Allow passing custom module_name to output_to_verilog and output_verilog_testbench (#474)

Author: devmam999

pyrtl/importexport.py

@@ -768,10 +768,11 @@ def _extra_checks(self, str):
 
 
 class _VerilogOutput:
-    def __init__(self, block: Block, add_reset: bool | str):
+    def __init__(self, block: Block, add_reset: bool | str, module_name="toplevel"):
         block = working_block(block)
         self.gate_graph = GateGraph(block)
         self.add_reset = add_reset
+        self.module_name = module_name
 
         if not isinstance(self.add_reset, bool) and self.add_reset != "asynchronous":
             msg = (
@@ -951,14 +952,17 @@ def _to_verilog_header(self, file: IO, initialize_registers: bool):
         """Print the header of the verilog implementation."""
         print("// Generated automatically via PyRTL", file=file)
         print("// As one initial test of synthesis, map to FPGA with:", file=file)
-        print('//   yosys -p "synth_xilinx -top toplevel" thisfile.v\n', file=file)
+        print(
+            f'//   yosys -p "synth_xilinx -top {self.module_name}" thisfile.v\n',
+            file=file,
+        )
 
         # ``declared_gates`` is the set of Gates with corresponding Verilog reg/wire
         # declarations. Generated Verilog code can refer to these Gates by name.
         self.declared_gates = self.gate_graph.inputs | self.gate_graph.outputs
 
         # Module name.
-        print(f"module toplevel({', '.join(self.io_list)});", file=file)
+        print(f"module {self.module_name}({', '.join(self.io_list)});", file=file)
 
         # Declare Inputs and Outputs.
         print("    input clk;", file=file)
@@ -1309,7 +1313,9 @@ def output_verilog_testbench(
             print("    integer tb_addr;", file=dest_file)
 
         io_list_str = [f".{io}({io})" for io in self.io_list]
-        print(f"    toplevel block({', '.join(io_list_str)});\n", file=dest_file)
+        print(
+            f"    {self.module_name} block({', '.join(io_list_str)});\n", file=dest_file
+        )
 
         # Generate the clock signal.
         print("    always", file=dest_file)
@@ -1414,6 +1420,7 @@ def output_to_verilog(
     add_reset: bool | str = True,
     block: Block = None,
     initialize_registers: bool = False,
+    module_name: str = "toplevel",
 ):
     """A function to walk the ``block`` and output it in Verilog format to the open
     file.
@@ -1434,8 +1441,12 @@ def output_to_verilog(
         When this argument is ``True``, a register like ``Register(name='foo',
         bitwidth=8, reset_value=4)`` generates Verilog like ``reg[7:0] foo = 8'd4;``.
     :param block: Block to be walked and exported. Defaults to the :ref:`working_block`.
+    :param module_name: name of the module. Defaults to toplevel
+        if the user puts nothing.
     """
-    _VerilogOutput(block, add_reset).output_to_verilog(dest_file, initialize_registers)
+    _VerilogOutput(block, add_reset, module_name=module_name).output_to_verilog(
+        dest_file, initialize_registers
+    )
 
 
 def output_verilog_testbench(
@@ -1446,6 +1457,7 @@ def output_verilog_testbench(
     cmd: str | None = None,
     add_reset: bool | str = True,
     block: Block = None,
+    module_name: str = "toplevel",
 ):
     """Output a Verilog testbench for the block/inputs used in the simulation trace.
 
@@ -1499,8 +1511,10 @@ def output_verilog_testbench(
         value passed in here should match the argument passed to
         :func:`output_to_verilog`.
     :param block: Block containing design to test. Defaults to the :ref:`working_block`.
+    :param module_name: Name of the module the user chooses. Defaults to toplevel
+        if nothing is inputted.
     """
-    _VerilogOutput(block, add_reset).output_verilog_testbench(
+    _VerilogOutput(block, add_reset, module_name=module_name).output_verilog_testbench(
         dest_file, simulation_trace, toplevel_include, vcd, cmd
     )
 

tests/test_importexport.py

@@ -1309,6 +1309,18 @@ def test_bit_slice_inputs(self):
         # bit-slice.
         self.assertTrue("assign tmp3 = c" in buffer.getvalue())
 
+    def test_custom_module_name(self):
+        a, b = pyrtl.Input(1, "a"), pyrtl.Input(1, "b")
+        out = pyrtl.Output(name="out")
+        out <<= a & b
+
+        buf = io.StringIO()
+        pyrtl.output_to_verilog(buf, module_name="custom_top")
+        text = buf.getvalue()
+
+        self.assertIn("module custom_top", text)
+        self.assertNotIn("module toplevel", text)
+
 
 verilog_input_counter = """\
 module counter (clk, rst, en, count);
@@ -1654,6 +1666,21 @@ def test_only_initialize_memblocks(self):
         # The testbench should not touch the RomBlock.
         self.assertTrue("my_rom" not in buffer.getvalue())
 
+    def test_custom_module_name_testbench(self):
+        # Minimal design
+        a, b = pyrtl.Input(1, "a"), pyrtl.Input(1, "b")
+        out = pyrtl.Output(1, "out")
+        out <<= a & b
+
+        buf = io.StringIO()
+        # Generate a testbench with a custom module name
+        pyrtl.output_verilog_testbench(buf, module_name="custom_tb")
+        text = buf.getvalue()
+
+        # Verify the custom module name is used
+        self.assertIn("custom_tb block(", text)
+        self.assertNotIn("toplevel block(", text)
+
 
 firrtl_output_concat_test = """\
 circuit Example :