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14957 Discussions

Quartus cannot properly interpret VHDL2008 select? statements.

pnutboy
Beginner
423 Views

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: 

 

    --/-----------------------------\
    --| OPCODE INSTRUCTION DECODING |
    --\-----------------------------/
    with fetched_instruction select?
    next_decoded_opcode <= 
    LB         when "-----------------000-----00000--", 
    LH         when "-----------------001-----00000--", 
    LW         when "-----------------010-----00000--", 
    LBU        when "-----------------100-----00000--", 
    LHU        when "-----------------101-----00000--", 
    SB         when "-----------------000-----01000--", 
    SH         when "-----------------001-----01000--", 
    SW         when "-----------------010-----01000--", 
    BEQ        when "-----------------000-----11000--", 
    BNE        when "-----------------001-----11000--", 
    BLT        when "-----------------100-----11000--", 
    BGE        when "-----------------101-----11000--", 
    BLTU       when "-----------------110-----11000--", 
    BGEU       when "-----------------111-----11000--", 
    JALR       when "-------------------------11001--", 
    JAL        when "-------------------------11011--", 
    Addi       when "-----------------000-----00100--", 
    SLLI       when "-----------------001-----00100--", 
    SLTI       when "-----------------010-----00100--", 
    SLTIU      when "-----------------011-----00100--", 
    XORI       when "-----------------100-----00100--", 
    ORI        when "-----------------110-----00100--", 
    ANDI       when "-----------------111-----00100--", 
    SRLI       when "-0---------------101-----00100--", 
    SRAI       when "-1---------------101-----00100--", 
    ADD        when "-0---------------000-----01100--", 
    SUB        when "-1---------------000-----01100--", 
    inst_SLL   when "-----------------001-----01100--", 
    SLT        when "-----------------010-----01100--", 
    SLTU       when "-----------------011-----01100--", 
    inst_XOR   when "-----------------100-----01100--", 
    inst_SRL   when "-0---------------101-----01100--", 
    inst_SRA   when "-1---------------101-----01100--", 
    inst_OR    when "-----------------110-----01100--", 
    inst_AND   when "-----------------111-----01100--", 
    AUIPC      when "-------------------------00101--", 
    LUI        when "-------------------------01101--", 
    CSRRS      when "-----------------010-----11100--", -- NEEDS IMPLEMENTATION--
    CSRRW      when "-----------------001-----11100--", -- NEEDS IMPLEMENTATION--
    CSRRC      when "-----------------011-----11100--", -- NEEDS IMPLEMENTATION--
    CSRRSI     when "-----------------110-----11100--", -- NEEDS IMPLEMENTATION--
    CSRRWI     when "-----------------101-----11100--", -- NEEDS IMPLEMENTATION--
    CSRRCI     when "-----------------111-----11100--", -- NEEDS IMPLEMENTATION--
    INVALID when others;

 

However, even though inside Quartus, the file is marked as a VHDL2008 file, synthesis still fails,  citing that:

"Error (10500): VHDL syntax error at controller.vhd(159) near text "?"; expecting "(", or an identifier, or a string literal"

The above statement synthesizes completely fine within Xilinx's Vivado, so I'm not quite sure what Quartus is trying to see that Vivado can handle.

Why is Quartus having issues with the 'select?' clause, and what can I do to remedy this while maintaining the syntax (eg: I still want to use with/select? and have the wildcards available for easy reading)

0 Kudos
6 Replies
pnutboy
Beginner
410 Views

It may also be prudent to note that the 'case when' syntax using wildcards is also broken:

 

    --/-----------------------------\
    --| OPCODE INSTRUCTION DECODING |
    --\-----------------------------/
    case? fetched_instruction is
    when "-----------------000-----00000--" =>
    next_decoded_opcode <= LB;    
    when "-----------------001-----00000--" =>
    next_decoded_opcode <= LH;    
    when "-----------------010-----00000--" =>
    next_decoded_opcode <= LW;    
    when "-----------------100-----00000--" =>
    next_decoded_opcode <= LBU;    
    when "-----------------101-----00000--" =>
    next_decoded_opcode <= LHU;    
    when "-----------------000-----01000--" =>
    next_decoded_opcode <= SB;    
    when "-----------------001-----01000--" =>
    next_decoded_opcode <= SH;    
    when "-----------------010-----01000--" =>
    next_decoded_opcode <= SW;    
    when "-----------------000-----11000--" =>
    next_decoded_opcode <= BEQ;    
    when "-----------------001-----11000--" =>
    next_decoded_opcode <= BNE;    
    when "-----------------100-----11000--" =>
    next_decoded_opcode <= BLT;    
    when "-----------------101-----11000--" =>
    next_decoded_opcode <= BGE;    
    when "-----------------110-----11000--" =>
    next_decoded_opcode <= BLTU;    
    when "-----------------111-----11000--" =>
    next_decoded_opcode <= BGEU;    
    when "-------------------------11001--" =>
    next_decoded_opcode <= JALR;    
    when "-------------------------11011--" =>
    next_decoded_opcode <= JAL;    
    when "-----------------000-----00100--" =>
    next_decoded_opcode <= Addi;    
    when "-----------------001-----00100--" =>
    next_decoded_opcode <= SLLI;    
    when "-----------------010-----00100--" =>
    next_decoded_opcode <= SLTI;    
    when "-----------------011-----00100--" =>
    next_decoded_opcode <= SLTIU;    
    when "-----------------100-----00100--" =>
    next_decoded_opcode <= XORI;    
    when "-----------------110-----00100--" =>
    next_decoded_opcode <= ORI;    
    when "-----------------111-----00100--" =>
    next_decoded_opcode <= ANDI;    
    when "-0---------------101-----00100--" =>
    next_decoded_opcode <= SRLI;    
    when "-1---------------101-----00100--" =>
    next_decoded_opcode <= SRAI;    
    when "-0---------------000-----01100--" =>
    next_decoded_opcode <= ADD;    
    when "-1---------------000-----01100--" =>
    next_decoded_opcode <= SUB;    
    when "-----------------001-----01100--" =>
    next_decoded_opcode <= inst_SLL;    
    when "-----------------010-----01100--" =>
    next_decoded_opcode <= SLT;    
    when "-----------------011-----01100--" =>
    next_decoded_opcode <= SLTU;    
    when "-----------------100-----01100--" =>
    next_decoded_opcode <= inst_XOR;    
    when "-0---------------101-----01100--" =>
    next_decoded_opcode <= inst_SRL;    
    when "-1---------------101-----01100--" =>
    next_decoded_opcode <= inst_SRA;    
    when "-----------------110-----01100--" =>
    next_decoded_opcode <= inst_OR;    
    when "-----------------111-----01100--" =>
    next_decoded_opcode <= inst_AND;    
    when "-------------------------00101--" =>
    next_decoded_opcode <= AUIPC;    
    when "-------------------------01101--" =>
    next_decoded_opcode <= LUI;    
    when "-----------------010-----11100--" =>
    next_decoded_opcode <= CSRRS;       -- NEEDS IMPLEMENTATION--
    when "-----------------001-----11100--" =>
    next_decoded_opcode <= CSRRW;       -- NEEDS IMPLEMENTATION--
    when "-----------------011-----11100--" =>
    next_decoded_opcode <= CSRRC;       -- NEEDS IMPLEMENTATION--
    when "-----------------110-----11100--" =>
    next_decoded_opcode <= CSRRSI;      -- NEEDS IMPLEMENTATION--
    when "-----------------101-----11100--" =>
    next_decoded_opcode <= CSRRWI;      -- NEEDS IMPLEMENTATION--
    when "-----------------111-----11100--" =>
    next_decoded_opcode <= CSRRCI;      -- NEEDS IMPLEMENTATION--
    when others =>
    next_decoded_opcode <= INVALID;
sstrell
Honored Contributor III
402 Views

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_lis...

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."

pnutboy
Beginner
361 Views

Interesting, One can select VHDL 2008 in the lite edition, I assume that it is vestigial. One can read more about the ? artifact here: https://www.doulos.com/knowhow/vhdl/vhdl-2008-small-changes/

 

Tl;DR: it allows wildcards in the when statements.

pnutboy
Beginner
378 Views

I'm not sure what happened to my other message, I'm sure I wrote them...

 

 

One can read more on the 2008-VHDL ? artifact here: https://www.doulos.com/knowhow/vhdl/vhdl-2008-small-changes/

 

Tl;DR: It allows the used of wildcards in select / case / when statements.

KhaiChein_Y_Intel
360 Views

Hi,

 

May I know which software edition you are using?

 

Thanks

Best regards,

KhaiY

KhaiChein_Y_Intel
344 Views

Hi,


We do not receive any response from you to the previous question/reply/answer that I have provided. This thread will be transitioned to community support. If you have a new question, feel free to open a new thread to get the support from Intel experts. Otherwise, the community users will continue to help you on this thread. Thank you


Thanks

Best regards,

KhaiY


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