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Yosys Open SYnthesis Suite
https://yosyshq.net/yosys/
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Yosys Verilog frontend: module parameters #3004

Open SiliconWizard opened 2 years ago

SiliconWizard commented 2 years ago

It looks like Yosys frontend for Verilog is not fully compatible with the Verilog output of GHDL synth when it comes to module parameters.

It chokes on the following:

module ODDRX1F

(

GSR)

(input SCLK, input RST, input D0, input D1, output Q); endmodule

with the following error:

Test.v:3: ERROR: In pure Verilog (not SystemVerilog), parameter/localparam with an initializer must use the parameter/localparam keyword

I'm not good enough at Verilog to know what Verilog standard the above is compliant with, or if it's even standard Verilog. But GHDL synth generates this kind of module definitions for VHDL components that have generics.

mwkmwkmwk commented 2 years ago

You can try using yosys in SystemVerilog mode, via the -sv option to the Verilog frontend (or via naming the input file something.sv).

Better yet, I recommend using the yosys GHDL plugin instead of going from GHDL to yosys via Verilog.

SiliconWizard commented 2 years ago

I tried having Yosys use the SV mode, but then it issues another error on the line that instantiates the above module:

ODDRX1F sdram_clock #( .GSR("01000101010011100100000101000010010011000100010101000100")) (

with the following error:

Test.sv:689: ERROR: syntax error, unexpected '#', expecting '(' or '[' Parsing SystemVerilog input from `Colorlight_i5_Test2.sv' to AST representation.

I'll have to try the yosys GHDL plugin, I assumed there was no real difference. Does the plugin not use Verilog as an intermediate?

mwkmwkmwk commented 2 years ago

Now that looks like plain old incorrect code (the #(...)param assignment is supposed to come before sdram_clock instance name).

The GHDL plugin goes directly from GHDL IR to yosys IR, it doesn't involve Verilog.

mwkmwkmwk commented 2 years ago

Also the value given for the parameter is definitely incorrect — it somehow converted an "ENABLED" string into its binary representation, then emitted that as a string, there's no way this could possibly work.

SiliconWizard commented 2 years ago

Thanks! I'll have to report this to the GHDL team I guess.

Using the yosys GHDL plugin, yosys completes successfully.