rintf.c raw

   1  #include <float.h>
   2  #include <math.h>
   3  #include <stdint.h>
   4  
   5  #if FLT_EVAL_METHOD==0
   6  #define EPS FLT_EPSILON
   7  #elif FLT_EVAL_METHOD==1
   8  #define EPS DBL_EPSILON
   9  #elif FLT_EVAL_METHOD==2
  10  #define EPS LDBL_EPSILON
  11  #endif
  12  static const float_t toint = 1/EPS;
  13  
  14  float rintf(float x)
  15  {
  16  	union {float f; uint32_t i;} u = {x};
  17  	int e = u.i>>23 & 0xff;
  18  	int s = u.i>>31;
  19  	float_t y;
  20  
  21  	if (e >= 0x7f+23)
  22  		return x;
  23  	if (s)
  24  		y = x - toint + toint;
  25  	else
  26  		y = x + toint - toint;
  27  	if (y == 0)
  28  		return s ? -0.0f : 0.0f;
  29  	return y;
  30  }
  31