__fpclassify.c raw

   1  #include <math.h>
   2  #include <stdint.h>
   3  
   4  int __fpclassify(double x)
   5  {
   6  	union {double f; uint64_t i;} u = {x};
   7  	int e = u.i>>52 & 0x7ff;
   8  	if (!e) return u.i<<1 ? FP_SUBNORMAL : FP_ZERO;
   9  	if (e==0x7ff) return u.i<<12 ? FP_NAN : FP_INFINITE;
  10  	return FP_NORMAL;
  11  }
  12