trunc.c raw

   1  #include "libm.h"
   2  
   3  double trunc(double x)
   4  {
   5  	union {double f; uint64_t i;} u = {x};
   6  	int e = (int)(u.i >> 52 & 0x7ff) - 0x3ff + 12;
   7  	uint64_t m;
   8  
   9  	if (e >= 52 + 12)
  10  		return x;
  11  	if (e < 12)
  12  		e = 1;
  13  	m = -1ULL >> e;
  14  	if ((u.i & m) == 0)
  15  		return x;
  16  	FORCE_EVAL(x + 0x1p120f);
  17  	u.i &= ~m;
  18  	return u.f;
  19  }
  20