what is linux vcs

Linux vcs is a compiled verilog simulator, a tool used to simulate and view waveforms; it is similar to tools such as modelsim and questasim under windows, as well as quartus and vivado simulation operations.

#The operating environment of this tutorial: linux5.9.8 system, Dell G3 computer.

What is linux vcs?

The basic use of VCS tools

VCS is The tools used to simulate and view waveforms under Linux are similar to tools such as modelsim and questasim under Windows, as well as quartus and vivado simulation operations.

1.Basic instructions for vcs

Common instruction suffixes for vcs

You can compile all the source code in the .f fileRun immediately after compilation, that is, execute immediately after compilation is completedWhen the source file is modified, only the modified **.v* will be recompiled * file, saving compilation time. Turn on support for Set simulation accuracyThe executable file generated by compilation is

Command	Meaning
-l readme.log	is used to compile the information generated Place it in the log file
v2k	is the standard that makes VCS compatible with verilog before 2001
-debug_all	Files required to generate debug
##-f verilog_file.f
-R	./simv
-Mupdate
-sverilog	Systemverilog and use it when compiling Systemverilog files.
-timescale=1ns/1ns
-o simv_file	simv by default. You can use -o to change the executable file name. If you modify it here, you will not use simv but the corresponding o name when executing the simulation.

Common commands for simv

CommandMeaning Save the execution log fileOpen with graphical interface

2. Example of using vcs

The official tutorial of full adder is used. First, the execution process without using a script is introduced.
(1) First execute vcs to add the corresponding full_adder file

vcs -sverilog  -debug_all   -timescale=1ns/1ps  full_adder.v  full_adder_tb.v -l com.log

Write full_adder.v here first because The tb file needs to call it, so write the called file first. This statement will generate a simv file (if -o simv_file is used, the corresponding file name will be generated).
(2) You can use the ./simv file to execute the waveform interface, or you can use the following command to open an interface in the background.

dve  &或者

./simv -l run.log -gui

(3) If you execute it with ./simv, you will see the wave file directly. If you use dve &, you need to add the simv file yourself. To view the waveform, select simulator->Setup and add the generated simv file.

run all below, if no time scale is given, an error will be reported here. If there is no error, it means that our function is completely correct. Right-click to add the waveform file and press f to display the waveform.
(4) The following four keys function
The first one: Track who drives the signal ctrl d
The second one: Track the value change of the signal ctrl shift d
The third one: Tracking the unknown state
The fourth one: Tracking who is used to drive

3.How to write the makefile

The script writing method of vcs can help express express to simulate and obtain waveform files.
Among them, .PHONY can specify which keywords correspond to the make operation.

.PHONY:vcs sim dve clean 

OUTPUT = adder

VCS = vcs -sverilog +v2k -timescale=1ns/1ns                             \
          -debug_all                                                    \
          -o ${OUTPUT}                                                  \
          -l compile.log                                                \SIM = ./${OUTPUT} -l run.log


vcs:        ${VCS} -f verilog_file.f


sim:        ${SIM}dve:
		dve -vpd    vcdplus.vpd &  clean:       rm -rf *.log  csrc  simv*  *.key *.vpd  DVEfiles coverage *.vdb

In this way, make vcs executes the vcs statement, make sim executes the simv statement, make dve opens the wave file, and make clean removes some redundant files.
Among them, verilog_file.f is a list of files, which can be generated using the following statement, so that all file names ending with v are written to the target file.

find  -name  ".*v"   > file.list

Related recommendations: "Linux Video Tutorial"

./simv -l run.log
./simv -gui

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