sverilog errors with design compiler

[3wais]

I'm trying to use this open source file with Design Compiler.
I analyze it as sverilog. and it gives me those warnings:

Warning:  ./src/Memory/DRAM_Controller.v:103: The construct 'declaration initial assignment' is not supported in synthesis; it is ignored. (VER-708)
Warning:  ./src/Memory/DRAM_Controller.v:104: The construct 'declaration initial assignment' is not supported in synthesis; it is ignored. (VER-708)
Warning:  ./src/Memory/DRAM_Controller.v:105: The construct 'declaration initial assignment' is not supported in synthesis; it is ignored. (VER-708)
Warning:  ./src/Memory/DRAM_Controller.v:106: The construct 'declaration initial assignment' is not supported in synthesis; it is ignored. (VER-708)
Warning:  ./src/Memory/DRAM_Controller.v:143: the undeclared symbol 'ckinb' assumed to have the default net type, which is 'wire'. (VER-936)
Warning:  ./src/Memory/DRAM_Controller.v:177: the undeclared symbol 'pllfb0' assumed to have the default net type, which is 'wire'. (VER-936)
Warning:  ./src/Memory/DRAM_Controller.v:184: the undeclared symbol 'locked' assumed to have the default net type, which is 'wire'. (VER-936)
Warning:  ./src/Memory/DRAM_Controller.v:143: The delay specification for net declaration is ignored. (VER-976)
Warning:  ./src/Memory/DRAM_Controller.v:177: The delay specification for net declaration is ignored. (VER-976)
Warning:  ./src/Memory/DRAM_Controller.v:184: The delay specification for net declaration is ignored. (VER-976)

I just ignore the warnings and go directly with the elaboration. but elaboration gives me these error and warnings:

Warning:  ./src/Memory/DRAM_Controller.v:1149: signed to unsigned assignment occurs. (VER-318)
Warning:  ./src/Memory/DRAM_Controller.v:1157: signed to unsigned assignment occurs. (VER-318)
Warning:  ./src/Memory/DRAM_Controller.v:1165: signed to unsigned assignment occurs. (VER-318)
Error:  ./src/Memory/DRAM_Controller.v:176: value of double type is not supported in synthesis. (ELAB-379)
*** Presto compilation terminated with 1 errors. ***

at line 176 there are no numbers or values. so my assumptions is this error is related to the analyze command warning at line 177.
I have no knowledge of verilog or system verilog. Can anybody help ??

 

[jrwebsterco]

This Verilog appears to be written specifically for a Xilinx FPGA - did you realize this?
(you can see this because it instantiates BUFG cells, and also refers to the XILINX_ISIM simulator via some of the ifdefs)

You get the "declaration initial assignment" warnings because DC is not really intended to support initial values in general-purpose flops (but FPGA flops *can* do this).
Instead, DC expects initialization to occur via async or sync reset inferrences with the "always @(...)" blocks.

The "undeclared symbol/default net type" warnings are really just informational, since instantiated cells/modules are allowed to refer to undeclared wires which will then be implicitly auto-declared, i.e. is legal Verilog.
(you could suppress that warning if you wanted to)

Signed-to-unsigned warnings are likely due to the fact that the parameters are untyped, and thus default to signed 32-bit.
(these kinds of warnings are common and can oftentimes be ignored)

It is unclear where the VER-976 warnings are coming from.
The ELAB-379 error is also a bit mysterious.
However, I suspect they are both due to the fact that "parameterized" sub-modules are being instantiated, and you did not firstly read them in as HDL code.
This is again related to the fact that this code is targeted for a Xilinx FPGA, which *would* have modules with those names (e.g. from the CORE Generator utility).

I suspect you need to re-evaluate whether this IP is suitable for an ASIC implementation, which is what you appear to be doing here.
Maybe that was the short answer?

 

[3wais]

How about trying to use the Core Generator libraries with design compiler as a workaround. would that do the trick ??
As I found in search Core Generator contains vhdl and verilog source codes.

 

[jrwebsterco]

You need to clarify your goal.
Are you actually targeting a Xilinx FPGA, or are you instead trying to port this IP to an ASIC std-cell design?

If targeting a Xilinx FPGA, then perhaps you should have the Xilinx 3rd-party libraries for Design Compiler.
(assuming those are even still supported, noting that Synopsys has since moved to Synplify for FPGA synthesis)

Note that I mis-spoke about the need for the Xilinx CORE Generator.
Instead, this RTL code is already referring to Xilinx Spartan-6 family *primitives* (e.g. PLL_BASE, OSERDES2, BUFG and possibly other cells).

Note also that the project summary for this Open Core IP states "Heavily optimised for Xilinx Spartan 6 FPGA family".
If you are targeting a Spartan-6 FPGA then I suggest you change to the Xilinx ISE toolset.
Otherwise, you have a lot of non-trivial work to do to modify and retarget this IP to an ASIC flow, including the need to find PLL and serdes macros that are suitable, among other details.