVHDLtest_fixpt:0 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.
OneRVHDLtest_fixpt:0 Error Found an unsupported unbounded loop structure, at Function 'sortIdx' (#53.18405.18482), line 530, column 1 Function 'sortIdx' (#53.17756.17862), line 507, column 9 Function 'sortIdx' (#53.11676.11779), line 333, column 5 Function 'sortIdx' (#53.3899.4005), line 105, column 13 Function 'sort' (#45.3187.3277), line 72, column 5. This loop may be user written or automatically generated due to the use of specific vector expressions or functions.
OneRVHDLtest_fixpt:0 Error Found an unsupported unbounded loop structure, at Function 'sortIdx' (#53.19212.19330), line 561, column 13 Function 'sortIdx' (#53.17756.17862), line 507, column 9 Function 'sortIdx' (#53.11676.11779), line 333, column 5 Function 'sortIdx' (#53.3899.4005), line 105, column 13 Function 'sort' (#45.3187.3277), line 72, column 5. This loop may be user written or automatically generated due to the use of specific vector expressions or functions.
OneRVHDLtest_fixpt:0 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.
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Accepted Answer
Kiran Kintali
on 19 Apr 2020
It looks like the error is originating from the unsupported functions calls on these lines.

HDLCoder team is aware of the issue with traceability of error messages from deep inside MATLAB toolbox library functions. The team is working on enhancing this behavior and making the experience better when reporting unsupported constructs. The above message shows future behavior from such calls until those restrictions are removed.
For now consider writing your own median function using supported MATLAB constructs.
Hope this helps.
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More Answers (1)
Kiran Kintali
on 18 Apr 2020
Typically this error means you have loop bounds that are not static and determinable at compile time. Compiling MATLAB functions to synthesizable hardware targeting FPGA/ASIC designs require fixed size loops.
Please provide the testbench and MATLAB HDLCoder project for this design.
Thank you.
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