From 0821309cb715d239f03f815a7c2c1a5e29932dbf Mon Sep 17 00:00:00 2001
From: Peter Wu <lekensteyn@gmail.com>
Date: Sun, 27 Nov 2011 13:31:39 +0000
Subject: Support assignment using '=', support symbolic names (variables)

---
 pp2cc.py | 49 +++++++++++++++++++++++++++++++++++++++++--------
 1 file changed, 41 insertions(+), 8 deletions(-)

diff --git a/pp2cc.py b/pp2cc.py
index ff81fc5..d09d792 100755
--- a/pp2cc.py
+++ b/pp2cc.py
@@ -264,7 +264,7 @@ class Parse(object):
         self.addSource("@DATA")
         for varName in self.globalVars:
             padding = " " * (16 - len(varName) - 1)
-            self.addSource(varName + padding + " DW 1")
+            self.addSource(self.nameToVar(varName) + padding + " DW 1")
         self.addSource()
         self.addSource("@CODE")
         for line in self.codeSegment:
@@ -277,6 +277,13 @@ class Parse(object):
     def defineGlobalVar(self, linked_node):
         varname = linked_node.node.name
         self.globalVars.append(varname)
+    def nameToVar(self, name):
+        """Returns the variable name which will be used in assembly
+        
+        Keyword list:
+        name -- This name will be returned with the var_ prefix
+        """
+        return "var_" + name
     def defineFunction(self, linked_node):
         node = linked_node.node
         linked_node.incrementLevel()
@@ -617,8 +624,12 @@ class Parse(object):
         else:
             raise RuntimeError("Unsupported constant type: " + node.type)
         return [self.asm.binary_op("LOAD", register, value)]
-    def parseID(self, linked_node):
-        raise RuntimeError("Not implemented yet: symbolic names")
+    def parseID(self, linked_node, register="R0"):
+        name = linked_node.node.name
+        if not name in self.globalVars:
+            raise RuntimeError("Use of undefined variable '{}'".format(name))
+        var_name = self.nameToVar(name)
+        return [self.asm.binary_op("LOAD", register, "[GB+" + var_name + "]")]
     def parseIf(self, linked_node):
         linked_node.incrementLevel()
         node = linked_node.node
@@ -759,14 +770,35 @@ class Parse(object):
         for expr in linked_node.node.exprs:
             lines += self.parseStatement(expr, linked_node)
         return lines
+    def parseAssignment(self, linked_node):
+        lines = []
+        node = linked_node.node
+
+        # XXX support other types like pointers
+        if not isinstance(node.lvalue, c_ast.ID):
+            raise RuntimeError("Currently only assignments to symbolic names"
+                               "are allowed")
+
+        name = node.lvalue.name
+        # name of variable as it appears in the ASM code
+        if not name in self.globalVars:
+            raise RuntimeError("Assignment to undefined variable '{}'".format(name))
+        var_name = self.nameToVar(node.lvalue.name)
+        
+        expr_result = self.parseStatement(node.rvalue, linked_node)
+        lines += expr_result
+        result_reg = self.registers.find_register(expr_result)
+        if node.op == "=":
+            lines.append(self.asm.binary_op("STOR", result_reg, "[GB+" + var_name + "]"))
+        else:
+            raise RuntimeError("Unsupported assignment operator: " + node.op)
+        return lines
     def parseStatement(self, node, parent_linked_node, level_increment=False):
         linked_node = LinkedNode(node, parent_linked_node, level_increment=level_increment)
         self.asm.level = linked_node.level
         lines = []
-        if isinstance(node, c_ast.Assignment):
-            raise RuntimeError("Not implemented for type " + repr(node))
-        elif isinstance(node, c_ast.Decl):
-            self.defineGlobalVar(linked_node, parent_linked_node)
+        if isinstance(node, c_ast.Decl):
+            self.defineGlobalVar(linked_node)
         elif isinstance(node, c_ast.FuncDecl):
             raise RuntimeError("Not implemented for type " + repr(node))
         elif isinstance(node, c_ast.PtrDecl):
@@ -774,7 +806,8 @@ class Parse(object):
         else:
             for entry in ("Compound", "BinaryOp", "If", "Constant", "ID",
                           "Return", "FuncCall", "UnaryOp", "Cast",
-                          "TernaryOp", "DoWhile", "While", "For", "ExprList"):
+                          "TernaryOp", "DoWhile", "While", "For", "ExprList",
+                          "Assignment"):
                 if isinstance(node, getattr(c_ast, entry)):
                     lines += getattr(self, "parse" + entry)(linked_node)
                     break
-- 
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