src/math/frexp.c

   1 #include <math.h>
   2 #include <stdint.h>
   3
   4 double frexp(double x, int *e)
   5 {
   6         union { double d; uint64_t i; } y = { x };
   7         int ee = y.i>>52 & 0x7ff;
   8
   9         if (!ee) {
  10                 if (x) {
  11                         x = frexp(x*0x1p64, e);
  12                         *e -= 64;
  13                 } else *e = 0;
  14                 return x;
  15         } else if (ee == 0x7ff) {
  16                 return x;
  17         }
  18
  19         *e = ee - 0x3fe;
  20         y.i &= 0x800fffffffffffffull;
  21         y.i |= 0x3fe0000000000000ull;
  22         return y.d;
  23 }