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pnutboy's avatar
pnutboy
Icon for New Contributor rankNew Contributor
5 years ago

Quartus cannot properly interpret VHDL2008 select? statements.

Hello, I'm attempting to make my own RISC V processor, and part of that is selecting the correct OPCode, I have the following VHDL which is supposed to do this: --/------------------------...
sstrell's avatar
sstrell
Icon for Super Contributor rankSuper Contributor
5 years ago

You don't indicate which version of Quartus (Lite, Standard, or Pro) you are using, but VHDL2008 is not supported in Lite. The supported 2008 features in Pro are listed here:

https://www.intel.com/content/www/us/en/programmable/quartushelp/current/index.htm#hdl/vhdl/vhdl_list_2008_vhdl_support.htm

TBH, I'm trying to understand what the ? there does and the only paragraph I can find in the standard that describes it (section 10.5.4) is a little vague:

"If a selected signal assignment statement includes the question mark delimiter, then the equivalent sequential statement includes a question mark delimiter after both occurrences of the reserved word case; otherwise the equivalent sequential statement does not include the question mark delimiters."