ANTLR4-Verilog-Python

Generated files from ANTLR4 for Verilog parsing in Python

Tutorial

Install this Python package

python3 -m pip install antlr4_verilog

Use your own listener to walk through the AST:

from antlr4_verilog import InputStream, CommonTokenStream, ParseTreeWalker
from antlr4_verilog.verilog import VerilogLexer, VerilogParser, VerilogParserListener

design = '''
    module ha(a, b, sum, c);
        input a, b;
        output sum, c;

        assign sum = a ^ b;
        assign c = a & b;
    endmodule
'''

class ModuleIdentifierListener(VerilogParserListener):
    def exitModule_declaration(self, ctx):
        self.identifier = ctx.module_identifier().getText()

lexer = VerilogLexer(InputStream(design))
stream = CommonTokenStream(lexer)
parser = VerilogParser(stream)

tree = parser.source_text()
listener = ModuleIdentifierListener()
walker = ParseTreeWalker()
walker.walk(listener, tree)
print(listener.identifier) # 'ha'

Take a look at other listener methods for Verilog and SystemVerilog

You may find more examples in the test file

How to generate those files

System requirements (Ubuntu):

sudo apt-get install -y default-jre
sudo apt-get install -y default-jdk
sudo apt-get install -y curl

1. Get ANTLR4:

curl https://www.antlr.org/download/antlr-4.10.1-complete.jar -o extra/antlr-4.10.1-complete.jar

2. Get ANTLR grammars:

git clone https://github.com/antlr/grammars-v4.git extra/grammars-v4

3. Call ANTLR for Verilog grammar:

java -Xmx500M -cp "extra/antlr-4.10.1-complete.jar:${CLASSPATH}" org.antlr.v4.Tool -Dlanguage=Python3 -visitor `pwd`/extra/grammars-v4/verilog/verilog/VerilogLexer.g4 `pwd`/extra/grammars-v4/verilog/verilog/VerilogParser.g4 `pwd`/extra/grammars-v4/verilog/verilog/VerilogPreParser.g4 -o src/antlr4_verilog/verilog

3. Call ANTLR for SystemVerilog grammar:

java -Xmx500M -cp "extra/antlr-4.10.1-complete.jar:${CLASSPATH}" org.antlr.v4.Tool -Dlanguage=Python3 -visitor `pwd`/extra/grammars-v4/verilog/systemverilog/SystemVerilogLexer.g4 `pwd`/extra/grammars-v4/verilog/systemverilog/SystemVerilogParser.g4 `pwd`/extra/grammars-v4/verilog/systemverilog/SystemVerilogPreParser.g4 -o src/antlr4_verilog/systemverilog

How to test the grammar

1. Generate Java files:

java -Xmx500M -cp "extra/antlr-4.10.1-complete.jar:${CLASSPATH}" org.antlr.v4.Tool -Dlanguage=Java -visitor `pwd`/extra/grammars-v4/verilog/verilog/VerilogLexer.g4 `pwd`/extra/grammars-v4/verilog/verilog/VerilogParser.g4 `pwd`/extra/grammars-v4/verilog/verilog/VerilogPreParser.g4 -o test/testrig/verilog

java -Xmx500M -cp "extra/antlr-4.10.1-complete.jar:${CLASSPATH}" org.antlr.v4.Tool -Dlanguage=Java -visitor `pwd`/extra/grammars-v4/verilog/systemverilog/SystemVerilogLexer.g4 `pwd`/extra/grammars-v4/verilog/systemverilog/SystemVerilogParser.g4 `pwd`/extra/grammars-v4/verilog/systemverilog/SystemVerilogPreParser.g4 -o test/testrig/systemverilog

2. Compile these recently generated files:

javac -cp "extra/antlr-4.10.1-complete.jar:${CLASSPATH}" test/testrig/verilog/*.java

javac -cp "extra/antlr-4.10.1-complete.jar:${CLASSPATH}" test/testrig/systemverilog/*.java

3. Create JAR files:

jar cf test/testrig/verilog.jar -C test/testrig/verilog .

jar cf test/testrig/systemverilog.jar -C test/testrig/systemverilog .

4. Finally, for test.v and test.sv files:

java -Xmx500M -cp "extra/antlr-4.10.1-complete.jar:test/testrig/verilog.jar:${CLASSPATH}" org.antlr.v4.gui.TestRig Verilog source_text test/testrig/test.v -tree

java -Xmx500M -cp "extra/antlr-4.10.1-complete.jar:test/testrig/systemverilog.jar:${CLASSPATH}" org.antlr.v4.gui.TestRig SystemVerilog source_text test/testrig/test.sv -tree

You can use -gui to test it interactively

Acknowledgement

We would like to appreciate the work from the ANTLR team and the Verilog/SystemVerilog grammar written by Mustafa Said Ağca.