src/math/modff.c

   1 #include "libm.h"
   2
   3 float modff(float x, float *iptr)
   4 {
   5         union {float f; uint32_t i;} u = {x};
   6         uint32_t mask;
   7         int e = (int)(u.i>>23 & 0xff) - 0x7f;
   8
   9         /* no fractional part */
  10         if (e >= 23) {
  11                 *iptr = x;
  12                 if (e == 0x80 && u.i<<9 != 0) { /* nan */
  13                         return x;
  14                 }
  15                 u.i &= 0x80000000;
  16                 return u.f;
  17         }
  18         /* no integral part */
  19         if (e < 0) {
  20                 u.i &= 0x80000000;
  21                 *iptr = u.f;
  22                 return x;
  23         }
  24
  25         mask = 0x007fffff>>e;
  26         if ((u.i & mask) == 0) {
  27                 *iptr = x;
  28                 u.i &= 0x80000000;
  29                 return u.f;
  30         }
  31         u.i &= ~mask;
  32         *iptr = u.f;
  33         return x - u.f;
  34 }