src/math/roundf.c

   1 #include "libm.h"
   2
   3 #if FLT_EVAL_METHOD==0
   4 #define EPS FLT_EPSILON
   5 #elif FLT_EVAL_METHOD==1
   6 #define EPS DBL_EPSILON
   7 #elif FLT_EVAL_METHOD==2
   8 #define EPS LDBL_EPSILON
   9 #endif
  10 static const float_t toint = 1/EPS;
  11
  12 float roundf(float x)
  13 {
  14         union {float f; uint32_t i;} u = {x};
  15         int e = u.i >> 23 & 0xff;
  16         float_t y;
  17
  18         if (e >= 0x7f+23)
  19                 return x;
  20         if (u.i >> 31)
  21                 x = -x;
  22         if (e < 0x7f-1) {
  23                 FORCE_EVAL(x + toint);
  24                 return 0*u.f;
  25         }
  26         y = x + toint - toint - x;
  27         if (y > 0.5f)
  28                 y = y + x - 1;
  29         else if (y <= -0.5f)
  30                 y = y + x + 1;
  31         else
  32                 y = y + x;
  33         if (u.i >> 31)
  34                 y = -y;
  35         return y;
  36 }