Allow for (optional) const declaration.
diff --git a/Tools/bgen/bgen/bgenBuffer.py b/Tools/bgen/bgen/bgenBuffer.py
index bc11e64..a07e8f0 100644
--- a/Tools/bgen/bgen/bgenBuffer.py
+++ b/Tools/bgen/bgen/bgenBuffer.py
@@ -38,19 +38,26 @@
         self.sizeformat = sizeformat or type2format[sizetype]
         self.label_needed = 0
 
-    def getArgDeclarations(self, name, reference=False):
+    def getArgDeclarations(self, name, reference=False, constmode=False):
         if reference:
             raise RuntimeError, "Cannot pass buffer types by reference"
-        return (self.getBufferDeclarations(name) + 
+        return (self.getBufferDeclarations(name, constmode) + 
                 self.getSizeDeclarations(name))
 
-    def getBufferDeclarations(self, name):
-        return self.getInputBufferDeclarations(name) + self.getOutputBufferDeclarations(name)
+    def getBufferDeclarations(self, name, constmode=False):
+        return self.getInputBufferDeclarations(name, constmode) + \
+        	self.getOutputBufferDeclarations(name, constmode)
 
-    def getInputBufferDeclarations(self, name):
-        return ["%s *%s__in__" % (self.datatype, name)]
+    def getInputBufferDeclarations(self, name, constmode=False):
+    	if constmode:
+    		const = "const "
+    	else:
+    		const = ""
+        return ["%s%s *%s__in__" % (const, self.datatype, name)]
 
-    def getOutputBufferDeclarations(self, name):
+    def getOutputBufferDeclarations(self, name, constmode=False):
+    	if constmode:
+    		raise RuntimeError, "Cannot use const output buffer"
         return ["%s %s__out__[%s]" % (self.datatype, name, self.size)]
 
     def getSizeDeclarations(self, name):
@@ -105,13 +112,13 @@
 
 class InputOnlyBufferMixIn(InputOnlyMixIn):
 
-    def getOutputBufferDeclarations(self, name):
+    def getOutputBufferDeclarations(self, name, constmode=False):
         return []
 
 
 class OutputOnlyBufferMixIn(OutputOnlyMixIn):
 
-    def getInputBufferDeclarations(self, name):
+    def getInputBufferDeclarations(self, name, constmode=False):
         return []
 
 class OptionalInputBufferMixIn:
@@ -186,8 +193,12 @@
         FixedInputOutputBufferType.__init__(self, "sizeof(%s)" % type)
         self.typeName = self.type = type
 
-    def getInputBufferDeclarations(self, name):
-        return ["%s *%s__in__" % (self.type, name)]
+    def getInputBufferDeclarations(self, name, constmode=False):
+    	if constmode:
+    		const = "const "
+    	else:
+    		const = ""
+        return ["%s%s *%s__in__" % (const, self.type, name)]
 
     def getSizeDeclarations(self, name):
         return []
@@ -195,7 +206,9 @@
     def getAuxDeclarations(self, name):
         return ["int %s__in_len__" % (name)]
 
-    def getOutputBufferDeclarations(self, name):
+    def getOutputBufferDeclarations(self, name, constmode=False):
+    	if constmode:
+    		raise RuntimeError, "Cannot use const output buffer"
         return ["%s %s__out__" % (self.type, name)]
 
     def getargsArgs(self, name):
diff --git a/Tools/bgen/bgen/bgenHeapBuffer.py b/Tools/bgen/bgen/bgenHeapBuffer.py
index f9b3daf..c9c4232 100644
--- a/Tools/bgen/bgen/bgenHeapBuffer.py
+++ b/Tools/bgen/bgen/bgenHeapBuffer.py
@@ -16,7 +16,9 @@
     def __init__(self, datatype = 'char', sizetype = 'int', sizeformat = None):
         FixedInputOutputBufferType.__init__(self, "0", datatype, sizetype, sizeformat)
 
-    def getOutputBufferDeclarations(self, name):
+    def getOutputBufferDeclarations(self, name, constmode=False):
+    	if constmode:
+    		raise RuntimeError, "Cannot use const output buffer"
         return ["%s *%s__out__" % (self.datatype, name)]
 
     def getargsCheck(self, name):
@@ -74,7 +76,7 @@
     Call from Python with buffer size.
     """
 
-    def getInputBufferDeclarations(self, name):
+    def getInputBufferDeclarations(self, name, constmode=False):
         return []
 
     def getargsFormat(self):
diff --git a/Tools/bgen/bgen/bgenType.py b/Tools/bgen/bgen/bgenType.py
index 00dd9d7..3cbd18f 100644
--- a/Tools/bgen/bgen/bgenType.py
+++ b/Tools/bgen/bgen/bgenType.py
@@ -29,13 +29,18 @@
         for decl in self.getAuxDeclarations(name):
             Output("%s;", decl)
 
-    def getArgDeclarations(self, name, reference=False):
+    def getArgDeclarations(self, name, reference=False, constmode=False):
         """Return the main part of the declarations for this type: the items
         that will be passed as arguments in the C/C++ function call."""
         if reference:
-            return ["%s& %s" % (self.typeName, name)]
+            ref = "&"
         else:
-            return ["%s %s" % (self.typeName, name)]
+            ref = ""
+        if constmode:
+            const = "const "
+        else:
+            const = ""
+        return ["%s%s%s %s" % (const, self.typeName, ref, name)]
 
     def getAuxDeclarations(self, name):
         """Return any auxiliary declarations needed for implementing this
@@ -208,7 +213,7 @@
         self.substitute = substitute
         self.typeName = None    # Don't show this argument in __doc__ string
 
-    def getArgDeclarations(self, name, reference=False):
+    def getArgDeclarations(self, name, reference=False, constmode=False):
         return []
 
     def getAuxDeclarations(self, name, reference=False):
diff --git a/Tools/bgen/bgen/bgenVariable.py b/Tools/bgen/bgen/bgenVariable.py
index 7848a4f..ef0e6d2 100644
--- a/Tools/bgen/bgen/bgenVariable.py
+++ b/Tools/bgen/bgen/bgenVariable.py
@@ -45,9 +45,12 @@
         elif self.flags != SelfMode:
             self.type.declare(self.name)
 
-    def getArgDeclarations(self):
+    def getArgDeclarations(self, constmode=False):
         refmode = (self.flags & RefMode)
-        return self.type.getArgDeclarations(self.name, reference=refmode)
+        if constmode:
+        	constmode = (self.flags & ConstMode)
+        return self.type.getArgDeclarations(self.name,
+        	reference=refmode, constmode=constmode)
     
     def getAuxDeclarations(self):
         return self.type.getAuxDeclarations(self.name)