Round float from cygwin

sourceware.org Git - newlib-cygwin.git/blob - newlib/libm/common/fdlibm.h

and https://stackoverflow.com/questions/4572556/concise-way-to-implement-round-in-c

typedef union
 {
  float value;
  __uint32_t word;
} ieee_float_shape_type;
#define GET_FLOAT_WORD(i,d)      \
 do {                            \
   ieee_float_shape_type gf_u;   \
   gf_u.value = (d);             \
   (i) = gf_u.word;              \
} while (0)    \
#define SET_FLOAT_WORD(d,i)      \
 do {                            \
   ieee_float_shape_type sf_u;   \
   sf_u.word = (i);              \
  (d) = sf_u.value;              \
} while (0)    \
  
float roundfG(float x)
{
 int signbit;
 __uint32_t w;
 /* Most significant word, least significant word. */
 int exponent_less_127;
 GET_FLOAT_WORD(w, x);
 /* Extract sign bit. */
 signbit = w & 0x80000000;
 /* Extract exponent field.*/
 exponent_less_127 = (int)((w & 0x7f800000) >> 23) - 127;
 if (exponent_less_127 < 23)
 {
  if (exponent_less_127 < 0)
  {
   w &= 0x80000000;
   if(exponent_less_127 == -1)
   /* Result is +1.0 or -1.0. */
   w |= ((__uint32_t)127 << 23);
  }
  else
  {
   unsigned int exponent_mask = 0x007fffff >> exponent_less_127;
   if((w & exponent_mask) == 0)
   {
    /* x has an integral value. */
    return x;
   }
   w += 0x00400000 >> exponent_less_127;
   w &= ~exponent_mask;
  }
 }
 else
 {
  if(exponent_less_127 == 128)
  {
   /* x is NaN or infinite.*/
   return x + x;
  }
  else
  {
   return x;
  }
 }
 SET_FLOAT_WORD(x, w);
 return x;
}