Support global static variables

1 files changed, 23 insertions, 14 deletions

diff --git a/Variables.py b/Variables.py
index 424f6bd..617113f 100644
--- a/Variables.py
+++ b/Variables.py
@@ -55,13 +55,15 @@ class Variables(object):
         if self.parent_variables:
             return self.parent_variables.getAddress(name)
         raise RuntimeError("Use of undefined variable '{}'".format(name))
-    def declName(self, name, size=1, is_param=False):
+    def declName(self, name, size=1, is_param=False, is_static=False):
         """Declares a variable in the nearest scope
 
         Keyword arguments:
         name -- The symbolic name of the variable
         size -- The size of the memory to be allocated in words (default 1)
         is_param -- Whether the name is a function parameter or not
+        is_static -- Whether the variable should be static or not. Values of
+        static variables are retained between function calls
         """
         if name in self.local_vars or name in self.param_vars:
             raise RuntimeError("Redeclaration of variable '{}'".format(name))
@@ -101,31 +103,38 @@ class GlobalVariables(Variables):
         if name in self.global_vars:
             return ("GB", self.global_vars[name])
         raise RuntimeError("Use of undefined variable '{}'".format(name))
-    def declName(self, name, size=1, is_param=False):
+    def declName(self, name, size=1, is_param=False, is_static=False):
         """Declares a variable in the nearest scope
 
         Keyword arguments:
         name -- The symbolic name of the variable
         size -- The size of the memory to be allocated in words (default 1)
         is_param -- Whether the name is a function parameter or not
+        is_static -- Whether the variable should be static or not. Static
+        variables in this global scope are only visible in the file itself
         """
         if name in self.global_vars:
             raise RuntimeError("Redeclaration of variable '{}'".format(name))
 
         if is_param:
             raise RuntimeError("Parameter '{}' declared in global context".format(name))
+
+        if is_static:
+            # static globals are prefixed with "svar_" and not shared between
+            # files
+            var_name = self._uniqName("svar_" + name)
         else:
             # global variables are prefixed "var_". Don't use _uniqName because
-            # globals are by definition global and may be declared multiple
-            # times
+            # globals may be declared multiple times and are still shared
             var_name = "var_" + name
-            self.global_vars[name] = var_name
-            if var_name in self.defined_names:
-                old_size = len(self.defined_names[var_name])
-                if size != old_size:
-                    raise RuntimeError("Size {} of global '{}' does not equal"
-                                       " an earlier definition {}"
-                                       .format(size, name, old_size))
-            else:
-                # insert size items, initialized with 0
-                self.defined_names[var_name] = ["0"] * size
+
+        self.global_vars[name] = var_name
+        if var_name in self.defined_names:
+            old_size = len(self.defined_names[var_name])
+            if size != old_size:
+                raise RuntimeError("Size {} of global '{}' does not equal"
+                                   " an earlier definition {}"
+                                   .format(size, name, old_size))
+        else:
+            # insert size items, initialized with 0
+            self.defined_names[var_name] = ["0"] * size