nextafterf.c raw

   1  #include "libm.h"
   2  
   3  float nextafterf(float x, float y)
   4  {
   5  	union {float f; uint32_t i;} ux={x}, uy={y};
   6  	uint32_t ax, ay, e;
   7  
   8  	if (isnan(x) || isnan(y))
   9  		return x + y;
  10  	if (ux.i == uy.i)
  11  		return y;
  12  	ax = ux.i & 0x7fffffff;
  13  	ay = uy.i & 0x7fffffff;
  14  	if (ax == 0) {
  15  		if (ay == 0)
  16  			return y;
  17  		ux.i = (uy.i & 0x80000000) | 1;
  18  	} else if (ax > ay || ((ux.i ^ uy.i) & 0x80000000))
  19  		ux.i--;
  20  	else
  21  		ux.i++;
  22  	e = ux.i & 0x7f800000;
  23  	/* raise overflow if ux.f is infinite and x is finite */
  24  	if (e == 0x7f800000)
  25  		FORCE_EVAL(x+x);
  26  	/* raise underflow if ux.f is subnormal or zero */
  27  	if (e == 0)
  28  		FORCE_EVAL(x*x + ux.f*ux.f);
  29  	return ux.f;
  30  }
  31