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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: 

    --/-----------------------------\
    --| 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)

6 Replies

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

    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'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."

  • KhaiChein_Y_Intel's avatar
    KhaiChein_Y_Intel
    Icon for Regular Contributor rankRegular Contributor
    5 years ago

    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