src/math/nextafterf.c

   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 }