Improve cpuif customization support. Add docs & testcases

test/lib/cpuifs/base.py

@@ -16,15 +16,33 @@ class CpuifTestMode:
     cpuif_cls = None # type: CpuifBase
 
     # Files required by the DUT
+    # Paths are relative to the class that assigns this
     rtl_files = []  # type: List[str]
 
     # Files required by the sim testbench
+    # Paths are relative to the class that assigns this
     tb_files = [] # type: List[str]
 
+    # Path is relative to the class that assigns this
     tb_template = ""
 
-    def _translate_paths(self, files: List[str]) -> List[str]:
-        class_dir = os.path.dirname(inspect.getfile(self.__class__))
+
+    def _get_class_dir_of_variable(self, varname:str) -> str:
+        """
+        Traverse up the MRO and find the first class that explicitly assigns
+        the variable of name varname. Returns the directory that contains the
+        class definition.
+        """
+        for cls in inspect.getmro(self.__class__):
+            if varname in cls.__dict__:
+                class_dir = os.path.dirname(inspect.getfile(cls))
+                return class_dir
+        raise RuntimeError
+
+
+    def _get_file_paths(self, varname:str) -> List[str]:
+        class_dir = self._get_class_dir_of_variable(varname)
+        files = getattr(self, varname)
         cwd = os.getcwd()
 
         new_files = []
@@ -33,18 +51,23 @@ class CpuifTestMode:
                 os.path.join(class_dir, file),
                 cwd
             )
-            if relpath not in new_files:
-                new_files.append(relpath)
+            new_files.append(relpath)
         return new_files
 
+
     def get_sim_files(self) -> List[str]:
-        return self._translate_paths(self.rtl_files + self.tb_files)
+        files = self._get_file_paths("rtl_files") + self._get_file_paths("tb_files")
+        unique_files = []
+        [unique_files.append(f) for f in files if f not in unique_files]
+        return unique_files
+
 
     def get_synth_files(self) -> List[str]:
-        return self._translate_paths(self.rtl_files)
+        return self._get_file_paths("rtl_files")
+
 
     def get_tb_inst(self, tb_cls: 'SimTestCase', exporter: 'RegblockExporter') -> str:
-        class_dir = os.path.dirname(inspect.getfile(self.__class__))
+        class_dir = self._get_class_dir_of_variable("tb_template")
         loader = jj.FileSystemLoader(class_dir)
         jj_env = jj.Environment(
             loader=loader,