libf2c/libF77/pow_qq.c

   1 #include "f2c.h"
   2
   3 longint
   4 pow_qq (longint * ap, longint * bp)
   5 {
   6   longint pow, x, n;
   7   unsigned long long u;         /* system-dependent */
   8
   9   x = *ap;
  10   n = *bp;
  11
  12   if (n <= 0)
  13     {
  14       if (n == 0 || x == 1)
  15         return 1;
  16       if (x != -1)
  17         return x == 0 ? 1 / x : 0;
  18       n = -n;
  19     }
  20   u = n;
  21   for (pow = 1;;)
  22     {
  23       if (u & 01)
  24         pow *= x;
  25       if (u >>= 1)
  26         x *= x;
  27       else
  28         break;
  29     }
  30   return (pow);
  31 }