Reorganizing source code. Created util dir

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>

src/util/ext_gcd.h

@@ -0,0 +1,52 @@
+/*++
+Copyright (c) 2006 Microsoft Corporation
+
+Module Name:
+
+    ext_gcd.h
+
+Abstract:
+
+    <abstract>
+
+Author:
+
+    Leonardo de Moura (leonardo) 2007-06-09.
+
+Revision History:
+
+--*/
+#ifndef _EXT_GCD_H_
+#define _EXT_GCD_H_
+
+template<typename numeral>
+void extended_gcd(const numeral & in_a, const numeral & in_b, numeral & gcd, numeral & x, numeral & y) {
+    numeral a = in_a;
+    numeral b = in_b;
+    x = numeral(0);
+    y = numeral(1);
+    numeral lastx(1);
+    numeral lasty(0);
+    numeral tmp;
+    numeral quotient;
+    while (!b.is_zero()) {
+        tmp       = b;
+        quotient  = div(a, b);
+        b         = mod(a, b);
+        a         = tmp;
+        
+        tmp       = x;
+        x         = lastx - (quotient * x);
+        lastx     = tmp;
+
+        tmp       = y;
+        y         = lasty - (quotient * y);
+        lasty     = tmp;
+    }
+    gcd = a;
+    x   = lastx;
+    y   = lasty;
+}
+
+#endif /* _EXT_GCD_H_ */
+