From eabfc84fac0e42635cccabf5c8f883585da60de8 Mon Sep 17 00:00:00 2001
From: Peter Wu <lekensteyn@gmail.com>
Date: Tue, 29 Nov 2011 11:49:26 +0000
Subject: Fix value for substraction in constant expressions

---
 pp2cc.py | 4 ++++
 1 file changed, 4 insertions(+)

(limited to 'pp2cc.py')

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
-- 
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