frexp.c raw

   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  }
  24