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Verilator: Fast, Free Verilog HDL Simulator

veripool.org

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Re: Verilator: Fast, Free Verilog HDL Simulator

#11

During my short experience with hardware design at the university I never had the chance of using Verilog. Are there advantages in using it instead of VHDL?

In my experience, it's:

1) Less verbose and easier to write, but slightly more "error" prone (think: Java vs. Python).

2) More widely used in industry. VHDL is more heavily used in the defense industry (it came out of DoD).

3) Better support for verification (e.g., SystemVerilog).

Re: Verilator: Fast, Free Verilog HDL Simulator

#13

During my short experience with hardware design at the university I never had the chance of using Verilog. Are there advantages in using it instead of VHDL?

Open-Source tooling support (Yosys/NextPNR flow, Yosys formal verification flow, Verilator, IVerilog).

VHDL only has GHDL. And there's a bunch of small projects to translate synthesizable VHDL into Verilog (to then feed into the aforementioned tooling), but none of them are good.

Re: Verilator: Fast, Free Verilog HDL Simulator

#15
post #5

One cool thing you can do with Verilator is use the API to simulate other hardware. For example, here's a Verilog Gameboy being simulated realtime by simulating the display attached to it: https://twitter.com/zephray_wenting/status/11126917323936645...

You can do this with any simulator that has a FFI interface - just use the SystemVerilog DPI.

Re: Verilator: Fast, Free Verilog HDL Simulator

#18

Verilator has some serious limitations: The driving test bench is C/C++ It is a cycle simulator, not a delta-time simulator: it will only simulate synthesizable code (not test bench code) It cannot do back-annotated timing simulations It cannot use encrypted vendor libraries (no simulations with Xilinx IP, for example) It has no mixed-HDL language capabilities It requires Gtkwave to view waveforms with (opinion, but…

> It requires Gtkwave to view waveforms with (opinion, but I hate the UI)

It dumps a value-change file (vcd) which can be viewed by anything, no? Sure it's not very compressed (and the compile-time for vcd-generation is unfortunate), but it's not a show-stopper.

Re: Verilator: Fast, Free Verilog HDL Simulator

#19
post #18

Verilator has some serious limitations: The driving test bench is C/C++ It is a cycle simulator, not a delta-time simulator: it will only simulate synthesizable code (not test bench code) It cannot do back-annotated timing simulations It cannot use encrypted vendor libraries (no simulations with Xilinx IP, for example) It has no mixed-HDL language capabilities It requires Gtkwave to view waveforms with (opinion, but…

> It requires Gtkwave to view waveforms with (opinion, but I hate the UI) It dumps a value-change file (vcd) which can be viewed by anything, no? Sure it's not very compressed (and the compile-time for vcd-generation is unfortunate), but it's not a show-stopper.

This is correct; although I am unaware of a FOSS vcd viewer which improves upon Gtkwave.

I would be exceedingly happy to find one, however; please let me know.

Re: Verilator: Fast, Free Verilog HDL Simulator

#20
post #9

Verilator has some serious limitations: The driving test bench is C/C++ It is a cycle simulator, not a delta-time simulator: it will only simulate synthesizable code (not test bench code) It cannot do back-annotated timing simulations It cannot use encrypted vendor libraries (no simulations with Xilinx IP, for example) It has no mixed-HDL language capabilities It requires Gtkwave to view waveforms with (opinion, but…

The first two are a feature for me. Not to mention not being crippled by Xilinx 'IP Core' DRM.

Crippled by extant, available code which is shipping in millions of devices?

Is it perfect? Hell no. But it's a bit drastic to throw out an entire catalog of the most battle-tested HDL code in the world, isn't it?

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