Handle two\'s complement numbers.

Revision:
0:b495118be5a7
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/SignExtend.h	Thu Jan 20 20:01:36 2011 +0000
@@ -0,0 +1,1 @@
+int SignExtend( int value, const int bit_width );
\ No newline at end of file