+ if (exp < 0)
+ {
+ exp = -exp;
+ factor = 0.5L;
+ }
+ else
+ factor = 2.0L;
+
+ if (exp > 0)
+ for (bit = 1;;)
+ {
+ /* Invariant: Here bit = 2^i, factor = 2^-2^i or = 2^2^i,
+ and bit <= exp. */
+ if (exp & bit)
+ x *= factor;
+ bit <<= 1;
+ if (bit > exp)
+ break;
+ factor = factor * factor;
+ }