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Altera_Forum's avatar
Altera_Forum
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12 years ago

SystemVerilog Interface Synthesis Quartus 13

Quartus 13 Synthesis has the limitation that interface attributes cannot be used conveniently in a module. I am looking for a work around as this limitation does not appear in other tools.

Given a simple SV interface definition: 

interface avalon_bus
#(
    parameter ADDR_WIDTH = 16,
    parameter DATA_WIDTH = 8
)
(
    input logic clock,
    input logic reset
);   
    // aliais/short-cut for address and data widths
    localparam AW = ADDR_WIDTH-1;
    localparam DW = DATA_WIDTH-1;
    localparam MaxAddress = 2**ADDR_WIDTH;
    logic  address;
    logic  writedata;
    logic  readdata;
    modport per (
        input clock,
        input reset,
        input address,
        input writedata,
        output readdata
   );
endinterface

and a module that uses the interface: 

module avalon_mux
(
    interface bus
);
    
    localparam AddrThreshold = bus.MaxAddress/2;
    logic  pipe_a, pipe_b;
    
    always @(posedge bus.clock) begin
        if (busin.address <= AddrThreshold) begin
            pipe_a <= bus.writedata;
        end else begin
            pipe_b <= bus.writedata;
        end 
    end 
    
endmodule

Quartus throws errors because it does not like the use of the "hierarchy separator" in most expressions. Does anyone know of a work around? Example, is there another way to express / localparam AddrThreshold = bus.MaxAddress/2 /? I have tried / const integer / and some other hacks but no luck, yet :( I have also attached an example Quartus project.

Regards,

Chris

7 Replies

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    12 years ago

    No it didn't disappear, it was automatically moderated down by the forum's overzealous spam detection system.

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    12 years ago

    This is legal, but many not be supported by Quartus yet.

    Try a continuous assignment 

    int AddrThreshold;
assign AddrThreshold = bus.MaxAddress/2;
  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    12 years ago

    I was pleasantly surprised the continuous assignment worked

    for the /AddrThreshold/ expression. But it doesn't work for the

    other uses cases, like: 

    
    logic  pipe_a, pipe_b;

    Best I can tell, I wont be able to use the parameters that are

    part of the interface. I will need to reduplicate all the parameters

    to the module: 

    
    module avalon_mux
   # (
       MaxAddress = 16,
       DW = 16
    )
    (
        interface bus
    );
    
        localparam AddrThreshold = MaxAddress/2;
        logic  pipe_a, pipe_b;
    
        always @(posedge bus.clock) begin
            if (busin.address <= AddrThreshold) begin
                pipe_a <= bus.writedata;
            end else begin
                pipe_b <= bus.writedata;
            end 
        end 
    
    endmodule

    And then instantiate like: 

    
avalon_mux 
  # (MaxAddress=bus.MaxAddress, DW = bus.DW)
   M1(bus);

    which partially defeats the purpose of using interfaces.

    Regards,

    Chris