1 files changed, 4 insertions, 0 deletions
diff --git a/pp2cc.py b/pp2cc.py
index ecd73a8..a1d1bbd 100755
--- a/pp2cc.py
+++ b/pp2cc.py
@@ -1112,6 +1112,10 @@ class Parse(object):
             else:
                 operand1 = self.determineConstValue(node.left)
                 operand2 = self.determineConstValue(node.right)
+                if op == "-":
+                    # ensure that the result of substraction is positive by
+                    # setting the (WORDSIZE+1)-nth bit on the first operand
+                    operand1 |= pow(2, self.WORDSIZE)
                 if op in ("<", ">", "<=", ">="):
                     value = int(getattr(operator, op)(operand1, operand2))
                     # 0 < 1 and -2 < -1 holds, but -1 < 0 does not. If the sign