Support indirection operator and pointer assignment

1 files changed, 28 insertions, 14 deletions

diff --git a/pp2cc.py b/pp2cc.py
index 0e3fe28..742faaf 100755
--- a/pp2cc.py
+++ b/pp2cc.py
@@ -643,8 +643,7 @@ class Parse(object):
         elif op == "&":
             raise RuntimeError("Address operator '&' is not supported.")
         elif op == "*":
-            # XXX support writing to addresses? (IOAREA)
-            raise RuntimeError("Indirection operator '*' is not supported.")
+            lines.append(self.asm.binary_op("LOAD", reg, "[" + reg + "]"))
         elif op == "sizeof":
             raise RuntimeError("Sizeof operator 'sizeof' is not supported.")
         elif op == "p++" or op == "p--":
@@ -917,25 +916,40 @@ class Parse(object):
         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.parseExpression(node.rvalue, linked_node)
         lines += expr_result
         result_reg = self.registers.find_register(expr_result)
+
+        self.registers.alloc(result_reg)
+        lvalue_reg = self.registers.alloc()
+        self.registers.free(lvalue_reg)
+        self.registers.free(result_reg)
+        lines += self.parseLValue(LinkedNode(node.lvalue, linked_node),
+                                  register=lvalue_reg)
+
         if node.op == "=":
-            lines.append(self.asm.binary_op("STOR", result_reg, "[GB+" + var_name + "]"))
+            lines.append(self.asm.binary_op("STOR", result_reg,
+                                            "[" + lvalue_reg + "]"))
         else:
             raise RuntimeError("Unsupported assignment operator: " + node.op)
         return lines
+    def parseLValue(self, linked_node, register="R0"):
+        lines = []
+        if linked_node.type == "UnaryOp" and linked_node.node.op == "*":
+            lines += self.parseLValue(LinkedNode(linked_node.node.expr,
+                                                 linked_node), register)
+            lines.append(self.asm.binary_op("LOAD", register,
+                                            "[" + register + "]"))
+        elif linked_node.type == "ID":
+            name = linked_node.node.name
+            if not name in self.globalVars:
+                raise RuntimeError("Use of undefined variable '{}'".format(name))
+            var_name = self.nameToVar(name)
+            lines.append(self.asm.binary_op("LOAD", register, "GB"))
+            lines.append(self.asm.binary_op("ADD", register, var_name))
+        else:
+            raise RuntimeError("Expected a lvalue (pointer or names)")
+        return lines
     def parseDecl(self, linked_node):
         lines = []
         varname = linked_node.node.name