+
+/*
+ copy & paste from scm_gcd (GUILE).
+ */
+static int
+gcd (long u, long v)
+{
+ long result = 0;
+ if (u == 0)
+ result = v;
+ else if (v == 0)
+ result = u;
+ else
+ {
+ long k = 1;
+ long t;
+ /* Determine a common factor 2^k */
+ while (!(1 & (u | v)))
+ {
+ k <<= 1;
+ u >>= 1;
+ v >>= 1;
+ }
+ /* Now, any factor 2^n can be eliminated */
+ if (u & 1)
+ t = -v;
+ else
+ {
+ t = u;
+ b3:
+ t = t >> 1;
+ }
+ if (!(1 & t))
+ goto b3;
+ if (t > 0)
+ u = t;
+ else
+ v = -t;
+ t = u - v;
+ if (t != 0)
+ goto b3;
+ result = u * k;
+ }
+
+ return result;
+}
+
+